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Growth of fishes in different salinities 1957

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GROWTH OP FISHES IH DIFFERENT SALINITIES by PASCARAPATHT GANAGARATNAM B . S c , UNIVERSITY OF CEYLON, 1951 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OP ARTS i n the Department of Zoology Ve accept t h i s thes is as conforming to the standard required from candidates f o r the degree of MASTER OF ARTS Members of the Department of Zoology i THE UNIVERSITY OF BRITISH COLUMBIA March, 1957. ABSTRACT Juvenile sodceye, coho, and chum salmon and adult g o l d f i s h were studied f o r a period of ten weeks to determine whether varying degrees of s a l i n i t y influenced t h e i r growth. The possible influences of such factors as temperature and food were r i g i d l y controlled. Coho and chum salmon showed higher percent weight increase i n the saline media. Coho grew best i n 12#o s a l i n i t y and chum had a higher percent increase i n weight i n 30#° s a l i n i t y . The growth of sockeye i n the saline medium was retarded f o r the f i r s t eight weeks, but during the l a s t two weeks i t surpassed that of the corresponding group of sockeye i n fresh water. The early retardation i n growth of sockeye, i n the saline medium, i s attributed to i t s longer fresh water l i f e . The adult g o l d f i s h did not show any s i g n i f i c a n t difference i n weight increase. The records of the sizes attained by several species of f i s h inhabiting both sea and fresh waters show that s a l i n i t y enhances growth. The evidence from experimental study, by other workers, on the influence of d i f f e r e n t environmental fac t o r s on growth of f i s h e s , ind- icates that changes i n meristie counts or body proportions, i n early development, produces di f f e r e n t growth rates. These changes could eventually a f f e c t the ultimate s i z e . The physiological mechanisms of growth of fishes are not well understood, but i t has been suggested that the influence of hormones on growth i s probably ameliorated i n the marine environment. In presenting this thesis i n p a r t i a l fulfilment of the requirements fo r an advanced degree at the University of B r i t i s h Columbia, I agree that the Library s h a l l make i t f r e e l y available for reference and study. I further agree that permission for extensive copying of t h i s thesis for scholarly purposes may be granted by the Head of my Department or by his representative. It i s understood that copying or publication of t h i s thesis f o r f i n a n c i a l gain s h a l l not be allowed without my written permission. Department of ~Z-oo A ° ^ y The University of B r i t i s h Columbia, Vancouver 8, Canada. ACKNOWLEDGEMENTS The author wishes to express h i s gratitude to Dr. W.S. Hoar, F.R.S.C. f o r suggesting,the problem and supervising the work. He wishes to thank sincerely Dr. W.A. Clemens, P.R.S.C., and Dr. C.C. Lindsey f o r t h e i r many useful suggestions and c r i t i c i s m s . He also thanks Messrs. E.J. Crossman and D.E. M c A l l i s t e r f o r t h e i r help and Mr. D.F. Alderdice of the B i o l o g i c a l Station, Nanaimo, B r i t i s h Columbia, f o r supplying the chum salmon used i n t h i s experiment. This work was made possible through an award of a Colombo-Plan Scholarship by the Technical Co-operation Service, Department of Trade and Commerce, Ottawa, on an application made by the Government of Ceylon. - i - TABLE OF CONTENTS Page INTRODUCTION 1 LITERATURE SURVEY 2 EXPERIMENTAL METHODS 9 Procedures 10 Diets 11 Feeding • 12 Weighing the Fish 13 EXPERIMENTAL RESULTS 15 Sockeye • 15 Coho - Series 1 19 Coho - Series 2 19 Chum 19 Goldfish 21 SUMMARY OF EXPERIMENTAL RESULTS 24 DISCUSSION 26 Environmental Ef f e c t on Growth • 26 Meristic Changes 26 Body Proportions 27 Growth and Size of Fishes 28 S a l i n i t y and Size 31 Physiological Mechanisms Responsible f o r Growth.... 32 Osmotic Stress 32 Endocrine Function 32 S a l i n i t y and Thyroid A c t i v i t y 34 SUMMARY 36 LITERATURE CITED 37 APPENDICES 42 - i i - LIST OF TABLES Table Page I. Sizes at maturity of marine, brackish, and fresh,water fishes .. 3 I I . Length and weight of spring salmon from New Zealand and B r i t i s h Columbia 7 I I I . Fish used i n experimental study 9 LIST OF FIGURES " Figure 1. Mean weekly weight of sockeye i n fresh water and 6$o s a l i n i t y 16 2. Mean weekly weight of coho series 1 and 2 i n fresh water and i n the various s a l i n i t i e s ... 17 3. Mean weekly weight of chum i n 6$o and 30%° s a l i n i t y 18 4. Percentage increase i n weight of i n d i v i d u a l chum i n and 30?£o s a l i n i t y 20 5. Mean weekly weight of goldfi s h in.fresh water and 6foe s a l i n i t y 22 6. Percentage increase i n weight of a l l groups i n fresh water and i n the various s a l i n i t i e s at f i v e and ten weeks 23 - i i i - APPENDICES Appendix Page I. Dr. E. Percival's l e t t e r to Prof. Hoar, and data on spring salmon from New Zealand 42 I I . Sockeye. Weekly record of weight increase i n fresh water ... 47 II I . Sockeye. Weekly record of weight increase i n 6?&o s a l i n i t y 48 17. Coho series 1. Weekly record of weight increase -in fresh water 49 V. Coho series 1. Weekly record of weight increase i n 6 # ° s a l i n i t y 50 VI. Coho series 1. Weekly record of weight increase i n 12% o s a l i n i t y 51 VII. Coho series 2. Weekly record of weight increase i n fresh water ... 52 VIII. Coho series 2. Weekly record of weight increase i n 18^o s a l i n i t y 53 IX. Chum. Weekly record of weight increase i n 6%o s a l i n i t y 54 X. Chum. Weekly record of weight increase i n 30#o s a l i n i t y 55 XI. Chum. Data on in d i v i d u a l weights 56 XII. Goldfish. Weekly record of weight increase i n fresh water 57 XIII. Goldfish. Weekly record of weight increase i n 6%0 s a l i n i t y 58 INTRODUCTION Landlocked teleosts are usually smaller than t h e i r marine counterparts (of the same species). For example, the kokanee salmon (Oncorhynchus nerka kennerlyi (Suckley) reaches a size of 200 mm. to 400 mm. at maturity, while the sea-going sockeye salmon, Oncorhynchus nerka nerka (Walbum), averages 605 mm. i n length and has been reported to a t t a i n 831 mm. Non-migratory anadromous f i s h sometimes show an exhaustion of the thyroid gland (Hoar, 1952) and since the hormone produced by t h i s gland i s essential f o r the growth of most vertebrates, i t has been suggested (Hoar, 1956) that the excessive osmotic stress i n fresh water could account f o r the smaller s i z e . Since some species, such as the smelt (Osmerus mordax) and the sea-trout (Salmo t r u t t a ) , grow equally well i n fresh water and i n the ocean, i t i s evident that t h i s s i t u a t i o n i s not universal. In t h i s work an attempt i s made to evaluate the effect of osmotic stress and s a l i n i t y on the growth of three species of salmon and the gold f i s h . Two l i n e s of research have been followed:- (a) the l i t e r a t u r e has been reviewed and an attempt made to correlate sizes of mature anadromous f i s h and other species with the s a l i n i t y of t h e i r environment, (b) experiments have been designed to tes t the s a l i n i t y effect when divorced from dietary and such environmental variables-aa temperature, aeration and volume of water. LITERATURE SURVEY An extensive search, of the l i t e r a t u r e was made fo r sizes of f i s h of d i f f e r e n t species that occur i n habitats of d i f f e r e n t s a l i n i t i e s . Only a few records of sizes (either length or weight) of f i s h other than the anadromous forms have been found. Eleven species of f i s h occuring i n two or three dif f e r e n t habitats are l i s t e d i n Table I, together with t h e i r sizes at maturity or as otherwise indicated. In a l l cases but one, Osmerus mordax, the marine and brackish water inhabitants are the larger. Some show appreciable differences and warrant the conclusion that the marine environment favours growth i n these species. Even among marine species, such as the P a c i f i c herring, Olupea harengus. or the giant perch, Lat es c a l c a r i f e r the larger sizes occur i n higher s a l i n i t i e s . S a l i n i t i e s of brackish or estuarine waters, and also those of "purer" sea water, vary considerably i n the dif f e r e n t parts of the world. The A t l a n t i c herring, Clupea harengus. measures from 240 mm. to 350 mm. while the same species occuring i n the B a l t i c measures 160 mm. to 200 mm. The s a l i n i t y of the B a l t i c varies from 20$° i n the south to 1$ i n some of the northern regions. Hodgson (1934) states that the s a l i n i t y i n the regions which the herring, frequents i s roughly one-seventh that of the A t l a n t i c (35#<>). Si m i l a r l y the giant perch, Eat es c a l c a r i f e r . of the Indo-Pacific varies i n size i n the different regions (Roughley, 1953), but no records of the s a l i n i t i e s , temperatures, or the pro d u c t i v i t i e s of the waters i s given. Anadromous forms, that mature i n the sea, and t h e i r related forms that mature i n lakes present some v i v i d contrasts. Some of the forms, f o r which measurement data were available, have been included i n Table I. The sockeye TABLE I - S i z e s at maturity of marine, brackish and freshwater fishes SPECIES MARINE BRACKISH WATER PRESHWATER AUTHORITY Chanos chanos (milk f i s h ) 600 mm. - 1500 mm. Jordan and (Hawaian fresh Evermann, water ponds) 1903 1800 mm. (Gulf of Mannar, Munro, 1955 Indian Ocean) Over 1500 mm. Weber and (Indian Ocean) Beaufort, 1913 1500 mm. (Australian Rdughley, 1953 estuarine waters) 257 mm.1 403 mm.1 604 mm.1 Chidambaram (Krusadai, (Mandapam Camp, (Rameswaram, and Unny, India) India) India) 1943 Clupea harengus (Atlantic herring) 240 mm.