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Egg size and egg number in some freshwater fish of British Columbia Cartwright, John William 1959

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EGG SIZE AND EGG NUMBER IN SOME FRESHWATER FISH OF BRITISH COLUMBIA by JOHN WILLIAM CARTWRIGHT B. A., University of British Columbia, 1956 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE In the Department of ZOOLOGY We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA April, 1959 i i ABSTRACT Fecundity data were obtained for twelve species of British Columbia freshwater fishes by use of a displacement method. Data for an additional fourteen species were obtained from the literature. Fecun-dity relative to a unit body weight was considered superior to absolute fecundity for use in racial studies. Egg diameter was significantly larger in anterior than in posterior regions of ovaries from five species tested. Egg diameter was positively correlated with fork length within and between species. Amongst twenty-six freshwater species considered, egg diameter was found significantly correlated with reproductive characteristics. Fish with eggs of large mean diameter generally have amber to salmon colored eggs, non-adhesive eggs, long incubation periods, redd construction, stream spawning and variable spawning season. Fish with eggs of small mean diameter have white to yellow eggs, adhesive eggs, short incubation period, lack of redd construction, variable spawning location and spring or summer spawning season. In p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g of t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department The U n i v e r s i t y of B r i t i s h Columbia, Vancouver 8, Canada. Date APRIL. /3 , 1^9. i i i TABLE OF CQNTEETTS Page INTRODUCTION 1 METHODS MD MATERIALS 3 RESULTS 10 EGG BOMBER 10 Variation i n Absolute Egg Number ... 10 Variation i n Egg Number Between Areas 11 Variation i n Egg Number With Latitude 15 EGG DIAMETER 19 Variation i n Egg Diameter Within Individual Fish .... 19 Variation i n Egg Diameter: With Parent Length 29 RELATIVE FECUNDITY 33 Relationship to Egg Diameter 33 Variations Between Species 39 Variation i n Gonad Weight as Fish Weight Increases .. 39 RELATIONSHIP OF EGG DIAMETER TO REPRODUCTIVE CHARACTERISTICS 43 DISCUSSION 50 CONCLUSIONS 62 LITERATURE CITED 64 APPENDIX 68 i v TABLES Table Page I Comparison of displacement with weight methods of egg enumeration using two species of f i s h . 5 II Scientific names, common names and collection sites of species used in this thesis. 7 III Comparison of mean egg number, fork length and weight for six species of f i s h from different geographic locations. .. 1 3 17 Mean egg number and fork length of Chinook salmon from Appendix Table I, of Hounsefell ( 1 9 5 7 ) 1 7 7 Results of s t a t i s t i c a l sign test applied to egg measurement data of fiv e species 26 71 Percentage body weight attributable to gonads (maturity Index) for sixteen species, arranged according to increasing body weight 42 711 Reproductive characteristics of twenty-six species i n relation to mean egg diameter, ii. 46 7III Relationship of six pairs of reproductive characters to mean egg diameter (greater or less than 3*20 mm. V FIGURES Figure Page 1 . Relationship of relative fecundity to fork length of three species of fish from different latitudes 18 2 . Comparison of mean egg number and mean egg diameter with fork length of kokanee (C> nerka, kennerJyO, from Meadow Creek, B. C. , 2 2 3 . Comparison of mean egg number and mean egg diameter with fork length of rainbow trout (s_. ealdnerl) from Paul Lake, B. C 23 4 . Comparison of mean egg number and mean egg diameter with fork length of eastern brook trout (s,. fontinalls,) from several localities 2 4 5 * Comparison of mean egg number and mean egg diameter with fork length of longnose sucker (C. catostomus) 2 5 6 . Comparison of mean egg number and mean egg diameter with fork length of largescale sucker (C. macrochellus) 2 6 7 . Comparison of mean egg number and mean egg diameter with fork length of redside shiner (Jk. balteatua) 2 7 8. Comparison of mean egg number and mean egg diameter with fork length of peamouth chub (M,. caurlnumT 28 9* Mean egg diameter compared with fork length and age at maturity for thirty rainbow trout from Paul Lake 3 1 1 0 . Comparison of mean egg diameter with mean fork length for 2 2 species of freshwater fish, representing 1 2 genera and 7 families 3 2 1 1 . Relationship between egg diameter and relative fecundity for 2 3 species of freshwater fish. 3 5 1 2 . Regression of mean egg diameter (xlO) on relative fecundity (xlO) for 23 species of fish. 3 6 1 3 . Comparison of relative fecundity with mean fork length for 2 0 species of fish 3 7 v i Figure Page 14. Comparison of relative fecundity with mean fork length for lb species of fish 38 15. Relationship of ovary weight to body weight for two species. 41 v i i ACKNOWLEDGMENTS The writer would like to express his thanks to Dr. C. C. Lindsey and Dr. P. A. Larkin of the Institute of Fisheries at the University of British Columbia for suggesting the thesis pro-blem. The investigation was made possible largely through the sponsorship of the Fish and Game Branch, and the Institute of Fisheries. The direction, suggestions and criticisms of Dr. C. C. Lindsey throughout the study are most sincerely appreciated. INTRODUCTION In a l l types of fisheries work a knowledge of the repro-ductive potential of fi s h species under study i s fundamental to any understanding of population relationships or densities. A considerable amount of -work has been done i n the past, primarily by fish-cultural organizations, i n attempts to use egg number as a means of rac i a l separation. Some of these attempts apparently had a limited success, but the majority were of l i t t l e value because of wide v a r i a b i l i t y between samples taken at different times from a single area. In the present study an attempt was made to determine the degree of v a r i a b i l i t y i n egg number and egg diameter of some common fish of British Columbia. Egg number and egg diameter were compared with fork length of several species. Egg diameter was also compared with fish age i n rainbow trout from Paul Lake, Brit i s h Columbia. A study was made of relationships between egg diameter and characteristics of the reproductive l i f e history of a number of species. A l l f ish examined by the author were from collections of the Institute of Fisheries at the University of Brit i s h Columbia. Additional data were obtained from a review of literature. In this thesis "relative fecundity" refers to the number of eggs carried by a mature female, relative either to one unit fork length -2-or to one unit body weight. "Absolute fecundity", or simply "fecundity" refers to the to t a l number of eggs carried by a mature female immediately prior to spawning. -3-METHODS AND MATERIALS Early methods of egg enumeration were extremely crude, con-sisting i n general of such procedures as that of Page (1888) who refined earlier techniques by determining average numbers of ova per quart for each species, rather than for individual females. Von Bayer (1908) devised a more elaborate technique involving the principle that the volume of a sphere varies as a cube of i t s diameter. After the early 1900»s l i t t l e change took place i n methods of egg enumeration u n t i l Burrows (1951) attempted a review of several methods. Burrows examined the Von Bayer method, i n which egg numbers were determined from dia-meters by the use of prepared table; the Canaday weight method i n which the weight of a known number of drained eggs taken at random from a large number i s compared with the to t a l sample weight; the improved weight method involving more careful water removal than the Canaday method; and the displacement method of Burrows i n which water displaced by samples of known number i s measured i n accurately calibrated burettes and compared proportionately with water displaced by large numbers of eggs. The Von Bayer method was the only one producing a biased s t a t i s t i c . Calculated egg numbers were found to be consistantly higher than numbers obtained by direct counts. A l l three of the other techniques produced unbiased results. The Canaday weight method showed a wide v a r i a b i l i t y which was reduced substantially i n the improved weight method. The displacement technique was the most accurate. Time involved i n making the various measurements was an important consideration. In the tests made by Burrows, the Von Bayer -4-technique required the greatest number of man-hours for evaluation of large numbers of eggs. The two weight methods were found extremely fast, and because of i t s greater accuracy, the improved weight technique i s the more favorable. The displacement technique though requiring twice as many man-hours as the weight techniques, i s s t i l l more accurate, and should therefore be used i n detailed fecundity studies where accuracy i s more important than time. In the present investigation the improved weight method was compared with the displacement method. In each case samples of known egg number were measured, compared proportionately with measures of tot a l ovary weight or volume, and tot a l egg number calculated. Actual egg number i n the ovaries was then determined by counting a l l eggs. Results of this comparison appear i n Table I. The displacement method was found superior i n that v a r i a b i l i t y tetween samples appeared to be considerably lower than for the weight method. For this reason the displacement technique as described by Burrows (1951) was used i n a l l fecundity determinations made by the author. Measurements of egg diameter were made i n a V-shaped alumi-num trough, i n the bottom of which was fixed a metric rule. Twenty eggs were taken from each of the anterior, middle and posterior regions of an ovary and placed i n the trough. The average diameter for these twenty eggs was taken as representative of that particular region of the ovary. The majority of specimens used i n the present investigation were obtained from the f i s h museum of the Institute of Fisheries at the University of British Columbia. The remainder were collected by the author. Additional data were obtained by personal communication and Table I. Comparison of displacement with weight methods of egg enumeration using two species of fish. Species Total Volume Total Weight Egg Ho. Egg Ho. Egg Ho. Percent Percent Ovary of 100 Ovary of 100 by by by Error Error Volume % g Weight Egg Volume Weight Count by by (cc) Samples (go) Sample Volume Weight (cc) (gm) (#) Mylocheilus 34.60 0.27 37.2 0.27 12,815 13,777 12,970 -1.20 +7.15 caurinum 32.30 0.27 32.9 0.29 11.962 10,972 11,146 •7.32 -2.46 (Summit Lk.) 39.65 0.27 42.7 0.29 14,865 14,788 15,175 -2.04 -2.55 (Prince 35.80 0.26 37.2 0.28 13,769 13,286 14,417 -4.48 -7.84 George) Mylocheilus 4.0 0.25 1,952 2,025 -3.06 caurinum 5.5 0.28 — — 1,964 — 1,863 *5.