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Energetics of fast-starts in northern pike, Esox lucius Frith, Harold Russ 1990

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ENERGETICS OF FAST-STARTS IN NORTHERN PIKE, Esox lucius by HAROLD RUSS FRITH B.Sc, University of Victoria, 1979 M.Sc. University of South Carolina, U.S.A., 1985  A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY  in THE FACULTY OF GRADUATE STUDIES Department of Zoology  We accept this thesis as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA December, 1990 © Harold Russ Frith, 1990  In  presenting  degree freely  this  at the  thesis  in  partial  fulfilment  University  of  British  Columbia,  available for  copying  of  department  this or  publication  of  reference  thesis by  for  his  this  and study. scholarly  or  thesis  for  her  Department  of  Zoology  The University of British C o l u m b i a Vancouver, Canada  Date  DE-6 (2/88)  1 7  A  P  r i l  '  1  9  9  1  the  requirements  I agree  I further  purposes  representatives.  financial gain  permission.  of  that  agree  may  be  It  is  shall not  that  the  Library  an  advanced  shall make it  permission for  granted  by  understood be  for  allowed  the that  without  extensive  head  of  my  copying  or  my  written  ABSTRACT  Fast-starts  are  high  powered  events of  short  duration, used  by fish for prey capture and escape from predation. energetic  cost  fast-start  fast-starts  specialist,  determined This  of  is  and done  in  the  northern  physiological by  escape  and  comparing  and prey pike,  capture  Esox  behavioural costs  Here, the  lucius,  constraints  with  for a  literature  are  assessed.  values  for  physiological limits set my muscle mechanics and biochemistry, and comparing costs with other components of the energy budget. The combination of high speed film analysis (200-250Hz) and hydrodynamic models hydrodynamic capture  are used  efficiencies  (S-starts)  and power  and  post-exercise oxygen  to determine  escape  consumption  output  the of  behaviour (EPOC)  is  mechanical costs, fast-starts  in prey  (C-starts).  Excess  used  to  estimate the  metabolic cost of fast-starts. A  comparison  (acceleration) similar region  force  to  of  model  estimates  previous  findings  including the  predictions  shows at  results  lower  caudal, dorsal  are  film  and anal  with  required  within  22% and  speeds. fins  The caudal contribute  the  most to thrust (>90%) and the dorsal and anal fins contribute 28%. Due to the necessity for deceleration tail beat, kinematics  are not always  of fin sections during each optimal as predicted by the  Weihs model. Mechanical kinematic attack prey  of  power  parameters the  capture  hydrodynamic  (maximum velocities  caudal and  output,  fin)  escape.  are  and  and maximum angle of  determined  for  Hydrodynamic efficiency ii  efficiency  fast-starts during averages  0.37  (range: 0.34  to 0.39)  for C-starts and 0.27  (range: 0.16 to 0.37)  for S-starts.  The acceleration of added mass contributes the most  to power output at 39%. Power output and efficiency are  more  variable  than  C-starts  and  for S-starts  hydromechanical  efficiency  increases with number of tail beats for S-starts. Maximum muscle power  output  and  maximum muscle  stress  during  fast-starts  in  comparison to literature values  for muscle function shows muscle  power  is  output  during  fast-starts  at  its  physiological  limit but  muscle stress is not. Metabolic S-starts  at  efficiency 0.047.  is  higher  However,  at  0.094  muscle  for  efficiency  C-starts than estimates  are  similar averaging 0.252 for both fast-start types. Mean energetic J/kg  for  C-starts  observation before  that  cost of fast-starts and  pike  18.6  J/kg  and on  determined to  for  can repeatedly  becoming exhausted  is  S-starts.  fast-start  up  estimates  of  be 26.5  Based to  on  170  the times  available energy  reserves from literature values for ATP and CrP concentrations in white muscle, the duration of fast-starts  is  concluded to  not be  limited by muscle physiology. Average power output is found to be similar for C and S-starts at 406 to 412 W/kg. Only hydrolysis of ATP and CrP can supply energy at this rate. Therefore, based on fish white muscle biochemistry and mechanics, power output during fast-starts appears to be limited by muscle physiology. The cost of fast-starts represents 0.03 costs for pike and therefore  only  5  to  to 2% of maintenance 30  fast-starts  per day  would be required to increase the daily energy budget by 10%. In addition,  the  surplus  energy  cost  of  available  fast-starts from  represents assimilated iii  0.52 prey.  to  27.4%  of  Therefore,  the  cost  of  duration is  fast-starts  can  be  a probable strategy  significant  and  reducing  for minimising activity  thus increasing the energy available for growth or reproduction.  iv  fast-start costs and  TABLE OF CONTENTS  Abstract Table  i i  of Contents  v  L i s t of Tables  vii  L i s t of F i g u r e s  viii  Aknowledgements  x  Chapter 1: I n t r o d u c t i o n  1  A. E n e r g e t i c Cost B. M o r p h o l o g i c a l  of F a s t - S t a r t s and K i n e m a t i c C o n s t r a i n t s  C. P h y s i o l o g i c a l C o n s t r a i n t s D.  E c o l o g i c a l and B e h a v i o u r a l  E. Chapter O u t l i n e  4 8 9  Constraints  10 12  Chapter 2: Mechanics of the S t a r t l e Response i n the N o r t h e r n p i k e , Esox l u c i u s A.  Introduction  14  B. M a t e r i a l s and Methods  16  C. R e s u l t s  24  D.  52  Discussion  Chapter 3: Hydromechanical E f f i c i e n c y and M e c h a n i c a l Power Output D u r i n g F a s t - s t a r t s by N o r t h e r n p i k e , Esox lucius A.  Introduction  58  B. M a t e r i a l s and Methods  59  C  Results  63  D. D i s c u s s i o n  79  v  Chapter  4: M e t a b o l i c  Cost  of F a s t - s t a r t s i n Norhtern  Pike,  Esox  lucius A. I n t r o d u c t i o n  88  B. M a t e r i a l s and Methods  90  C. R e s u l t s . . . . ...  93  D. D i s c u s s i o n  Chapter 5:.Mechanical Cost lucius  110  o f F a s t - s t a r t s by Northern P i k e ,  Esox  A. I n t r o d u c t i o n  118  B. M a t e r i a l s and Methods  120  C. R e s u l t s  122  D. D i s c u s s i o n . . . .  133  Chapter 6: Summary.....  141  References  145  vi  LIST OF TABLES  T a b l e 1: K i n e m a t i c Table  25  Average f o r c e c o n t r i b u t i o n from i ) l i f t and a c c e l e r a t i o n f o r c e s i i ) c a u d a l and d o r s a l - a n a l fin s e c t i o n s and i i i ) f i s h w i t h and without median f i n s  ..48  T a b l e 3: P r e d i c t e d performance parameters d e r i v e d from t h e Weihs model and r e q u i r e d f o r c e e q u a t i o n  51  Table  2:  c h a r a c t e r i s t i c s of three C-starts  4: Maximum v e l o c i t i e s , caudal f i n .  angles  and f o r c e s  f o r the 69  T a b l e 5: U s e f u l power e s t i m a t e s f o r C and S - s t a r t s Table  6: Power output e s t i m a t e s based on p o s i t i v e o n l y o r t h e a b s o l u t e v a l u e o f power  T a b l e 7: T o t a l power and hydromechanical by stage f o r C and S - s t a r t s Table  Table  70  efficiency  power 72  values .-.  .73  8: R e s t i n g m e t a b o l i c r a t e s o f f i v e p i k e p r i o r t o exercise and in the second hour of recovery.  .95  9: Maximum oxygen consumption six pike during 10, 20 o r 30 recovery  T a b l e 10: Oxygen debt exhaustion  f o r an i n d i v i d u a l  fish  rates for minutes o f 96 exercised to 109  vii  LIST OF FIGURES  Figure  1:  A) Side-view of a N o r t h e r n pike showing l o n g i t u d i n a l body s e c t i o n d i v i s i o n s B) Schematic showing v e l o c i t y v e c t o r s and angles used i n e q u a t i o n 2...  Figure  2: K i n e m a t i c s o f a C - s t a r t  Figure  3: R e l a t i o n s h i p and time.  Figure  Figure  Figure  Figure  4:  Figure Figure Figure  27  between t h e angle o f body  sections 29  R e l a t i o n s h i p between s e c t i o n s and time  lateral  velocity  of body 32  5: R e l a t i o n s h i p between p e r p e n d i c u l a r body s e c t i o n s and t i m e . . . .  velocity  of 34  6: R e l a t i o n s h i p and time  between momentum o f body  7: D i s t r i b u t i o n  o f added mass and body mass  the  sections 37 along  f i s h ' s length  39  8: V e l o c i t y and angle o f a t t a c k o f f i n s e c t i o n s 9:  Acceleration, l i f t d i r e c t i o n o f motion  and  total  forces  41  i n the 43  10: F o r c e c o n t r i b u t i o n from c a u d a l f i n , d o r s a l - a n a l fin section and a l l sections in the d i r e c t i o n o f motion  Figure  11: K i n e m a t i c s o f an S - s t a r t  Figure  12: V e l o c i t y p r o f i l e s for  19  46 .65  o f the f i s h ' s c e n t e r  t h r e e C - s t a r t s and t h r e e  of mass  S-starts  67  Figure  13: Components o f power l o s s f o r C and S - s t a r t s  75  Figure  14: R e l a t i o n s h i p between hydromechanical e f f i c i e n c y and stage number f o r C and S - s t a r t s  78  Figure  15: R e l a t i o n s h i p between hydromechanical e f f i c i e n c y and relative speed for continous, b u r s t - a n d - c o a s t and f a s t - s t a r t swimming  83  Figure  Figure  16:  Histogram of oxygen consumption b e f o r e and a f t e r e x e r c i s e  17: Histogram o f r e c o v e r y starts  with  times a f t e r 0 t o 20  time 98 fast100  viii  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  Figure  18: E f f e c t o f sampling r a t e work e s t i m a t e s  ( f i l m speed) on m e c h a n i c a l 102  19: R e l a t i o n s h i p between oxygen debt and number of f a s t - s t a r t s f o r C and S - s t a r t s 20:  21:  R e l a t i o n s h i p between oxygen debt m e c h a n i c a l work f o r C and S - s t a r t s R e l a t i o n s h i p between oxygen debt m e c h a n i c a l work f o r C and S - s t a r t s  22: L o g - l o g p l o t S-starts  of d i s t a n c e  25:  T o t a l metabolic S-starts. .  useful 107  and  total 115  v e r s u s time f o r C and 124  23: T o t a l m e t a b o l i c c o s t v e r s u s d i s t a n c e S-starts. . 24:  and  105  cost  Muscle power • output S-starts. .  versus  time  f o r C and 127 for C  and 129  versus  time  for C  and 132  26: R e l a t i o n s h i p between r e a c t i o n time o f p r e y and a t t a c k d i s t a n c e of p r e d a t o r  ix  140  AKNOWLEDGEMENTS  I would like to thank my supervisor, Dr Robert Blake for introducing me to biomechanics and for his support and guidance throughout this project. I would also like to thank my research committee; Drs Don McPhail, Dave Randall, Dolph Schluter, Dan Ware and  Roily  particularly for and  Brett  for  indebted to  their  encouragement  fellow  graduate  and  student,  advice.  I  am  Dr Dave Harper,  his assistance in the laboratory and to Dave, Paulo Domenici other  Animal  graduate  Locomotion  students  and  Laboratory  undergraduate  for  many  students  hours  of  in  the  valuable  discussion. This thesis could not have been completed without the support of my family. I would like to thank my parents, Mr and Mrs Harold Frith for their financial and moral support throughout my graduate studies.  Most of  all, I would like to  thank my wife,  Nancy for her love, support and endurance to the very end.  x  CHAPTER 1 INTRODUCTION Fast-starts  are rapid  accelerations  of  fish  from rest  (Weihs,  1973; Webb, 1975a; Harper and Blake, 1990a,fc; Domenici and Blake, in press). This locomotor behaviour is used by most fish species for evasion from predator attack and by some specialized forms in prey capture (e.g. Webb and Skadsen, 1980; Rand and Lauder, 1981; Webb,  1984;  1986;  Harper and Blake, I990a,b). Success in prey  capture and escape depend, in part, on the acceleration rate and velocities  achieved  (Howland,  1974;  Elliot  et  al.,  1977;  Vinyard,  1982; Weihs and Webb, 1984; Harper and Blake, 1988). Maximum acceleration velocities been  rates ranging ranging  reported  performance production  by  acquisition  (see  limits  1973). Despite  and  from  and  are  muscles  from 0.9  to  2.7  assumed  to  and  survivorship,  hydromechanical  work  efficiencies  245  m/s  and  m/s  2  during  Blake, depend  fast-start  and its  on  done,  fast-starts  maximum power (Weihs,  performance on energy impact  published values metabolic  during  have  Fast-start  efficiency  potential  are few  and maximum  1990a).  hydromechanical  the importance of  mechanical  to  Harper  gonad production, there  output,  25  work  fast-starts  on  growth  for power done,  (Webb,  or  1978a;  Vinyard, 1982; Puckett and Dill, 1984). It is commonly assumed that power production by muscles is maximal during fast-starts (Weihs,  1973). Though escape behaviour  of  to  carridean  physiology  shrimp  (Daniel  is  and  reported Meyhofer,  be  1989),  constrained a  similar  by  muscle  analysis  for  fish fast-starts is yet to be conducted. The  intensity  and duration of fast-starts may also be limited 1  by  biochemical  energy  reserves  and  their  rate  of  mobilization  (Hochachka and Somero, 1984). Few studies compare performance and tissue  biochemistry  (Bennett  et  al.,  1984;  Huey  et  al.,  1984).  Bennett et al. (1984) shows that maximum locomotory performance of lizards and  during lactate  escape  accumulation.  locomotion  and  lacking  correlates  its  and  with  is  activity  5  to  essential  enzyme  quantification . of j ..,.the;^ cost  Direct  comparison  anaerobic  available  for  energy  reserves  demonstrating  of is  physiological  constraint of performance based on the above factors. In order for performance to be maximal during maximum power output  of  must  also  required  muscles, be  for  the  efficiency  maximal  of  (Weihs,  mechanical  1973).  energy  The kinematic  maximum; hydrodynamic efficiency  transfer conditions  during a  fast-start  are outlined by Weihs (1973) but are rarely used to evaluate the hypothesis  that  efficiency  is  maximal.  predicts that the posterior placement Northern  pike,  performance. fast-starts  Whilst  lucius, pike  are greater  quantitative known.  Esox  These  issues  of  of  is  the  are  Weihs  model  also  anal and dorsal fins in  advantageous  acceleration  than trout  contribution  The  rates  for achieved  (Harper and Blake, median  fins  important  in  fast-start  to  during  1990a), the  thrust  are  demonstrating  not that  performance is constrained by morphology and kinematics in pike. In the absence of near their physiological  any evidence  that fish perform fast-starts  maximum, observed intensity  and durations  may be behaviourally determined at submaximal levels. This would be  advantageous  significantly energy  large  if so  the as  to  energetic  cost  increase  activity  of costs  fast-starts  is  and reduce  available for growth or gonad production. The significance 2  of  activity  costs  is  apparent  for  continous  swirnming  behaviour  where migratory fish are observed to swim at speeds which minimize the cost of transport (Ware, 1978). Few studies have • evaluated the ecological  significance  of  fast-start  energetics  (e.g.  Puckett  and  Dill, 1984). Another behaviours  is  common  assumption  that the  duration of  cost of locomotion  to contribute  budget or foraging costs of studies on fast-starts Dill,  the is  1984).  performance  to  activity  is  significantly  too  small  However, , in  these  of  is  in  studies prey  similar  short for the daily energy  1986). In the few  (Vinyard,  sub-maximal  and  to the  prey capture  be  predators  fast-starts  animals (Bennett,  energetics of  reported  for  fish,  the  1982;  Puckett and  size  is  compared  cost of  small and to  fast-start  ability of fish (Harper and Blake, 1990&). Harper and Blake (1988) model (i.e.  the  cost  fast-start)  of  activity  and predict  for  pursuit,  that  the  cost  attack of  and prey the  strike  strike is  the  dominant contributor to the total cost of prey capture activity. Here, and  the  escape  energetic  behaviour  cost in  of  the  fast-starts  Northern  during prey  pike,  capture  Esox lucius is  evaluated.  The energy required for fast-starts will be compared to  literature  values  reserves  and  determine constrained. useful  for  rates  whether  daily of  work  for  budget,  mobilisation,  fast-starts  Transfer of  energy  are  mechanical  locomotion  is  constraints on performance discussed.  3  and  muscle  ecologically work  biochemical  done  determined  or by and  energy  mechanics  to  physiologically muscles  into  morphological  Energetic Cost of Fast-Starts: Methodology  The  cost  of  animal  locomotion  has  been  successfully  determined by the combination of high speed film and biomechanical models  or the  1963;  1964;  direct measurement  Pennycuick,  1968;  of  metabolic  rate  (e.g.  Brett,  Webb, 1971a,fc; Wardle and Reid,  1977; Blake, 1979; Taylor et al., 1982; Daniel, 1983; Blickhan and Full,  1987;  Full,  1987;  Full  et  al.,  1990).  A  few  studies of  continous swimming in fish have combined both methods and compared the two estimates of energetic Using  this  models  cost (Webb, \91\a,b; Webb, 1974).  approach, errors in  are  evaluated  assumptions  (Lighthill,  1971).  of  the biomechanical  However,  conversion  of  useful mechanical work done to metabolic cost requires knowledge of  propulsive  potential  and  source  muscle  of  error.  efficiency  Whilst  which  efficiency  provides  values  another  for  continous  swimming are well understood (Webb, 1975&), this is not the case for fast-starts. Sustained,  aerobically  more  fuelled  frequently  activity  than  at  studied  far  activity  (e.g.  Pennycuick,  Webb,  \915b;  Bennett,  1986;  Alexander, 1989). Because  unsteady  1968;  unsteady,  constant  speed  anaerobically  is  fuelled  Norberg,  1976;  motion requires  a more accurate record of kinematics than steady motion and its short  duration  makes  measure directly, few of  fast-starts.  