-350 mm. 160 mm.-200 mm. Hodgson, 1934 (Atlantic) (Baltic) Clupea p a l l a s i ( P a c i f i c herring) 450 mm. Jordan and (Ca l i f o r n i a to Evermann, 1903 Alaska) Clemens and Wilby, 1949 1 - These measurements were taken only a f t e r one year's growth of the milk f i s h i n the various experimental ponds. TABLE I - continued. SPECIES MARINE BRACKISH WATER FRESHWATER AUTHORITY Lates c a l c a r i f e r (Giant perch) Salmo gairdneri gairdneri (Steelhead trout) 263 Kg. (Bay of Bengal) 1134 mm. ( B r i t i s h Columbia) 27 Kg. - 45 Kg. (Australian estuaries) 1500 mm. (Australian estuaries) Roughley, 1953 Munro, 1955 Clemens and Wilby, 1949 Salmo gairdneri kamloops (Kamloops trout) Oncorhynchus nerka nerka (Sockeye) 830 mm. ( B r i t i s h Columbia) 907 mm. ( B r i t i s h Columbia) Ca r l and Clemens, 1953 Carl and Clemens, 1953 i I Oncorhynchus nerka kennerlyi (Kokanee) 200 mm. - 402 mm. 160 mm. - 380 mm. 220 mm. - 410 mm. (Cultus Lake, B r i t i s h Columbia) Carl and Clemens, 1953 Ricker, i1940 2 - The maximum sizes on record. TABLE I - continued. SPECIES MARINE BRACKISH WATER FRESHWATER AUTHORITY Salmo salar 480 mm. (Atlantic salmon) (Nova Scotia) 350 mm. (Grand Lake, Nova Scotia) Wilder, 1947 Pomolobus pseudoharengus (Alewife) 258 mm. 145 mm. (Lake Ontario) Pritchard, 1929 Osmerus mordax (Smelt) 150 mm. - 250 mm. (New Brunswick) 150 mm. - 250 mm. McKenzie, 1941 Dymohd, 1944 Salvelinus f o n t i n a l i s (Eastern brook trout) 334 mm. (New Brunswick) 274 mm. (New Brunswick) Wilder, 1952 Coregonus , clupeaformis (Whitefish) 403 mm. - 466 mm. 1359 gm. - 1812 gm. 479 mm. 2038 gm. (Redberry Lake, Saskatchewan) 1132 gm. - 1585 gm. (Lake Winnipeg, Manitoba) Rawson, 1946 Rawsbn, 1946 Hinks, 1943 - 6 - salmon of the P a c i f i c coast Oncorhynchus nerka nerka and i t s non- migratory r e l a t i v e , given a subspecific status (Oncorhynchus nerka kennerlyi) form an i n t e r e s t i n g comparison. Ricker (1940) states that the only known morphological difference between these two forms i s the smaller average siz e , at maturity, of the non- migratory salmon. Non-migratory sockeye consist of two types - the residents or kokanee, the progeny of the lacustrine form and the "residual", the progeny of the migratory forms (Ricker, 1938). Both forms are d i s t i n c t l y smaller than the migratory sockeye, as w i l l be seen from the figures given i n Table I. The alewife, Pomolobus pseudoharengus and the Eastern brook trout, Salvelinus f o n t i n a l i s . are also smaller i n the fresh water environment. The two forms of trout, Salmo gairdneri. i n the two environs also show differences i n s i z e . These two forms of trout have been regarded as subspecies f o r convenience, but they do not have any r e a l morphological difference (Lindsey, 1956). The data on s i z e of Spring salmon i n New Zealand i s summarized i n Table I I . These data have been very kindly supplied by Dr. E. P e r c i v a l (1956). The difference between the average lengths of the sea-run Quinnat salmon and of the "land- f o T m locked" form ranges from 170 mm. to 400 mm. The sea-run^is comparable to that of the west coast of Canada. Johnsen (1944) mentions several species that vary i n size i n the di f f e r e n t North European waters - the 15-spined stickleback, Spinachia spinachia, two-spotted goby, Gobius flavescens. l a n t e r n f i s h , Myctophum g l a c i a l e . and p l a i c e Pleuronectes platessa. to mention a few, are some of the species that show great v a r i a t i o n i n the size at maturity. He states that when a species varies i n size within i t s habitat, i t usually finds the optimum conditions i n places where i t reaches the largest s i z e . Temperature and food are mentioned as the chief c o n t r o l l i n g factors but there i s no statement regarding the s a l i n i t y i n the d i f f e r e n t areas. For Instance, Myctophum gl a c i a l e i n the Mediterranean i s h a l f the size of that found TABLE II - Length and weight of spring salmon (Oncorhynchus tschawytscha) from New Zealand (data obtained from Dr. E. Percival) and B r i t i s h Columbia. "Type", Place Freshwater habitat "Landlocked", Quinnat salmon, Macdonald creek, Westland Date May, 1955 May, 1956 Average length mm. 569 546 Average weight gm. Sea-run f i s h Quinnat salmon - Waimakariri 1944 746 4800 " " - Opihi 1944 900 6000 Spring salmon - B r i t i s h Columbia 907 1 1 - Carl and Clemens, 1953. These salmon a t t a i n 1450 mm. and weights from 4500 gm. to 22,500 gm. on record. - 8 - i n the Norwegian waters. The difference i n the s a l i n i t y i n the two areas ranges from 5#« to 10$o (Sverdrup et_ a l , 1942). Pleuronectes platessa i n i t s fifth--year of growth ranges from 210 mm. to 400 mm. i n Iceland, hut only from 170 mm. to 280 mm. i n the West B a l t i c . In t h i s species-in the West B a l t i c , the size range i s generally smaller-for a l l the groups beyond the t h i r d year. The s a l i n i t y i n the West B a l t i c never exceeds 16$<> while i n Iceland i t i s about 35$° . Johnsen stresses only the variations i n the temperature and the nutrients i n these waters but never mentions the variations i n the s a l i n i t i e s . Hodgson (1934) on the other hand states- d e f i n i t e l y that the size v a r i a t i o n i n the A t l a n t i c herring i n the B a l t i c may be due to both temper- ature and s a l i n i t y . EXPERIMENTAL METHODS Details of the fish used in this experimental study are given in Table III. TABLE III - Pish used in experimental study. SPECIES SOURCE INITIAL SIZE (average) PREVIOUS HISTORY Oncorhynchus nerka (Sockeye) University hatchery. Eggs from Gultus lake, 2.78 cm. 0.207 gm. Eggs received 25th November, 1955. Oncorhynchus keta (Chum) Nanaimo Biological station. Eggs from Jones creek. 6.7 cm. Eggs received 12th November, 1955. 2.42 gm. Hatched January 2, 1956. Alevin began feeding February 18, 1956 - l iver four times a day. Were raised in salinity. One orhynchus kisutch CCoKo) 1st Series University hatchery. Eggs from Capilano river. 3.6 cm. 0.469 gm. Eggs received 25th November, 1955. Oncorhynchus kisutch 2nd Series 4.2 cm. 1.007 gm, Carassius Stouffville, auratus Ontario. (Goldfish) 8.4 cm. Received as adults and held at Univ- 12.07 gm. ersity hatchery for about two months. - 10 - Procedures The f i r s t series of coho and the sockeye were kept i n f i v e glass tanks (50.4 cm. x 27.7 cm. x 30.3 cm.)\ Two long tanks (181.5 cm. x 18.9 em. x 26.5 cm.) were used f o r the second series of coho and the chums occupied two tanks (45.5 cm. x 24 cm. x 20 cm.). The goldfish were kept i n two glass tanks (60.5 cm. x 45.5 cm. x 40 cm.). The three tanks of the f i r s t series of coho and the two tanks containing sockeye were placed i n a large metal trough, through which tap water was continuously c i r c u l a t e d . This maintained the temperature of the tanks at that of the tap water. A l l these tanks were subjected to the same v a r i a t i o n i n temperature. Temperature was thus maintained within a range Q tanks of 2 0 . The second series of coho tanks aid chuntywere s i m i l a r l y placed i n water baths so that each group compared was subject to the same v a r i a t i o n . Goldfish tanks were kept i n a room i n the laboratory and although the v a r i a t i o n i n temperature was greater (5 C°) i t was the same f o r both tanks. S a l i n i t i e s of 6#o, 12$ 0, 18$«, and 30%o were used i n the- experiment. These were prepared from sea water (taken from Burrard Inlet) supplied weekly i n large carboys. Each week a sample of the fresh sea water was t i t r a t e d by the modified Mohr method. At the beginning of the experiment the s a l i n i t y of the sea water ranged from 20$o to 22$° and during the l a s t few weeks i t was i n the neighbourhood of 28% o . Proportionate quantities of dechlorinated water were added to make up the various s a l i n i t y strengths 18%o and below, and sea s a l t was added to make up the 30$o strength. Samples from each tank were t i t r a t e d to v e r i f y the s a l i n i t y . A l l tanks were cleaned d a i l y by siphoning the faecal deposits and decomposing food from the bottom. Water i n a l l tanks was completely changed twice a week. There was no provision f o r the r e c i r c u l a t i o n of water. A steady flow of i r was maintained i n each tank. The long tanks had two a i r breakers placed at equal distances from the ends. - 11 - Diets The daily amount of food necessary for proper growth of fish was taken as 10$ of the body weight (Barrett and Hum, 1954). Several ingredients listed below were mixed in the proportions indicated to produce an acceptable and convenient diet. Canned salmon 60 gm Ground liver (beef) 25 gm Clark's trout food 12 gm Pablum (mixed cereal) .... 