^2 — (White Lk.) 5.3 0.21 — — 2,524 — 2,491 •1.32 — (Salmon Arm) 5.1 0.21 — — 2,429 — 2,561 -1.25 — Oncorhynchus 5.^3 nerka 21.6 5.26 23.4 413 494 415 -0.48 •19.04 kennerlyi 20.0 5.66 28.0 5.94 353 358 360 -1.98 -0.55 26.7 5.71 26.8 5.71 484 471 462 •4.76 *1.95 (Nicola lk.) 28.7 4.78 30.3 5.00 589 591 597 -1.3* -1.01 -6-from a review of literature. A l l specimens were originally fixed i n 5 to 1Q% solutions of formalin, and were subsequently transferred to isopropyl alcohol for permanent storage i n the museum. Shrinkage and weight loss due to preservation were thus considered comparable i n a l l specimens. A l i s t of species used, and collection sites is provided i n Table II. Geographic locations were obtained from the Gazetteer of Canada—British Columbia, 1953. In the text reference i s generally made to common names only. Table II. Scientific names, common names and collection sites of species used in this thesis. Scientific Name Common Name Collection From Location Position Prosopium Mountain whitefish wllliamsoni (Girard) Thymallus Arctic grayling arcticus signifer (Eichardson) Coregonus Lake whitefish clupeaformis (Mitchill) Prosopium cylindraceum (Eichardson) Prosopium coulteri (Eigenmann & Eigenmann) Oncorhynchus keta (¥albaum) Oncorhynchus "tehawyt-scha (Walbaum) Oncorhynchus nerka kennerlyl (Suckley) Salmo gairdneri (Eichardson) Salmo clarki Eichardson Bound whitefish Pygmy whitefish Chum salmon Chinook salmon Cutthroat trout Nicola Lk., B.C. Lewis E. Yukon Swede-Johnson Lk. Swede-Johnson Lk. Dease Lk., B.C. I.W.T. Cassiar Dist. See Literature See Literature See Literature See Literature N.E. of Merritt 50° 120° SW. N.W.T. H.W.I. 58° 130 SB. Kokanee Meadow Ck., B.C. Kootenay Dist. 50° 116° SW. Nickola Lk., B.C. N.E. of Merritt 50° 120° SW. Shawnigan Lk. B.C. Vancouver Is. 48° 123° NW. Eainbow trout Paul Lk., B.C. Kamloops Dist. 50° 120° NE. Peterhope Lk. B.C. Kamloops Dist. 50° 120° SE. Knouff Lk., B.C. Kamloops Dist. 50° 120° NE. Jacko Lk., S. C. Kamloops Dist. 50° 120° NE. Table II. Cont'd. Scientific names, common names and collection sites of species used in this thesis. Scientific Bame Common Same Collection From Location Position Salmo trutta Linnaeus Brora trout See Literature Salmo salar Linnaeus Atlantic salmon See Literature Salvellnus Eastern brook trout See Literature fontinalis (Mitchill) Salvellnus Dollyvarden See Literature malma (Walbaum) Salvelinus Lake trout See Literature namaycush (Walbaum) 54° Catostomus catosto- Longnose sucker Shelley Slough,B.C. N.E. of Prince 122° SW. mus (Forster) George 10-Mile Lk., B.C. I. of Qnesnel 53° 122° SE. Catostomus commer- White sucker Baker Lk., B.C. N.E. of Qnesnel 52° 122° NW. sonl (Lacepede) Summit Lk., B.C. Hart Highway 5k° 122° SW. Catostomus macro- Largescale sucker Wolfe Ck., B.C. Simllkameen Dist. 1*9° 120° SE. cheilus Grirard Little Bull R.,B.C. Kootenay Dist. 115° SE. Richards onius Bedside shiner Paul Lk., B.C. Kamloops Dist. 50° 120° NE. balteatus Shelley Slough,B.C. H.E. of Prince (Eichardson) George 540 122° SW. Trembleur Lk., B.C. Coast District 54° 125° HE. Table II. Cont'd. Scientific names, common names and collection sites of species used in this thesis. Scientific Name Common Name Collection From Location Position Bhinichthys cata-ractae (Cuvier & Valenciennes) Longnose dace Tulameen E., B.C. Similkameen Dist. 120° SW. Mylocheilus caurinum (Eichardson) Peamouth chub White Lk., B.C. Shuswap Dist. 50° 119° HE. Hansard Lk., B.C. Cariboo Dist. 540 122° SE. Terrace, B.C. Coast Dist. 540 128° HW. Lota lota (Linnaeus) Burbot Dutch Ck., B.C. Kootenay Dist. 50° 115° SW. Ferca flavescens (Mitchill) Yellow perch See Literature Micropterus dolmieui Lacepede Smallmouth black bass See Literature Micropterus salmoides (Lacepede) Largemouth black bass See Literature Cottus asper Eichardson Prickly sculpin Bella Coola E., Coast Dist. 52° 126° SW. B.C. -10-RESULTS EGG NUMBER Variation i n Absolute Egg Number Many workers i n the past have counted egg numbers i n a few species of game fi s h , i n attempts to estimate t o t a l fish production as a result of natural spawning i n a lake or stream system. A few workers have done a considerable amount of work on variations i n egg number with increasing parent size, variations between races of a single species, and so on. Ricker (1932) found a logarithmic relation-ship between total egg number and fork length of parent f i s h i n eastern brook trout. FotJrster and Pritchard (1941) described a positive correlation between egg number and parent length and weight i n the genus Oncorhynchus. Rounsefell (1957)> has demonstrated for the Salmonidae i n general, given a wide range i n fork length, that t o t a l egg number shows a curvilinear relation with length, although within the genus Oncorhynchus, i n which the size range of mature adults i s small, the relationship could be regarded as linear. In addition Svardson (1949) refers to enormous variation i n egg number because of the correlation with parent size. Scott (1955) showed a positive correlation between f i s h length and egg number i n rainbow trout. Donaldson's (1955) breeding experiments with rainbow trout do not show such a close relationship, but- the same general trend -11-i s present. In the present study, insufficient data were available from mature fis h i n the museum at the Institute of Fisheries to permit plotting of quantities of data for a species from any one l o c a l i t y . However, sufficient data were available to permit grouping into length classes, and calculation of mean egg numbers for each length class. These data were plotted i n Figures 2 to 8, i n which seven species for three families are represented. For each species, regardless of family, a positive correlation exists between egg number and fi s h length. As fork length increases, absolute fecundity increases at an accelerating rate. There i s every indication, therefore, that the findings of earlier workers regarding a curvilinear relationship between to t a l egg number and fish length for certain species of salmonid fishes can also be applied to other families of freshwater f i s h . Variation i n Egg Number Between Areas In the preceding section the importance of parent size i n determining t o t a l egg number has been pointed out. Therefore i n any attempt to observe differences i n fecundity within the geographical range of a species, fish of a comparable size-range must be used. Many attempts have been made, frequently without recog-nition of the numerous variables involved, to use fecundity as a means of r a c i a l separation. This i s particularly true of Pacific salmon of the genus Oncorhynchus. McGregor (1923) attempted, apparently with some success, to separate river races of chinook salmon i n ocean-caught f i s h on the basis of egg counts. Ward (1952), however, attempted a similar -12-type separation of races of Fraser Hiver sockeye salmon, and found i t impossible because of considerable overlap in ranges in egg number. Foerster and Pritchard (19^1) strongly caution against use of egg num-ber i n such racial studies because of large, unaccountable fluctuations in fecundity among f i s h from one run, collected at the same location at different times. Table III i s a comparison of length, weight and range in egg number for five species of freshwater fish, each species represented from two or more l o c a l i t i e s . The same range in length has been used for each loc a l i t y . It i s apparent from Table III, in spite of the small number of specimens available from each area, that considerable variation exists i n range and mean egg numbers of f i s h from different l o c a l i t i e s . On this basis i t might appear that mean egg number and range could be used in a limited way as a means of rac i a l separation. Scott (1955) stated that resorption of ova i n rainbow trout was a process, continuous almost u n t i l complete maturity was reached. Variations i n food abundance in different environments induced different amounts of resorption, resulting in variations i n ultimate egg number. If this i s true for other species of freshwater f i s h , then species having large numbers of small eggs might be expected to show even greater absolute v a r i a b i l i t y in fecundity in different environments. Reference in Table III, to a single size range of mountain whitefish, redside shiner and peamouth chub from two or more l o c a l i t i e s within the pro-vince, indicates that this may be the case. The great v a r i a b i l i t y i n Table III. Comparison of mean egg number, fork length, and weight for six species of f i s h from different geographic locations. Species Number in Sample Locality Range in Length (cm) Range in Weight (gm) Range in Egg Number Mean Egg Number Kokanee 3 2 Nicola Lake Kootenay Lk. 23.0-25.0 23.0-25.0 159.6- 164.5 124.1- 133.7 360- 462 309- 345 412 327 Mountain whitefish 5 6 Nicola Lake Montana 25.0-28.0 25.0-28.0 19^ .5- 302.5 170 - 227 1,555- 3,306 1,426- 2,160 2,803 1,747 Large scale sucker 2 1 Wolf Creek L i t t l e Bull River 45.0-46.0 45.0-46.0 1,156 -1,349.5 1,648 21,117-22,662 20,000 21,890 20,000 Redside shiner 3 8 4 Paul Lake Shelley Slough Trembleur Lake 10.0-12.0 10.0-12.0 10.0-12.0 15.3- 18.1 14.5- 22.7 19.5- 23.1 1,129- 1,372 1,071- 1,694 1,508- 2,568 1,363 1,343 2,208 Peamouth chub 3 2 White Lake Terrace 24.0-25.0 24.0-25.0 218.5-226.7 194.7-219.3 10,974-12,381 13,261-13,376 11,777 13,318 Table III. Cont'd. Comparison of mean egg number, fork length and weight for six species of fis h * from different geographic locations. Species Number Locality Range Range Range Mean in i n Length in Weight i n Egg Sample (cm) (gm) Egg Number Number Rainbow trout - California 40 . 