fast-starts ability  advances  biochemistry  measure  metabolism  more  difficult  to  studies have attempted to measure the cost  Recently,  and  to  anaerobic  these  of  in  biomechanical  exercise  costs  in  accurately  analysis  fish  improve  (Harper  and  of our  Blake,  1989a,fc; Scarabello, 1989; Schulte, 1990). Harper  and  Blake  (1989a,fr) 4  demonstrate  the  importance  of  image magnification and film speed to the magnitude of analytical error.  Inaccuracies . in  displacement  measurements  and  their  subsequent influence on cost estimates for unsteady motion can be minimised  by  maximising  image  magnification  and  choosing  the  optimal film speed (see equations in Harper and Blake, 1989a). The optimal  speed  for  filming  pike  fast-starts  was  determined  to be  200 to 250 Hz for a 1:1 magnification. Maximum acceleration rates are still  underestimated  by  30%  at this  speed  and magnification  (Harper and Blake, 1989a). The  simplist  from high speed fish's  center of  acceleration  model film  for  is  determining  the  by measuring the  cost  of  fast-starts  displacement  of the  mass and calculating work from the product of  force  and  displacement.  The  acceleration  force,  also  referred to in this study as the required force, can be written as  F  = (m + m) a  (1)  a where m is the mass of the fish, m is the longitudinal added mass a  and a is the acceleration of the fish's center of mass. The added mass refers to water entrained by the fish in forward motion. Webb (1982a)  experimentally  determined  longitudinal  fast-starts by trout to be 20% of the fish's  added  mass  for  mass. This value is  assumed to be the same for other species. The by  force  propulsive  fish's  body.  theory  for  acceleration  required to forces  Weihs  generated (1973)  application and lift  accelerate  to  forces  in  undulatory  modified fish over  is  also represented  movements  Lighthill's  fast-starts. the  5  a fish  length  large  The of  the  of  the  amplitude  theory fish's  sums body  and resolves the force in the direction of motion. The Weihs model is  more complex  positions  along  accumulation theory  of  than equation  to  comparison  body  which  measurement  errors.  In  flex  of  requiring digitization of many  the \ fish's  assumes fins  observed  1,  act  like rigid  (Bainbridge,  may  result  addition,  large  plates when  1963;  they  McCutcheon,  required and propulsive  forces  in  the  amplitude have been  1970).  provides  a  The useful  check of the propulsive model. If the only purpose was to estimate the  energetic  cost  of  fast-start  activity,  the  simpler  and  less  time consuming required force equation would be prefered. However, the Weihs model is required for determining total mechanical power output  and  hydromechanical  required forces  efficiency.  Weihs  with model predictions  (1973)  and finds  a  compares  12  to 30%  discrepancy. However, film records at 64 Hz were used which is now known to be low and subject to large digitizing errors (Harper and Blake,  1989a,fc).  predictions  for  An accuracy propulsive  test  forces  of  the  and  Weihs  useful  (1973) model  work  done  is  necessary for the higher film rates used here before power output and hydromechanical efficiency estimates can be interpreted. Hydrodynamic  efficiencies  for  fish  fast-starts  have  never  been measured but are expected to be low. Webb (1978a) predicted that  fast-start  McCutcheon  efficiency (1977)  values  determined  of  0.1  to  0.2  hydrodynamic efficiency  are  realistic.  from  flow  visualisation of the zebra danio wake in the push and coast mode and reported values ranging from 0.3 to 0.7. These are lower than hydrodynamic efficiency  for continous swimming fish which average  0.8 to 0.9 (Webb, 1988). Muscle  efficiency  is  approximately 6  20-30%  for  aerobic red  muscle  in  vertebrates  (Goldspink,  1977;  Hill,  1950).  A  recent  study by Altringham and Johnston (1986) shows efficiency of white anaerobic muscle in fish are 50% less than red muscle. However, the  muscle  was  stimulated  to  contract  isometrically  and whether  these findings apply to isotonic contractions is as yet unknown. The  direct  determination  of  metabolic  rate  during  fast-starts  would provide a direct estimate of total cost and allow comparison of  literature values  for  muscle  efficiency  derived value. Muscle efficiency  with  an experimentally  can be expressed  as a ratio of  mechanical work done divided by metabolic cost. Though this ratio is  affected  by  errors in  force equation (equation  the  biomechanical  model,  the required  1) for unsteady motion does not require  knowledge of drag coefficients,  the major source of model error in  continous swimming (Lighthill, 1971). Traditionally, activities  are  estimates  determined  with  this  concentrations  alone  of  (Dobson  the  tissue  cell  sampling  concentrations  metabolic  from  accumulated after exercise problems  of  the  (Bennett,  quantities  The  can  (Dobson  of  anaerobic  end  sufficient  measurement to  product  significantly  of  assess the  and Hochachka, 1987).  time  for  1986). There are a number of  method.  are not  cost  Also,  affect  and Hochachka, 1987;  lactate  energy state handling and  tissue  Schulte,  metabolite 1990). This  may not be so much a problem for fish exercised to exhaustion, but is  more  fast-starts).  apt  to  Finally,  influence the  method  lower is  levels  destructive  of  activity  (i.e.  and  thus requires  a large number of individuals for analysis. The calorimetry  alternative is  is  to  technically  use  a  difficult 7  non-destructive whereas  method. Direct  indirect  calorimetry  is  easily  oxygen  accomplished. consumption  After  anaerobic  above  resting.  exercise, This  animals  excess  increase  post-exercise  consumption (EPOC) was originally refered to as oxygen debt and was  hypothesised  to  represent  lactate. More recent evidence  the  energy  required to  metabolise  shows a fast and a slow phase of  EPOC where the fast phase is thought responsible for ATP, CrP and oxygen  replenishment  and the  slow  phase  for  lactate  metabolism  (Gaesser and Brooks, 1984). A test of the oxygen debt hypothesis in trout after  exhaustive  exercise clearly  shows a slow and fast  recovery phase (Scarabello, 1989). Given our present knowledge of the  role  oxygen  of  oxygen  debt  debt  in  recovery  measurements  non-destructuve  method  for  from  are  anaerobic  potentially  assessment  of  a  partial  exercise, valuable, costs  of  activity.  Morphological and Kinematic Constraints  Maximum  performance  requires  not  production by muscles, but maximum use  only of  maximum  power  that power for the  production of useful force. Weihs (1973) predicts from his model that thrust is maximized when the lateral velocities of the caudal region  are  predictions  high  and the  have  never  characteristics  of  pike  angle  been are  of  attack low. ;  However, these  experimentally . tested. Morphological considered  favorable  for  high  thrust  during fast-starts due to a large surface area caudally and a high percentage of body musculature. Harper and Blake (1990a) reported the over  superior trout,  intraspecific  acceleration  ability  of  northern  pike,  Oncorynchus mykiss, during fast-starts. comparisons  of  unsteady  8  swimming  Esox lucius, In  addition,  performance  for  coho salmon, Oncorynchus kisutch (Taylor and McPhail, the  three  spined  stickleback,  1985) and  Gasterosteus aculeatus (Taylor and  McPhail, 1986), show that fish populations with greater body depth and caudal fin depth are capable of greater maximum and average velocities. caudal  Webb  surface  reduced  in  (1977) area  trout  provides  influences  after  the  only  fast-start  amputation  of  direct  ability. caudal  evidence  that  Performance  was  fin  lobes  but not  after removal of centrally placed median fins. Though the caudally placed  anal  fast-start  and  dorsal  performance,  fins  the  of  pike  are  contribution  of  assumed these  to  fins  increase td  thrust  has never been determined.  Physiological Constraints  Fast-starts  are  frequently  assumed  to  limited by their power requirements (e.g. power  output  duration limit  that  average  of  muscles  may  limit  a particular power velocities.  physiologically  Weihs, 1973). Maximum acceleration  output  Muscle power  be  rates  or  the  can  be  maintained may  output  is  limited by the  rate of energy supply from ATP hydrolysis, replenishment of CrP and ATP pools by anaerobic glycolysis and the intrinsic maximum power of muscle (Bennett, 1980; Hochachka and Somero, 1984). The latter  varies  particular  depending  power  output  on  load  depends  (Hill, on  1964).  the  size  Duration of  of  energy  a  pools  (Bennett, 1986). An  alternative  viewpoint  expressed  in  the  literature  is  that  locomotory performance is limited by maximum stress of muscles and not maximum power output. Early  studies of maximum swimming  performance in fish and mammals assume performance is limited by 9  maximum muscle power (Gray, 1936). Though theory and observation did  not  match,  differences  appropriate drag coefficients  were  later  resolved  by  using more  and values for maximum power (Blake,  1983). Blake (1983) also shows burst swimming speeds are within limits set by maximum power of muscles. Daniel and Webb (1987) predict  maximum speed  muscle  stress  prediction  is  (Webb,  optimal  size  shrimp  based  limiting. 1976).  and tail on  should decrease  the  Observations Daniel  and  with  fish  do  not  Meyhofer  size assuming support (1989)  this  predict  morphology for escape ability in carridean assumption  that  muscle  stress  is  limiting.  However, mechanics of isolated muscle preparations shows power and stress are interdependant where maximum power output occurs at 0.3 maximum stress (Pennycuick and Rezende, 1984). As maximum power is load dependant, both muscle power and force are required to assess performance limitations of, muscle. The rate of CrP and ATP hydrolysis is 1.5 to 6 times faster than  their  (Hochachka,  rate 1985).  of  replenishment  The  duration  that  from  anaerobic  maximum power  glycolysis can be  maintained is therefore limited by CrP and ATP reserves. A lower power output can be supported for a longer time period and is limited  by  glycogen  reserves.  Alternatively,  intermittent maximum  power output is possible for longer periods if rest periods allow time for replenishment of CrP and ATP pools. Muscle performance will therefore be limited by CrP and ATP pool sizes if the power required for  fast-starts  is  greater  anaerobic glycolysis.  10  than the  power  supplied from  Ecological and Behavioural Constraints  Foraging models assume surplus power or net energy gain (NEG) per unit time are maximised and yet the cost of locomotion is often  ignored  (Ware,  1978;  1982).  Movement  is  energetically  expensive and organisms must trade-off the cost of locomotion with encounter rate of prey (Ware, 1978). The energetic attack may also  be  significant.  cost of prey  Harper and Blake (1988) predict  attack by predatory fish at maximum speed is more expensive than searching or pursuit. The  significance  of  the  cost of  attack is  determined when  expressed as a percentage of daily maintenance costs. Puckett and Dill  (1984)  showed  that  juvenile  territorial  salmon  expend only  0.09% of daily maintenance for each prey attack. 112 attacks per day would be required to increase daily maintenance costs by 10%. However,  these fish  (Puckett,  1983)  involving  acceleration  affect  are reported to  which for  illustrates short  charge that  periods  192  the of  times  cost  time  can  of  in  16h attack  significantly  the daily energy budget. Given that maintenance metabolism  and activity costs consume approximately 50% of assimilated energy in non-migratory fish, a 10% increase in these costs could reduce growth or reproductive output by 20 to 30% (Kitchell, 1983). More analyses  of this type are clearly needed to assess the ecological  costs of high powered, short term activities. Costs of prey capture can also be expressed as a percentage of the energy content of a prey. A common argument is that the energy  content  of  prey  is  so  much greater  capture, the latter can be ignored (Bennett, the cost of capture is expressed 11  than  the  cost of  1986). However, when  as a percentage  of the energy  available content  for of  growth prey,  Assimilation  or  the  efficiency  1  reproduction  rather  cost  is  more  for  largemouth  than  apt  to  the be  bass,  energy  important.  a  carnivorous  sedentary fish, is approximately 70% and maintenance costs consume 25  to 96% of the remainder depending on ration size (Kitchell,  1983). This leaves 3 to 50% of the energy content of prey for growth,  reproduction and activity.  Therefore,  on  low  rations, an  activity cost of only 3% would consume all available energy for growth or reproduction. This implies that activity costs consuming a small precentage  of the energy content of prey should not be  ignored. The cost of  an activity can constrain behaviour  in other  ways. Fish exercised to exhaustion require 24 to greater than 96 hours to remove lactate from white muscle and replenish glycogen reserves (Schwalme and Mackay, 1985; Dobson and Hochachka, 1987). During  the  recovery  possibly  increasing  a  period, fish's  anaerobic  activity  vulnerability  to  is  restricted,  predation  or ability  to capture prey. This may explain the restricted use of anaerobic activity  for  Duration  life  or  and intensity  death of  situations  or  for  fast-starts may be  limited  durations.  behaviourally limited  to maintain maximum scope for activity.  Thesis Outline  In  . ;  chapter  2,  the  Weihs  model  is  used  to  predict  the  propulsive forces generated and the mechanical work done during an escape fast-start. estimation of  of  predictions  The predictive power of the model is tested for  performance with  those  and energetic derived 12  parameters  by comparison  from required forces.  Optimal  morphology  and  kinematic  predictions  of  the  Weihs  model  are  evaluated for pike. In chapter 3, escape  and  the Weihs model is  prey  capture  hydrodynamic efficiency are  compared  preparations  total  mechanical  power  and  determined. Power output and muscle stress  with  to  and  applied to fast-starts in  literature  determine  values  whether  for  isolated  fast-start  muscle  performance  is  constrained by muscle physiology. Metabolic cost of comparing  fast-starts is  excess oxygen  mechanical  cost  derived  relationship  provides  an  determined in chapter 4 by  consumption  after  from  tapes.  The  muscle  efficiency.  video  estimate  of  fast-start  slope  cost estimates are compared with literature values reserves energy  for  pike  supply  to  and other white  fish  muscle  to  of  this  Metabolic  for biochemical  determine  and energy  activity with  if  pool  the  rate of  sizes constrain  behaviour. The required force equation is applied to a larger number of replicates  in  hydrodynamic  chapter and  5  muscle  than  in  efficiency  previous values  chapters previously  and  the  determined  incorporated to estimate metabolic cost. The purpose is to see how the  cost  of  fast-starts  varies  in  prey  capture  and  escape and  whether any evidence for behavioural adjustment of power output or duration exists.  In  addition, the  cost of  fast-starts  are compared  with maintanance costs and the energy content of prey. Literature values  for  evaluated  in  prey  capture  energetic  success,  terms  and  and the  feeding ecological  frequency  are  significance  of  the cost of prey capture discussed. In chapter 6, the results and conclusions are summarised. 13  CHAPTER 2  MECHANICS O F T H E STARTLE RESPONSE IN T H E N O R T H E R N P I K E , Esox lucius  INTRODUCTION  Lighthill's (1971) large amplitude theory and its use by Weihs (1973) for  for  fish  determining  during  fast-starts the  a fast-start.  fast-start  energetics,  together  propulsive Before the  provide  forces  theoretical  and mechanical  these models accuracy  a  of  basis  work  done  can be used to estimate model  predictions  for  the  quantification  of  experimental system used here must be evaluated.. In angles  order and  to  calculate  velocities  of  propulsive  all  body  forces,  sections  is  required (Weihs,  1973). In this way, the contribution of each body section to thrust can  be  evaluated  quantified.  and the  Though  hydrodynamic  section,  angle  relative  contribution of  determined  by  of  contribution of  attack  theory  median predicts  and lateral velocity each  body  incorporation of  section  observed  fins that  determine  to  to thrust depth  of  thrust, the  thrust can only be  kinematic  parameters from  high speed film records into the model. The forces  to  attack  of  Weihs model sums the contribution of lift and acceleration thrust.  High  propulsive  acceleration sections  rates  favors  and  large  a  lift  forces and is optimal for maximum thrust (Weihs, when  sections  decelerate  forces  are negative or zero  or  velocity  is  and thrust is 14  large and  angle  of  acceleration  1973). However  constant,  acceleration  sub optimal. Similarly,  when  angle  low.  Due  of to  11  attack the  of  propulsive  motion  of  swimming, variation in velocity sections  is  a  natural  the  sections  is  caudal  fin  and angle  consequence  and  of  small,  thrust  during  is  fast-start  attack of propulsive  optimal  conditions  for  maximum thrust can not always be maintained. A previous description of  how  lift  and acceleration  forces  interact  is  reported for fish  turning (Weihs, 1972) but not for fast-starts. Three issues are addressed here. (1) The accuracy of the Weihs (1973)  model  magnification Blake,  for  for  1989a,£)  displacement,  fastrstarts  which in  optimal  analytical error  predicting  average  (at  velocity,  eight  is  film  and  minimized, Harper and  performance  maximum  speeds  velocity,  parameters; final  total  velocity,  average acceleration, maximum acceleration, maximum force and total work done. total  thrust.  (2) The contribution of acceleration and lift forces to (3)  The  relative  contribution  anal fins to total thrust.  