2. gm Brewers yeast 1 gm Pew drops of cod l iver o i l 100 gm. Clark's trout food is said to contain a l l the necessary ingredients for trout growth, but the salmon were unaccustomed to i t and did not take i t readily. The importance of vitamin B complex (Phillips, 1946) and vitamin A (Davis, 1927; Outsell, 1939; Phillips, 1940) in trout diet, has been stressed. Davis and Gutsell (1939) believe that cod l iver o i l in the diet was a successful method of including vitamin A but Phillip et a l (1940) maintain that the best source is beef-liver. The mixture, as given above, contained the essentials and since the fish fed well i t was used throughout the experiment. During the f irs t week of the experiment the proportions varied somewhat while the best formula was being developed. Since food was principally canned salmon i t was called "salmon paste". The ingredients listed above were mixed well and ground into a fine paste. Usually about two weeks supply was prepared at one time. The paste was spread in thin even layers and placed in the cooler part of a refrigerator to harden and desiccate quickly. The hardened paste may be broken up into fine particles or powdered depending on the size of fish to be fed. Small fish feed well only on finely ground particles. There are several advantages in using dried food. In an experiment of this type the amount of food fed is an important factor and dried food can be weighed accurately. The - 12 size of the food p a r t i c l e s can be selected to suit the size of the f i s h being fed. Young salmon and even goldf i s h show a preference f o r feeding on food p a r t i c l e s f l o a t i n g on the surface and dried food p a r t i c l e s f l o a t f o r sometime. Since very l i t t l e food sinks to the bottom the lo s s of food value due to leaching i s i n s i g n i f i c a n t , and po l l u t i o n of the tank due to decomposing food i s at a minimum. Feeding The t o t a l weight of each group of f i s h was recorded at the beginning and weekly thereafter. The quantity of dried salmon paste fed per day was equal to 10% of the body weight of the f i s h . "The foodfor each group was weighed separ- ately d a i l y and fed i n approximately equal amounts three times a day (8 a.m., 11 a.m., and- 2- p>. mv-)v During the f i r s t week much of the food was not consumed because the f i s h were frightened when the investigator approached the tanks. From the second week onwards they came to the surface and swam about a c t i v e l y u n t i l fed. Coates and Schwab (1956) report that f i s h tend to be healthier when given t h e i r natural food and that young salmon grew well on brine shrimp n a u p l i i . It was decided, therefore, to add l i v i n g brine shrimp n a u p l i i to the salmon paste d i e t . Brine shrimp eggs were hatched i n three-gallon glass jars under heavy aeration. Two and a-half gallons of water were added to each j a r . About one t h i r d of the volume was sea water and the s a l i n i t y made up to about 28%o by adding sea s a l t . One teaspoon of dried shrimp eggs was added to each j a r and the temperature was kept at about 29 C° u n t i l hatching was completed. Bach j a r was heated separately by placing a 75 watt flood l i g h t at a suitable distance from the j a r such that the temperature i n the j a r never exceeded 29 C° or dropped below 26 C°. Under these conditions i t took about two days f o r complete hatching and about 75% of n a u p l i i production was obtained. The n a u p l i i were separated by f i l t e r i n g through a piece of No. 9 bol t i n g s i l k - 13 - (6.5 em. diameter) stitched and sealed overr-ar p l a s t i c j a r . The brine shrimp n a u p l i i were fed to f i s h d a i l y at about 5 or-6 p.nr. Since i t was summer there was ample l i g h t f o r feeding. The chum tanks were i n a dark room and an automat- i c l i g h t i n g system was operated so that a l l had an equal amount of l i g h t . The amount of t h i s feed was proportional (by volume) to the weight of the groups of f i s h . The f i l t e r e d shrimps were washed with fresh water into a 250 ml. graduated cylinder. This was then shaken well and the proportionate volumes were quickly decanted into beakers and reehecked before introduction into the tanks. For instance, i f there were four tanks containing 10, 15, 10 and 15 grams of f i s h i n each, then they would receive 50, 75, 50 and 75 ml. of the brine shrimp n a u p l i i respectively. This was not considered a very accurate method, but the most conven- ient when i t i s remembered that the tiny shrimp n a u p l i i had to be a l i v e . According to Coates and Schwab (1956) the shrimp n a u p l i i l i v e f o r about twelve hours i n fresh water. An examin- ation of the water each morning showed complete absence of n a u p l i i - dead or a l i v e . Weighing the F i s h Fish were weighed at the s t a r t , and weekly thereafter u n t i l the termination of the experiment. Dip nets that f i t t e d the tanks were used t o scoop out the f i s h . In order to prevent them from unnecessary s t r a i n and exhaustion when out of water, a small canvas bag was f i t t e d i n the middle of the net. The f i s h were thus collected i n the bag which was f u l l of water, and transferred into a large beaker which was l i n e d with a p l a s t i c coated bag-net. The beaker with f i s h , water and the bag-net was weighed on a balance which had a s e n s i t i v i t y of 0.1 gnu The bag-net was then l i f t e d up to the edge of the beaker and held there f o r about f i v e seconds so that nearly a l l the water, except that adhering to the f i s h or held between f i s h , drained into the beaker. The f i s h were then quickly transferred - 14 - from the bag-net into t h e i r tank. The beaker, water and the bag-net were then weighed. The difference gave the weight of the f i s h . This method of weighing was checked with a group of f i f t y coho taken from the same stock as the one used i n the experiment. An error of only 0.5$ was found i n the. mean, when the highest or lowest weights were taken i n twenty five, attempts. With fewer f i s h i t was found that the error diminished, but d i d not drop below 0.2$. When chums were weighed singly an-error up to~5$ could be anticipated. - 15 - EXPERIMENTAL RESULTS A l l f i s h used i n the experiments were transferred d i r e c t l y from fresh water into the different s a l i n i t i e s up to 12$° . Coho transferred to 18$» were f i r s t kept i n lower concentrations f o r two days. The chums were not acclimatized since they were o r i g i n a l l y raised i n sea water of 20$ o s a l i n i t y . The detailed measurements of weight w i l l he found i n Appendices II - XIII. Results are summarized i n Figures 1 - 6. Sockeve i n fresh water and 6 $ o s a l i n i t y . (Appendices II and I I I , and Figures 1 and 6). These groups of f i s h showed a high mortality. The resul t s , however, show a marked weight increase i n the ten week period. In fresh water the mean weight at the beginning was 0.192 gm. f o r 69 f i s h , and at the end of f i v e weeks the average reached 0.560 gm. f o r the ten surviving f i s h . This gave a 192$ increase on the i n i t i a l average. At the end of the tenth week there were only 8 l e f t and the average weight was 0.806 gm., an increase of 320$. There was a better survival (35$) of sockeye f r y i n 6 $ o s a l i n i t y , although, during the f i r s t week the mortality was also high. The 138 available f r y were i n i t i a l l y divided equally by numbers and then weighed before being introduced into the tanks. The average i n i t i a l weight of f i s h i n 6$<> s a l i n i t y was s l i g h t l y higher than that of the f i s h used i n the fresh water tank. It will-be seen from Appendix I I I , that a f t e r f i v e weeks there was only a 117$ increase i n weight f o r the 24 f r y l e f t i n the 6$» s a l i n i t y tank which was much lower than the 192$ increase of sockeye i n fresh water f o r the same period. At the end of the ten weeks the percentage increase (336$) was s l i g h t l y higher than the 320$ increase of the fresh water ones (Fig. 6). The number of sockeye i n t h i s tank, a f t e r the f i r s t week, remained constant throughout the experimental period. - 16 - Figure 2 Mean weekly weight of coho series 1 and 2 i n fresh water and i n the various s a l i n i t i e s . - 18 - Figure 3 Mean weekly weight of chum i n 6$o and 3C>o s a l i n i t y . 