2,400 California 50 3,900 California 60 5,600 California 70 7,600 28 Paul Lake 38.5 2,121 9 Knouff Lake 43.6 2,510 6 Peterhope Lake 45.75 2,280 8 Jacko Lake 63.4 7,04l -15-fecundity shown within one length range of redside shiner (from Shelley Slough and Trembleur Lake, approximately 110 miles apart) i s indicative of the magnitude of variation encountered. Variation in Eg;g Number With Latitude Certain morphological characters of f i s h have been observed to form clines throughout the range of a species. Egg number has "been thought to form a somewhat similar cline in a north-south direction. Unfortunately, much of this work has dealt with family or generic groups of fishes rather than with any single species. Sv^rdson (19^9), postu-lated lower fecundity and larger eggs in northern latitudes, as did Marshall (1953) for seven families of deep-sea fishes. Eounsefell (1957) attempted to determine whether there was any relation between fecundity and latitude for five species of Oncorhynchus. Plotting mean egg number against fork length, Eounsefell was able to show that for four species egg number i n the most southern l o c a l i t y was higher than expected for the average length of the fis h . However he used only samples containing twenty f i s h or more in his figure i l l u s t r a t i n g latitudinal differences, and appears to have overlooked smaller samples from other areas. Table IV contains data for Chinook salmon, taken from Appendix Table I of Eounsefell (1957)- It i s evident from figures presented in Table IV, that mean fork length at maturity tends to increase in a northerly direction. In addition, considering the small increase i n size involved between California and British Columbia collections (with the exception of Namu), the fluctuations i n mean egg number are strongly -16-suggestive of, and quite within the range of, environmentally induced variations. In 0 . nerka (sockeye), on the other hand, in view of the increasing mean size at maturity, there does appear to be a va l i d trend toward lower fecundity i n more northerly regions. Much of this previous work with regard to c l i n a l variation was carried out solely with Salmonid species. Data from Table II have been plotted in Figure 1 for two cyprinid and one coregonid species, comparing relative fecundity against fork length of f i s h from different latitudes. Solid symbols indicate the southernmost samples of each species. A s t a t i s t i c a l analy-sis was made on mean relative fecundity from samples in more northerly areas in comparison with the means of the southernmost samples, and each difference was significant ( P ^ O . 1 0 ) . The southernmost mountain whitefish have a lower mean relative fecundity (P . 0 5 - . 1 0 ) than would be expected i f a cline was present toward larger eggs and lower fecundity in more northerly latitudes. Likewise the southernmost peamouth chub have a lower mean relative fecundity (P . 0 2 ) than expected. The redside shiner on the other hand has one group with higher and another with lower mean relative fecundity ( P * . 0 1 ) than would be expected i f clearly defined clines existed. The influence of environment on fecundity i s strongly indicated by these results which, i n general, apparently do not support findings of some workers for certain salmonid species. -17-Table IV. Mean egg number and fork length of Chinook salmon from Appendix Table I, of Eounsefell (1957). Locality- Average Egg Number Average Fork Length (cm) Number in Sample Fecundity Belative to /Unit Length (cm) Sacramento E. Calif. 4670 80.2 108 58.2 Fort Bragg, Calif. 5034 80.8 53 62.3 Klamath E., Calif. 3708 81.2 199 45.7 Fraser E., B.C. 4944 87.1 12 56.8 Cowichan E., B.C. 3885 86.4 25 45.0 Namu, B. C. 8426 103.4 11 81.5 -18-0 to 3 - 4 — D E a> Z3 ?z c C o o i_ . a in E a CO o o =) ~ CO z: o _J CO r> LU Q SOPI .OCH or < X o _ i o tr >-Q. 2 cc - <>• <3 ~" 1 r • 0 in ro O ro m ^ CM O I X I-o z CM UJ or o in < UJ - in o o o 00 o CO o o CM 9 9 3 Figure 1. 1 H 9 I 3 M AOOa WVd9/d38WnN Relationship of relative fecundity to fork length of three species of fish from different latitudes. Solid symbols indicate data from southernmost locations. -19-EGG- DIAMETER Variation i n Egg Diameter Within Individual Fish Egg diameter was measured from anterior and posterior regions of each ovary for several species of f i s h . Actual measurements are presented i n Appendix 1. Sufficient data were available for fiv e species, the longnose sucker, coarsescale sucker, peamouth chub, redside shiner, and mountain whitefish, to permit s t a t i s t i c a l analysis. Accord-ingly, the s t a t i s t i c a l sign test described by Dixon and Mood (19^6) was applied to egg measurement data for these species. Results of these tests are shown in Table V. No significant difference was found in egg diameter between right and l e f t ovaries, or between dorsal and ventral regions of ovaries. Data for these measurements are therefore not presented. A very significant difference was observed between egg diameter from anterior and posterior regions of both right and l e f t ovaries. Egg diameter for each of the five species was found to be almost invariably-greater i n the anterior than in the posterior region of an ovary. It was at f i r s t thought that this difference might be the result of differing rates of maturation of ova from the anterior and posterior regions of ovaries. Eggs from anterior parts of ovaries might mature prior to those In the posterior parts and would thus appear the larger i f f i s h sampled were not completely mature. However, suckers and -20-Table V. Results of s t a t i s t i c a l sign test applied to egg measurement data of five species. Species Number of pairs of Obser-vations Number with Larger Anterior Eggs Number without Larger Anterior Level of Signlfi-cance Longnose sucker 20 18 2 <.01 Largescale sucker 16 14 2 <.01 Feamouth chub 36 36 0 <.0l Redside shiner 30 29 * < « 0 1 Mountain whiteflsh 12 10 2 .05 -21-cyprlnids, unlike salmonids, have a closed "oviduct" extending from the posterior portion of the ovaries (which fuse together)btoithe genital aperature. In both suckers and the cyprinids examined, eggs were com-pletely free of ovarian tissue in the fused posterior portions of the ovaries, and in some cases free eggs were actually present in the duct. These fish were obviously fully mature and ready to spawn. Eggs of these fish were found to be consistently larger in the anterior than in the posterior portions of the ovaries. 22^ O N C O R H Y N C H U S n e r k a k e n n e r l y i 240 UJ ao CD 235 230 < UJ 225 •(15) / ^ ' " ( 7 ) (2) (15) 0.45 t r HO.44 |_ UJ 0.43 0-42 < Q o o UJ 0-41 2 < UJ 0.40 J9 20 21 22 23 M E A N F O R K L E N G T H — CM. Figure 2. Comparison of mean egg number and mean egg diameter with fork length of kokanee (0. nerka kennerlyi), from Meadow Creek, B. C. 3 0 0 0 cr Li) CO O < UJ 2 0 0 0 S A L M O g a i r d n e r i ; ( 4 ) i i V(8) / Q> / 1000 (2) ft 2) _l L E G G D I A M E T E R J i i i_ 3 0 3 4 38 42 M E A N FORK L E N G T H — C M --I L_ .46 10.50 J I cr LU h-LU < JO.40 Q o o UJ UJ 5 10.30 5 0 Figure 3. Comparison of mean egg number and mean egg diameter \idth fork length of rairibot* trout (S. gairdneri) from Paul Lake, B. C. 2500 2000 cr LU o U J 1500 < u 1000 500 0 -24-S A L V E L I N U S f o n t i n a l i s /(5) / / / / / / / / V E R M O N T W Y O M I N G 10 20 30 40 (5) 0.45 0.40 cc U J r -U J < Q O O U J z < U J 0.35 M E A N F O R K L E N G T H — C M . Figure 4. Comparison of mean egg number and mean egg diameter with fork length of eastern brook trout (S, fontinalis) from several l o c a l i t i e s . =2$=. C A T O S T O M U S c a t o s t o m u s / ( 4 f (I) 20,000 tr 16,000 L U m Z) •z. co 12,000 C D L U < LU 8,000 ,*(4) '(2) 0. 17 4,000 0 28 •(2) 30 32 0. 16 0.15 34 36 Q C D C D L U U J M E A N F O R K L E N G T H — C M . Figure 5- Comparison of mean egg number and mean egg diameter with fork length of longnose sucker (C. catostomus). -26-C A T O S T O M U S m a c r o c h e i l u s 24,000 . M E A N F O R K L E N G T H — C M . Figure 6. Comparison of mean egg number and mean egg diameter with, fork length, of largescale sucker (C. macrocheilusJ. - 2 7 -R I C H A R D S O N I U S b a l t e a t u s M E A N F O R K L E N G T H — C M . Figure 7 . Comparison of mean egg number and mean egg diameter with fork length of redside shiner (E. balteatus). 1 6 , 0 0 0 M Y L 0 C H E I L U 5 c a u r i n u m / ' ( 5 ) 2,000 /*(8) 8,000 / ^ / / / CD / 09 / / 0 , 1 7 2 4,000 0 •(3) *(3) _L 2 0 2 2 2 4 2 6 M E A N FORK L E N G T H C M . 0 . 1 6 4 0 . 