15  of  caudal,  dorsal and  MATERIALS AND METHODS Fish Thirty Northern pike, Esox lucius, (35-45 cms, 300-500g) were seined from Babtiste Lake in the Athabasca drainage system 200 km north of Edmonton, Alberta, Canada. Fish were flown to Vancouver, B.C. within 6 hours of collection and placed in 10001 holding tanks at the  University  dechlorinated  of  British Columbia.  tap water  at 5  month acclimation period was  Tanks were supplied with  1/min and constant allowed before  aeration.  A one  experimentation  began.  Fish were fed every two to three days. Temperature was maintained at 10 to 14°C.  Experimental Procedure •'• Fish  were  brought  into  the  laboratory  24  hours  before  experimentation and placed in an experimental arena, a 122 x 245 x 47cm tank. A mirror angled at 45° ran the length of the tank and provided an overhead view of the entire tank for filming. A two centimeter grid was placed on the bottom of the tank for a film scale reference. The arena was provided with the same dechlorinated tap water  as the  temperature  was  holding facilities  maintained  to  at  within  a rate 1-2°C of  of  1-2  the  1/min and  holding tank  (10-14°C). The experimental arena was illuminated with 2 Berkey 800 Watt beams which were switched on directly before filming. A 16mm high speed cine camera (LOCAM model 51-0002) was used with Kodak 7250 film  at 250  introduction of  Hz. A  C-type fast-start  a meter  was  induced by  stick vertically into the 16  the rapid  water and within  20cm of the fish's head. The fish responded by swimming away from the  stick.  The camera was  switched  on  1-2  seconds  before the  fast-start was induced so that it was up to speed when the event was  filmed. The camera was  approximately 1/3  to  1/2  positioned  such  that  the  the diagonal of the total film  minimize digitizing error (Harper and Blake, 198%)  fish  was  frame to  and include the  entire fish within each frame throughout the fast-start. Fish were allowed to rest for 30 minutes to one hour after 3 to  5  successive  fast-starts.  The  time  interval  between  fast-starts  was only 2-3 seconds but fish showed no signs of fatigue. No more than three experimental trials were conducted within a day. After 30 to 50 fast-starts were induced, the fish was anesthetized with a 5% solution of MS222, total length measured and weight taken on a beam balance to the nearest 0.1 gram. This procedure was repeated for five fish.  Film Analysis  Film sequences were viewed on an image analyzer (Photographic Analysis directly  Limited to  fast-starts  a  Projection  computer.  showing  Analysis  Three  minimal  Unit,  sequences  interference  ZAE 76) from  from  disturbance of the water surface were chosen  tank  a  total walls  connected of  76  and no  for further analysis.  The fish image on the analyzer was divided into nine sections (Fig. la). anal  The caudal fin, the portion of the body with the dorsal and fins  section  and the  head region each  division occurred at  the  formed a section.  center  of  mass.  Also, a  Other divisions  were chosen to form sections of similar length (0.11 ± 0.04L [X ± "  17  Figure 1: A) Side view of a .Northern pike, Esox lucius showing the positions of the body sections 1-9. The star indicates the center of :  mass  location  along  the  length  of  the  fish's  body.  B) Diagram  showing the velocity vectors and angles for a propulsive section and the velocity vector, Vcm, for the for the fish's tangent  to the X-axis;  V  is  center of mass,  the velocity vector for a propulsive  section where w is the component perpendicular to the backbone of that  section  and u  is  the  tangent  component.  In  the magnified  portion of the diagram, dl is the length of the propulsive section. The  velocity vector V  can also be described by vector components  dy/dt and dx/dt. The iangle, 6, is that angle subtended by the vector V  and u, and the angle, a, that angle subtended by the tangent to  the propulsive section and the X-axis.  18  19  ls.d.]).  The  coordinates the  determined)  end  involve stage  mid-point  of three  (stage  the  of' each  division  was  for  frame  during  second  stages, 2)  a  and  each tail  flip  (stage  preparatory stage a  variable  digitized a  2).  (stage  third  (i.e.  fast-start  C-type 1),  stage.  x,y until  fast-starts  a propulsive  Performance  of  fast-starts from film are commonly determined to the end of stage 2 (Weihs, 1973; Webb, 1975a; 1977; 1978ft). The  coordinates were  stored on computer disc for subsequent  analysis.  Calculations  The Weihs (1973) model assumes that thrust in the direction of motion (F ) is generated by the acceleration of added mass (volume of  water  influenced  by  a  propulsive  section)  and  lift  forces  generated by median fins (caudal, dorsal and anal).  F  = d/dt ^ row (dy/dl) dl  M  where m  a  angle  (2)  Le  is added mass, w is the velocity vector for a propulsive  section perpendicular to the fish's the  + ^ 1/2 p S. V* C .e.  between  the  backbone, dy/dl is  propulsive section  and the  the  sine of  fish's direction  of motion (Fig. lb), dl is the length of the propulsive section and L  is  total fish  water density (* area, V. is its lift  coefficient  length. In the lgm/cm  3  for fresh water), S. is  absolute velocity, with  angle  second term on the r.h.s.,  of  C Q. is attack,  sectional surface  the rate of  L  0.,  and  p is  k  is  change of the  total  i  number of fins. 9. describes the angle between the fin section (i) 20  and its  velocity  vector,  V. (Fig.  lb).  All velocities  are relative  to the background grid. Lighthill (1975) defines added mass as  m  =  1/4  S TU 2  p  (3)  where s is the depth of a propulsive section and {3 is a shape factor  (*  1 for  all cross-sectional  shapes  of  pike; see  Lighthill,  1970). The Lighthill line.  perpendicular (1971)  for  a  The direction of  velocity  vector,  continuously fish's  w,  was  calculated  swimming fish  motion defines  the  in x-axis  by  a straight and the  water far from the fish is at rest, dy dx _ dx dy dl al dl al  ( 4 ) w  where dy/dt and dx/dt are velocity vectors for a propulsive section normal and tangential to the fish's  direction of motion and dy/dl  and dx/dl are the sine and cosine  of that sections angle relative  to the direction of motion (Fig. lb). The rate of  change of  lift  coefficient  relative to the angle  of attack, C Q, for steady motion is given by L  C  -  S,8 ~  rc..  1 + 0.5 AR  AR  (5) w  (Robinson and Laurmann, 1956) where AR is the aspect ratio of a fin (AR=span/fin 2  area).  The aspect  ratios 21  for  pike  median fins are  1.53,  1.27 and 1.83 for anal, dorsal and caudal fins respectively.  The  motion  of  fins  during  a fast-start  is  highly  unsteady. The  reduced frequency parameter (a = col/U where col is  the angular  velocity  provides a  of  the  fin  and U  is  the  fish's  velocity)  relative measure of the contribution of unsteady forces. An average value  of  0.4  for  was  o  calculated  for  pike  fast-starts  which  indicates C Q is 70% of the steady motion value from equation 5 L  (see figure lb in Daniel and Webb, 1987). C Q for anal, dorsal and L  caudal  fins  derived  from  equation  5  and  after  correction  for  unsteady motion are 1.77, 1.59 and 1.95 respectively. Estimates  of  displacement,  calculated from  the  model  The  calculated  latter  are  velocity  (equation from  2)  F • =  and  acceleration  are  and required forces  (F).  ma  R  acceleration of  the  fish's  center  of  ,  where  a  is  the  v  mass and m  is  the virtual  mass of the fish (body mass + longitudinal added mass). Estimates of  acceleration, predicted from the model and required forces, are  calculated as  a = F/m  where  F = F  v  or F .  R  Velocities and  M  displacements are derived from acceleration estimates, where  v. = v. + [(a. j+a.)^] At  (6)  d. = d.  (7)  4  and  mi  Model  estimates  forces  rather  +  are  than  |  [(v. +v.)/2] At  compared with  with  observed  those  derived  displacements 22  or  from required velocities  to  ensure both estimates are subject to the same smoothing errors. The minimum smoothing necessary required a sequence of 2 point followed by 3 point averaging for each of the two differentiations involved. Smoothing results both  model  in underestimation  estimates  and estimates  of  performance parameters for  derived from  required forces.  Webb (1982ft) provides the only estimate of longitudinal added mass (m^ for a fast-starting fish. Based on experiments  with trout, m  }  = 20% of the total fish mass. Total work done (W) is calculated from required forces or model estimates of propulsive forces where n W=XF.d., n is number of frames to the end of stage 2, d is the jj j displacement of the fish's center of mass and F is the force (F R  23  RESULTS Kinematics  The  kinematic  analyzed similar,  for  a  characteristics  single  and only  fish  one  (0.41m  is  body follows  (1973)  C-start.  position, stage,  a  the  trout  fish  stage  bends  1; Table 1).  in  length, detail  from  a C-shape  the  opposite  A change  direction.  The  fast-starts  0.398  (C-start  a  kg) #1).  stretched  within  are The  direction  of  straight  0.06s (preparatory  in orientation  this stage. A propulsive stage (stage 2) follows, in  three  the pattern described by Weihs  Starting  into  the  total  described  bending of the fish's for  of  occurs during  forming a C-shape motion  is  constant  throughout the propulsive stage with little lateral movement  of the  head region (Fig. 2). The duration of stage 2 is the same as stage 1 for C-start #1 (0.06s, Table 1). According to Weihs (1973), large dy/dl=sin a (where a = the angle  of  a body  fish's  center  (proportion fish's  of  of  section mass  total  relative  to  the lb)  [CM]; Fig.  thrust  in  the  velocity favors  direction  vector thrust  of  motion  of  the  efficiency of  the  is initially 90° (dyldl^l', Fig.  center of mass). The angle a  3) for all sections. This is due to the lateral displacement of the center of mass during C-formation in stage 1 (Fig. 2). By the end of stage 1/ a is again close to 90° (i.e. dy/dl = -1) for sections 1-4  (Fig.  3a,b).  During  maintained (dy/dl = 0.8 (1-4).  The  more  stage to  posterior  2,  1.0; a the  a  large  = 75-90°)  section  angle  of  attack  is  at posterior sections  position  relative  to  the  center of mass, the closer a is to 90° and the longer large angles are  maintained  (Fig.  3a,b).  A  high 24  a  directs  thrust  from  the  TABLE 1: Kinematic  c h a r a c t e r i s t i c s of three C - s t a r t s .  C-START #1  TURNING ANGLE degrees (radians) a  DURATION 0 F STAGE 1 STAGE 2  The  angle  (0.50)  65  115  (1.14)  between  0.068 0.064  0.060 0.060  the i n i t i a l  over t h e d u r a t i o n o f a " f a s t - s t a r t  b  C-START #3  (2.01)  b  (  a  29  C-START #2  and f i n a l  0.064 0.072  o r i e n t a t i o n of the  fish  t e r m i n a t i n g a t t h e end o f stage  t i m e zero i s t h e b e g i n i n g o f t h e C bend from a s t r e t c h e d - s t r a i g h t  position.  25  2.  Figure 2: Kinematics of Esox  lucius  where each line represents a  tracing of the fish's backbone at 0.012s intervals. The numbers mark the  head and tail  of  subsequent  tracings.  The filled  circles mark  the center of mass on the fish's backbone and the arrows are at the head.  26  Figure 3: The relationship between the angle of each section =  sin(oc)) and time. The arrows indicate end of  respectively.  A)  Sections  1,2,3.  B)  Sections  7,8,9. Error bar in A) shows measurement error range.  28  stage  4,5,6.  C)  (dy/dl  1 and 2 Sections  — SECT 1 (0.00-0.14L) SECT 2 (0.H-0.23L) - SECT 3 (0.23-0.321)  —  c75  1 <-»'"*  0.5 0.0  \.\ y.\ ^ V • **  -1.0 0.00  SECT 4 (0.32-0.42L) SECT 5 (0.42-0.511} SECT 6 C0.51-0.60L;  0.06 1 S1  — SECT 7 (0.60 • • • SECT 6 (0.71 SECT 9 (0.80  0.12 TIME  29  T S2  0.18  acceleration of added mass in the direction of motion favoring high propulsive  efficiency  and maximizing  thrust  (Weihs,  1973). Sections  anterior to the center of mass (7, 8 and 9) show large angles only during C-formation in stage 1 and smaller angles in stage 2. The  lateral  sections (7-9) lateral  (dy/dt;  velocities  Fig.  4)  of  the  anterior  are maximal during bending in stage 1. The greatest  velocities  occur  in  the  caudal  sections  (1-3)  during  the  propulsive stage (peak values of 3.0 to 4.0 m/s; Fig. 4). Sections closer  to  the  center of  mass have  smaller  lateral  velocities and  shorter durations of maximum velocities (Fig. 4). For (Fig. for  the  posterior  5)  are lower  more  central  4,5).  sections  (1-3)  perpendicular  section  sections  is  these  conditions,  (perpendicular  to  w  than lateral velocities dy/dt (Fig. 4), whereas w  (4-6)  and  dy/dt are  This occurs when dxldl is close to 1 (i.e.  body  velocities  perpendicular  to  w  same  has  the  the  its  direction of  direction direction  motion  of  similar  (Figs.  dy/dl=0) and the of  motion. Under  of  motion  as dy/dt  the  fish's  center of  mass) and therefore  makes no contribution to thrust in the useful  direction.  central  for  Therefore,  useful  thrust  sections do  despite  high  not  have favorable  perpendicular  angles  velocities  (w).  According to Weihs (1973), dy/dt and dy/dl must both be large for thrust which  to  be  is  the  perpendicular (dy/dt) when sections  (1-3)  than more  in  the  direction  case  for  velocities  (w)  section still  central  motion  posterior are  angles have  of  higher  ones (4-6).  sections  low  (a)  In  (i.e.  relative  are  large.  maximum addition, 30  useful (Figs.  to  direction), 3,4).  lateral  Even  But,  velocities  so,  posterior  perpendicular  velocities  maximum perpendicular  Figure with  4: time.  respectively.  The The A)  change  in  lateral  arrows  indicate  Sections  1,2,3.  velocity, the B)  dy/dt,  of  each  of  stage  1  end Sections  7,8,9. Error bar in A) shows measurement error range.  31  4,5,6.  C)  section and  2  Sections  32> 4.0n  2.00.0SECT 1 (0.00-0.14Q SECT2(0.14-0.23L) SECT 3(0^3-0.321)  -2.0-4.0-  \ 4.0-j E m 2.00.0o  §  — SECT 4 (0.32-0.42L) • • • SECTS (0.42-0.51 L) - • SECT 6 (0.51 -0.60L)  -2.0-4.04.0-1  2.00.0-  • * «s  N — SECT 7 (0.60-0.71 L) • • • SECT 8 C0.71-0.80L' - SECT 8 (0.60-1.00L,  -2.0-4.00.00  0.06  |  0.12  TIME  S1  J S2  32  0.18  Figure  5: The change in the velocity,  w  (vector perpendicular to  each section) with time for sections A) 1,2 and 3 B) 4,5 and 6 and C) 7,8 and 9. Error bar in A) shows measurement error.  33  3.0J  34  velocities and  (w)  occur during the  posterior  peak  (1-3)  velocities  duration  of  sections,  during  propulsive  whereas  turning  maximum  anterior  (stage  velocities  stage for  1;  (4-6)  (7-9)  show  sections  Fig.  increases  central  5).  Again,  the  from  the  posteriorly  center of mass. The  contribution of  fish  body  added mass (momentum=mw[dy/d/]„7 ) motion  is  dominated  by  the  momentum of  in the opposite direction to the  >  fish's  sections to  the  posterior  four  sections during  the propulsive stage (1-4; Fig. 6). The combination of large added mass  (Fig. 7)  and high  w and  a  results  in  posterior  sections  contributing the most to momentum. For the caudal peduncle, w and a are  high.  However,  m  is  a  low  and  this  results  in  a  small  contribution to the total momentum of this area. Sections 1 and 3 where the fins are located contribute most to the total momentum. The  caudal  fin  has  characteristics  more  favorable  than section 3 containing the dorsal and anal fins. 1,  lift  Velocity maintained  varies (V)  directly  and angle  longer  than  with (0) the  fin for  the  dorsal  surface area of the caudal fin (3.52 the  combined  10"m). 3  2  surface  area of '  the  velocity  and  and  caudal  fin  anal  fins  for  lift  From equation surface are  area.  larger and  (Fig.  8).  The  x 10"m) is also larger than 3  2  dorsal and anal fins  (2.72  x  t]  Forces  Figure 9 shows two positive  thrust peaks,  a minor peak in  stage 1 followed by a major peak ( maximum of 59.7 N) early in stage 2, and a cycle from positive to negative forces within stage 35  Figure 6: The change of momentum in the direction of motion (in Newton, seconds) with time for sections A) 1,2 and 3 B) sections 4,5 and 6 and  C) 7, 8 and 9. Error bar in A) shows measurement error  range.  36  SECT 1 (0.00-0.14L) SECT 2 (0.14—0.23L) SECT 3 (0.23-0.32L)  -0.50  J  CO 0.50-1  B  SECT 4 (0.32-0.42L) SECT 5 (0.42-0.51 L) SECT6(0.51-0.60L)  cn 0.25 0.00 :-0.25 0.50 •» 0.50-1  C  SECT 7 (0.60-0.71 L) SECT8 (0.71-0.B0L) SECT 9 (0.60-1.00L)  0.250.00 -0.25 •0.50 0.00  t  0.06  S1  0.12  TIME (s) J  S2  37  0.18  Figure 7: The distribution of added mass and body mass along length of the fish where distance is from the tail tip.  38  39  Figure 8: The change in total velocity, V, and angle of attack, 0, with time for A) caudal fin solid  line  represents  the  and B) dorsal-anal fin  velocity,  V,  angle of attack, 0.  40  and  the  section. The  dashed  line,  the  A) CAUDAL FIN  B) DORSAL-ANAL FINS  J TIME (s) S1  J S2  41  Figure thrust  9:  Contribution  of  in the direction of  acceleration motion.  and  lift  Arrows indicate  forces  to  total  beginning of  stage 1 (0), end of stage 1 (I) and end of stage 2 (II). A) C-start #1 B) C-start #2 C) C-start #3. Error bar in A) shows measurement error range.  42  43  2.  The  result  equally total  large thrust  is  a  large  deceleration patterns  positive during  are  found  acceleration  the for  followed  by an  phase.  Similar  fast-starts  though  propulsive all  three  the major positive thrust peak is bimodal rather than unimodal in the other two fast-starts.  A single stage 2 peak occurs when peak  thrust from sections 1 plus 3 are in phase and two peaks result when they are out of phase; section  1 forms the second peak in  stage 2 and section 3 the first peak (Fig. 10). Average 1,  whereas  2).  During  forces  the  average the  are  However,  acceleration lift  forces forces  propulsive  small  relative  acceleration  contribution of  forces  dominate  during  are greater during  stage  (stage  2)  lift  forces  in  to  cycle  acceleration  turning in stage  from  forces  average all  positive to  stage 2 (Table acceleration  three to  positive  fast-starts.  