19 * Coho - Series 1. (Appendices IV - VI, and Figures 2 and 6). Survival of coho i n the three tanks with 0 $ o , 6 $ o , and 12 $ o s a l i n i t i e s , was good, and the numbers remained constant a f t e r the second week. The i n i t i a l average weights of the 50 f i s h i n each tank were s i m i l a r . The percentage increase was highest i n the 12$° s a l i n i t y tank at both stages (end of the f i f t h and the tenth weeks). The percentage increase-on the i n i t i a l average weights i n the 0 $ o , 6$° , and 12$° s a l i n i t i e s at the end of the f i f t h and tenth weeks were 77.2, 88.1, 155.8, and 215.1, 251.2, 421.5 respectively. Coho - Series 2. (Appendices VII and VIII, and Figures 2 and 6). The second series of coho was used, mainly, to observe the effect of a higher concentration (18$<> ) of s a l i n i t y . Since these coho had a higher i n i t i a l average weight t h e i r weight increase was compared with another group, from the same stock, i n fresh water. Again the coho survived well. The average i n i t i a l weight i n each tank (0$° and 18$o s a l i n i t y ) was a l i t t l e over twice that of the average i n i t i a l weight of series 1. The per- centage increase was again greater i n the 1 8 $ o s a l i n i t y . F i s h were not kept i n s a l i n i t i e s higher than 18$o owing to the reported high mor t a l i t i e s i n f r y and f i n g e r l i n g s experienced by other workers (Black, 1951). Chum. (Appendices IX - XI, and Figures 3, 4, and 6). In t h i s experiment the f i s h i n 30$o s a l i n i t y f a i l e d to survive a f t e r the f i f t h week. This i s hot attributed to the s a l i n i t y since the experimental conditions f o r t h i s group of f i s h were f a r from i d e a l (because of the small size of the tanks). The percentage increase at the end of t h i s period was 166 f o r 11 f i s h , as compared with 120 f o r eight f i s h i n 6$» . s a l i n i t y . These f i s h were active and fed well throughout the experiment. The precise cause of death of the chum i n 30$* s a l i n i t y tank was not known. - 20 - Figure 4. Percentage increase i n weight of individual chum i n 6$c and 30$• s a l i n i t y . Groups A to B represent pairs of chum of approximately similar weights at beginning of experiment. - 21 - With the remaining ehum (2 i n 30$° s a l i n i t y and 8 i n 6$« s a l i n i t y ) i n the two tanks, another experiment was begun, where ind i v i d u a l weights were recorded and f i s h ident- i f i e d by c l i p p i n g the f i n s . Three f i s h were taken from the lower s a l i n i t y tank and acclimatized i n s a l i n i t i e s of 10$° , 18$o , and 25$° , (two days each) before being introduced into 30$° s a l i n i t y . The f i s h were selected so that t h e i r weights i n each p a i r (the one i n the 6$° s a l i n i t y and the corresponding one i n the 30$° s a l i n i t y ) were s i m i l a r . For the second time the f i s h i n 30$« s a l i n i t y died a f t e r the t h i r d week, three f i s h died i n the fourth week i n the 6$° s a l i n i t y tank. This experiment was discontinued a f t e r the t h i r d week. Even during t h i s short period each of the f i v e f i s h in-3©$" s a l i n i t y showed an increase i n weight over that of each of the corresponding f i v e f i s h i n 6$° s a l i n i t y (Pig. 4). Goldfish. (Appendices XII and XIII, and Figures 5 and 6). Goldfish were used primarily to test the effect of s a l i n i t y on a purely fresh water type. Comparison of growth was made only i n fresh water and 6$» s a l i n i t y , since higher s a l i n i t i e s are l e t h a l . Pora (1939) observed that gol d f i s h were able to l i v e i n half sea water (about 12$° - 16$° ) f o r only a week or so. The 15 f i s h i n each of the two tanks were mature and any appreciable increase i n growth was not anticipated. At the end of the f i f t h week the percentage increase i n fresh water was s l i g h t l y higher, but at the end of the tenth week the ones i n 6$° s a l i n i t y showed a very small increment over that of the fresh water group. - 22 - W E E K S i I . . . Figure 5. Mean weekly weight of adult goldfish i n fresh water and 6$« s a l i n i t y . 4 5 0 n 5 1 0 5 1 0 5 1 0 5 1 0 5 W E E K S Figure 6. Percentage increase in weight of a l l groups in. fresh water and i n the various s a l i n i t i e s , at five and ten weeks. A - Sockeye; B - Coho series 1; B-, - Coho series 2; C - Goldfish; D - Chum. - 24 - SUMMARY OF EXPERIMENTAL RESULTS In a l l the groups of f i s h there was an appreciable increase but those i n 6$o , 12$o , 18$ 0 , or 30$o s a l i n i t y showed greater increase than the corresponding ones i n fresh""water. Even i n the case of g o l d f i s h there was a very s l i g h t increase shown by the group i n 6$o s a l i n i t y . The h i s t o - gram (Fig. 6) shows the growth attained during the two. periods (5 and 10 weeks) of the experiment, f o r a l l the groups. Up to f i v e weeks sockeye and goldf i s h grew better i n fresh water. In chum and i n both series of coho, increased s a l i n i t i e s were associated with greater percentage weight increase. There were two instances where the fresh water groups indicated better growth at the half-time period of the experiment. In the f i r s t case, the sockeye i n 6$° s a l i n i t y grew poorly at the beginning, but a f t e r the f i f t h week began to grow rapidly, and even surpassed that of the sockeye i n fresh water. The growth increment i n goldfish p a r a l l e l e d that of the sockeye. The f i n a l increments of these two groups i n the saline medium were too small to make any statement regarding the s u i t - a b i l i t y of the medium i n promoting better growth. The experiment, with the i n d i v i d u a l weights of the chum salmon, was encouraging, but unfortunately the f i s h did not survive a f t e r the t h i r d week. The growth increase of chum i n 30$o s a l i n i t y , within t h i s short period, seems s t r i k i n g (Fig. 4). Growth curves (Figs. 1, 2, 3, and 5) f o r the various series show many int e r e s t i n g features. Only i n the case of goldfish do the growth curves (Fig. 5) tend to run p a r a l l e l to each other. The i n i t i a l weight of the chum used i n the experiments was much higher- than that of the other two species and the growth eurves (Fig. 3) show the greatest increase within the time period. The curves (Fig. 2) f o r the fresh water groups of the two series of coho run almost p a r a l l e l . The curves - 25 - within the series deviate markedly. In sockeye the growth curves (Pig. l ) do not deviate u n t i l a f t e r the eighth week. The increase i n growth i n 6$o s a l i n i t y i s quite sharp i n the l a s t two weeks of the experimental period. - 26 - DISCUSSION Environmental E f f e c t On Growth. The growth of f i s h i s governed by two main factors - heredity and environment. Inherent characters are influenced to a marked extent by favourable or unfavourable environmental features, p a r t i c u l a r l y i n the early stages of growth. These effects may be s u p e r f i c i a l (e.g. colour) or deep seated (e.g. changes i n meristic counts and s i z e ) . Of the influencing environmental factors, temperature, s a l i n i t y and the food supply are some of the most important. Meristic Changes. Al t e r a t i o n i n meristic counts i n the embryo, effected by v a r i a t i o n i n environmental factors, produce v a r i a t i o n i n the size at hatching, and consequently change the rate of growth i n l a t e r l i f e . Several investigators have shown that changes i n temperature and s a l i n i t y may increase or decrease the number of vertebrae or f i n rays i n many species of f i s h . Schmidt (1919) studied the effect of high temperatures during development of the young of guppy, Lebistes reticulatus« and concluded that a higher number of f i n rays were produced. Taning (1952) found, i n experiments on sea-trout, Salmo t r u t t a , that the number of dorsal, anal, and pectoral f i n rays were greatest at intermediate temper- atures. Higher or lower temperatures decreased the number. Increase i n number of vertebrae i n several species of f i s h have been reported i n many experimental r e s u l t s . Hubbs (1921) on cabezon, Leptocottus armatus. Schmidt (1930) on A t l a n t i c cod, Gadus c a l l a r i a s . and Sund (1943) on Norwegian herring, Clupea harengus. to mention but a few, have a l l indicated that lower temperatures tend to produce higher vert- ebral counts. The a l t e r a t i o n i n the number of vertebrae i n Salmo t r u t t a i s effected well before hatching as shown by Taning (1944, 1946). l i k e temperature, s a l i n i t y too a l t e r s the meristic characters of f i s h e s . Heuts (1947) l i s t e d several species i n which s a l i n i t y probably produces higher vertebral counts. Schmidt's (1917, 1920) experimental work with viviparous blenny, Zoarces viviparous. indicated that not only low water temperat- ures and high s a l i n i t i e s produce high numbers of vertebrae, hut also high s a l i n i t i e s alone bring about the same eff e c t , lindsey (1952) studied the e f f e c t s of s a l i n i t y on vertebral count i n the three-spined stickleback, G-asterosteus aculeatus. and found that a f t e r making adjustments according to parental influence (hereditary), a r i s e i n s a l i n i t y at 16 C° or 18 C G produced an increase i n vertebral count., while a r i s e at 12 C° produced a decrease. The o v e r a l l effect of the environment on taxonomie characters of f i s h e s has been reviewed by Vladykov (1934). He