1 5 6 lO. 148 Figure 8. Comparison of mean egg number and mean egg diameter with fork length of peamouth chub (M. caurinum). -29-Variation i n Egg Diameter with Parent Length Very l i t t l e work has been done on fis h egg diameter except i n a crude way for f i s h cultural purposes. A number of authors such as Titcomb (1897) and Belding (1934) refer to increasing egg diameter as parent size increases in brook trout and Atlantic salmon respectively. In neither case are data presented to substantiate the hypothesis. On the other hand Scott (1955) found no significant correlation between egg diameter and parent size for hatchery reared rainbow trout in the size range studied. Scott used both wild and hatchery reared trout, but con-sidered only a small range in size. In the present investigation, egg diameter data have been collected from seven species, representing six genera and three families of freshwater f i s h . Families represented are the Salmonidae, Cyprinidae and Catostomidae. Figures 2 to 8 are plots of mean egg number and diameter against mean fork length for the seven species referred to above. Five of the seven indicate an increase in mean egg diameter as fork length increases. Brook trout display a comparable increase i n diameter with the exception of the two largest size groups which show a decline i n diameter. This decline may be the result of old age, or of specimens from different lakes. Data available for the longnose sucker do not indicate any consistent tendency towards larger eggs i n larger f i s h . This v a r i a b i l i t y may be due to a lack of complete maturity in some of the few specimens available, or may indicate an absence of the trend in this species. -30-Age might be a major cause of larger eggs i n larger fish, since Scott (1955) found i n specimens from Penask Lake that second spawners had larger eggs than first-time spawners. However, mean fork length of the second-time spawners was greater than that of f i r s t spawners. Figure 9 i s a plot of mean egg diameter against fork length for three age-classes of rainbow trout from Paul Lake. Data were collected by J. C. Lyons in 1950. The scale readings may be questionable for 2-year-old f i s h since mature 2-year-old female rainbow trout are rare (in nature). It i s nevertheless apparent, considering only 3 and 4-year-old fish, that the trend tonrards larger eggs i s more dependent on f i s h length than on age. Scott (1955) found no significant difference i n egg size within the size range used in his study, however, he used only a very small range i n size. In many cases the number of specimens available was small; nevertheless, the persistence of the trend regardless of the number of specimens involved is in i t s e l f indicative that larger eggs i n larger f i s h of a species i s frequently a very real phenomenon. Figure 10 presents mean egg diameter and mean fork length data for 21 species. A definite tendency is evident for larger f i s h to have larger eggs. The burbot is one noteable exception. Therefore, on the basis of data presented above i t appears that i n gener*al mean egg diameter increases with increasing fork length, not only within a single species, but also within a group of different species. -31-S A L M O g a i r d n e r i 0 . 5 0 5 o LU U J O O UJ 0 . 4 5 0 . 4 0 o« A < UJ 0 . 3 5 A _ 2 Y E A R O L D O - 3 Y E A R O L D • - 4 Y E A R O L D 0 . 3 0 3 0 3 5 4 0 F O R K L E N G T H 4 5 5 0 — CM. Figure 9» Mean egg diameter compared with fork length and age at maturity for 30 rainbow trout from Paul Lake. 'WW — H313WVI0 9 9 3 N V 3 lAi Figure 10. Comparison of mean egg diameter with mean fork length for 22 species of freshwater f i s h , representing 12 genera and 7 families. Numbers refer to species l i s t e d in Table VII. -33-RELATI7E FECUNDITY Total egg number was shown i n a previous section to be a poor method of comparing fecundities of several different species of f i s h , because of the close dependence of egg number on f i s h length. Egg num-ber per unit body weight (in grams) or per unit body length (in centi-meters) was considered less variable for fecundity comparisons in which different sized f i s h were involved. Theoretically this measure, which may be referred to as relative fecundity, would help to reduce large differences in fecundity as a result of f i s h length, and at the same time would not be seriously effected by differences i n body shape. Accordingly data were plotted Stn egg number per gram body weight vs. fork length for eight species of freshwater fish. In a l l species relative fecundity was found to vary, but no trend was observ-able as f i s h length increased. Relative fecundity varied within certain definite limits characteristic of each particular species, but these limits were not found to alter their range of variation with increasing f i s h length as did total fecundity. Relative fecundity therefore i s considered a preferable measure to absolute fecundity when i t i s desired to make precise comparisons of fecundity within, or between, species. Relationship to Egg Diameter Total egg number in any f i s h i s influenced considerably by egg diameter; similarly, relative fecundity w i l l be influenced by egg diameter. Tladykov (1956) compared relative fecundity of eastern brook trout with egg diameter, and found that when plotted, a curve resulted -34-from which relative fecundity could he approximated for any given diameter of egg. Data presented i n Appendix ( i i i ) , for 23 species, representing 12 genera and 8 families have been plotted on arithmetic axes in Figure 11, and on log-log axes in Figure 12. Figure 11 shows that for a l l species, regardless of "body shape, decreasing egg diameter i s accompanied by an accelerating rate of increase i n relative fecundity. This i s to be expected in view of the demonstrated (approximate) cubic relationship between egg diameter and egg volume. Considering the diverse phylogenetic relationships of species examined and the body shapes involved, remarkably l i t t l e deviation i s shown from the curve. In Figure 14 the same data have been plotted on log-log axes, transforming the curve of Figure 11 into a straight line described by the regression equation log 10X s 5.866-2.670 log 10T. This line has a high correlation coefficient (r e_0 . 9 7 ) . Dotted lines indicate 9 9 percent confidence limits.-From Figure 12 i t would be possible to calculate (within limits) the approximate total egg deposition of a population of spawning f i s h . For this calculation mean egg diameter and mean weight of mature females, as well as an estimate of numbers of mature females i n a popu-lation must be known. Total approximate egg deposition can then be calculated. This method has the advantage of saving considerable time over displacement or weight methods of egg enumeration. -35-~ i — 1 i 1 i — i — r - 1 — i — • — i — ' i • i — i — i — r -T 1 1 1 , 1 . | • , 1 1-5 0 2 I o o _ UJ z •a p L o g IOX = 5 . 8 6 6 - 2 . 6 7 0 L o g I O Y I I I I l , i , I , I . I I I I I I , 1 , 1 , 1 , 1 1 1 1 1 I I , 1 , 1 , 1 I L 10 1 0 0 1 0 0 0 M E A N E G G N U M B E R / G R A M B O D Y W E I G H T U I O ) Figure 12. Regression of mean egg diameter (xlO) on relative fecundity (xlO) for 23 species of fish. Ninety-nine percent confidence intervals indicated (logarithmis axes). i vo ON I CYPRINID 75 60 T C D U J > Q O C O < CC e> 451 cc U J C D z C D C D U J 30 U J 2 95 6 C O T T I D 6 C Y P R I N I D 6 C Y P R I N I D 10 20 30 40 \ 6 645 L o l a l o t a S A L M O N I D 50 0 — u n d e r 3.20 m m . m e a n d i a m e t e r . • — o v e r 3.20 m m , m e a n d i a m e t e r . ' 1— I s t a n d a r d d e v i a t i o n . IS 60 70 80 M E A N F O R K L E N G T H — C M . Figure 13. Comparison of relative fecundity with mean fork length for 20 species of f i s h . -39-Variatlons Between Species In the preceding section the close dependence of relative fecundity on egg diameter was demonstrated. Data on fecundity relative to length and weight were available for twenty species. These data have been plotted graphically in Figure 13 and 14. Figure 13 i s a plot of mean fork length against mean egg number per unit body weight, while Figure 14 i s a similar plot using mean egg number per unit body length. The following observations can be made from these data: 1. Each family of fishes appears to have a characteristic range of relative fecundity, 2. Standard deviations from mean relative fecundity appear to increase as relative fecundity increases, and hence as egg size decreases, 3. It is noteable, as in Figures 10, 11 and 12, that the burbot, only freshwater representative of the otherwise marine family Gadidae, does not conform to the pattern shown by freshwater families of fishes. Variation i n Gonad Weight as Fish Weight Increases. Data have been presented in the preceding section suggestive of a decline in fecundity, relative to body weight, as f i s h length increases. In Figure 15 data are presented for two species, and are indicative of a slight decline in the ratio between gonad weight and total f i s h weight. This might account for the decline i n relative fecundity observable in the previous section. However, percentage -40-body weight attributable to gondas was calculated for sixteen species and arranged in Table VI i n order of increasing f i s h size. No consistent trend toward a decline in maturity index can be observed as f i s h size increases. It would therefore appear that increasing egg diameter as f i s h length increases i s at least partly responsible for the observed decline i n relative fecundity. Table VI. Percentage body weight attributable to gonads (maturity index) for sixteen species, arranged according to increasing body weight. 1 !  