negative, thrust  in  and the  first half of stage 2 is similar to that of lift forces (60 ± 15% for  lift  and 43  ±  18% for acceleration  forces;  Table  2).  Also,  maximum acceleration forces are either the same as or greater than maximum lift forces (Fig. 9). Peak lift force lags behind peak acceleration forces Positive  lift  forces  overlap  with  negative  acceleration  (Fig. 9).  forces  and  reduce the magnitude of negative total thrust in the second half of stage 2 (Fig. 9). Lift forces constitute 48 to 77% of total thrust i •  during the positive portion of stage 2 (Table 2). The for section  thrust-time  sequence  1 and for section  for  total  thrust is  1 plus 3 (Fig. 10).  similar to that The average  total thrust for stage 2 is generally less than that for section 1 or sections 1 plus 3 (Table 2). Section 1 contributes 81 to 93 % to 44  Figure 10: Contribution of the caudal fin (sect. 1) and the combined caudal force  fin  and dorsal-anal  fins  (sect.  (all sections). Arrows indicate  1 and 3)  beginning  of  to stage  total  thrust  1(0), end  of stage 1 (I) and end of stage 2 (II). A) C-start #1 B) C-start #2 C) C-start #3. Error bar in A) shows measurement error range.  45  S1 60-  1  S2  30< 0  -30  - - SECT 1 • • • SECT 1 & 3 TOTAL FORCE  -60 J  0.00  0.06  0.12  TIME (s)  46  0.18  TABLE forces,  2:  Average  from section  force  contributions  1 and sections  from lift  1 plus  sections with (total) and without dorsal and anal fins.  47  3  and acceleration  and from all body  LIFT  ACCELERATION  SECT 1  SECT 1&3  TOTAL-FINS  -5.66 (-141)  1.52 (38)  -1.67 (-42)  4.00  3  TOTAL  C-START #1 STAGE 1  -2.14 (-54)  STAGE 2  6.14 ; :  <  1  5  4  >  18.83 (160)  -7.03 (-60)  11.68 (99)  14.27 (121)  7.63 (65)  11.79  9.32 , (23)  29.29 (73)  43.00 (107)  29.23 (72)  40.32  -17.94 (248)  -4.15 (57)  -6.73 (93)  -6.77 (93)  -7.22  +STAGE 2  b  31.00 (77)  -STAGE 2  b  10.71 (-150)  C-START #2 STAGE 1  1.49 (17)  7.41 (83)  3.28 (37)  4.29 (48)  1.78 (20)  8.90  STAGE 2  10.69 (c)  -11.05 (c)  3.79 (d)  4.68 (d)  -5.38  -0.36  +STAGE 2  15.12 (48)  18.47 (59)  23.88 (76)  36.86 (118)  19.15 (61)  31.33  -STAGE 2  -2.42 (7)  -30.70 (85)  -27.76 (77)  -31.67 (88)  -29.75 (83)  -35.97  -2.68 (-42)  2.10 (33)  2.90 (46)  6.35  17 .24(139)  10.31 (83)  12.44  C-START #3 STAGE 1  -1.15 (-18)  STAGE 2  19.66 (158)  -7.22 (-58)  16.03 (129)  +STAGE 2  23.69 (54)  20.10 (46)  36.46 (83)  ,46.59 (106)  36.31 (83)  43.79  -37.64 (121)  24.37 (78)  -28.17 (91)  -30.97 (99.5)  -31.12  -STAGE 2  6.52 (-21)  :  7.50 (118)  48  NOTE: Average force in Newtons "Calculated  using  the  original  (% of total). kinematic  pattern  of  an  intact  fish  but with estimates for anal and dorsal fins removed. Average forces for the positive  b  (+ stage 2)  and negative phases (-  stage 2) of the total thrust curve in stage 2. °Total  force  is  very  small  as  lift  and  acceleration  forces  cancel.  Percentage of total would not be very informative in this case. d  Again,  the  total  force  is  too  small  to  justify  expressing  thrust  from sections 1 and 3 as a precentage of total thrust. The average !  contribution of forces from sections 1 and 3 are 3 to 4 Newtons higher than Total average forces which is C-starts.  49  similar to the other two  the  average  thrust  from  sections  1 plus  3.  Thrust  positive to negative in stages 1 and 2. Sections  cycles from  1 and 3 explain  110 % of positive total thrust and section 1 explains 77 % . During the negative total thrust, sections 1 and 3 explain 91  % of the  average  during the  and  dominant  thrust  contributes of  section  1  phase  explains in  approximately  70  stage  71  % .  2,  the  % of  the  Therefore, caudal  positive  fin  (section  1)  thrust contribution  the caudal fin (section 1) and the section containing the dorsal  and anal fin (section 3). The anal and dorsal fins (TOTAL - [TOTAL - FINS]) contribute on average 16 and 26% to total thrust during stages 1 and 2 and 28% to positive total thrust during stage 2 (Table 2). Model are  estimates  compared  with  for those  performance derived  parameters  from  (predicted values)  required forces  (expected  values). All parameters were determined to the end of stage 2. Six of  eight performance parameters  were predicted within 4  to 22%  (Table 3). The two exceptions were useful work (9-31%) and final velocities (5-75%).  50  TABLE 3: P r e d i c t e d performance parameters (equation  (A) d e r i v e d  1) a r e compared w i t h e x p e c t e d performance  from t h e model parameters  (B)  d e r i v e d from r e q u i r e d f o r c e s f o r t h r e e C - s t a r t s .  C-START #1 A  .152  B  .127  , . ,A (m/s) VELOCITY B  1.23  , . ,A (m/s) B  2.40  . . ,A (m/s) B  1.93  TOTAL  , (m) %  DISTANCE AVERAGE  MAXIMUM VELOCITY FINAL VELOCITY  ,.2, A (m/s ) B ACCELERATION  AVERAGE  (17)  (17)  (5)  (7) - •  (8)  16.83  FORCE WORK DONE  (Joules)  A  69.7  B  59.7  A  6.31  B  4.37  (15)  1.90  1.60  (75)  (14)  133.14  (17)  (19)  6.49 5.34  (15)  3.19  (47)  3.19  (15)  24.65  (16)  20.80 (4)  167 .26  (11)  185.69 (15)  66.2 (31)  1.48  2.71  138.84 57.6,  (15)  4.68  1.32 12.09  .202  1.70  9.81  , . 2 , A 160.98 (19) (m/s ) ACCELERATION B 129.88 , , (N)  1.08  C-START #3  .232  3.32  MAXIMUM  MAXIMUM  (14)  1.24  2.51  15.63  .142 .163  1.02  2.06  C-START #2  72.4  (22)  88.6 (18)  8.47  (9)  9.19  NOTE: V a l u e s i n p a r e n t h e s e s a r e p e r c e n t d i f f e r e n c e s between p r e d i c t e d and e x p e c t e d values;;  ;i  51  DISCUSSION Sources of Error  Six  of  ' ,, i  eight performance parameters  predicted by  the Weihs  (1973) model agree with expected values to within 4 - 22%. This is the first complete  test of this model for parameters dependant on  instantaneous forces or average forces. Weihs (1973) compared model predictions and observed values for maximum acceleration in stage 1 (12%  difference)  difference)  for  Though we  and a  average  single  acceleration  fast-start  in  sequence  between . model  predictions  parameters  at  similar  additional  performance  250  Hz, a  parameters  and  error and  is  2  filmed . at  are unable to show a significant  difference  stage  (24%  64  Hz.  improvement of the expected  performance  demonstrated  the  variability  for  six  in  these  from  film  differences is shown for three C-starts. Expected data  and  are  parameters. predicted  performance subject  parameters  to  Therefore,  the  same  independent  and expected  are  also  derived  digitizing  of  their  maximum acceleration  errors  as  model  differences,  both  rates  may  be more  accurate at 250 Hz in this study than at 64 Hz in the Weihs (1973) study. Harper and Blake (1989ft) tested the accuracy of maximum acceleration estimates  rate from  estimates film  records  for with  found a 30% discrepancy at film differences  between  film  and  fish  fast-starts  accelerometry  by  comparing  measurements  and  speeds of 250 Hz. At 50 Hz,  accelerometer  derived  estimates were  as high as 75% . Both predicted and expected parameter estimates are subject to digitizing  error  which  typically  results 52  in  under  estimation  of  true  performance  digitizing  parameters  errors may be  (Harper and  lower  than' for  inversely  the  proportional  center to  However,  of propulsive sections are much  of  the  1989ft).  for parameters predicted from the  model because lateral displacements greater  Blake,  mass  observed  and  digitizing  displacement.  error  In  is  contrast,  the integration of momentum of added mass in equation 2 involves the summation of errors for velocity and angle estimates over nine sections. The assumption that fins act like flat plates and do not flex is  unlikely  potential  (Bainbridge,  source of  1963;. McCutcheon,  1970)  and this  is  a  error for model predictions. The magnitude of  this error would be difficult to assess. The longitudinal added mass used in calculating the required force is assumed to be 0.2 based on experimentally derived values for  fast-starts  fineness  ratio  by and  trout  (Webb,  fast-start  1982a).  kinematics  Given  the  between  similarity  pike  and  in  trout  (Harper and Blake, 1990a), any error in this assumption is expected to be minimal. Though no other values for longitudinal added mass have been determined for a fish coefficients  swimming unsteadily,  added mass  for fish assuming a rigid body range from 0.05  to 0.1  and suggest a 5% error in required force estimates at a maximum (see Webb, 1982a). \ The most  difference  performance  significantly summation of  , between  expected  parameters  different acceleration  are  (t-test, and lift  and  predicted  within , 22% p<0.05). forces  required to propel a pike during a fast-start. 53  This accounts  estimates  of  none  are  and  suggests for  the  the forces  The direction  forces of  described  motion  of  by  the  the  fish's  model  are  center  of  resolved mass  for  the  and therefore  account for the linear thrust forces only. Rotation of the body and rotational  motion  of  accomplished by  the  center  acceleration  but lateral to the fish's  of  mass  forces,  lift  during  forces  a  C-start are  and possibly  drag,  direction of motion. Given that expected  performance parameters are derived from required forces displacement of the center of  for linear  mass, predicted and expected  forces  and the performance parameters derived from them, are based on linear motion only.  Contribution of Lift and Acceleration Forces  The  present  analysis  demonstrates  the  importance  of  lift  during highly unsteady motion. Drag may also become important at high angles of attack, but due to the lateral direction of motion of  the propulsive sections,  and contribute little unsteady  the  drag  force  will  also  act laterally  to thrust in the forward direction. For other  propulsive  systems,  relative to acceleration forces  drag  is  commonly  (Blake,  1986;  motion  of  insignificant  Gal and Blake, 1988;  Daniel and Meyhofer, 1989). The inertial  highly forces  contributor The  to  large  unsteady  should total  positive  dominate,  force  yet  averaged  acceleration  lift over  forces  half of the propulsive stage (stage 2) maximum and average negative  acceleration  lift  forces,  forces  in  fast-starts  but, the  forces the  are  the  fast-start  observed  that major  (Table 2).  during  the  first  are equal in magnitude to due to second  54  implies  the  half  equally large of  stage  2,  acceleration  forces  averaged  (Table 2; Fig. 9) contrast, to  lift  remain  propulsive (relative  for  stage  are  small  and contribute little to average  forces  are  always  positive  and  contribute  elements to  2  should  their  positive.  maximally  maintain  direction  of  For  a  negative  total force. In  acceleration  forces  to  thrust,  small  motion)  or  useful  angle  during  of  attack  acceleration  whilst  maintaining values greater than or equal to 90° during deceleration (Daniel, 1984). For a fish or shrimp whose main purpose is to remove itself from the attack trajectory of in  an approaching predator, displacement  a short time period is  (Daniel make the  and Meyhofer, a  significant  displacement  forces  occur  earlier  movement  likely  path  1989).  sooner  a  of  positive  the  fish  during  a  than  lift  forces  and  away  cause deceleration  Acceleration forces  contribution (43% of  of  more important than average  from  predator.  during  the  the fish would have, effectively  the  fish's  Though latter  the  context  forces)  to  Accelerative  therefore  initial  of  this  total  fast-start.  negative  half  in  velocity  result  location  in  and the  acceleration  forces  propulsive phase,  removed itself from the attack path  of a predator by this time, and further displacement may not be important. The prediction from the Weihs (1973) model that for thrust to be maximal, the angle of attack of propulsive elements should be small small positive  applies angle lift  as element  to of  element  attack  forces velocities  results  counter  acceleration. in  large  negative  During negative  acceleration  decelleration,  forces. However, forces  are high. Therefore, maintainance of 55  a  as  long  a sharp  angle  of  attack  during  element  decelleration  benefits  lift  production and implies favourable and possibly optimal kinematics.  Contribution of Caudal, Dorsal and Anal Fins to Total Thrust  Thrust from the caudal fin and the section which contains the dorsal  and anal fins  propulsive (a),  account  for  stage. The combination  and larger depths in  thrust. Of these two  these  > 88% of of  higher  total  thrust in the  velocities  sections all  and angles  contribute  to higher  sections, the caudal fin contributes  the most  to thrust making up 81 to 93% of the total thrust and 64 to 78% of positive  thrust  from  both  sections  combined.  The  posterior  placement of dorsal and anal fins in northern pike contributes 26% of  total thrust and 28% of positive  thrust. The fins  increase the  depth of section and therefore the added mass of that section, and also trout  generate lift that  forces  caudally  approximately 27  (Weihs,  placed  1973). Webb (1978a) found for  dorsal  and  anal  fins  contribute  % to total thrust. These results are very similar  considering differences in fin shape and size. The estimates of anal and dorsal fin thrust assume these fins have the same kinematics as the fish's backbone. Though films were not sufficiently fins,  they  clear to record the kinematics  were  observed  to  flex  resulting  of in  relative to the the fish's direction of motion (a) backbone. Greater a  dorsal and anal greater  angles  than the fish's  will result in lower forces produced by these  fins but a greater fraction of these forces direction and consequently  thrust force  will be in the useful  estimates of the fins  on the kinematics of the backbone are probably accurate. 56  based  The posterior placement of the dorsal and anal fins may serve other functions  in addition to  anal  fins  contribute  than  the  caudal  to  fin  thrust enhancement.  thrust  during the  and result  in  The dorsal and  propulsive  acceleration  stage  sooner  beginning  earlier.  This would benefit predator escape as well as prey capture. Dorsal and anal fins are capable of slow undulations and are important in very  slow  locomotion  and  orientation  addition, the posterior location for  maneuvering  dorsal  towards  and anal fins  of  a prey  may be  (personal  these fins without  observation).  may be  startling  In  advantageous  it.  And lastly,  important in balancing  side  forces  during prey capture swhen no turn occurs in stage one and direction of motion is maintained (S-start). The placement  of dorsal and anal fins only partially explains  the greater accelerative  performance of pike over trout. Harper and i  Blake  (198%)  therefore  have  '  "  show pike a  100%  accelerate  100%  faster  greater required force  than  for the  trout, and same body  mass. Only 26 to 28% of this is explained by the contribution of dorsal  and  anal  fins.  To  account  for  the  remaining  difference  between pike and trout performance,  hydromechanical efficiency  and  power  Though  structural  and  thrust,  the  output  physiological posterior  must features  location  of  be  considered.  of dorsal  pike  contribute  and anal fins  thrust during fast-starts.  57  other  to  useful  in pike  does enhance  CHAPTER 3 HYDROMECHANICAL EFFICIENCY OUTPUT  AND MECHANICAL POWER  DURING FAST-STARTS: A COMPARISON OF C AND S-STARTS  INTRODUCTION The  angle of turn is a major performance difference between  escape  (C-type)  and  C-starts  involve  a  prey  sharp  attack turn  (S-type)  whereas  fast-starts  in  S-starts  in  pike.  directionality  is maintained (Webb, 1977; Webb and Skadsen, 1980). The formation of  a C shape during escape produces unbalanced side forces and  results in a turn whereas the S form used in prey attack balances side  forces  show  maintaining  differences  C-starts influences efficiency  which  in  directionality. the  distance-time  suggests kinematics  swimming  Webb  of  performance.  and  Skadsen  relationship S  A  and study  C of  for type  (1980) S  and  fast-starts  hydrodynamic  and mechanical power production may reveal a functional  basis for the  observed performance difference  and the assumption  that fast-starts operate at a physiological maximum can be tested. The  purpose  hydromechanical  here  efficiencies  is  to for  (1) C  and  determine S-starts  and (2)  compare determine  mechanical power output for C and S-starts and compare power requirements and maximum muscle stress estimates with known limits of muscle function.  58  MATERIALS AND METHODS The  collection  procedure and holding facilities  are described  in Chapter 2. The fish used for this part of the study ranged in length from 0.396 to 0.412 m and weight from 0.397 to 0.430 kg.  Experimental Procedure  The  laboratory  set-up  and  acclimation  procedure  described in Chapter 2. Both C and S-type fast-starts  are  as  are filmed  at 200-250 Hz for each ,fish. Individuals were induced to C-start by the rapid introduction of a meter stick within 30 cm of the fish's  head and were  induced to  S-start  by introducing goldfish  prey after 72 hours of, no food. The lights and camera were turned on  1 to 2 seconds before the fast-start event to allow time for  lighting conditions and the film rate to stabilize. The Ten  film  positions  similar  records along  intervals  were  the  were  analysed  on  an  dorsal mid-line of  recorded  for  each  electronic the  digitiser.  fish's  frame  of  body at  a  fast-start  event (see Chapter 2).  Analysis  The useful  hydrodynamic efficiency  power  mass in the  (i.e.  P,  power  direction of  (E) is  defined  required to  motion)  to  as the ratio of  accelerate  total  power  the  (i.e.  fish's  P , the T  power required to accelerate the water and the fish's mass), E = PJPj-  The  knowledge (i.e. center  calculation of  Fy,  the  of  useful  propulsive  power force  (P in  =  y  the  F^rj) requires useful  direction  direction of motion), and D, the displacement of the of  mass.  The Weihs  (1973)  model 59  is  used  fish's  to calculate  propulsive  forces  directly  (equation  2).  