states that low temperatures, large space or area of habitat, or high degree of s a l i n i t y i n a given area are each correlated with a high number of segments and t h e i r components. The characters considered were vertebrae, scales, median f i n s , g i l l rakers and body proportions, and of these the least affected by temperature was vertebrae. He also states that the number of segments decrease from north to south i n the Northern Hemisphere, from s a l t water to fresh water, from open to closed areas, from o f f - shore to inshore and from r i v e r s to brooks. These changes, although small, could ce r t a i n l y a f f e c t the growth and size of fishes i n the e a r l y stages. Body Proportions. The r e l a t i v e growth of f i s h e s i s characterized by a series of stanzas and each stanza has a d i f f e r e n t growth constant. The change from one stanza to another i s quite abrupt and i s known as an i n f l e c t i o n . Martin (1949) demonstrated that the differences i n developmental rate i n iLshes, when controlled by temperature or by di e t , could produce differences i n body form. He also found experimentally that the length-weight relationship i n trout could be a l t e r e d under d i f f e r e n t temper- ature conditions. By increasing temperature the length of trout - 28 f r y was increased, and t h i s increased size at growth i n f l e c t i o n altered the r e l a t i v e growth i n weight. His experimental evidence supports the theory that differences i n body form may be effected by differences i n body size at growth i n f l e c t i o n . Small d i f f e r - ences i n the early stages of development w i l l probably produce large differences i n body form i n l a t e r l i f e . Growth and Size of Pishes of d i f f e r e n t species i n dif f e r e n t environments has been the subject of study by many investigators. In the l i t e r a t u r e , the main items considered have been temperature and food. Pew workers have t r i e d to determine the s a l i n i t y effect on growth and s i z e . Gibson and H i r s t (1955) state that an isotonic solution (physiologically saline solution) produces better growth than fresh water i n the pre-adult l i f e of guppies. In t h e i r experiments they raised guppies i n fresh water f o r an average period of ten-weeks or u n t i l mature, at various temperatures and found that the fastest growth occurred-at 23 C° and 25 C°. Above and below these l i m i t s the growth was slow. Guppies i n 25$ sea water and at 30 0° surpassed the growth rate of the fresh water f i s h at 25 0° during a period of sixt y to eighty days ©f age. The fastest growth they have on record occurred at 23 C° and 25$ sea water. The f i s h also flourished i n 50$ sea water and 20 C° or 25 C°. The growth curve f o r the one at 20 G° and 50$ sea water was steeper than that f o r 25$ sea water and the same temperature. They state that t h i s difference may be genetic. Since the investigators discontinued the experiments as soon as the males were mature, there i s no experimental evidence to show that sea water enhances the size of adult f i s h or ultimate s i z e . Nevertheless, there i s the p o s s i b i l i t y of obtaining l a r g e r guppies i n the optimum sea water medium. Pish culture experiments carried out i n India with the milk f i s h , Chanos chanos. demonstrate that food i s the most important factor governing growth.' Chidambaram and Unny (1946) report that t h e i r experiments with these f i s h , which are marine forms entering estuaries to spawn, indicated best growth - 29 - i n fresh water. Chanos fi n g e r l i n g s (7 mm. to 8.5 mm.) were raised i n three tanks, one with fresh water, one with brackish water and the t h i r d with sea water. The growth of these f i s h was observed f o r a period of one year. Since the growth recorded (Table I) indicated progressive decrease with increasing s a l i n i t y , an analysis of the plankton i n a l l tanks was carried out. The sea water pond was the poorest i n plankton, and especially i n algae which i s the main diet of these f i s h . From a l l t h i s evidence they concluded that the best growth i n Chancre f i n g e r - - l i n g s was produced by fresh water. It i s rather d i f f i c u l t to accept such a statement, unless i t could be proved that the sea water does not support a good growth of the algae, the most essential constituent of the diet of the f i s h . Chanos spawns i n estuaries or lagoons and the f r y enter mouths of r i v e r s or streams. Fry are often trapped by high tides i n stagnant pools, where they may grow to a moderate si z e , depending larg e l y on the size of the pool, the amount of water and the food available. They never mature sexually i n fresh water. In Hawaii and some South East Asian countries where an extensive programme f o r f i s h culture i s i n progress, these f r y are raised i n fresh water ponds. The lengths attained vary, but never equal those captured i n the sea (Table I ) . Introduction of fresh water whitefish - Coregonus clupeaformis - i n 1940 into a saline lake of Saskatchewan (which contained no f i s h ) , resulted i n a small commercial fi s h e r y i n 1945 (Rawson, 1946). The s a l i n i t y of the lake was 15$« . The pote n t i a l f i s h food supply was of the same order as that i n larger fresh water lakes where whitefish are produced i n large quantities. Whitefish were introduced as f r y , and a f t e r four years measured from 403 mm. - 466 mm. and weighed 1359 gm. - 1812 gm. (Table I ) . This shows a rate of growth twice that of the same species i n fresh water, as i n Lake Winnipeg or the Great Lakes (Rawson, 1946). Hinks (1943) states that i n Mani- toba commercial catches, the average weight of whitefish i s within the range 1130 gm. - 1585 gm. and the bulk of the f i s h so caught are 6 - 8 years old. - 30 - Aim (1934) states that those A t l a n t i c salmon which never enter the sea do not show the same growth as those that go to sea, although they have equally good feeding cond- i t i o n s . Salmon i n the B a l t i c precincts show a preference f o r the southern waters. Aim (1934) assumes that the warmer waters and higher s a l i n i t i e s of the southern B a l t i c are b e n e f i c i a l and hence the smolts from the northern r i v e r s concentrate i n t h i s region. The s a l i n i t y here ranges from 8 $ o to 10$. i n the surface and from 15$<> to 20$0 i n the deeper parts, whereas the northern part of the B a l t i c never exceeds 3.5$<> • The temperature too increases southwards. The records of the sizes of salmon i n the various parts of the B a l t i c show considerable differences (Dixon, 1934). Fi s h retained i n fresh water were smaller than those normally migrating to sea. Fraser (1918) reared sockeye salmon i n fresh water and compared them with sea-run f i s h of the Fraser r i v e r . The fresh water forms reached an average length of 250 mm. while the sea-run averaged 566 mm. The growth i n the f i r s t year i n both cases was very nearly the same, but i n the second, t h i r d , and fourth years there was almost a three-fold difference i n the sea-run form. Foerster (1947) showed experimentally that offspring of non-migratory sockeye or kokanee i n Cultus lake, B r i t i s h Col- umbia, would grow to the same siz e as that of the sea-run f i s h from the same lake, i f they had the opportunity of going to sea as smolts. He li b e r a t e d 63,874 yearlings of kokanee, a f t e r c l i p p i n g the p e l v i c s , along with the normal sockeye seaward migrants. In the f i f t h year 25 individuals, with the pelvics o f f , were taken i n the commercial fishery (34$ of which was sampled). The lengths of those recovered were larger than the normal four year old Cultus sockeye but well within the range of the f i v e year olds. This experiment demonstrated that the size difference i n the sockeye and kokanee could not be hereditary, but probably environmental. 