Species Number Total Gonad Body Weight Authority in Body Weight attributable Sample Weight (gm) to gonads Pygmy whitefish 63 13.4 — 15.05f Bschmeyer & 16.0 2.4 Bailey, 1954 Cartwright Bedside shiner 29 14.80 Longnose Dace 6 18.0 1.7 9.0$ Cartwright Prickly sculpin 2 103.0 12.5 12.1$ Cartwright Peamouth chub 19 170.0 25.4 14.90 Cartwright Kokanee 37 245.5 57.6 23.50 Cartwright Mountain whitefish 27 359.0 51.1 14.20 Brown, 1952, 69.8 18.40 Cartwright Burbot 7 380.0 Carlander, 1950, 444.0 12.40 Cartwright Longnose sucker 15 55.2 Cartwright "Eastern brook trout 27 499.0 68.0 13.60 Vladykov, I956 White sucker 2 599-0 62.0 10.40 Cartwright Brown trout 37 600.O 90.5 15.10 Eounsefell, 1957 Bainbow trout 42 934.0 126.5 13.50 Cartwright Largescale sucker 8 1124.0 142.4 12.70 Cartwright Lake trout 25 4819.0 699.0 14.50 Dymond, 1928 Atlantic salmon 534 4999.0 1000.0 200 Eounsefell, 1957 -43-RELATIONSHIP OF EGO DIAMETER TO PRODUCTIVE CHARACTERISTICS Scott (1955) stated that egg diameter in rainbow trout was under strong genetic control. Results presented indicate that while this may be the case in Scott's experimental f i s h , diameter can and does vary within relatively wide limits i n many species. Correlations have been shown to exist between fecundity (hence in part egg diameter) and l i f e history among some marine species. Hickling and Rutenberg (1936) showed for hake, haddock, herring and p i l c h a r d , that duration of spawning period could be approximated by graphically plotting egg diameter against frequency of occurrence in the ovaries. Neave (1948) stated that fecundity was closely linked with l i f e history i n Pacific salmon. Sv&rdson (1949) suggested that selection forces i n an environment effected egg size and number. On the basis of relationships between fecundity and l i f e history or environment suggested above, an attempt was made to determine whether or not any relationships existed between a number of reproductive characteristics and egg diameter. An index system was set up, i n which eggs of small or large mean diameter from twenty-six species, representing fourteen genera! and eight families of fishes were compared with adhesive or non-adhesiveness of the eggs, coloration of the eggs, hatching time of the eggs, spawning season of the parents, spawning location of the parents, and degree of parental care(as exemplified by construction or non-construction of redds). In a comparison of this type a boundary had to be selected to differentiate f i s h with eggs of large or small mean diameter. Species i n Table VII are arranged i n ascending order of egg diameter. A figure of 3.20 mm. was selected as a dividing point between small and large eggs not only because i t occurs in a gap separating species with dis-similar reproductive characteristics, but also because i t occurs near the mean diameter of the species. Selection of a division of this type has a number of disadvantages, however, i n view of similarities i n repro-ductive characters among species with small or large mean egg diameter, the author feels selection of the chosen boundary justified. Chi-square tests were then made on each pair of characters in comparison with mean egg diameter above or below the selected boundary. Results of these tests, recorded i n Table VIII, indicate that a l l six characters tested are significantly related to egg diameter. In view of the relationships shown in Table VIII, i t i s desir-able to know in precisely which way the characters tested are related to egg diameter as well as which species, i f any, di f f e r from the general trend. In this way, certain ecological relationships might be demon-strated. Table VII is an attempt to il l u s t r a t e similarities and d i f f e r -ences in reproductive characteristics for the twenty-six species tested i n Table VIII. Plus signs indicate the presence of the characteristic, "o" indicates the absence of i t . In general, species having eggs in excess of 3.20 mm. appear to be much more consistent in the presence or absence of a character than do species having eggs smaller than this value. This is undoubtedly due in part to the fact that species with larger eggs are a l l of one family, Salmonidae, representing only 3 genera, while those with small eggs represent 11 genera of 8 families. Nevertheless, i n view of the -45-diverse number of families and genera possessing small eggs, i t would be surprising to obtain Chi-square values or distributions like those observed in Tables VII and VIII i f there were no relationship between egg diameter and the characteristic tested. The presence of the above relationship i s made more evident by the fact that v a r i a b i l i t y i n the relationships of reproductive characters occurs only as egg diameter becomes larger, at which time more and more v a r i a b i l i t y i s observable. As egg diameter increases s t i l l further, an almost complete shift i n the relationships of characteristics i s evident. Similarities can be seen to exist in Table VII between repro-ductive characteristics and groups of fishes which exhibit similar ranges in mean egg diameter. Chi-square tests were applied to the interrelations between each pair of characteristics with the result that a number of generalizations can be made. With three exceptions, species of fi s h tested with a mean egg diameter less than 3.20 mm. had adhesive eggs. On the basis of Chi-square tests, the following reproductive characteristics also were found representative of this group of fishes: 1. Eggs were predominantly white to yellowish, 2. Incubation period was generally short (under four weeks), 3. Spawning occurred predominantly in spring and early summer, 4. No redd construction occurred. 5. Spawning occurred in either lakes or streams. A group of seven species with an intermediate range in egg diameter, and possessing a mixture of reproductive characteristics i s also evident. This group forms a "transition" zone between the two -46-Table 711. Reproductive characteristics of twenty-six species i n relation to mean egg diameter. Plus indicates the pre-sence of a characteristic, "o" the absence of i t . sppea Sp? q\ou od •I 4-4 4- 4- 4 + + 4-o o o o o o o o o 4- + 4- 4 4 4 4-o o o o o o o sureaj^g UMBOS • 4 4- 4-4 4 4 + 4-• + o 0 4 4 0 0 + *• 4 O + 4 + 4-o o + o o o + + o -cms-gu^jdg uweas o o o o o o o o + 4 -4-44 + + + + O + O O + + O 4 O 4 4 O O + o •2|» ij JC3A0 U.O+t?H o o o o o o o o o + •+ 4 4- 4 4 + •• 4 O + O O 4 + O 4 O 4 4 O O 4 o - Q + T U W U O U T T B S -•leqnre 4- 4 4 4 - 4 4 4 4 4 o o o o o o o o o 4 4 O O 4 O O O O + 4 O 4 4 O 4 3 A T S -eqpB-uojS eAtsexiPY O O O O O O O O O 4 4-4 4-4 + 4 4 4 4 O + O O + O O 4 O • 4- O 4 4 O j:aq.8ureT(I oo vo o v o o - c o o v o v o VO t-i (SI CO vn VT\vO 00 Ov • « • • • • • O r-i r-i r-l r-l rH r-l rH rH —S~nr 0 - H O • H O -P H 6 to 3 r-i O 5 aj - P O oi cfl o m to pj 01 • H CD g a> +3 o . 3 ft -p o o oi o u o rH O +» O CO VO O o cvi CO VO • • • • CVI CM CM CM -3- CO CO V O tN- rH CM CM CO o o s E I 0 s c l s <fi HJ o cfl -p o CO •H a O ca u A o O pi CD CD CD Cfl co M o cfl -p cfl o co • H -P 5 8. o co CD CO g a 6 CD o o a co CD co t> O <H - P co a) o o - P u a <D O ft, u CD - P o o I o u o -p o u « u CO CD •r l O p<-e O CO co o o -P f-l cfl C4 O CO . H ? * CO CO CO CD U CD f J 0) *H © «r! rH fl i H r H - H - P 0 o §) ii d S) O H CD O H TH J-I O o h <H f> a o nj O jf i H O E-l S rH rH "#H o &1 CO «H o o SH Pi I 01 CD > r-i Cfl CO jequtnij setoedg CM CO-* vo vO N CO OS o rH r-i CM CO Tiaras mtfjpeH •ran 0 2 •£ mam o CM • to CD u - M CD • > 3 cfl o -47-Table VII. Cont'd. Reproductive characteristics of twenty-six species i n relation to mean egg diameter. Plus indicates the presence of a characteristic, "o" the absence of i t . sppej S-pp ^ era off. sppej gfff o o o o o + o 4 4 + 4 + + 4 o o 4 4 smears UMBOS 4 4 + 4 4 4 4 O O 4 O O 4 O 4 4 o o. jrenrams-^tr-cjdg uwecLg O 4 4 O + 4 4 4 O O 4 O O O 4 4 o o •S2[to. J9A0 •S3[iA +7 jepun. 4 4 - 4 4 4 4 4 o o o o o o o 4 4 o o j»ioii8j£-e^ -fxitt uonrr/es-.ieqmy o o o o o o o 4 4 4 4 4 4 4 o o 4 4 eAfserrpB-uojj eAfsexqpv 4 4 + 4 4 4 4 o o o o o o o 4 4 o o j9Q.etuBfC[ vo c\ co cv ^ i " rH o O CM CM VO ON VT\ H . . . . . . • -3- -4- -3- uv^O IN- O-S K I 0 a s Salmo gairdneri Salvellnus fontinalls Oncorhynchus nerka kennerlyl Salmo clarkl Salmo trutta Salvelinus namaycush Salmo salar Oncorhynchus tschawytscha Oncorhynchus keta jeqimajj sefoedg -3" VPi \D O- CO ON o •H rH H i-l i—1 rH CM rH CM CM CM jeq.enreT(i S3*! •mm oz'C XQAO -48-Table VIII. Relationship of six pairs of reproductive characters to mean egg diameter (greater or less than 3.20 mm.) Test Characteristic No. of Characters Tested Calculated Chi-square values (X 2 at .01=6.635) Egg Egg colour Incubation period Spawning season Spawning location Parental care Adhesive Non-adhesive Amber-salmon White-yellow Under 4 weeks Over 4 weeks Spring&Summer Fall&Winter Lakes Streams Dig redds Do not dig redds 16.76 16.76 13.99 7.83 6.20 28.76 -49-extremes, the only consistent characteristic of this group "being that none of these species construct redds. Species tested with a mean egg diameter i n excess of 3.20mm. a l l had non-adhesive eggs. On the basis of Chi-square tests the f o l -lowing reproductive characteristics were found representative of this group of fishes: 1. Eggs were a l l amber to salmon coloured, 2. Incubation period was generally long (over four weeks), 3. Spawning may occur in spring, f a l l , or winter, 4. A l l species tested (possibly one exception) constructed redds, 5. Spawning occurred predominantly i n streams. -50-DISCUSSION Each individual f i s h of any species f i r s t approaches maturity with a fixed number of primary oflcytes in i t s ovaries, a l l of which represent potential ova. This i n i t i a l number i s almost cer-tainly genetically controlled, and may to some extent he size dependent. However, egg number i s essentially similar to other morphological characters, and as such, is subjected to numerous selective forces imposed by fluctuating environmental conditions which may alter egg number during subsequent development. In the present