An  alternative  approach  is to determine the required forces (F ) given that the propulsive '' "'  K.  forces  experienced  by  a  fish  For  fast-starts,  resistive  should  forces  equal are  the  resistive  dominated  forces.  by  the  acceleration reaction (Webb, 1982a; see equation 1). The  Weihs  (Lighthill's  model  elongate  for  body  is theory)  based used  on  to  the  same  calculate  theory  the  other  terms in the efficiency equation (equation 8 is the denominator of the ratio, Py/Pj)therefore  less  analytically  But, equation  error  1 involves  accumulation.  In  fewer  addition,  simpler requiring determination of . if •  frame; the fish's  .i  •  parameters and equation  only one  1  is  point per  •  center of mass.  An experimental comparison of  estimates derived from these two equations are shown to be within 22% (Chapter 2). Weihs could  (1973)  be  proposed that  described  by  total  power  Lighthill's  large  (Lighthill, 1975), given by P„, = PU + i/2, ma w Ula=0 T  for  fish  amplitude  + d/dtI f1/2 m w o7 a  2  2  1  fast-starts theory (8)  0  where U is the forward velocity of the fish. The other parameters are as described for equation 2. The first term on the r.h.s. of equation (i.e.  8  useful  describes power),  the the  power  required to  second term describes  accelerate  the  fish  the kinetic energy  lost in the wake arid the third term describes the power required to accelerate  the added mass of water by all propulsive sections  (equation  3).  Equation  accelerate  the fish  8  accounts  for  in the direction of  60  the  energy  required to  motion (described by the  displacement vector of account  for  the  the  fish's  center of  power ' required  to  mass)  accelerate  but does not the  fish  body  sections laterally. The latter is defined by (9)  This term is added to equation 8 and  (10)  The last two terms on the r.h.s. of equation 10 are the power required to accelerate the added mass and body mass of propulsive sections  laterally.  When  these  terms  are  positive,  the  values  reflect positive work done by the fish. Negative power refers to the loss of kinetic energy  (i.e.  lateral deceleration of  body and  added mass), but may not reflect negative work done by the fish. Negative  work  elastically. on muscle Tidball body  or  energy  gain  Experiments on show  fish  occurs bone  when  energy  and connective  these tissues store little energy  and Daniel,  1986).  sections requires either  To  realize  positive  stored  tissues and  (Hebrank, 1982;  lateral  work by  is  deceleration  the  fish  of  or no  work. The latter is true if we assume lateral deceleration occurs due to passive forces  resistance  within the  considered here,  fish.  where  by the Both  active  surrounding water and resistive  active  and passive  deceleration is  deceleration are  calculated by taking  the absolute value of the second and third term of equation 10 and  61  passive deceleration by summing only the positive values for these terms.  62  RESULTS Three C-starts and three S-starts were chosen for analysis in which  no  greater  interference  than  responded  1  BL  a  startle  to  occured away  with  from  stimulus  tank  tank with  walls  (i.e.  walls). a  were used for prey attacks (Fig. 11).  fish  Pike  was  consistantly  C-start whereas  S-starts  A typical C-start involves  the formation of a C body shape from a stretched straight position in  stage 1 (preparatory stage), followed by a rapid tail flip to  form a reverse C at the end of stage 2 (propulsive stage). A third stage  generally  involves  braking  or  coasting.  In  contrast,  S-starts involve the formation of an S-shape at the end of stage 1 (preparatory  stage)  and a  (propulsive  stage).  Swimming  involves been  1 to  4  described  reverse  three  by  continues  additional tail  in  S  until  flips.  stages  the  end prey  Fast-starts  where  the  of  stage  capture  2  and  have previously  third  stage  involves  coasting or continued swimming (Weihs, 1973; Webb and Skadsen, 1980). For most S-starts, pike continue to accelerate beyond stage 2 and thus each subsequent tail flip  (1/2  a tail beat cycle) is  also considered a stage. Pike never continued swimming beyond the initial position of the prey which required 1.5 to 3 tail beats (3 to 6 tail flips) for the three S-starts analyzed here. Maximum velocities 0.13s)  are  comparison,  similar  (2.3  for  to 2.8 all  m/s) and durations (0.08  three  S- start performance is  C-starts  (Fig-  12).  to By  more variable where maximum  velocities range from 1.7. to 3.4 m/s and durations from 0.075 to 0.19s.  C-starts  S-starts the  end  but, of  show  a  more rapid  unlike S-starts, stage  2.  do  not  initial  acceleration  continue  Therefore, greater 63  to  rate than  accelerate  maximum velocities  after are  Figure  11:  Kinematics  of  an  S-start.  Each  backbone of the fish on which the head ( • ) the  stretched-straight  fish  ( #  )  are  marked.  the position of the fish at 0.015s intervals.  64  line  defines  the  and center of mass of The  numbers  identify  30 cm  65  Figure  12: Velocity profiles of pike for three C-starts and three  S-starts. Error bars show measurement error range.  66  4.0 CO  • C—START #1 .. O C-START#2 A C-START #3  2.0+ O  •  LU — i  1 — — i —  0.000 0.050 0.100 0.150 0.200 TIME (s) ^4.0 CO  \3.0 ^2.0-F  o  bJ  • S-START #1 O S-START #2 A S-START #3  A AA A A A A AA « A A AA^A A *  AA,  I  0.0  -1.0 0.000 0.050 0.100 0.150 0.200 TIME (s)  67  realized  by  some  S-starts  over  C-starts,  despite  a  lower  acceleration rate. Maximum  lateral  and perpendicular velocities  fin are greater on average respectively; increase 2  for C-starts than S-starts (74 and 77% show  a  in lateral and perpendicular velocities  from  stages  the  4).  the caudal  S-starts  with  Table  of  Both  exception  of  C  lateral  and  velocities  for  consistant  S-start  1 to  #2.  The  maximum angle of attack (the angle of a fish section relative to the velocity vector of the fish's fin  was  126%  greater  for  center of mass) for the caudal  C-starts  than  S-starts.  The  largest  maximum angles occur in stage 2 for C-starts and stage 3 for S-starts (Table 4). Maximum forces in the direction of motion are . 1 2.8 to 8.7 times greater in stage 2 than stage 1, averaging  17.6N  in stage 1 and 71.5N in stage 2. A comparison of forces by stage between C and S-starts shows maximum forces in the direction of motion are not significantly different in stage 1 (averaging for  S-starts  versus  17.6N  for  C-starts),  but  are  16. IN  significantly  lower for S-starts in stage 2 (averaging 45.8N compared to 71.5N for  C-starts; p<0.01, t-test). However, the greatest maximum force  for an S-start (stage 3 of S-start #3)  exceeds that for a C-start  by 27%. A  comparison  of  two  useful  power  accelerate  the fish)  equations  1 or equation 2 (Table 5)  consistant,  estimates where useful  directional  difference.  (i.e. force  power is  used  to  derived from  are found to not show a  However,  differences  between  i  these two useful power estimates range from 14 to 31% for the six fast-starts analyzed here. Power  output  values,  assuming  deceleration 68  of  propulsors  Table  4: Maximum v e l o c i t i e s ,  propulsive refers  element,  to velocity  direction  angles  the caudal  and f o r c e s f o r t h e dominant  f i n . The l a t e r a l v e l o c i t y ,  of the caudal  f i n lateral  o f motion and p e r p e n d i c u l a r v e l o c i t y ,  dy/dt,  t o the f i s h ' s  w, r e f e r s  t o the  v e l o c i t y of the caudal f i n perpendicular t o the f i n ' s long a x i s .  MAXIMUM VELOCITY (m/s)  (dY/dT)  (w)  MAXIMUM ANGLE  {degrees)  MAXIMUM FORCE (N)  C-START #1  1 2  3.44 .3.89  1.77 2.87  116.3 142.8  18 .7 59.7  C-START #2  1 2  .3.84 5.92  2.38 4.66  116.1 166.7  24.0 66.2  C-START #3  1 2  3.38 6.25  1.24 4.41  117 . 9 .165.8  10.2 88.6  S-START #1  1 2 3  1.15 3.56 2.73  0.75 1.60 2.12  24.6 37.1 52.6  2.9 49.5 44.0  S-START #2  1 2 3 4 5  1.48 1.37 1.77 1.36 1.76  1.00 1.47 1.19 1.07 1.00  22.4 34.5 83.9 40.4 59.2  31.1 29.1 53.8 22.9 21.1  S-START #3  1 2 3 4 5 6  2.14 2.76 3.38' 3.14 3.89 2.73  1.86 3.17 2.59 2.26 2.49 1.69  36.9 32.0 73.7 36.6 43.2 30.5  14.3 58.9 112.8 39.9 56.5 27.2  69  Table  5: A comparison  starts.  a  of useful  P r o p u l s i v e power > ^  x O.  power  estimates f o r C  b Required power = F  R  and S  x U. F i s h  ranged i n weight from 0.397 t o 0.430 kg.  Propulsive a  Power (Watts)  Required  %  Propulsive  Difference  Power  Required  %  b Power (Watts)  (Watts)  Power  Difference  (Watts)  CI  16.9  20.1  17  SI  2.0  2.3  14  C2  17.9  13.4'  28  S2  5.6  4.1  31  C3  32.0  40.1  23  S3  24.8  20.5  19  70  requires positive work by the fish, are 12 to 37% (X = 30%) greater  than  values  where  the  process  is  assumed  passive  and  requires no work (Table 6). This increase in total power decreases hydrodynamic efficiency by 29 to 39% (X = 33%). Because the amount of  positive  work required for deceleration is  conservative  power  and  efficiency  unknown, the more  estimates  based  on  the  assumption that deceleration is passive are used for comparison. Total power output ranges from hydrodynamic  efficiency  comparison of  varies  from  C and S-starts  total power or efficiency. output  of  12.6 16  power  total  hydrodynamic  efficiency  C-starts versus 0.16  to 0.37  to  39%.  W and total (Table 7).  shows no consistant  But, total  total  to 92.3  C-starts  difference for  hydrodynamic efficiency  are  less  ranges  variable  from  for S-starts  A  than  0.34  to  and  S-starts; 0.39  for  and total power output  ranges from 45.6 to 81.2W for C-starts versus 12.6 to 92.3W for S-starts  (Table  output can be  7).  Therefore,  much : lower  S-start  efficiency  than for  and  total  C-starts. There is  power also a  tendency for power output to increase from stage 1 to 2 for all but one  fast-start  (Table 7).  For S-starts  with  greater than two  stages, power output in general remains the same for stages 2 to 6. The S-starts  greater variation in hydromechanical efficiency over  C-starts  is  related  Figure 13 shows that efficiency beats. C-starts  S-starts (0.24  have to  lower  0.44)  to  the  number of  found for tail  beats.  increases with the number of tail efficiencies  during  stages  (0.02 1  and  to 2  0.19) (Table  than 7).  Efficiencies for S-starts in stages 3 to 6 range from 0.24 to 0.66 i  and are greater than in the first two stages. Even within stages 71  6: A c o m p a r i s o n  T a b l e  p o s i t i v e r e f e r s a r e  p o w e r  t o  t h e  i n c l u d e d  p o w e r  r e f e r s  v a l u e  o f  r a n g e d  o n l y  o r  t h e  s u m m a t i o n f o r t h e t o  t h e  t w o  i n w e i g h t  P o s i t i v e P o w e r  o f  t h e  o f  t w o  t o t a l p o w e r a b s o l u t e t o t a l  v a l u e  p o w e r  o f  i n t e g r a l t e r m s 0.397 t o  t o t a l i n  0.430  o f  e s t i m a t e s p o w e r .  w h e r e  i n t e g r a l t e r m s  s u m m a t i o n  f r o m  o u t p u t  o n l y  i n  P o s i t i v e p o s i t i v e  e q u a t i o n  p o w e r  e q u a t i o n  w h e r e 5  b a s e d  a r e  5. t h e  o n p o w e r  v a l u e s A b s o l u t e a b s o l u t e  t a k e n .  F i s h  k g .  A b s o l u t e  %  P o w e r  D i f f e r e n c e  P o s i t i v e P o w e r (Watts)  A b s o l u t e P o w e r  % D i f f e r e n c e  (Watts)  (Watts)  CI  45.6  66.5  37  SI  12.6  16.8  29  C2  52.4  74.1  34  S2  28.5  32.1  12  C3  81.2  114.9  34  S3  92.3  127.1  32  72  (Watts)  T a b l e 7: T o t a l power and hydromechanical  e f f i c i e n c y v a l u e s i n each  stage and f o r t h e e n t i r e f a s t - s t a r t f o r C and S - s t a r t s .  EFFICIENCY (PU/PT)  POWER (W)  C-START #1  0.24 0.44 0.37  32.0 60.1 45.6  C-START #2  0.32 0.36 0.34  62.3 84.5 73.1  C-START #3  0.25 0.44 0.39  39.8 118.0 81.2  S-START #1  0.09 0.19 0.26 0.16  3.9 11.0 21.1 12.6  S-START #2  0.10 0.02 0.58 0.48 0.66 0.37  13.1 12.9 13.5 11.8 14.1 15.2  S-START #3  0.06 0.12 0.36 0.24 0.28 0.41 0.27  36.6 112.0 97.7 106.7 95.2 74.4 92.3  1 2 TOTAL 1 2 TOTAL  •  1 2 TOTAL 1 2 3 TOTAL 1 2 3 4 ' 5 TOTAL 1 2 3 4 5 6 TOTAL ;  73  !  Figure  13: The relationship between hydromechanical efficiency and  fast-start refer  .1  to  kinematics for pike C and S-starts. the  end  of  each  tail  flip.  Error  measurement error range.  74  The stage numbers bar  shows  average  75  differences  occur.  For  example,  hydromechanical  efficiencies  for  S-start #3 in stages 3 to 6 are consistantly lower and average 56% less than values for S-start #2. Total power can be broken down into its component parts as described  in  equation  accelerate  the fish  10  (Fig.  averaged over  14).  The  power  all fast-starts  is  required  to  30% of total  power which is similar to the 39% required to accelerate the added mass  of  the  propulsors  (Fig.  14).  contributes a smaller but consistant  Acceleration  of  body mass  amount to total power  (16%)  where as the loss of kinetic energy in the wake is more variable (15%  ranaging  percentage  from  contribution  2 of  to  39%).  power  Greater  terms  variability  occurs  between  in  the  S-starts  than between C-starts. The greatest difference is the 39% loss of kinetic energy found in S-start #1 versus a 2% loss in S-start #2.  76  Figure 14: A comparison of power output for C and S-starts. The subdivisions represent the four r.h.s. terms in equation 10.  P  = P„ + 1/2 m w Ul 2  m  T  U  a  + dldt r 1/2 m w dl 2  'a=0  + dldt f 1/2 iri dyldt dl  J  a  2  J  o  b  Error bar shows average measurement error for total power.  77  (10)  DISCUSSION Sources of Error  A comparison of useful power estimates in this study, where the forces for acceleration were determined from the Weihs model or  the  forces  required  found no consistant  to  accelerate  difference  the  fish's  virtual  mass,  and estimates were within 14 to  31% for both C and S starts. In chapter 2, a comparison of work estimates for an accelerating pike where the forces  involved were  calculated from the same two models shows a 12 to 30% difference. Similar  differences  acceleration  rates  differences  between  consistant  were for  a  the  difference  representative  of  fast-start.  In  rationale  exists  to  trout  for  methods  implies  that  forces  are  the  the  one  estimate based on required forces  and  (Weihs,  the  Weihs  14  by to  method  lack  (1973) a  of a  model  fish  31%  over  maximum  1973). Though  high,  encountered  despite  choose  average  fast-start  two  actual  addition,  found  is  during a  difference,  another,  and  is equally representative  no the  of the  mechanical power required to propel a fish. The 14 to 31% error may in part be explained by unrealistic assumptions of the model. For example, the propulsive elements are assumed to  be rigid during a fast-start  when in fact  they  flex  (Weihs, 1973). This is particularly true of the median and caudal fins  which  are  the  major  contributors  to  total  thrust  in pike  (Chapter 2). Errors in film analysis are also important. Harper and Blake (1989a,ft) contributors  emphasize to  film  analytical  speed error.  and  magnification  According  to  their  as  important  results,  the  conditions in my experimental system at 200 to 250 Hz would result 79  in a 30% underestimation of maximum acceleration rates. I argue in Chapter 2 forces  that  analytical 'errors influence  differently  and  thus  propulsive  contribute  to  and required  discrepancies  in  estimates of force, work and power output. As efficiency estimates are based on a ratio where , !,. "  .  the  numerator and denominator are  f.  I '  derived from the same theory, errors would cancel for terms common to  both  and the  analytical  error.  affected  by  resultant Total  estimates  power  analytical  would  estimates,  error  less  affected  however,  and  are  would  underestimated.  by  directly  therefore  be  !  The power required to accelerate laterally  be  during  pike  fast-starts  body mass of fish sections  averages  16%  of  total  power.  Exclusion of this component would result in the overestimation of hydrodynamic efficiency  by 4%. The magnitude of the acceleration  of body mass depends on the lateral acceleration rate of body and fin sections and their mass (see equation 2). Power loss occurs when kinetic energy deceleration  of  propulsive elements.  is  The energy  lost due to the cost to  depends on whether deceleration is an active process energy  expenditure  or passive  requiring no energy  the fish  and requires  cost. Including  the power loss term as a positive cost or no cost results in total power output values that differs by 13 to 36% and hydrodynamic efficiency  values  insufficient  that  differ  information  importance  of  active  by  exists forces  29  to  to  39%.  quantify  (i.e.  muscle  Unfortunately, the  relative  contraction)  to  deceleration of lateral body movements. There is some evidence to suggest backbone  both  passive  passively  and resists  active bending  forces and 80  contribute. requires  The no  fish's energy  jr.-  expenditure  (Hebrank,  connective similarly.  tissue  1982).  and  skin  contrast, j the  In  Other are  internal  expected  stretching  of  structures  to  active  like  resist  bending  muscles  provides  resistance and requires energy expenditure (Goldspink, 1977).  Hydrodynamic Efficiency  Hydrodynamic (0.16 to 0.37)  efficiencies  for  fast-starts  by  pike  are lower  on average than values for other swimming modes  involving  body  and  caudal  fin  undulations.  The  highest  efficiencies  reported are for continous swimming at 4 to 8 BL/s Si'-' : !<  (where BL/s is the velocity of the fish normalized to the fish's length, U/L) ranging from 0.7  to 0.9  (e.g.  Webb,  1975ft;  1988;  Videler and Hess, 1984). McCutcheon (1977) found hydromechanical efficiency for push and coast swimming to be intermediate ranging from  0.18  efficiencies  to  0.7.  between  There  is,  swimming  however, modes  significant  (Fig.  15).  