1 - 31 - S a l i n i t y and Size, Changes i n s a l i n i t y not only"affects the growth and size of fishes bat also that of other organisms. Ekman (1935) states that the B a l t i c was formerly 5$<> more saline than at present. This was supported by a study of the then inner l i m i t s of d i s t r i b u t i o n of certain molluscs, especially L i t t o r i n a . I t was during the l i t t o r i n a stage of the B a l t i c that the sizes of the molluscs Cardium edule and Mytilus edulis were larger than at present and i n the same l o c a l i t y . Sverdrup et a l (1942) state that among the euryhaline animals, those l i v i n g i n reduced s a l i n i t i e s have a smaller maximum size than those of the same species inhabiting higher s a l i n i t i e s . Reduced size may result from the scarcity of food organisms, which must be adapted to l i v e i n or near the same biotope. These authors state "whatever the cause may be, i t should be noted here that i t i s a strange and unexplained fact that with few exceptions marine animals from groups with fresh water representatives are larg e r than the fresh water r e l a t i v e s and usually the size difference i s enormous". - 32 P h y s i o l o g i c a l Mechanisms Responsible F o r Growth. The present experimental r e s u l t s show a tendency f o r b e t t e r growth i n j u v e n i l e salmon s p e c i e s i n the s a l i n i t i e s used. F a c t o r s such as food, temperature, volume of water and a e r a t i o n were c o n t r o l l e d c a r e f u l l y , so t h a t the only v a r i a b l e was the s a l i n i t y of the medium. Although the causes f o r the d i f f e r e n c e s i n s i z e were not i n v e s t i g a t e d i n t h i s p r o j e c t , some s p e c u l a t i o n i s perhaps p e r m i s s i b l e . Osmotic S t r e s s . I t has been suggested t h a t the f r e s h water f i s h must expend energy i n combating the e f f e c t s of the hypotonic medium i n order t o maintain an osmotic e q u i l i b r i u m . Experiment- a l evidence to date i s c i r c u m s t a n t i a l but the passage of l a r g e amounts of water through t i s s u e s might c r e a t e e x t r a demands e i t h e r on kidney or s a l t a b sorbing mechanism. E x t e n s i v e experimental work has been conducted to a s c e r t a i n the s p e c i f i c b i o l o g i c a l e f f e c t or f u n c t i o n of the v a r i o u s i o n s i n sea-water. The f u n c t i o n of the s a l t s i n sea water cannot be e n t i r e l y ; r e l a t e d t o osmotic pressure c o n t r o l , s i n c e i n many i n s t a n c e s and p a r t i c u l a r l y i n f i s h e s , t h e y are not i s o t o n i c w i t h sea water (Baldwin, 1949). Many i n l a n d l a k e s have s u f f i c i e n t c o n c e n t r a t - i o n s of v a r i o u s s a l t s t o m a i n t a i n s u i t a b l e osmotic pressure f o r marine organisms, but l a c k c e r t a i n e s s e n t i a l s a l t s and-are, t h e r e f o r e , not conducive to s u p p o r t i n g marine l i f e * Endocrine F u n c t i o n . Hormonal c o n t r o l of the metabolie a c t i v i t i e s may be one e x p l a n a t i o n of the i n f l u e n c e of s a l i n i t y on growth. Rate of r e s p i r a t i o n , maintainance of osmotic e q u i l i b r i u m , or water balance, changes i n . e x t e r n a l appearance before m i g r a t i o n , and maturity,-are: a l l , . : , i n - one~way~~or - another, r e l a t e d to changes in' a c t i v i t y of the endocrine system. The p i t u i t a r y and t h y r o i d glands are important endocrines i n c o n t r o l l i n g growth o r metabolism. T h e i r r o l e i n mammals and amphibians i s w e l l known and i c t h y o l o g i s t s have spec u l a t e d on the p o s s i b i l i t y o f e x p l a i n i n g the changes i n met- abolism i n f i s h through the a c t i v i t y of the t h y r o i d . - 33 - The f i r s t contribution to our knowledge of the p i t u i t a r y growth hormone i n r e l a t i o n to the growth of f i s h was made by Pickford-and Thompson (1948). They observed that the growth of mimmiehog. Pundulus heteroclitus. was accelerated a f t e r p u r i f i e d mammalian growth hormone was administered i n t r a - peritoneally. Hoar (1951) suggests that t h i s treatment could have produced stimulation of the thyroid gland which may have been responsible f o r the observed e f f e c t . Growth stimulation i n f i s h was observed as a result either of feeding powdered p i t u i t - ary gland (Regnier, 1938), or i n j e c t i n g the extract (Nixo- Nicoscio, 1940). However, these results are not necessarily attributable to the isola t e d effect of the growth promoting hormone, since i n the f i r s t case the effect may be dietary, and i n the second the extract may have included several hormones. Indirect tests f o r the function of the thyroid and i t s part i n the growth of fis h e s has been attempted by many investigators. Thiourea, an anti-thyroid chemical, was used to assess the d i f f i e i e n c e s that develop i n f i s h . Goldsmith et a l (1944) and N i g r e l l i et a l (1946), have both reported that thiourea i n h i b i t s the formation of thyroid hormone as well as producing reduced growth i n the hybrid Platypoecilus-Xiphor- phorus. This observation was also made i n the P a c i f i c salmon (Hoar and B e l l , 1950). Thyroid hormone administration has been used to study changes i n growth rate, sexual maturation, oxygen consumption in- r e s p i r a t i o n , and i n migration behaviour. Smith and Everett (1943) pointed out a f t e r experimenting on Lebistes reticulatus that thyroxine does not always produce growth acceleration i n f i s h . They also concluded that i t i s not possible to consider thyroxine as a s p e c i f i c growth promoting fac t o r i n f i s h as i s the p i t u i t a r y growth hormone f o r the mammals. Hoar (1951)» i n an exhaustive review of the hormones i n f i s h , lays emphasis on the fact that, although p i t u i t a r y growth hormone has not been conclusively demonstrated, there i s much evidence to support the b e l i e f that the thyroid - 34 - gland i s related to growth of f i s h , and that a thyrotropic hormone i s produced by the p i t u i t a r y . S a l i n i t y and Thyroid A c t i v i t y . There i s some evidence suggest- ing that thyroid hormone i s related to osmoregulation and growth of f i s h . Olivereau (1948) found that when a marine f i s h i s placed i n d i l u t e sea water there i s an Increase i n thyroid a c t i v i t y . Hoar and B e l l (1950), showed that i f anadromous f i s h were retained i n fresh water a f t e r t h e i r natural seaward migration time, they developed hyperplastic thyroids. The importance of iodine f o r thyroid a c t i v i t y i s well known and i t may be that those forms that could l i v e i n sea water had the added advantage of having a copious supply of t h i s element to b u i l d up s u f f i c i e n t supplies of the hormone f o r growth. In fresh water, osmoregulation i s more d i f f i - c u l t and i t has been shown to be r e l a t e d to the supply of thyroid hormone (Black, 1951b). Smith's (1956) study on trout indicated a f a l l i n thyroid a c t i v i t y with increase i n s a l i n i t y and i n j e c t i o n of thyroxine raised the s a l i n i t y tolerance. When thiourea and t h i o u r a c i l were administered the s a l i n i t y tolerance was reduced i n trout. Hoar (1952) suggests that when both osmoregulation and growth are dependent on the a v a i l a b i l i t y of thyroid hormone, and when the supply i s inadequate, growth Is probably reduced. Fontaine (1956) states that much of the work done i n t h i s f i e l d i s s t i l l inconclusive and that the suggestions made by Hoar (1952) are very a t t r a c t i v e i n not only attempting to explain t h i s altogether hazy phenomenon, but also i n d i c a t i n g some l i n e s of research that may be f r u i t f u l . Another observation made i n the present experiment i s worth mentioning. The growth increase i n sea water was delayed i n the case of the sockeye. This species spends one, two or three years i n fresh water before i t s seaward migration. The growth difference of the experimental f i s h reared i n f r e s h and sea water was i n s i g n i f i c a n t . Coho go to sea a f t e r a year i n fresh water (Carl and Clemens, 1953) and i n the case of the chum almost immediately a f t e r emerging from the gravel. These two - 35 - species survived better and grew better i n the various concentrations of sea water. Since sockeye spend a longer period i n fresh water, the physiological adjustments necessary f o r l i f e i n sea water are delayed. The retarded growth of sockeye observed i n the saline medium ( 6 $ o s a l i n i t y ) during the f i r s t eight weeks of the experiment, was probably due to the f a i l u r e of the physiological mechanisms^ to respond to the hypertonic medium. However, these sockeye f r y , i n 6%o s a l i n i t y , showed a marked increase i n growth during the l a s t two weeks. The results of t h i s experiment show that s a l i n - i t y alone may bring about a difference i n growth rate and s i z e . Data taken from records of sizes of some fishes also show that those i n sea water grow to a greater s i z e . These indicate that there must be -some factor or combination of factors i n sea water- that contributes to t h i s enhanced growth. Several environmental factors and t h e i r influence on the growth of fishes either on the whole animal or on some parts have been discussed. It i s yet to be seen whether the thyroid controls f u l l y the metabolism of f i s h and to what extent i t may do so i n the fresh water and marine environments. Study of hormonal control of growth should be a productive f i e l d of investigation that may throw l i g h t on t h i s phenomenon of s a l i n i t y and growth of f i s h . - 36 - SUMMARY 1. In the l i t e r a t u r e , records of the sizes attained at maturity by several species of f i s h , inhabiting both sea and fresh waters, indicate that the marine environment promotes better growth. 2. The experiments on growth of juvenile salmon indicate better growth i n sea water and p a r t i c u l a r l y i n the higher s a l i n i t i e s used. 3. Sockeye i n 6$o s a l i n i t y showed only a very s l i g h t increase i n weight, over that of the fresh water group. Growth i n t h i s saline medium was retarded during the f i r s t eight weeks of the experiment and t h i s i s probably due to the longer fresh water l i f e of t h i s species. 