investigation, as well as i n previous l i t e r a -ture, a positive correlation was found between f i s h length and egg number. As f i s h length increases, so does the size of the body cavity. JTish gonads continue growth just as do other parts of f i s h anatomy, and when mature occupy most of the available space in the body cavity. Egg diameter, however, determines the number of eggs that can be packed into any given space. Fecundity, therefore, although positively cor-related with f i s h length (hence with size of body cavity), i s also in part dependent on egg diameter. A similar type of relationship was observable between fecundity and f i s h weight, but since the variations were considerably greater than when length was compared with fecundity, this comparison has been omitted. Environment has been demonstrated to have an influence on fecundity. For example, varying degrees of food abundance during the period of gonad maturation have been shoxvn to alter fecundity in one size-range of rainbow trout. Eounsefell (1957) showed s t a t i s t i c a l l y -51-that low sea temperatures were significantly correlated with greater egg number in pink salmon from Queen Charlotte Islands. Perhaps c l i n a l variations i n egg number with latitude or altitude, as suggested by some workers, are indirect reflections of the influence of environmental variables. Many fecundity variations almost certainly are. Since existing knowledge of freshwater f i s h and their biology is limited, i t is impractical to attempt to classify lakes according to their productivity for each species of f i s h present. Most f i s h species occupy diverse habitats, each of which i s under the influence of a variable environment. It is therefore impractical, i n view of the numerous unknown variables, to use fecundity alone as a ra c i a l or c l i n a l separation. Egg diameter as well as number has been shown, i n the present study, to undergo considerable variation. The presence of larger eggs at the anterior than at the posterior of the ovaries of five species of mature freshwater fish i s an i l l u s t r a t i o n of v a r i a b i l i t y i n egg diameter within a single f i s h . This appearance of larger eggs i n anterior regions of ovaries i s an unusual phenomenon i n view of the fact that eggs of most species are f i r s t deposited from the posterior end of the ovaries. Eggs in posterior regions of ovaries, i f f i r s t to mature, should pre-sumably be larger than immature eggs i n more anterior regions. Such does not appear to be the case. In Salmonids, eggs from dorsal parts of ovaries mature f i r s t and are probably f i r s t to pass through the genital aperture. Ho significant difference was observed in egg dia-meter from these two regions. If the blood supply, innervation and physiology of developing ova are considered, one possible explanation -52-becomes apparent. The richest "blood supply i s presumably located towards the anterior, where ovarian blood vessels f i r s t contact the ovary. Nutrient i s absorbed into eggs by diffusion from the blood supply. Therefore, eggs in anterior regions of ovaries, i f subjected to slightly higher concentrations of oxygen and nutrient than those i n posterior regions might absorb slightly more nutrient, produce more yolk, and hence reach a slightly greater size. The existence of the above phenomenon emphasizes the need for a standardized sampling procedure whenever egg diameters are to be measured. Egg diameter has been demonstrated to increase with increasing fork length i n most species studied. The p o s s i b i l i t y of a relationship between age and egg diameter was studied using rainbow trout. Age was found to have no consistent effect on egg diameter, except that occasionally the oldest fi s h were also the largest and hence had the largest eggs. This- phenomenon may be the result of continuous growth throughout l i f e as i s common for most morphological structures of the-majority of fishes. In view of the v a r i a b i l i t y in egg diameter mentioned above, the author must take exception to the hypothesis put forward by Scott (1955) that food a v a i l a b i l i t y during the period of maturation influences egg number, but not diameter, and that egg diameter was fixed within rather narrow genetic limits. Firs t , the question arises regarding the effect food a v a i l -a b i l i t y has on egg size. If food is scarce and competition for i t intense, sufficient nutrient may not be obtained to permit much growth. Maturation processes, however, continue. The result is that fi s h -53-mature at a small size and have small eggs. On the other hand i f food i s abundant and easily obtainable, f i s h mature at a larger size and con-sequently have larger eggs. Therefore food a v a i l a b i l i t y during the period of maturation does influence egg diameter. Second, while l i t t l e argument can be advanced regarding genetic control of egg diameter within upper and lower limits, the r i g i d i t y of this control between these limits i s questionable. The magnitude of difference observed i n egg diameter in the present study (as much as forty-five percent i n rainbow trout from Paul Lake) indicates that egg size i s quite variable, and i s dependent on parent size, but indirectly on food ava i l a b i l i t y , prior to maturity. Much of the substance' responsible for egg size i s yolk. In order to produce yolk, nutrients must be transported in the blood of the parent to the tissues surrounding each individual ovum as i t develops, and subsequently must be absorbed by the ova. These nutrient materials, once absorbed, are lost as nourishment to the parent f i s h except where resorption of ova occurs as was suggested by Scott (1955) a ^ d Vladykov (I956). Possibly, however, when ova undergo regression the'follicles'' take on a hormone secretory function Brown (1957), in which ease nutrients are s t i l l required by the f o l l i c l e s . Obviously a parent f i s h can provide only so much nutrient, dependent on feeding conditions, without endangering her own existence prior to spawning. On the basis of Scott's (1955) observations excessive resorption of developing ova occurred under conditions of low food abundance. Therefore, given con-ditions of great food abundance (and availability) more nutrient could theoretically be made available to ova over their whole period of develop-ment. This could result i n the production of greater numbers of ova, as -54-well as the absorption of larger quantities of nutrient by individual ova. In Figure 10 data were presented on egg diameter for twenty-six different species in which a general trend toward larger eggs in larger f i s h is apparent. Therefore, considerable care should be exercised in selecting f i s h size i f egg diameter i s to be used in comparisons of groups of even closely related species, collected over wide ranges within the distribution of the species. Furthermore, Marshall (1953) presents data i n Table I of his paper, for four families of fishes which range from arctic to boreal regions. In two of these families the adult f i s h i n arctic regions are substantially larger than in boreal regions. Data presented by Eounsefell (1957) also indicates that for many salmonids, spawners from the northern parts of their range are not only larger, but also frequently older than those from the southern parts of their range. They consequently would tend to have larger eggs. Perhaps this i s one of the major reasons for the observation of larger eggs in polar regions, whether within or between species. The relationship between total egg number and f i s h length has been shown to be too variable for use in any comparative studies. Fecundity relative to a single unit of body length or weight, however, might have p o s s i b i l i t i e s . This system would in large part compensate for differences in length of parent f i s h , even when different species were involved. Fish weight increases roughly as a cube of the increase i n length. Egg number, bec ause of i t s relationship with body cavity size and condition of the parent fi s h , does likewise. Examination of data has -55-indicated that considerably less v a r i a b i l i t y occurred i n fecundity rela-tive to a unit weight than to a unit length. Also, no consistent change was observed as f i s h length increased. For the above reasons, relative fecundity could be an extremely valuable tool i n comparative fecundity studies, as f i s h of different species, in almost any siae range, can be compared directly with one another. Relative fecundity was shown in Figures 13 and 14 to be closely linked with egg diameter. Because of the correlation (r = -0.97) observed in Figure 14, i t i s possible to approximate relative fecundity for any given mean egg diameter. This method could prove a valuable tool, and time saver, i n population studies as i t obviates the necessity of counting large numbers of eggs when attempting to estimate total egg pro-duction of a spawning population of fish. If mean egg diameter, mean f i s h weight and approximate number of f i s h are known, approximate total egg number can easily be calculated. Relative fecundity has seldom been used in the study of interspecific relationships. However, in view of the close relationship demonstrated between relative fecundity and egg diameter, the use of this measure might prove f r u i t f u l . Within each family of f i s h a tendency can be seen to decrease fecundity relative to body weight, while at the same time an opposing tendency can be seen to increase i t relative to body length, as fork length increases. This can be accounted for by the demonstrated increase in egg diameter as f i s h length increases. Egg number, assuming constant diameter, should increase in almost a direct