overlap  in  Efficiency  of  continous swimming at low speeds (lBL/s) are 0.3 for pike and 0.46 for trout (Webb, 1988) and increase with speed. A similar positive relationship occurs for push and coast efficiency efficiencies velocities  for  fast-starts  occur attained  in  show  stages  1  a  similar  and  are less than 2  swimming. Hydromechanical  2  trend.  of  The  S-starts  BL/s. Though  lowest  where  velocity  the is a  variable for all swimming modes shown, the decrease in efficiency from  continuous  velocities.  These  to  fast-start  results  show  swimming that  the  propulsive mechanism, the lower the efficiency.  81  is  consistant more  at  unsteady  all the  Figure 15: The relationship between hydromechanical efficiency and relative speed (BL/s). Data for continous swimming in pike ( A ) and trout ( A ) are from Webb (1988). Push and coast swimming data (O ) ^  fr°  m  study are shown and  averaged  McCutcheon (1977). The fast-start data from this averaged over stages 1 and 2 ( • ) for S-starts  over the entire fast-start  S-starts.  82  ( • ) for both  C and  COWTWOUS SWIMMING  BURST AND COAST  1.0  2.0  3.0  4.0  5.0  VELOCITY (BL/s)  83  6.0  O  7.0  Why, then, are fast-starts so expensive? The energy required to  accelerate  contributing  added mass is 39%  on  a major component  average.  For continous  of  total power  swimming,  the time  average of this component is zero where deceleration of added mass is  assumed  to  represent  an energy  gain  by  1975). The alternative; approach taken here,  the  fish  where  (Lighthill,  deceleration of  added mass is assumed to incur zero cost or a positive cost, has not been used for energetic  analyses of fish  continous swimming  using body undulations for propulsion. However, this approach has been used in the analysis of other swimming modes (Blake, 1979; 1986). The resultant cost is positive amplitudes  and  frequencies  and  but due to lower tail beat  therefore  lower  acceleration  rates  (Webb, 1988), the cost is probably lower for continous swimming than for fast-starts. The  mass of  determinant  of  water  influenced  hydrodynamic  by  propulsive  efficiency  sections is a  (Alexander,  1983).  McCutcheon (1977) concluded energy loss by the zebra danio was not due to pushing on too little water. The average water mass in the trailing edge vortex of the zebra danio was 2.64 mass for stage 1 and 4.38 for stage 2. influenced  by pike during fast-starts  equation 3) is only  times the body  However, the added mass  (where added mass is from  1.2 times the body mass. This suggests the i  i  power lost due to pushing on a small volume of water is greater in pike.  ) Energy can also be lost by accelerating water in the wrong  direction. McCutcheon (1977) found this to be a major cause of the low  hydromechanical efficiency  push-and-coast  mode.  For pike  of  zebra danio  during C-starts, 84  swimming the  large  in the angles  maintained  by  the  caudal  region  favor  high  thrust  efficiencies  (Chapter 2). The lower caudal fin angles for S-starts suggests the lower  efficiencies  in  this  swimming  mode  are  in  part  due  to  pushing water laterally and not in the useful direction. The increase in efficiency start  parallels  a  declining  with each stage number of a fast acceleration  rate.  The  preparatory  stage involves very low efficiencies in part due to pushing in the wrong direction. and  the  As  stage number increases,  lateral  efficiencies.  The  velocities majority  of  increase prey  the  and  angle of  result  captures  by  attack  in  pike,  higher however,  occur within two to three stages (Rand and Lauder, 1981; Harper and  Blake,  efficiencies of  all  19906;  are implied,  three  S-starts,  comparison of  in  observation).  averaging and .0.14  0.3  Lower  for  for  the  the  hydromechanical  first  first  three stages 2  S and C-starts by stages shows that  more efficient 272%  personal  stages.  A  C-starts are  on average than S-starts by 225% in stage 1 and  stage 2.  However,  tail  beat frequency  for  S-starts is  approximately twice that for C-starts and based on time (end of stage 2 for C-starts occurs at the same time as the end of stage 4 for  S-starts;  i.e.  0.13s)  C-starts  are  only  50%  more  efficient  northern  pike,  expressed  than S-starts.  Maximum Performance  Maximum kilogram of  power , output  muscle,  ranges  for  from 228  to  406  per  W/kg for escape  behaviour and 63 to 462 W/kg for prey capture. Values are only slightly higher when expressed per kilogram of muscle fiber to 507.7 W/kg) due to .'! ' : !  the  high concentration ' 85  (91%)  (69.2  of muscle  fibers in fish white niuscle (Johnston, 1983). The largest maximum power output values for a C-start and an S-start are 446.2 and 507.7 W/kg muscle fiber respectively.  The maximum predicted for  ;  vertebrate anaerobic muscle is very similar at 500 W/kg (Weis-Fogh and  Alexander,  1977).  This  suggests  fast-start  performance  is  constrained by muscle power output where C-starts perform closer to the theoretical maximum on average (366.1 W/kg) than S-starts (219.9 W/kg). Maximum  power  output  reported for  isolated  fish  white muscle fibers is 313 W/kg or 63% of the maximum theoretical value  ( Johnston and ; Wokoma, 1986). Lower values  performance  from isolated  muscle  for muscle  preparations than predicted may  i  reflect  adverse  affects  of  the  laboratory procedures  (Johnston and  Salamonski, 1984). Maximum isometric stress of muscles may also constrain animal locomotory Myerhofer,  performance  QDaniel  and  Webb,  1987;  Daniel  and  1989). The maximum reported force per unit area for  fish white muscle  is 315 kN/m  2  at 8°C (Langfeld, Altringham and  Johnston, 1989). Alexander (1969) reported muscle fibers to run at 30  to  35° to  cross-sectional  the  area of  longitudinal a fish's  axis  in  fish.  This  implies  body  is  a conservative  the  estimate  of muscle fiber cross sectional area. The maximum force produced by, pike  divided  by  gives values of 32.1  cross-sectional to 73.2  area  at  the  dorsal-anal  fin  kN/m . Maximum muscle stress for 2  isolated muscle fibers (145 to 315 kN/m ) are at least twice these 2  values (Johnston and Salamonski, 1984; Johnston and Wokoma, 1986; Altringham Langfield,  and  Johnston,  Altringham  and  1988;  Curtin  Johnston,  1989).  and  Woledge,  But,  during  1988; cyclic  contractions, maximum power output occurs at 0.3 maximum isometric 86  stress.  The  appropriate  range  based  on  literature  values  is  therefore 43.5 to 94.5 kN/m and overlaps the measured range for pike.  This  implies  that  muscle  forces  are  operating  near  an  optimum for maximum power output and are not limited by maximum muscle stress.  87  CHAPTER 4 M E T A B O L I C C O S T O F FAST-STARTS  INTRODUCTION  Here, the metabolic cost of fast-starts  for prey capture and  escape are estimated using excess post-exercise (EPOC) avoid  measurements. errors  destructive  due  A  to  non-destructive  handling  methods.  Also,  and  method  tissue  the  oxygen consumption  ability  was  selected  to  sampling  required  in  to  make  repeated  measurements using a single specimen minimizes the number of fish required for study. Though die function of EPOC during recovery from  anaerobically j fuelled  activity  ;  (Gaesser  and Brooks,  1984),  is  not  estimates of  fully  energy  understood  expenditure can  still be determined. A fast and slow phase are observed where the fast phase is assumed to be responsible for repletion of ATP and CrP  reserves, and the slow phase represents lactate removal either  by oxidation or glycogenolysis (Scarabello, 1989). Mechanical  costs  of  fast-starts  are  determined simultaneously  with oxygen consumption measurements. Due to the large number of fast-starts  required for •'• this  not feasible.  study,  The alternative was  high to  speed  use  video  film  analysis  tape  was  analysis at  low film speed (30 Hz) which requires less time but incurs greater analytical  error  (Harper  and Blake,  1989ft).  However,  differences  between mechanical cost estimates at 30 and 200 Hz are consistant and a correction factor can be applied. Given limitations discussed.  an to  estimate fast-start  There is  of  the  metabolic  performance  by  cost energy  of  a  fast-start,  reserves  are  extensive literature on the biochemical energy ; -;' j  *  • 88  reserves  and  their  rate  of  (Hochachka and Somero, Hochachka,  1987;  mobilization  1984;  Scarabello,  during  exercise  Wieser et al, 1989).  The  1985;  energy  in  fish  Dobson and available  for  anaerobic metabolism and its rate of supply can be estimated and compared with the metabolic cost of a fast-start.  In this way, a  determination  limited  of  whether  amount of energy  fast-start  performance  is  by the  available from biochemical reserves or by their  rate of supply is possible. The purpose of this study is to (1) determine the metabolic cost  of  fast-starts  in  metabolic  cost  with  total  efficiency  from  the  metabolic  energy  prey  evaluate sampling rate  and  mechanical  slope of sources  capture  cost  escape  error and the  (3)  fast-start value  estimating mechanical costs of fast-starts.  89  compare  and estimate metabolic  this relationship constrain  (2)  of  assess whether behaviour  video  (4)  taping for  METHODS AND MATERIALS Fish were placed in a 90.1 1 plexiglass tank (.99m x .65m x .14m) the  12 hours prior to experimentation and allowed to adjust to laboratory  conditions.  The tank  was  supplied  with  aerated,  dechlorinated fresh water at 2-41/min and was immersed in a larger flow-through  water  bath  for  temperature  regulation.  Over  the  duration of experiments the water temperature ranged from 11.1 to 15.8°C but varied by no more than 2°C for any one fish. To measure oxygen consumption in the experimental tank, the system was closed and recirculated with a litde giant submersible pump. A YSI probe attached to a series 5510 meter was placed in series with the water pump for continous concentrations. temperature  The meter  automatically  and was accurate  to  monitoring of oxygen  corrected  within  0.03  for  changes in  mg OJl. Resting  oxygen consumption rates were measureable to within 0.005 mg OJl and  represent  a  sensitivity  ratio  of  1:30  over  a  ten minute  interval. The tank volume was turned over every 11 minutes and die tests showed minutes.  that water  The  measurements.  probe  in the closed was  calibrated  chamber mixed within 3 to  Winkler titration  When fish were removed, no measureable  change in  oxygen concentration occured. Pike activity during exercise and in recovery was recorded on a low light sensitivity video camera at 30 Hz. A mirrow angled at 45° provided an overhead view of the fish, and a 2 cm gride placed under the tank served as a scale reference on all tapes. Lighting was supplied by 2 100 W fluorescent aquarium lights located 1 m above  the water  opaque  plastic  surface. sheeting  The tank to  was completely  minimize 90  visual  enclosed by  disturbance  of  experimental  animals.  Activity  was  observed  through  the  video  monitor. At  the  begining  of  an experiment,  a plexiglass  sheet was  placed on the tank; top sealing the experimental system.  An over  head view for the video monitor was allowed through an overhead mirror angled at 45°. Oxygen consumption was monitored continously and concentrations recorded every ten minutes. rate had stabilized, such that the change over  three  successive ten  O^,  the fish  was  minute  Once the metabolic  in oxygen concentration  intervals  were - within  stimulated to fast-start.  0.01  mg  Escape responses were  induced by a mild electrical shock to the tail region. The lid was temporarily removed and two  electrodes attached to  placed within 10 cm of the fish's fast-start  from  0  to  20  tail. Fish were stimulated to  times within  immediately replaced. The removal of the  water associated  a pole were  4  minutes.  The lid was  the lid and disturbance of  with stimulating the fish  caused  at most a  0.02 mg 0 /l change in the oxygen concentration. To stimulate prey 2  capture behaviour, 4 to 8 goldfish (2.90 to '8.09 gms) were placed in  the  tank,  briefly  goldfish  is  minutes.  After  monitored  lifting  the  lid.  Oxygen  consumption  of  8  not measurable and all prey were capture within 10 exercise,  for  two  the  hours.  change  in  The oxygen  oxygen  concentration  concentration  was  was  always  greater than 72% saturation. Fish were allowed to recover for 72 hours before  the  next experiment.  Prey capture experiments were  repeated 4 to 6 times and escape responses 7 to 9 times for each fish.  After  weighed.  a  series  of  experiments,  fish  were  measured  and  A total of 5 fish were tested ranging in weight from  0.345 to 0.560 kg.  91  Video tape records were used to estimate the mechanical cost of  each fast-start. .Tracings of  the fish  at 0.033s intervals were  taken, the center of mass of the stretched-straight fish marked on each tracing and the displacement of this point measured between frames to the nearest mm. The center of mass was assumed to be 0.41BL (Webb, 1982) from the tip of the head and midway between the lines marking the sides of the fish. Knowing the displacement of the center of mass (d), the mass of the fish (m) and assuming b  a longitudinal added mass of 0.2 x body mass (Webb, 1982a), the mechanical cost can be determined. This is given by *n  |  r  W =T 1.2 m a.d.  (11)  L  Lt  b  i  i  i=l  where in  b  fish's  center  interval work  is the mass of the fish, a is the acceleration of the of  mass  (determined done  between  by  and d the the  frames  time is  displacement between  :  during  frames).  summed over  all  that time  Estimates of frames  for a  fast-start as indicated by the summation sign. Frame rates of 30 Hz at a XI magnification are known to result  in  >100%  underestimates  of  maximum  acceleration  rates  (Harper and Blake, 1989ft). However, the significance of this error to mechanical cost estimates is unclear. To determine a correction factor for this error, five prey capture and five escape responses previously filmed at 250 Hz were analyzed every 1, 2, 4, 8 and 25 frames simulating sampling rates of 10, 31.25, 62.5,  125 and 250  Hz. The mechanical cost was calculated for each sampling rate of 6 sequences. The oxygen debt from exercise was calculated by subtracting 92  the amount of oxygen consumed at rest from the amount consumed in the first hour of recovery. Oxygen consumption rates in the 30 minutes prior to The  rate of  stimulation are used to  consumption." stabilised  close  determine resting rates. to  resting rates within  the first hour of recovery. Oxygen debt measurements were converted to units of energy where 1 mg 0 yields 14.7 J (Goolish, 1989). 2  93  RESULTS  Undisturbed pike sat motionless and only occasionally swam at very low speed by paddling paired fins or by body and median fin oscillations. from  Experimental  • set-up  induced  some  activity  ranging  slow swimming to fast-starts, but undisturbed behaviour was  resumed within ten minutes. Fish minutes  reached of  resting  oxygen  experimental  set-up  rates were 75.6 ± 1.7 mg 0  consumption (Fig.  kgV  2  16).  rates  within  Pre-exercise  30  resting  (X ± 1SE; Table 8). By  1  comparison, Diana (1982) measured resting oxygen consumption rates at 14°C to be 121.8 mg 0„ kg" hr" for a 400 gm Northern pike 1  collected  1  from the same drainage basin as the fish used in this  study. Oxygen consumption rates were largest immediately exercise  and most  declined  to  resting  levels  within  following  20  to  30  minutes (Fig. 17). The highest oxygen consumption rates were 226.6 ± 3.1 mg 0  kg" hr' , and very similar to; maximum rates for a 1  2  1  pike exercised to exhaustion at 251.8 Oxygen debt in the first 76.5  mg 0  were  not  kg"  1  2  behaviour for  different  consumption  capture  rate for prey  behaviour.  1  to  2nd hour post-exercise, rates  from  = 0.05)  (paired  post-exercise is 39.2 mg 0 escape  1  pre-exercise  for  escape  t-  (paired t-test, a  prey  the  1  ....  kg" hr" (Table 9).  2  hour post-exercise ranged from 2.6  hr". During  significantly  mg 0  This  t-test,  but were significantly p  <  0.05).  capture behaviour in the  Mean  hr" compared to 29.2 mg 0 difference  is  also  oxygen  second hour 2  hr" for  significant  (paired  1  2  higher  1  t-test, p < 0.05). Figure  18  shows , total work estimates for fast-starts at four  sampling rates as a percentage of total work derived from 200 Hz 94  Table  8:  0 k g *hr ) 1  2  Weight  of  prior  experimental  to exercise  fish  and  resting  and i n t h e second  metabolic  rates  hour o f r e c o v e r y  (mg  for fish  i n escape and p r e y c a p t u r e .  BEHAVIOUR  WEIGHT (kg)  FISH  PRE-EXERCISE mg 0  ;  2  kg  1  hr  1  2ND HOUR POST-EXERCISE mg 0  2  kg  1  ESCAPE  0.385  1  81.2  67.3  ESCAPE  0.364  2  80.0  70.6  ESCAPE  0.345  3  96.8  93.4  ESCAPE  0 .535  4  58.9  49.6  ESCAPE  0.560  5  63.1  63.2  PREY CAPTURE  0.385  1  78.9  98.6  PREY CAPTURE  0.345  3  97.3  104.0  PREY CAPTURE  0.535  4  57.6  78.1  PREY CAPTURE  0 .560  5  59.3  73.7  95  hr  1  T a b l e 9: A comparison between f i s h to  o f maximum measured oxygen consumption  and between time  20 f a s t - s t a r t s  (fish  intervals  immediately  rates  f o l l o w i n g up  number 1 t o 5) o r 100 f a s t - s t a r t s  (fish  number 6 ) .  POST-EXERCISE FISH  l  b  (mg 0  10 MINUTES  0.385  208 .9 (2)  181.2  (3)  171, .4 (4)  2  20 MINUTES  3  3  30 MINUTES  3  2  b  0.364  265.2 (5)  191.1  (4)  167 .0 (3)  3  b  0.345  279.5  (6)  225.0 (5)  207 .1 (5)  4  b  0.535  159.8  (1)  155.4  (1)  143 .7 (1.5)  5  b  0.560  219.6  (4)  176.8  (2)  143 .7 (1.5)  6  C  0.341  251.8  (4)  227.7 (6)  note: rank o f oxygen consumption  a ,  ,  Time i n t e r v a l s  ,  ,  r e f e r t o immediately f o l l o w i n g e x e r c i s e  Less than o r e q u a l t o 20 f a s t - s t a r t s . 100  219 .6 (6)  r a t e w i t h i n row shown i n b r a c k e t s .  b c  kg h r )  WEIGHT (kg)  f a s t - s t a r t s and a p p r o a c h i n g e x h a u s t i o n .  96  bout.  Figure 16: Histogram of oxygen consumed by a single fish over ten minute intervals with time over the duration of an experiment. The fish  activity chamber was  experimental  set-up  and  sealed 25  at time  fast-starts  zero on completion of  induced  at  70  minutes.  