4. The best increase i n weight of the coho was obtained -in 12$o s a l i n i t y . 5. Ghum showed good growth i n both 6$o and 30$ o s a l i n i t i e s , but the percentage weight increase i n the l a t t e r medium was better. 6. Goldfish did not show any s i g n i f i c a n t difference i n weight increase i n the two media. 7. The effect of different environmental factors on growth of f i s h has been studied experimentally by several investigators, and t h e i r evidence shows that the a l t e r a t i o n i n meristic counts or body proportions, i n early development, produces diff e r e n t growth rates i n the successive stages of l a t e r l i f e , and consequently affects the ultimate s i z e . 8. The physiological mechanisms of growth of fishes are not well known. The influence of hormones on growth i s probably ameliorated i n sea water. LITERATURE CITED Aim, G-. 1934. Salmon In the B a l t i c precincts. Rapp. Cons. Expl. Mer. 92: 1-63. Baldwin, E. 1949. An Introduction to Comparative Biochemistry. 3rd Ed. University Press Cambridge. Barrett, I., and Hum, D.R. 1954. - A- manual of game f i s h culture f o r use i n B r i t i s h Columbia trout hatcheries. B r i t i s h Columbia Game Dept. Mimeo.40pp. Black, T.S'. 1951a. Changes i n body chloride, density, and water content of chum (Oncorhynchus keta) and coho (0. kisutch) salmon f r y when transferred from fresh water to sea water. J . Pish. Res. Bd. Can. 8: 164-177. Black, T.S. 1951b. Some aspects of the physiology of f i s h . I. Osmotic regulation i n teleost f i s h e s . Univ. Toronto Stud. B i o l . Ser. No. 59. Pub. Ont. Pish. Res. Lab. 71: 53-89. CarV G.C., and Clemens, W.A. 1953. The fresh water fishes of B r i t i s h Columbia. B r i t i s h Columbia Prov. Mus. No. 5, 136pp. Chidambaram, K., and Unny, M.M. 1946. Tariati o n i n the rate of growth of the m i l k - f i s h (Chanos chanos). Nature 157?375• Clemens, W.A., and Wilby, G.T. 1949. Pishes of the P a c i f i c coast of Canada. B u l l . Pish. Res. Bd. Can. No. 68:368pp. Coates, J.A., and Schwab, R.L. 1956. Brine shrimp feeding experiments. Prog. Report Washington Dept. of Pish. Mimeo. 7pp. Davis, H.S. 1927. Some feeding experiments with trout f i n g e r l i n g s . Trans. Amer. Pish. Soc. 57: 281-285; Dixon, B. 1934. The age and growth of salmon caught i n the Polish B a l t i c i n the years 1931 - 33. J . Cons. Expl. Mer. 9: 66-78. Dymond, J.R. 1944. Spread of the smelt (Qsmerus mordax) i n the Canadian waters of the Great Lakes. Can. F i e l d - Nat. 58: 12-14. Ekman, Sven. 1935. Tiergeographic des Meeres. Akad. Terlagsgesellsh. M.B.H., Liepzig. 542pp. Poerster, R.E. 1947. Experiment to develop sea-run from landlocked sockeye salmon (Oneorhynehus nerka kennerlyi). J . Pish. Res. Bd. Can. 7: 88-93. - 38 - Fontaine, M. 1956. The hormonal control of water and s a l t - e l e ctrolyte metabolism i n f i s h . Mem. Soc. Endocrinol. No. 5: 69-82. Eraser, C.McL. 1918. Rearing sockeye salmon i n fresh water. Contrib. Can. B i o l . 1917 - 1918: 105-109. Gibson, M.B., and H i r s t , B. 1955. The effect of s a l i n i t y and temperature on the pre-adult growth of guppies. Copeia No. 3: 241-243. Goldsmith, E.D., N i g r e l l i , R.E., Gordon, A.S., Charipper, H.A,, and Gordon, M. 1944. Effe c t of thiourea on f i s h development. Endocrinol. 35: 132-134. Outsell, J.S. 1939. Pingerling trout feeding experiments, leetown 1938. Prog. Fish-Cult. No. 45: 32-41. Heuts, M.J. 1947. The phenotypical v a r i a b i l i t y of Gasterosteus aculeatus L. populations i n Belgium. Meded. vlaamsche Acad. K l . Wet. 9: 5-63. Hinks, D. 1943. The fishes of Manitoba. 102pp. Hoar, W.S. 1951. Some aspects of the physiology of f i s h . I. Hormones i n f i s h . Univ. Toronto Stud. B i o l . No. 59. Pub. Ont. Fish . Res. Lab. 71: 1-51. Hoar, W.S. 1952. Thyroid function i n some anadromous and land- locked t e l e o s t s . Trans. Roy. Soc. Can. 46: 39-53. Hoar, W.S. 1956. The hormonal control of water and s a l t - e l e ctrolyte metabolism i n f i s h . Mem. Soc. Endocrinol. No. 5: 69-82. Hoar, W.S., and B e l l , G.M. 1950. The thyroid gland i n r e l a t i o n to the seaward migration of P a c i f i c salmon. Can. Res. D. 28: 126-136. Hodgson, W.C. 1934. The Natural History of the herring of the southern North Sea. Arnold London. 120pp. Hubbs, C.L. 1921. L a t i t u d i n a l v a r i a t i o n i n the number of v e r t i c a l fin-rays i n Leptocottus armatus. Occ. Pap. Mus. Zool. Univ. Mich. 94: 1 -7 . Johnsen, S. 1944. Studies on v a r i a t i o n i n f i s h i n north European waters. I. Variations i n si z e . Bergens. Mus. Arbok. 1944 (4) 1945: 3-129. Jordon, D.S. and Evermann, B.W. 1903. American Food and Game Fishes. New York. 572pp. - 39 - Lindsey, C.C. 1952. Environmental determination of the number of teleost f i n rays. Ph.D. Thesis. Cambridge University. Lindsey, C.C. 1956. Recommended common and s c i e n t i f i c names of B r i t i s h Columbia fresh water f i s h e s . Pish. Management Div. B r i t i s h Columbia Game Commission. Mimeo. 26pp. Martin, W.R. 1949. The mechanics of environmental control of body form i n fi s h e s . Univ. Toronto Studies, B i o l . No. 58, Pub. Ont. Pish. Res. Lab. 70: 5-76. McKenzie, R.A. 1946. The smelt fishery of northeastern New Brunswick. B u l l . Pish. Res. Bd. Can. 70: 1-20. Munro, I.S.R. 1955. The marine and fresh water fishes of Ceylon. Dept. of Ext. A f f a i r s . Canberra, A u s t r a l i a . 351pp. N i g r e l l i , R.F., Goldsmith, E.D., and Charipper, H.A. 1946. Effects of mammalian thyroid powder on growth and maturation of thiourea-treated f i s h e s . Anat. Rec. 94:79. Nixo-Nieoscio, N.V. 1940. The influence of hormones on growth i n f i s h . Proc. Moscow Zool. Park 1: 178-184. Olivereau, M. 1948. Influence d'une dimunition de s a l i n i t e sur l a a c t i v i t e de l a glande Thyroide de deu Teleosteens marins Muraena helena. CR. Soc. B i o l . Paris. 142: 176-177. Per c i v a l , E. 1956. Letter to Dr. W.S. Hoar, 9th Sept. 1956 (Copy i n Appendix I ) . P h i l l i p s , A.M. 1946. Vitamin B requirements f o r trout. Trans. Amer. Pish. Soc. 76: 34-45. P h i l l i p s , A.M., Tunison, A.V., Penn, A.H., M i t c h e l l , CR., and McCay, CM. 1940. Cortland hatchery report, N.Y. Cons. Dept., No. 9: 9-14. Pickford, G.E., and Thompson, E.P. 1948. The effect of p u r i f i e d mammalian hormone on the k i l l i f i s h (Fundulus heteroclistus (Linn.)). J . Exp. Zool. 109: 367-384. Pora, E.A. 1939. Sur l'adaptation d*un teleosteen dulcaquicole, Carassius carassius L., au mili e u s a l i n . B u l l . Soc. S t i . C l u j . , 9: 384-393. Pritchard, A.L. 1929. The alewife (Pomolobus pseudoharengus) i n Lake Ontario. Univ. Toronto Stud. B i o l . Ser. 33. Pub. Ont. Pish. Res. Lab. No. 38: 39-54. Rawson, D.S. 1946. Successful introduction of f i s h i n a large saline lake. Can. Pish C u l t u r i s t , Nov. 1946: 5-8. - 40 - Regnier, M.T. 1938. Contribution a 1'etude de l a sexualite' des Cyprinidontes vivipares (Xiphophorus h e l l e r i . Lebistes r e t i c u l a t u s ) . B u l l . B i o l . France-Belg. 72: 385-493. Ricker, W.E. 1938. "Residual" and kokanee salmon i n Cultus lake. J . Pish. Res. Bd. Can. 4: 192-218. Ricker, W.E. 1940. On the o r i g i n of the kokanee, a fresh water type of sockeye salmon. Trans. Roy. Soc. Can. 34: 121-135. Roughlfy, T.C. 1953. Pish and Fisheries of A u s t r a l i a , Sidney, 343pp. Schmidt, Johs. 1917. Racial investigations I. Zoarces viviparous and l o c a l races of same. Compt. Rend. Lab. Carlsberg. 13(3): 279-397. ' -Schmidt, Johs. 1919. Racial investigations I I I . Experiments with Lebistes reticulatus (Peters) Regan. Compt-Rend. Lab. Carlsberg. 14(5): 1-8. Schmidt, Johs. 1920. Racial investigations V. Experimental investigations with Zoarces viviparous L. Compt-Rend. Lab. Carlsberg. 14(9): 1-14. Schmidt, Johs. 1930. Racial investigations X. The A t l a n t i c cod (Gadus c a l l a r i a s L.) and l o c a l races of same. Compt-Rend. Lab. Carlsberg. 18(6): 1-72. Smith, D.C, and Everett, G.M. 1943. The effect of thyroid hormone on growth rate, time of sexual d i f f e r e n t a t i o n and oxygen consumption i n the f i s h , Lebistes r e t i c u l a t u s . J . Exp. Zool. 94: 229-240. Smith, D.C.W. 1956. The role of the endocrine organs i n the s a l i n i t y tolerance of trout. Mem. Soc. Endocrinol. No. 5: 83-101. Sund, 0. 1943. Variation i n the number of vertebrae i n the Norwegian winter herring. Ann. B i o l . Copenhague. 1: 56-57. Sverdrup, H.U., Johnson, M.W. and Fleming, R.H. 1942. The Oceans. Prentice-Hall, Inc. New York 1084pp. Taning, A. 1944. Experiments on meristic and other characters i n f i s h e s . I. On the influence-of temperature i n some meristic- characters i n sea trout and the fixation-period of these characters. Medd. Komm. Havundersg., Zbh. Ser. Pisk. 11: 1-66. Taning, A. 1946. Stage of determination of vertebrae i n teloestean f i s h e s . Nature 157:594. - 41 - Tailing, A. 1952. Experimental study of meristic characters i n f i s h e s . B i o l . Rev. 27: 169-193. Vladykov, V.D. 1934. Environment and taxonomic characters of fis h e s . Trans. Roy. Canadian Inst. 20: 99-140. Weber, M., and De Beaufort, L.F. 1913. Pishes of the Indo- Australian Archipelago. Vol. 2. 