proportion to increases in size of body cavity. Body cavity, in most fishes, increases i n almost -56-a direct proportion to increases In total fish weight which In turn increases in approximately a cubic ratio to each increment in fork length. It Is therefore apparent that absolute fecundity will increase much more rapidly for each additional unit of length increment than i t will for each unit of weight increment* Tor example, one centimeter increase in length would generally correspond with a greater fecundity rise than would one gram increase in weight. Belative fecundity behaves in a similar manner. Egg diameter, however, has been shown to Increase as fish length Increases. This increase in diameter may be sufficiently large to cause the apparent decline in relative fecundity observable in Figure 13. The presence of larger eggs in larger fish might well be the major cause of a decline in fecundity of older fish as observed by Calhoun (19^4) for yellowstone cutthroat (£. clarkl lewiel). The various points on Figures 13 and l4 have been separated into two groups, above and below 3*20 mm. mean egg diameter, in an attempt to illustrate the rather substantial differences in relative fecundity of the two groups. These differences may represent reflections of differences in l i f e histories or in ecological relationships of the various species. An outstanding example is the burbot, only freshwater representative of the otherwise marine family Gadidae, whose l i f e history and ecology differ from most other freshwater species of fish. Eeference to Figures 10, 11, 13 and,15 abundantly demonstrates the mag-nitude of differences in relative fecundity and egg diameter of the bur-bot as compared with other species. It is suggested that these differences, certainly genetically controlled, are also directly related to certain -57-phases of the l i f e history and ecology of this animal. Data presented in Tables 711 and T i l l lend further support to this hypothesis. If such environmental variables as food abundance (or quality), perhaps temperature, alter fecundity and egg diameter, ecological relation-ships could conceivably do likewise. Tables 711 and VIII present data which demonstrates the close relationship between certain "reproductive characteristics" and egg dia-meter in a number of species representing diverse phylogenetic and ecological groups. The presence or absence of most of the "reproductive characteristics" in these diverse groups, with eggs of either small or large mean diameter, is too consistent to be coincidental. They are in fact highly significant statistically. Small eggs, among species examined, appear invariably asso-ciated with adhesiveness and a white to pale yellow coloration. Small eggs are more buoyant than larger ones because of a larger surface area-volume ratio. They hence are much more easily transported by water currents than are larger eggs. Most spawning occurs on either lake shores where wave action supplies water currents necessary for adequate gaseous exchange, or in streams where running water is present. Simple deposition of ova on the substrate In such places would almost certainly result in excessive mortality as a result of washing away in currents, stranding, or transportation of eggs by water currents, to predators. Kb species tested with small eggs showed any indication of redd construction. The development of adhesive eggs, howeveE, would appear to have many advantages far outweighing the disadvantages. If adhesive, these small eggs could settle into narrow crevices between rocks, adhering to sides -58-and bottoms of stones where they contacted them as a result of water currents. Many would, of course, adhere to exposed surfaces where they would be openly subjected to predation. However, their small size and pale color render them almost indistinguishable, at times, from sand grains. In many cases eggs become encased in a "shell" of sand grains (grayling), rendering them virtually Invisible on any sandy substrate. It is thus possible to postulate processes of selection acting toward the development of neutral coloration and adhesiveness in fish with eggs of small diameter. On the other hand large eggs, among species examined, appeared Invariably associated with a lack of adhesiveness and an amber to salmon color: Because of the relatively large size of these eggs, fish mast have fewer of them. The eggs are consequently very valuable to the species as a whole. Wolf and Wales (1953) demonstrated that rainbow trout had a definite preference for food pellets or corks dyed red, with orange as a second choice. Ho other colors attracted any attention. Similar pre-ferences have been shown for other species of fish. They also showed rainbow trout to have a definite preference for bright red salmon eggs as compared with "pale" colored eggs. These large, amber-salmon colored eggs would appear to be exceedingly attractive to predators of many kinds. Brown (1957) suggested that the accumulation of carotenoid pigments In ova may be important in supplying chromatophore colors to the developing larvae, and as such, may be of considerable survival value. In addition, recent work indicates that carotenoid pigments of eggs may play an important part In fertilisation by stimulating chemotaxis in spermatozoa* The presence of brilliant pigmentation in most large eggs would thus -59-appear to be of some survival value to species which, because of large egg size, have considerably reduced egg numbers relative to fish with small eggs. If eggs of these species were broadcast randomly over the surface of the substrate, predators would soon be attracted, resulting in excessive losses. Some type of parental care would be essential to survival of these large eggs. Construction of redds appears to be the direction in which forces of natural selection have swung, since a l l species studied with large eggs are known to construct redds of one form or another; none are known to build nests or guard the young after hatching. In addition, construction of a pit into which the eggs are deposited may permit more thorough, mixing of sperm and eggs which, together with the suppected chemotactic effect of carotenoid pigments, may Insure a higher successful rate of fertilization than would be pos-sible i f the eggs were merely broadcast on the substrate. Therefore, both redd construction and pigmentation may be of considerable survival value to species with large eggs and reduced egg numbers. Eggs of large diameter, because of their relatively lower surface area to volume ratio require a greater flow of water for gaseous exchange than do eggs of small diameter. Hence this may represent a major reason for the prevalence of stream spawning in species with eggs of large mean diameter. Species with large eggs, and which spawn in lakes presumably do so in porous gravel through which springs flow. Perhaps this represents one reason why these species are selective as to spawning sites, for the gravel must- be extremely porous, and virtually free of any fine particulate matter, which has been shown by Hobbs (1937) -6o-and Stewart (1953)» to induce high mortality in eggs of rainbow and hrown trout. Adhesiveness appears to have been lost to eggs of large diameter. Adhesive eggs would cling to stones as they touched them, with the result that many could be crushed during the construction of redds. Non-adhesive eggs on the other hand would in a l l probability be moved aside by water currents from the moving stones, and subsequently come to rest in crevices between stones. Non-adhesiveness also prevents an excessive amount of "clumping" among larger eggs which otherwise could result in a curtailment of water flow around the eggs, or provide a favor-able medium for growth of fungus around dead ova. Oxygen uptake would be a minor problem with small eggs because of their greater surface area-volume ratio, and greater ease of gaseous exchange. Fungus is a very real problem among small as well as large eggs, and is probably offset by increased numbers of the small eggs. These processes of natural selection are almost certainly active at a l l times in a l l populations of fishes. Sv&rdson (19^9) postulated selection pressures acting toward the development of larger eggs in a l l species. Brown (195?) states that larger eggs produce larger fry than smaller eggs reared under identical conditions* If i t is true that fry from large eggs grow faster than those from small eggs, and may subsequently attain greater size, then there may be strong selection for fish to produce larger eggs. However, a l l fish do not have big, brightly colored eggs. It appears, therefore, that for many species, selection factors are acting very strongly towards development of small colorless eggs. Many factors could raver selection for small eggs. For example, -61-conslderably greater numbers of small eggs can be matured with. much, less drain on energy reserves of the parent fish than i f large eggs were matured. Mature fish may then survive to spawn two, three or even more times, thus adding much to the reproductive potential of a population. Try from small eggs, though frequently more numerous than those from large eggs may be more difficult for predators to find and hence in some cases may have greater chances for individual survival. The greater surface to volume ratio of small eggs may also be of considerable survival value in environments with restricted oxygen supplies, because of their greater ease of respiration. In almost every set of environmental conditions, natural selection is probably constantly affecting egg size and number. Under each set of conditions selection for larger or smaller eggs probably attains a more or less stable level, the upper and lower limits of which are under genetic control, and may fluctuate with genetic changes. Therefore, as environment changes along with climatic or geographic fluc-tuations, fecundity can also be expected to change, but not necessarily toward lower fecundity and larger eggs. Selection may become equally intense for greater numbers of smaller eggs. -62-COHCLUSIQNS 1. Basalts indicate that a positive correlation between fecundity and fork length exists for a l l species of fish examined as well as for salmonid species tested by earlier workers. 