Oxygen is monitored for 120 minutes following activity. The error bar shows measurement error range.  97  5» 0.20 o 0.15 0.10 z  o ° o 0.05 UJ  P 0.000 o  30  60  90  120 150 180  TIME (min)  98  Figure (5  17: Histogram of recovery times after 0 to 20  fish).  Recovery time refers  to  the  time required for oxygen  consumption rates to return to resting levels following exercise.  99  fast-starts  CY  0.5-1  0.4-  LU  0.3-  o  0.2-  z  UJ Cd  b_ 0.1-  0.0-  20  40  60  TIME (min)  100  80  Figure 18: Effect of sampling rate (film speed) on mechanical work estimates.  Work  is  expressed  derived from 200 Hz film.  101  as  a  percentage  of  estimates  N 1.25 X  g  1.00j CM ^  O . s  0.50  LiJ 0.25 J O  T O 1  T O 1  I  O  T  O 1  1  ry  Lj 0.00 D_  25  50  75  FILM SPEED (Hz)  100  125  film.  The mean of  10  estimates are  shown.  Five  prey capture  sequences and five escape sequences at 200 Hz were analysed and estimates  of  comparison difference  total  work  of  at  each  fast-start  sampling  behaviours  rate  determined.  finds  no  A  significant  and therefore data from both behaviours were combined  in figure 18. At 30 Hz, total work estimates are at least 50% of values determined at 200 Hz. Figures  19  positively  related  mechanical  cost.  and 20 to  show  the  that  metabolic  number  The best fit  of  cost  fast-starts  linear model for  (Cyiebt) and  is  their  escape behaviour  gives  MC  = 51.1 + 38.1 F ,  EF  MC  J  j  r = 0.54  (12)  r = 0.58  (13)  2  E  = 165.4 + 10.6 M ,  EM  2  E  where MC is the metabolic cost, F (or F) the number of fast-starts and M (or M) the mechanical work done. The subscript E refers to escape cost  behaviour. of  The  fast-starts  number of  explain  metabolic cost (i.e. r  2  a  fast-starts  similar  and  amount  is similar for equations  the mechanical of  in  12 and 13). Slopes  are not forced through zero because estimates of may represent a real elevation  variation  the Y-intercepts  in metabolic rate due to a factor  other than mechanical work done (e.g. excitement). Similar  positive  relationships  exist  for  prey  capture  behaviour where MC  pp  MC  = 258.6 + 54.8 F ,  r = 0.22  (14)  = 212.7 + 21.2 M .  r = 0.59  (15)  p  PM  P  103  2  2  Figure 19: Relationship between oxygen debt or metabolic cost and the  number  behaviour.  of  Error  fast-starts bar  for  shows  error.  104  escape  average  and  range  of  prey  capture  measurement  NUMBER OF FAST-STARTS  Figure 20: Relationship between oxygen debt or metabolic cost and useful  mechanical work done during escape  behaviour.  Error  bars  show  average  error.  106  ranges  or prey capture of  measurement  USEFUL MECHANICAL WORK DONE (J/kg)  R-squared for equation 15 is similar to that for equations  12 and  13 but greater than for equation 14. A comparison of equations 13 and 15 shows similar Y-intercepts but slope for prey capture is 100% greater than for escape behaviour. Data from five fish are combined to form equations 12, 13, 14 and 15. The slope and Y-intercepts for individual fish are assumed to  be  the  covariance costs  was  versus  significant  same.  the  To  test  these  assumptions  for  each  behaviour  conducted  number of  differences  were  fast-starts  found  for  or slope  an and  analysis for  metabolic  mechanical or  of  costs.  intercepts  (a  No =  0.05). An  individual pike  was  induced  to  fast-start  by  electrical  stimulation 25, 50, 75, 100, 125 and 170 times with a 72 hour rest between  experiments.  Oxygen  debt  measurements  were  found  to  increase up to 100 fast-starts but did not increase further at 125 and  170  fast-starts  (Table  10).  After  170  fast-starts,  fast-starts could be induced and the fish was assumed exhausted.  108  no further  Table  10:  Oxygen  Debt  f o r an  Individual  Fish  Exercised  to  Exhaustion  NUMBER OF FAST-STARTS  OXYGEN DEBT (mg 0  2  kg  1  MECHANICAL COST  hr ) 1  (J/kg)  25  55.4  804.6  50  75. 9  1102.3  75  99.1  1439.2  100  135.7  1970.8  125  109.8  1594.6  170  125.9  1828.4  109  DISCUSSION Film Rate Error  A  film rate of 25 Hz gives estimates of total work done  during a fast-start  that are 47% less than values  from 200 Hz  film. At 50 Hz, total work underestimates are only 25% less and increasing  sampling  This indicates different  rates  further  estimates of  from  actual  only  slighty  improve estimates.  total work at 200  Hz are not very  values.  Underestimates  of  maximum  acceleration rates are much higher ranging from 35 to 100% for 50 to 250Hz film (Harper and Blake, 1989ft). Though work estimates are calculated  using  instantaneous rates  acceleration  maximum values  and error  for  total  rates,  the  error  associated  with  are less than for lower acceleration  work  depends  on  average  acceleration  errors. Though the cause of error is the same for all variables derived  from  film  displacement  measurements,  the  magnitude  of  error for quantities calculated from an equation and dependant on a number of  variables will  equation  used.  determine  velocity  For  be  contingent  example,  on the  differentiating  and acceleration  rates  film  displacement  increases  product or addition of  two  product or addition of  errors. Therefore, film  form of the  error  derived variables results  to  and the in the  rate error is best  evaluated independantly for each quantity calculated.  Oxygen Debt Measurements  The oxygen debt , is assumed to represent the cost of recovery from  exercise.  stimulating  fish  Common to  criticisms  exercise  of  will  contribute to post-exercise oxygen 110  this increase  consumption,  approach  are  that  excitement  and  and that  the role  of  oxygen  consumption  in  recovery  from  anaerobically  fuelled  exercise is unclear. The contribution of excitement or  during  exercise,  is  consistantly  stimulate  activity  were unsuccessful  to oxygen consumption at rest  probably  low  with  in  visual  pike. or  and no change in oxygen  Attempts  auditory  to  stimuli  consumption resulted.  Pike tended to remain stationary in pre and post-exercise  periods  and showed low variability in resting oxygen consumption rates. Also,  the  metabolic  cost  of  a fast-start  is  estimated  from  the slope of the relationship between energy expenditure and work done  (Fig.  expenditure represents activity  19 due any  and 20) to  and any  excitement  increase  and possibly  in  is  consistant not  oxygen  due to  increase  included.  The  consumption  excitement.  in energy y-intercept  independant  of  Therefore, the metabolic  cost estimate of a fast-start is not confounded by excitement. The  oxygen  consumption after  debt  hypothesis  an exercise  associates  bout with  and Brooks, 1984). More recent evidence oxygen  lactate  excess  oxygen  removal (Gaesser  shows resting levels of  consumption are resumed long before  lactate  concentrations  in muscle tissues reach concentrations typical of a resting animal (see review by Gaesser and Brooks, 1984). Pike are no exception where  resting  levels  of  oxygen  consumption  after  exhaustive  exercise are achieved: after only 2 hours of recovery compared to 96 hours for replenishment of glycogen stores and lactate removal after exhaustion (Schwalme and Mackay, 1985). Gaesser and Brooks (1984)  suggest oxygen  phase  followed  fast-phase  by  a  debt can be slow  phase.  divided into Their  may function to restore adenylates  111  review  an initial  fast  suggests  the  and CrP. This is a  more acceptable  hypothesis  given  the  synchrony observed between  fast phase oxygen debt''measurements and CrP and ATP replenishment in fish (Wieser et al, 1985; Scarabello, 1989). Here, pike show no slow  phase of  similar  in  1989).  This  oxygen  to  duration  repeated  recovery and the the  fast  fast  phase  for  suggests ATP and CrP pools  fast-starts  but  anaerobic  phase  observed is  trout  were  (Scarabello,  depleted during  glycolysis  and  lactate  accumulation did not occur. This could be due to the high power requirements can  of  fast-starts  implying  that  only  sufficient  power  be supplied by CrP and ATP hydrolysis and not anaerobic  glycolysis.  ,  Energy Sources and Pool Sizes  Oxygen debt may therefore be a useful measure of anaerobic energy expenditure where CrP is not fully depleted and glycolysis has not yet contributed to ATP supply. Though the assumption that anaerobic glycolysis is not turned on until CrP is fully depleted may  not hold for humans (Bonen et al., 1989), evidence  sequential  mechanism  Concentrations of consistant  fish  is  clear  (Driedzic  et  white  muscle  CrP and ATP in fish  averaging  respectively  in  17.38±1.78  and  (Dobson and Hochachka,  7.62±1.88 1987;  al.,  et  1981).  are very  u,moles/gm  Driedzic  for a  tissue  al., 1981;  Guppy et al., 1979; Mallet, 1985). However, Dobson and Hochachka 1  (1987) show that 45% of the creatine pool is dephosphorylated at rest  and  CrP measurements  resting  concentrations.  shows  that  death  by  A  are  more  injection  gross  recent of  underestimates study  curare  by  of  actual  Schulte  (1990)  minimises  stress and  results in much higher estimates of resting CrP concentrations for 112  trout.  These  latter  two  studies  show  CrP concentrations  at rest  are at a maximum 45 |imoles/gm tissue. With the addition of ATP, 50(imoles energy  ATP/gm  tissue  supplied by  is  a  reasonable  CrP and ATP during  estimate the  for available  initial  stages of  anaerobic exercise. For pike, CrP and ATP pools of this size would provide 2130 J/kg fish for muscle work. This compares very well with the maximum oxygen debt observed after 100 to 170 fast-starts which was 135.7 mg O ^ g or 1970.8 J/kg fish. In addition, for the maximum of 20 fast-starts shown in figures 19 and 20, CrP and ATP pools can easily supply sufficient energy.  Muscle Efficiency  If oxygen debt is a realistic estimate of energy supplied by anaerobic metabolism for swimming activity then the slope of the linear regression and  total  Figure 20  between  mechanical  metabolic cost  energy  should  supplied for swimming  estimate  shows the relationship between  muscle  efficiency.  metabolic energy supply  and useful work done. The differences in slope between escape and prey  capture  efficiency  behaviour  similar  the  differences  in hydrodynamic  where the average value for prey capture is 0.19 and  for escape is 0.37 expressed  reflect  relative  (Chapter 3). When metabolic energy supply is to  total  mechanical cost  for both behaviours. Slope  (Fig. 21),  slopes are  for escape behaviour is  3.92  and for prey capture is 4.02. This implies a muscle efficiency of approximately  25%  which  is  in  the  middle  of  the  range for  vertebrate red muscle (i.e 20-30%, see review by Goldspink, 1977).  113  Figure 21: Relationship between oxygen debt or metabolic cost and total  mechanical  work  done  during  escape  or  prey capture  behaviour. Error bars show average measurement error ranges.  114  SIl  METABOLIC COST (J/kg) o 5> m o o > o 7s  o o z n  OXYGEN DEBT (mg0 /kg) 2  Power Required  Each fish  fast-start  is  estimated  to  cost  approximately  40-50J/kg  and lasts for 0.12s to 0.14s. A power supply of 286-417 W is  required. Only CrP and ATP hydrolysis can supply energy equivalent rate. By comparison, glycogen  fermentation  is  of magnitude slower (Hochachka and Somero, 1984). the  duration  of  concentrations.  fast-starts  However,  is  ATP and  energy for 40 to 50 fast-starts. a  fast-start  for  limited  prey  capture  by  an order  This suggests  ATP  CrP pools  at an  and  supply  CrP  sufficient  This implies that the duration of or  escape  is  not  determined by  energy stores and must be behaviourally constrained.  Specific Dynamic Action (SDA)  The  observed  increase  in  metabolic  rate  above  pre-exercise  levels in the second hour of recovery for pike after prey capture and  not  escape  requirements of  is  potentially  peristalsis  explained  by  the  and digestive processes (i.e  metabolic SDA). The  increase observed for pike was 23% above resting which is less than the  100%  average  increase  in maximum post-prandial oxygen  consumption previously  reported for  1981).  require  However,  maximum therefore  fish  metabolic  rates  12  after  fish  (see  review  by Jobling,  hours  on  average  to  ingestion  (Jobling,  achieve  1981)  and  the lower rates reported for pike after only two hours  are reasonable. An increase in metabolic rate of 23% above resting within 2 hours of feeding may seem higher than the average for fish  but  digestible  given protein  that in  temperature, diet  and  ration  activity  level  size, can  proportion  of  influence  this  value (Jobling, 1981; Moyle and Cech, 1982), variation around the  116  average for any given condition is probably high. For example, the increase  in metabolic  rate  above resting  after  food consumption  for pike ranged from 33% in summer to 126% in winter (Diana, 1982).  117  CHAPTER 5 M E C H A N I C A L C O S T O F FAST-STARTS INTRODUCTION  Fast-starts  are  described  by  three  stages;  a  preparatory  stage (stage 1), a propulsive stage (stage 2) and a variable third stage.  This  swimming  latter  and is  kinematics  or  stage  involves  coasting,  turning  or  continued  typically not included for analyses of  performance  (Weihs,  1973;  Webb,  fast-start  1975a;  1977;  1978a,ft; 1982a; Harper and Blake, 1989a,ft; Domenici and Blake, in press).  Whilst consistancy  of kinematics found in stage 1 and 2  may be important for comparison with previous  studies, additional  ;  tail  beats  in  stage  3  contribute  to  total  performance,  energetic  cost of the event and possibly success in escape from predation or capturing a prey. Here, the range  and frequency  energetics during escape and prey Distance-time  plots  are  between C and S-starts.  used  of  fast-start  capture  to  performance and  behaviour  compare  are assessed.  fast-start  performance  Rand and Lauder (1981) and Webb and  Skadsen (1980) show a similar analysis for pike S-starts only. A C and S-starts in pike by Harper and Blake  performance study of (1990ft) Here,  does  not  differences  discussed  include in  a  comparison  performance  of  between  with respect to kinematics  distance time plots. C  and die  and  S-starts  ecological  are  functional  of each behaviour. In  previous  fast-starts  are  illustration  of  chapters, determined  the  the  cost  for  distribution  the of  118  and first  fast-start  power time. costs  output  of  However, and  power  output requires a larger sample size. A comparison of how cost and power  output  consistancy predatory  vary with  of  distance  fast-start  stimuli  and  and time  performance show  in  whether  would  response  fast-start  demonstrate  to  a  the  feeding  responses  are  at  or a  physiological maximum or, under behavioural control. From  the  estimates  for  chapters,  total  cost  estimates  metabolic metabolic  and cost  in  this  chapter  propulsive and  its  efficiency  variation  These costs are compared to literature values budget  of  pike or the  energy  content  of  significance of the cost of fast-starts is evaluated.  119  and  can  for the  prey  in be  previous earlier assessed.  daily energy  and the  ecological  METHODS AND MATERIALS Twelve laboratory  northern and  stimulated by  pike  induced  were  to  individually  fast-start.  brought  Escape  the rapid introduction of  into  the  responses  a meter  stick  were  and prey  capture attempts were induced by the introduction of goldfish prey (3-5 gms). Experimental and filming procedures are as described in Chapter 2 using film rates of 100 or 200 Hz. A  total  of  29  fast-starts  are  chosen  for  analysis,  14  C-starts and 15 S-starts. For each sequence, the center of mass is digitized. to  The displacement  determine  distance  of  this point between frames is used  travelled  and  calculate  total  work  done  until the end of the fast-start. Due to variability in the number of  tail beats for each fast-start,  the end of the event is defined  by the end of the last positive acceleration. Total  distance  travelled is  defined  by  the  distance between  the position of the fish's center of mass at frame zero and the last frame. Total mechanical work (W ) is given by TO.  Wm = I . 1.2 m a.d/ E i i i = i  . '  (15)  where m is body mass, a is acceleration of the center of mass, d is  displacement  efficiency double  of  the  center  of  mass,  E  the hydromechanical  and i the< frame number. Acceleration is determined by differentiation  of  displacement  values.  First  of  all,  the  change in X and Y values for the center of mass are determined between frames. To realize a smooth AX and AY relationship with time,  2  point  smoothing , is  required for  100  Hz and 2 point  followed by 3 point smoothing for 200 Hz. From these smoothed 120  values  for  calculated  AX by  and  AY,'  the  division  acceleration  derived  further  point  3  from average,  displacement of  is  determined.  displacement  the  change  in  is  applied  after  velocity the  velocity and acceleration values for both film speeds.  121  Velocity  by with  time  is and  time.  A  determination  of  RESULTS  All  Northern pike respond to  a startle  of  a  these  events  involve  propulsive stage (stage 2)  stimulus  preparatory  with  stage  a C-start.  (stage  1),  a  and a variable third stage. The latter  involves a coast, brake or turn in 9 of 14 C-starts. The remaining 5 events show continued acceleration after stage 2 with one or two more tail beats. All 15 prey capture events show at least one tail beat after the end of stage 2 with 5 sequences showing 2 to 3 additional tail beats. Upon  introduction of  goldfish,  pike  orient  towards  or stalk  prey. The latter involves slow movement towards prey using median fins is  only  for  propulsion. Once within  employed.  For  12  of  the  15  strike distance,  fast-starts  an S-start  analysed,  a  strike  occurs within one body length of the predator. Mean  duration of  mean total distance not  significantly  (t-test,  p=0.4).  S-starts  at  C-starts  and  S-starts  is  0.20±0.02s.  