404pp. Wilder, D.G-. 1947. A comparative study of the A t l a n t i c salmon, Salmo salar Linneaus, and the lake salmon,Salmo salar sebago (GirardT Can. J . Res. D 25: 175-189. Wilder, D.G. 1952. A comparative study of anadromous and fresh water populations of brook trout (Salvelinus f o n t i n a l i s ) (Mitchell). J . Pish. Res. Bd. Can. 9: 169-203. APPENDIX - I C 0 P Y P. 0. Box 1471 Canterbury University College Christchurch, C. 1 New Zealand September IX, '56 Professor W. S. Hoar Zool. Dept. University Vancouver, B. G. Dear Professor Hoar, F i r s t , l e t me thank you f o r kindly sending some reprints of your work on f i s h behaviour and physiology which reached me some short time ago. Meanwhile, I have obtained d e t a i l s of spring salmon runs from the Marine Department and sent you them along with my material from Lake Coleridge. MacDonald's Creek, Westland, runs into a lagoon which, I think, i s brackish and resembles Lake Ellesmere on the east side of Canterbury from which I obtained a male and a female mature at 16" and 1 l b . 1 oz, t h i s l a s t May. It does look as i f your proposition carries a l o t of weight, v i z . that there i s "evidence of osmotic stress i n t h e i r r e l a t i v e l y reduced growth rate" ( B i o l . Rev., p. 444, Vol. 28, 1953). Presumably, the f i s h running i n from the sea resemble those going into Western Canadian r i v e r s during the spawning runs. Yours very t r u l y , "E. P e r c i v a l . " - 43 - APPENDIX - I - continued Oncorhynchus tschawytscha i n New Zealand Spawing run from a fresh water lake, Lake Coleridge, May, 1954 some freshly run and clean, some worn to varying extents. 3NGTH" WEIGHT SEX LENGTH" WEIGHT SEX (lb.oz.) (lb.oz.) 18 2.0 M 19* 2.6 P 19 2.0 19 2.6 P 18 2.0 M 18* 2.4 P 17* m t 2.0 P 19* 2.8 M 2.0 M 19* 2.10 P 17 3/4 2.0 M 19 2.6 P 17 1.8 M 18* 19* 2.4 P 15 1.2 M 2.8 M 19* 2.0 M 19* 2.10 P 20* 2.4 M 19* , 3.0 P 18* 2.4 M 18 3/4 2.10 P 18* 2.4 M 19* 2.8 M 19 2.4 P 18* 2.4 P 19 2.4 M 20* 3.8 P 18i 2.0 M 20* 2.8 P 18* , 2.0 M 18 3/4 2.10 P 18 3/4 2.0 P 17 3/4 2.2 P 19 3/4 2.4 P 17 3/4 1.12 P 18* 2.0 P 18 1.12 F 18* y 1.8 M 20* 2.4 M 18 3/4 1.14 M 19* 2.0 P 19 1.14 F 18* 2.0 P 18* 2.0 M 19* , 2.12 P 21 2.8 P 18 3/4 2.4 P 17 1.3 M 18 3/4 2.6 M 21* 2.0 M 19* , 2.4 M 18 3/4 2.0 M 18 3/4 2.4 P 17* 1.9 M 18 3/4 2.0 P 19* 2.7 M 19* 2.10 P 17* , 1.5 M 17* 2.0 P 19 3/4 2.2 P 18* 2.4 ? 18* 2.0 M 19 3/4 2.6 P 18 1.15 M. 18* 2.0 P 17* , 1.11 M 19* 2.8 P 18 3/4 2.1 M 18 2.6 M 18 1.9 M 18 3/4 2.12 P 18 3/4 1.13 M 18* 2.4 M 20 3/4 2.1 M 18 3/4 2.10 M 18 1.12 M 17 3/4 1.12 ? 19* , 2.6 P 19 3/4 2.6 P 19 3/4 2.8 M 19 1.14 M - 44 - APPENDIX - I - continued QUINNAT SALMON "LANDLOCKED" May. 1955 231" P 18" P 241" P 23" M 241" P 251" P 241" M 191" M 24" P 23" M 191" M 211" M MACDONALD'S CREEK. WESTLAND May. 1956 25" QUINNAT SALMON TAKEN Weight 16 l bs 15 19 15 15 11 20 8 111 10 7 H I 12 QUINNAT SALMON TAKEN Weight 15 l bs 8 8 11 12 81 9 15 16 13 14 12 9 8 9 91 10 91 24" 211" 20" 19" 21" 21" 22" M M P P P P P P RANGITATA - 1944 Length 30 inches 29 29 35 32 37 29 33 30 281 28 27 WAIMAKARIRI - 1944 Length 33 inches 28 29 31 31 27 30 33 34 32 34 31 28 27 28 29 30 28 APPENDIX - I - continued QUINNAT SALMON TAKEN - continued Weight 10 lbs 12 11 14 11 9 91 9 91 10 11 11 101 13 8 QUINNAT SALMON TAKEN Weight 12 lbs 17 19 21 16 18 18) 10) 12) 7) 16) Estimated Length 11) and Weight 21) 20) 8) 17) 16) 23 17) 16} 10) 21) Estimated Length 8) and Weight 14) 12) 18) 12) 17) l l ) WAIMAKARIRI - 1944 Length 29 inches 31 30 32 28 28 29 28 25 30 30 27 29 37 29 OPIHI - 1944 Length 32 inches 32 36 36 36 35 38 36 36 33 36 34 38 38 33 38 39 40 37 37 36 38 34 36 35 37 36 36 34 - 46 - APPENDIX - I - continued QtJINNAT SALMON TAKEN Weight 4 lbs 14 H i 12 11 11 8 12 13 10 12 12 10 10 13 RAKAIA - 1944 Length 20 inches Estimated 32 Length 30 and Weight 32 30 30 28 31 33 27 31 30 28 31 34 APPENDIX - II Sockeye: Weekly record of weight increase. SOCKEYE - Fresh water. 0$c SALINITY Temperature No. of Fi s h Weight i n gm. Mean weight i n gm. $ Increase C° I n i t i a l 69 13.3 0.192 13 1 17 4.8 0.283 11.8 2 16 5.8 0.363 12 3 16 6.4 0.400 12 4 10 4.8 0.480 12.5 5 10 5.6 0.560 191.7 12.5 6 8 4.9 0.613 13 7 8 5.3 0.663 13.5 8 8 5.8 0.730 13.5 9 8 6.1 0.763 13 10 8 6.5 0.810 319.8 13 No. of Weeks APPENDIX - III Sockeye: Weekly record of weight increase. SOCKEYE - 6$o SALINITY No. of Temperature Weeks No. of Pish Weight i n gm. Mean weight i n gm. fo Increase G° I n i t i a l 69 15.3 0.221 13 1 . 25 8.5 0.339 11.8 2 24 8.6 0.358 12 3 24 9.4 0.392 "~ 12 4 24 10.4 0.433 12.5 5 24 11.6 0.481 117.6 12.5 6 24 12.8 0.533 13 7 24 14.4 0.600 13.5 8 24 16.8 0.700 13.5 9 24 20.0 0.832 13 10 24 23.1 0.963 335.7 13 APPENDIX - IV Coho: Series 1. Weekly record of weight increase. C O H G - Fresh water. 0$o SALINITY Temperature No. of Fish Weight i n gm. Mean weight i n gm. $ Increase C ° I n i t i a l 50 22.8 0.456 13 1 39 21.7 0.556 11.8 2 38 21.8 0.574 12 3 38 22.6 . 0.595 12 4 38 27.5 0.724 12.5 5 38 30.7 0.808 77.2 12.5 6 38 35.1 0.924 13 7 38 39.2 1.032 13.5 8 38 44.1 1.161 13.5 9 38 49.8 1.311 13 10 38 54.6 1.437 215.1 13 No. of Weeks APPENDIX - V Coho: Series 1. Weekly record of weight increase. COHO - 6$o SALINITY J J 0 < 0 f Temperature Weeks No. of Pish Weight i n gm. Mean weight i n gm. $. Increase C° I n i t i a l 50 24.3 0.486 13 1 44 23.0 0.523 11.8 2 44 26.1 0.593 12 3 44 29.8 0.677 12 4 44 34.9 0.795 12.5 5 44 40.2 0.914 88.1 12.5 6 44 46.4 1.055 13 7 44 52.3 1.189 13.5 8 44 59.9 1.361 13.5 9 44 68.1 1.548 13 10 44 75.1 1.707 251.2 13 APPENDIX - VI Cohos Series 1. Weekly record of weight increase. COHO - 12$o SALINITY N o # o f Temperature Weeks No. of Pish Weight i n gm. Mean weight i n gm. $ Increase C° I n i t i a l 50 23.3 0.466 13 1 38 21.8 0.574 11.8 2 38 22.7 0.597 12 3 37 27.8 0.751 12 4 37 35.2 0.951 12.5 5 37 44.1 1.192 155.8 12.5 6 37 52.0 1.405 13 7 37 60.4 1.632 13.5 8 37 69.7 1.884 13.5 9 37 80.1 2.165 13 10 37 89.9 2.430 421.5 13 APPENDIX - VII i Coho: Series 2. Weekly record of weight increase COHO - Presh water. 0$o SALINITY K o . o f Temperature Weeks No. of Pish Weight i n gm. Mean weight i n gm. $ Increase C° I n i t i a l 50 49.6 0.992 13.5 1 48 52.7 1.098 14.4 2 27 56.8 1.209 13 3 47 60.7 1.278 13 4 47 65.4 1.391 13 5 47 72.2 1.536 53.2 13 6 47 78.1 1.662 12.8 7 47 85.0 1.809 12.5 8 47 90.1 1.917 11.5 9 46 95.5 2.080 11 10 46 101.1 2.200 121.8 10.5 APPENDIX - VIII Goho: Series 2. Weekly record of weight increase. Temperature $ Increase C° I n i t i a l 50 51.1 1.022 13.5 1 50 55.3 1.106 14.4 2 50 61.1 1.222 13 3 49 69.7 1.422 13 4 49 80.0 1.632 13 5 49 92.4 1.886 84.5 13 6 49 103.6 2.114 12.8 7 49 117.2 2.392 12.5 8 49 126.8 2.589 11.5 9 49 137.1 2.797 11 10 49 146.9 2.998 193.5 10.5 COHO - 18$ 0 SALINITY No. of Weeks No. of Pish Weight i n gm. Mean weight i n APPENDIX - IX Chum: Weekly record of weight increase. CHUM - 6fo0 SALINITY Temperature Weight i n gm. Mean weight i n gm. i» Increase C° I n i t i a l 11 27.6 2.509 12.6 1 11 30.0 2.727 13 2 11 33.8 3.073 12.8 3 9 39.1 4.344 13.5 4 9 42.4 4.710 12.8 5 8 44.2 5.530 120.4 13 No. of Weeks No. of F i s h APPENDIX - X Chum: Weekly record of weight increase. CHUM - 30$o SALINITY No. of Pish Weight i n gm. Mean weight i n gm. $ Increase No. of Weeks Temperature I n i t i a l 1 2 3 4 5 6 12 12 12 11 11 11 28.1 31.6 38.4 48.6 59.1 68.4 2.342 2.633 3.200 4.420 5.373 6.220 165.6 12.6 13 12.8 13.5 12.8 13 VJl VJ) 2 Experiment discontinued. APPENDIX - XI Chum: Data on individual weights in.gm. 6 $ o SALINITY 30$o SALINITY SQ M CD CD 'ri CD H E H 4^ H H o cd cd m •H •H t> «H H cd cd CD 0) o o H H« CQ CD O *H a P Pl 0) CO s <H •rl ft o 0) >tf P. o Hi H? 6.1 6.7 5.6 7.1 6.8 No rm al  f is h Le ft  P el vi c Ad ip os e Up pe r Ca ud al  Lo we r Ca ud al  <D U . 3 -P cd o U o CD Pi a CD E H 5.8 7.1 5.4 6.8 6.9 13 6.3 7.5 5.6 7.1 7.3 12.8 7.0 7.9 6.0 7.7 7.8 13 7.8 8.7 6.6 8.6 8.6 13 DEAD DEAD DEAD DEAD DEAD 13 34.5 23.0 22.2 26.5 24.6 VJl I n i t i a l 1 2 3 4 6.6 6.9 5.7 7.4 7.0 7.2 7.2 5.9 7.7 7.3 7.9 7.5 6.3 8.1 7.8 fa i n c r - ease 29.5 up to 3rd wk. 12.0 12.5 14.1 14.7 APPENDIX - XII Goldfish: Weekly record of weight increase. GOLDFISH - Fresh water. 0$o SALINITY No. of Temperature Weeks No. of F i s h Weight i n gm. Mean weight i n gm. $ Increase C° I n i t i a l 15 189.5 12.63 17.5 1 15 191.2 12.75 17 2 15 193.8 12.92 17.5 3 15 196.4 13.10 17.8 4 15 196.0 13.06 17 5 15 199.0 13.27 5.1 16.8 6 15 201.00 13.40 16.5 7 15 203.6 13.57 16.5 8 15 205.8 13.72 15 9 15 208.0 13.87 13 10 15 209.8 13.99 10.77; 12.5, APPENDIX - XIII Goldfish: Weekly record of weight increase. No. of Weeks GOLDFISH - 6$.SALINITY No. of Fi s h Weight i n gm. Mean weight i n gm. $ Increase Temperature «o I n i t i a l 15 172.8 11.52 17.5 1 15 173.1 11.54 17 2 15 175.0 11.67 17.5 3 15 176.6 11.77 17.8 4 15 177.0 11.80 17 5 15 178.6 11.91 3.4 16.8 6 15 181.2 12.08 16.5 7 15 184.1 12.27 16.5 8 15 186.2 12.41 15 9 15 189.1 12.60 13 10 15 192.8 12.85 11.5 12.5 00

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