The  travelled during a C-start is 0.25±0.08m, and  different Mean  from  total  26.5±2.7J/kg  that  work than  for  done, C-starts  S-starts however, at  at is  0.23±0.04m greater  18.6±2.8J/kg  for  (t-test,  p<0.002). A S-starts  log-log shows  plot a  of  distance  significant  22a,b). The regression  against  positive  relationships  time  for  relationship for  total  for  distance  C-starts and both (Fig. are  given  by  TD = 1.080 T ' 0  876  and  TD = 2.519 T ' 1  r=0.67  (16)  r=0.75  (17)  2  c  539  2  s  122  Figure 22: Log-log plot of total displacement versus time at the end of the fast-start event for A) C-starts and B) S-starts.  123  '0.50 Ld 0 0.20]  0.10 0.05 0.10  0.20  0.50  TIME (s) E  0.50  O  0.05 0.10  0.20  TIME (s) 124  0.50  The  slopes  have  a larger intercept  regression  are  lines  distance  for  significantly  explain  both  different  but  a  67  (t-test,  smaller  to  75%  behaviours.  Also,  p<0.01).  slope  than  C-starts  S-starts. The  of  the  variability  22  of  the  29  in  log  fast-starts  perform in the lower portion of the regression relationship in the time range of 0.1 to 0.25s and in the distance range of 0.09 to 0.40m (Fig. 22a,b\ The mechanical work done increases linearly with distance and time (Figs 23a,b and 24a,b).  The regression relationships for work  with distance are  W = -18.0±10.1 + 274.4±29.2 D  r=0.88  (18)  W = 23.2±10.1 + 100.5±17.7 D  r=0.71  (19)  c  c  S  The for  slopes  2  /  are  C-starts is  s  i  significantly lower  different  than for  2  (t-test,  p<0.02).  S-starts but slope is  Intercept more than  twice as high. These regression relationships explain more of the variability in mechanical work done for C-starts at 88% than for S-starts at 71%. Regression  relationships  for  mechanical  work  done  against  time are given by  W = -7.6±14.8 + 289.1±49.4 T c  r =0.74  c  N  W = 8.6+12.9 + 189.8±49.9 T s  fast-starts  r=0.53 2  s  Time explains less of than  (20)  2  (21)  the variation in mechanical work done in  distance.  But,  time  explains  more  of  the  variation during C-starts at 74% than for S-starts at 53%. Slopes 125  Figure 23: Plot of against  distance  total mechanical work done during at the end of  the  fast-start  event  fast-starts for A)  C-starts and B) S-starts. Error bar shows average measurement error range.  126 i  (J/kg)  o 100-^ < 75o 50 o  LU  25 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7  DISTANCE (m)  0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7  DISTANCE (m) 127  Figure  24: Plot of  against  time  at  total mechancial work done during fast-starts the  end  of  the  fast-start  event  for A)  C-starts and B) S-starts. Error bar shows average measurement error range.  128  (J/kg)  0.2  0.3  0.4  0.5  0.4  0.5  TIME (s)  O LU  25*. 0.0  0.1  0.2  0.3  TIME (s) 129  are found not to be significantly different between C and S-starts (t-test, p>0.25) but intercepts are different (t-test, p<0.002). The relationship between power output and time are shown in Fig.  25.  Power  output  is  relatively  constant  for  S-starts averaging 406 and 412W/kg muscle respectively.  130  both  C and  Figure 25: Plot of power output per gram of muscle against time at the  end  of  the  fast-start  event  for  A)  C-starts  S-starts. Error bar shows average measurement error range.  131  and B)  TOTAL POWER  o  cn  DISCUSSION Fast-start Performance  Successful maximising the  predator  avoidance  distance  travelled in  Harper and Blake, results  and  prey  a given  1988). For fast-starts,  in high acceleration  capture time  (Webb,  on  1986;  maximum power output  rates from a resting  log log relationship is expected  depend  position  and a  between distance and time. Figure  22 shows this model explains 67 and 75% of the variation in log distance  for  C-starts  and  S-starts  respectively.  Fish  may  not  always respond maximally in escape or prey capture behaviour which would  explain  the  observed  variation.  The  variation  in  power  output shown in Fig. 25 illustrates this point. Pike  initially  achieve  greater  distances  escape behaviour than in prey capture. efficiencies probable 0.12  unit  time  in  The higher hydrodynamic  of C-starts over S-starts during stages 1 and 2 are a explanation  to 0.3s  predator  per  (Chapter 3).  C-start performance  persists for  which Webb (1986) shows to be sufficient  escape.  The  superior  performance  of  time is due to higher, hydrodynamic efficiencies  S-starts  time for after  this  after stage 2 (see  Chapter 3) and a linear swimming path. A tendancy for power output to decrease with time for C-starts may also contribute to lower performance.  Webb and Skadsen  relationship of distance T  -  (1980) report a similar log log  versus time for Esox S-starts (D = 85.8  ) but also report data for C-starts from Webb (1978a) where  the slope is greater than for S-starts (D = 151 T ' ). A probable 1  explanation  for  this  difference  is  that  43  performance  in  Webb  (1978a) is monitored only to the end of stage 2 and accumulative distance  is  reported for the  curved path of  133  C-starts rather than  total displacement. The majority of C-starts observed for pike were terminated at the  end  of  stage  2  where  the  mean  distance  travelled  was  0.14±0.01m or 0.33 BL. This duration and performance is typical ;  for pike attacked by a predator for which a high escape success is realized (Webb, 1986). The majority of prey attacks by pike were within 0.1 to 0.3 meters or 0.23 to 0.69 BL. This short reaction distance is typical of Esox species preying on a number of fish species (Webb and Skadsen, 1980; Rand and Lauder, 1981) shorter  than  reaction  Stein,  1989).  These  distances studies  for show  and is  largemouth  bass  (Savino  and  that  have  higher  prey  pike  capture success than bass but a lower rate of capture at the same prey  densities.  distances  and  attacking.  Pike yet  are . capable  choose  Minimising  to  the  of  accelerating  minimise cost  reaction  of  over  distances  greater before  attack  is  a  possible  ranges  from  18  to  explanation.  Energetic Cost of Fast-starts  The J/kg.  mechanical  cost  of  fast-starts  The cost per unit distance  is  initially  greater  105  for S-starts  than C-starts but at distances over 0.24m the cost of C-starts is greater.  Again,  the  explanation  is  probably  the  differences  efficiencies and the linear path of swimming for S-starts. same  amount  of  work  over  50  J/kg,  S-starts  realize  in  For the greater  distances than C-starts. Reducing cost of capture may be important if energy reserves are low or the potential gain from a prey is low. The relationship between total mechanical work done and time 134  are  not  significantly  different  predicted  if  power  output  fast-starts.  Though  observed,  average values  there  is  for is  C  and  assumed  some  S-starts.  maximal  variation in  the  are similar and change  This  is  during  all  power output  little  with time  ir  for  C and S-starts (Fig. 25).  Combining both data sets, Work =  -1.04 + 246.8 T, r=64%. 2  The the  metabolic  total  cost of  mechanical  a fast-start  cost  by  is  estimated  metabolic  efficiency  by dividing (0.25  see  Chapter 4). The resultant costs range from 72 to 420 J/kg where the median value is than measurements the  179  J/kg. These metabolic costs are higher  in Chapter 4.  small chamber required for  limited performance. A prey  capture  events  larval  planktonic  by  Sacramento prey  oxygen  similar cost of juvenile  swimming (Puckett and Dill, for  A possible  is that  consumption  measurements  84  reported for  coho  J/kg is  salmon  involving  burst  1984). Much lower costs are reported  perch  ranging  explanation  from  capturing 1.5  to  evasive 6.3  x  and 10~J/kg 2  non-evasive (Vinyard,  1982). Given a greater range of cost, CrP and ATP reserves provide sufficient  energy  for  4  to  24  fast-starts  (see  discussion  in  Chapter 4). Glycogen reserves at 40 mmole/kg tissue (Scwalme and Mackay, The  1985)  provides energy for 8 to 46  performance  energy  reserves  during  a  assuming  fast-start complete  is  additional fast-starts.  therefore  recovery  not from  limited by any  prior  anaerobic activity. Ecological Significance of the Cost of Fast-starts  Repeated escape or prey capture behaviour could affect daily 135  energy expenditure. Resting metabolic rates of 75.6 (Chapter 4) similar  are equivalent  to  other  to 2.66  estimates  for  x  pike  10  mg 0  J kg"  4  1  day"  1  from  kg^hr"  2  and are  1  Alberta  lakes (Diana,  1982). To increase daily energy budget by 10% would require 2660 J/kg  or  conducted  6  to  by  37 pike  fast-starts. per  reasonable (see below), i  Though  day  is  the  number  unknown,  greater  of  fast-starts  than  five  is  ;  The number of fast-starts (X) used in prey capture can be estimated from feeding frequency (F), stomach content (N=number of prey) and capture success (S) where  X =^  (22)  Diana (1979) monitored the feeding habits of Northern pike in Lac St Anne and found that pike fed once every 2.66 days and captured 2.32  fish  per feed  averaged  over  the  summer months  (May to  October). Prey capture success by Northern pike varies with prey ;  species from 0.1 for bluegill to 0.78 Stein,  1988). The incorporation of  gives X values ranging from day.  Using  fast-start,  the  median  of  this is equivalent  for gizzard shad (Wahl and  these values into the equation  1.1  to  179  8.8  attacks  J/kg for  to 0.7  (fast-starts) per  metabolic  to 5.9%  cost  of a  of daily maintenance  costs. Larger numbers of attacks per day are possible  where prey  size is small and larger numbers of prey are required to fill the stomach. Diana (1979) found that <10% of pike with full stomachs contained 6 to 42 prey items which would require 2.9 fast-starts per day assuming S = 0.78.  This is equivalent  to  Therefore  13.8%  fast-starts  of  daily  required  maintenance to  capture  costs. prey  136  in  the  the  field  to  20.5  to 2.0  number of overlaps  the  range  required to  increase  daily  maintenance  costs  by  10% but  rarely exceeds it. The ; choice of strike distances of less than one body length by pike may 'be a strategy to reduce the energetic cost of capture. Other factors may also favor a short attack distance by pike. Prey capture success is known to decline with distance for many predators,  including  sit-and-wait  predators.  Presumably  this  is  due to an increase in closing time (the time required to reach the prey in an attack) with distance between predator and prey. Dill (1974)  developed  a model  for  closing time which  closing time is constant beyond a distance pike accelerating maximally at 20 m/s  of 0.4  predicts that meters  for a  and length of 0.4m (Fig.  5  26). This suggests prey capture success is constant beyond 0.4m or 1 BL attack distance. The benefit of a short reaction distance is again to minimize cost of capture. The importance of the cost of capture depends on the energy gained from a prey. The average  daily ration for pike in the  summer at Lac Ste. Anne is 47.8 kJ/kg day" for males and 72.9 1  kJ/kg  day"  for  1  fast-starts  per  females day  (Diana,  required  to  1979).  Given  attain  this  the  1.45  intake  to  8.7  (see  earlier  ranges  from  i.  discussion),  the  cost  of  prey  capture  (fast-starts)  0.14% to 7.6% of daily ration. Diana (1979) estimates that 27.7% of injested energy is used for somatic or gonad growth. That is, the  cost  of  available for  prey  capture  represents  0.52  to  27.4%  of  energy  growth. Therefore, the cost of prey capture activity  involving high powered anaerobic activity of short duration can be significant  (i.e.  represent  greater  than  10%  of  energy  for growth) when expressed relative to the energy content of prey. 137  available  Previous studies have used time to estimate cost of capture for pike assuming , activity i costs are constant 1984).  In  contribute  this  study,  significantly  the to  cost activity  of  (Hart and Connellan,  fast-starts  costs  is  shown  potentially  to  increasing  the daily energy budget and reducing net energy gain from prey. Without  knowledge  activity,  the  ' of  cost of  the  searching  mechanical  or  metabolic  and capture of  underestimated.  138  prey is  costs  of  seriously  Figure 26: The relationship between reaction time of the prey and attack  distance  of  the  predator  based  acceleration rate (calculated from Dill, 1974).  139  on  a  constant  140  CHAPTER 6 SUMMARY  A) Parameter estimation from the Weihs model A  comparison of propulsive force estimates using the Weihs  model with required forces shows maximum forces differ by 14 to 22% for three C-starts. The average difference similar  to  the  displacement, acceleration estimates  12  mean rate  to  30%  found  and final derived  are within 4  velocity,  from  to  by  17% which is  Weihs  (1973).  and mean  propulsive  19% for  is  Total  and maximum  and  required  C-starts. Estimates  force  of total  work done using required and propulsive forces are within 9 to 31% three C-starts and estimates of power output are within 14 to  for  31% for three C-starts and three S-starts. The use of higher film rates in this study than in the Weihs (1973) study (i.e. 250 Hz vs 65  Hz)  does  not  decrease  discrepancies  between  propulsive and  required force estimates on average and discrepancies are shown to vary by only 8%. Variability in the difference and  required  differences  force  between  estimates estimates  for  for  between propulsive  replicate  performance  fast-starts, parameters  and derived  from these forces are shown here for the first time.  B)  Estimates  of  hydromechanical  efficiency,  metabolic  efficiency  and the energetic cost of fast-starts. Hydromechanical 0.27  for  S-starts increased  S-starts.  (0.16 with  to  efficiency The  0.37)  each  averaged  range  of  beat  efficiencies  C-starts (0.34  than for  tail  0.37  and  141  speed  for was to  showing  C-starts and greater  for  0.39). Values a maximum  hydromechanical  efficiency  of  0.66  in  Hydromechanical  efficiency  increases  body-caudal  swimming  modes  fin  These  are  the  first  5  of  one  S-start.  with  speed  for  other  (push-and-coast  swimming) where values for fast-starts speeds.  stage  and  continous  are lower at all swimming  estimates  of  hydrodynamic efficiency  for fish fast-starts. Estimates of  metabolic  efficiency  are 0.094 for C-starts and  0.047 for S-starts.  Estimates of  metabolic efficiency  is the product of hydromechanical and muscle  efficiency, This  are  is  very  similar  for  similar to  S  white  and  muscle efficiency,  C-starts  estimates of  and  muscle  assuming  averages  0.252.  efficiency  for red  is 201.2±30.0  J/kg for  muscle at 0.20 to 0.30 (Goldspink, 1977; Hill, 1950). The  mean energetic cost of fast-starts  C-starts and 186.0±18.7  J/kg for S-starts.  Power output is similar  for C and S-starts ranging from 406 to 412 W/kg. These costs are higher  than  previously  reported  for  fast-start  like  activity  bursts in fish.  C) Morphological and Kinematic Constraints Lift  and acceleration forces  magnitude during During  acceleration  deceleration,  are both positive  of  the  acceleration  and similar in  dominant propulsive  forces  are  negative  sections.  whilst  lift  forces remain positive. The optimal conditions of a sharp angle of attack and high lateral velocities  predicted by Weihs (1973) only  apply  and  not  of  motion  must  during reverse  propulsive  acceleration the  sections,  direction  deceleration  142  is  deceleration. and  angle  essential  Because of and  fish  attack of optimal  conditions can not be maintained. The C body form of escape behaviour produces larger angles of attack  than  S-starts  body  form  which  allows  hydromechanical  results  in  maintainance  efficiency.  The  higher  of  efficiencies.  The S  direction  but  is  velocities  result  that  sacrifices are  higher in the first 0.3s for C-starts than for S-starts. The caudal fin and body section with the dorsal and anal fins contribute contribute prediction  >  90%  28% that  of  total  which the  thrust.  provides  posterior  The  anal  quantitative  location  of  and  dorsal  support  median  fins  to  fins the  increases  thrust in pike.  C) Physiological Constraint Maximum acceleration  ability of pike in C-starts and S-starts  is limited by maximum power output of muscles. The maximum power output for C-starts and S-starts are 446.2 and 507.7 W/kg muscle fiber  and very similar/ to the 500  muscle fibers  W/kg maximum predicted for  (Weis-Fogh and Alexander, 1977). Also, estimates of  muscle stress at maximum force are 32.1 to 73.2 kN/m  2  which are  less than 50% of literature values for maximum stress of isolated fish white muscle fibers. The observed stress for white muscle in pike are close to the optimal, for maximum power output at 0.3 maximum stress (Hill, 1950). Power output is not always maximal for C-starts and S-starts where 60% of C-starts and 65% of S-starts are in the 400 to 600 W/kg range. This suggests that both S and C-starts are at times under behavioural control.  143  Power demand during fast-starts ranges from 286 to 417 W. Only hydrolysis of ATP and CrP can supply energy at this rate. But, energy pool sizes of ATP and CrP are not limiting. More than 150  fast-starts  can  be  repeated  in  rapid  succession.  Literature  values for CrP and ATP concentrations in white fish muscle are sufficient  to  support 4  to  24  of  the  more expensive  fast-starts  reported in chapter 5. Given that energy reserves are much greater than demand for a single fast-start, and that pike are observed to fast-start to  be  repeatedly, limited by  fast-starts  appears  the  duration of  fast-starts  biochemical energy to  be  under  does  reserves.  behavioural  not appear  The duration of control  whilst  the  intensity of fast-starts is near the physiologically maximum.  E) Ecological Considerations The cost of a fast-start represents 0.3 to 1.97% of the daily energy budget and 0.52 to 27.4% of the energy available from diet. Therefore,  5  to  30  fast-starts  would  be  necessary  to  increase  metabolic rate by 10%. 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