2. Fecundity, because of large, unpredieatable, environmentally induced variations, as well as variations caused by size and age of fish, cannot be considered practical for extensive use in racial or clinal studies. 3. It cannot be positively stated, with a l l existing evidence whether or not egg diameter or number form latitudinal clines in any or a l l species. 4. Egg diameter is variable within a single ovary of a fish. Of five species tested, a l l had significantly larger eggs (.05 - *01 levels) in anterior than In posterior regions of their ovaries. 5. Egg diameter apparently increases as parent size increases, both within a species and between species. This indicates the necessity of using comparable sized fish in a l l instances in which egg diameter is to be used for racial or clinal studies. 6. Age was found to have no apparent direct effect on egg diameter of rainbow trout from Paul Lake. - 6 3 -7. Bang© in fecundity relative to a unit of fish length or weight is superior to total egg number for use in racial or clinal studies because of reduced variability with increases in total fish length or weight. 8. Considering sixteen species tested, body shape appears to have l i t t l e or no effect on relative fecundity. 9 . Relative fecundity is closely dependent on egg diameter. 10. The burbot, the only freshwater representative of what is otherwise solely a marine family, differs substantially in many aspects of fecundity (and l i f e history), from purely freshwater families. 11. In twenty-six species of freshwater fish, egg diameter was found significantly correlated with a number of reproductive character-istics. 12. Fish with eggs of small mean diameter generally have white to yellowish eggs, adhesive eggs, short Incubation periods, no redd construction (parental care), variable spawning location and spring or summer spawning season. 13» Fish with eggs of Intermediate mean diameter represent a group exhibiting variable reproductive characteristics. 14. Fish with eggs of large mean diameter generally have amber to salmon colored eggs, non-adhesive eggs, long incubation periods, redd construction (parental care), stream spawning and variable spawning season. -64-LITERATURE CITED Allen, G» H. 1956. Age and growth of "brook trout in a Wyoming "beaver pond. Copeia, ( l ) t l - 9 . Belding,D.L. 1934. The spawning habits of the Atlantic salmon* Trans. Am. Pish. Soc, jj4:211-216. Brown, C. J. D. 1938. Observations on the l i f e history and breeding habits of the Montana grayling. Copeia, (3):132-136. Brown, C. J. D. 1952. Spawning habits and early development of the rocky mountain whitefish (Proscmlum williamsonlJ, In Montana. Copeia, (2).109-113. Brown, C. J. D. and G. C. Kamp 1941. Gonad measurements and egg counts of brown trout (Salmo trutta) from the Madison Elver, Montana. Trans. Am. Pish. Soc, 71:195-200. Brown, M. E. 1946. The growth of brown trout. I—Factors influencing the growth of trout fry. J. Exp. Bio. gg(3 & 4): 118-129. Brown, M. E. 1957. !Ehe Physiology of Fishes, Academic Press Inc., I, Metabolism. Brunson, B. B. 1952. Egg counts of Salvelinus malma from the Clark 1s Fork Elver, Montana, Copeia, (3):197. Burrows, E. E. 1951* An evaluation of methods of egg enumeration. Prog* Fish Culturist, I3_(lfi»2).79-85. Cahn, A* R. 1936. Observations on the breeding of Lota maculosa. Copeia, (3):163-165. Calhoun, A. J. 1944. Black spotted trout In Blue Lake, California. Calif. Fish and Game, 3j.(l): 22-42. Car lander, K. C. 1950. Handbook of Freshwater Fishery Biology. W. C. Brown Go. Cramer, F. F. 1940. Notes on natural spawning of cutthroat trout (Salmo clarkl clarkj) In Oregon. Proc. Sixth Pac%Sci.^Congress, 2:335-339-Dixon, W. J. and A. M. Mood, 1946. The statistical sign test. Jour. Amer. Statist. Ass'n., 41:557-566. -65-Donaldson, L. E. and P. B. Olson. 1955* Development of rainbow trout brood stock by selective breeding. Trans. Am. Pish. Soc, Q$i93-101. Dymond, J. R. 1928. Some factors affecting the production of lake trout in Lake Ontario. Univ. Toronto Studies; Biological Secies, 21.27-41. Eddy, S. and T. Surber. 1943. Northern fishes with special reference to the upper Mississippi Valley. Univ. Minn. Press, 2 ed., 276 pp., Pigs. 1-57. Eschmeyer, P. H. 1955» Reproduction of lake trout In southern Lake Superior. Trans. Am. Pish. Soc, 84,:47-74. Eschmeyer, P. H. and P. M. Bailey. 1955* The pygmy whitefish Coregonus coulterl. in Lake Superior. Trans. Am. Pish. Soc, Sjfc: 161-199. Foerster, R. E. and A. L. Pritchard. 1941. Observations on the relation of egg content to total length and weight in the Sockeye salmon (Oncorhynchus nerka) and the pink salmon (Oncorhynchus gorbushha). Trans. Roy. Soc Canada, 25i Sec. V:51-60. Harlan, J. H. and E. B. Speaker. 1956. Iowa Fish and Pishing. Iowa Conservation Comm'n. pp. 124-127. Hart, J. L. 1930. The spawning and early l i f e history of the whitefish (Coregonus ciuueaformls« in the bay of Ojalnto, Gontr. Can. Bio. and'Hah. U.S., 6 (7). 167-214. Hickllng, C. F. and B. Eutenberg. 1936. The ovary as an indicator of spawning period in fishes. J. Marine Bio. Ass'n. U.K., N.S., 21(1)t311-318. Hobbs, D. F. 1937* Natural reproduction of Ojoinnat salmon, brown trout and rainbow trout in certain New Zealand waters. New Zealand Marine Dept., Bull. 6. Lagler, K. F. 1949. Studies in Freshwater Fishery Biology. J. V. Edwards, Ann Arbor, Michigan:218-222. Loftus, K. H. 1957* Studies on river-spawning populations of lake trout in eastern Lake Superior. Trans. Am. Fish. Soc., 22:259-277. McGregor, E. A. 1923. A possible separation of the river races of king salmon in ocean-caught fish by means of anatomical characters. Calif. Fish and Game, £(4):138-150. Marshall, N. B. 1953* Egg size in arctic, antarctic and deepsea fishes. Evolution, 2*328-341. -66-Mottley, C. McC. 1931. Temperature and propagation of trout. Prog. Repts. Pac. Bio. Stn., lo.8:11-14. Heave, P. 1948. Fecundity and mortality in pacific salmon. Trans. Roy. Soc. Canada, 42,, Ser. 3, Sec.5:97-105. Page, W. P. 1888. The most recent met ods of hatching eggs, Bull. U.S. Pish Comm., £.207-218. Prince, B. E. and A. Halkett, 1905-06. The eggs of the freshwater ling. The Ottawa Haturalist, 12*219-224. Scott, D. P. 1955* Effect of food quantity on the fecundity of Kamloops trout, Salmo galrdneri kamloous Jordan.. Unpub. PhD. thesis, U.B.C., 1956. Snedecore, 0. W. 1948. Statistical Methods. Iowa State College Press, 4 Ed. Stewart, T. A. 1953. Spawning migration, reproduction and young stages of loch trout (Salmo trutta |j.), Scottish Home Dept., Freshwater and Salmon Fisheries Bes. Bull.,#5. Svardson, G. 19**9» Hatural selection and egg number In fish. Inst. of Freshwater Res., Fish. Bd of Sweden, Rept. 29: 115-122. Rlcker, W. E. 1932. Studies of speckled trout (Salvellnua fontlnallq) In Ontario. Publ. Ontario Fish. Res. Lab. Ho.44: 67-110; in Univ. of Toronto Biol. Ser. Ho. 36. Rounsefell, G. A. 1957. Fecundity of Norths American Salmonidae , Bull. U.S. Fish and Wildlife Service, 5Z:451-468. Titcomb, J. W. 1897• Wild trout spawn: methods of collection and utility. Trans. H. Am. Fish. Soc. ,26:73-86. Vladykov, V. D. 1956. Fecundity of wild speckled trout (Salvelinus fontlnalls) in Quebec Lakes. Jour. Fish. Res. Bd. Canada, 13.(6): 799-8^1. Von Bayer, H. 1910. A method of measuring fish eggs. Bull. U.S. Bur. Fish., 22(2): 1011-1014. Ward, F. J. 1952. Egg counts as a means of identifying the races of Fraser River sockeye salmon. Unpub. B.A. thesis, U.B.C. Welsel, G. F. and J. B. Dillon, 1954. Observations on the pygmy whitefish (Proaoulum coulter!). from Bull Lake, Montana. Copeia, (2):124-127. -67-Wolf, H. and J. H. Wales, 1953. Color reception i n trout. Copeia (4): 234-236. -68-Appendix i . Fecundity data of some British Columbia fish arranged in phylogenetic order. Species Pork Egg Egg Egg No. Egg No. Length Weight Diameter Number Per cm. Per gm. (cm) (gm) (mm) Prosopium 26.5 222.5 2.86 2874 108.5 12.9 vllliamsoni 27.0 275.5 2.82 3282 121.6 11.9 27.0 255.5 2.77 3306 122.4 12.9 Nicola 27.5 302.5 2.66 2998 109.0 9.9 Lake 30.5 401.7 2.81 5128 168.1 12.8 30.7 382.4 2.88 38.34 124.9 10.0 Thymallus 27.3 2.55 Partially arcticus 29.2 - 2.70 siffaifer 26.0 - 2.50 spawned 27.9 - 2.40 Yukon 29.9 — 2.42 out Oncorhynchus 19.0 70.2 4.2 187 9.8 2.7 asrka. 19.7 78.0 3.9 271 13.8 3.5 kennerlyl 20.3 80.0 4.1 208 10.3 2.6 20.3 86.1 4.1 215 10.6 2.5 20.3 774.8 3.8 242 11.9 3.2 J.C.Lyons 20.3 77.2 4.1 164 8.1 2.1 (1950) 20.6 85.1 4.6 184 8.9 2.2 20.9 106.7 4.3 376 18.0 3.5 20.9 76.8 3.9 225 10.8 2.9 Meadow Creek, 20.9 91.1 4.4 105 5.0 1.2 B.C. 21.6 97.2 4.3 228 10.6 2.4 21.6 83.4 4.2 241 11.2 2.9 22.1 110.6 4.4 316 14.3 2.9 22.1 111.2 4.6 199 9.0 1.8 22.1 105.3 4.5 252 11.4 2.4 22.3 109.3 4.7 203 9.1 1.8 22.3 105.8 4.2 189 8.5 1.8 22.9 104.0 4.3 203 8.9 2.0 22.9 116.3 4.2 277 12.1 2.4 22.9 109.4 4.8 250 10.9 2.3 22.9 105.5 4.1 309 13.49 2.9 22.9 106.5 4.6 247 10.8 2.3 22.9 119.6 4.3 230 10.0 1.9 22.9 107.6 4.7 236 10.3 2.2 -69-Appendix i . Cont'd. Fecundity data of some British Columbia fish arranged in phylogenetic order. Species Pork Egg Egg Egg No. Egg No. Length Weight Diameter Number Per cm. Per gm. (cm) (gm) (mm) Oncorhynchus 22.9 116.9 4.6 184 8.0 1.6 nerka 22.9 110.5 4.5 263 11.5 2.4 fcennertaA, 22.9 114.3 4.5 236 10.3 2.1 J. C.Lyons, 24.1 133.7 3.8 309 12.8 2.8 (1950) 24.8 124.1 3.5 345 13.9 2.8 Meadow Creek, B.C. Hicola Lake, 23.3 159.6 4.5 462 19.8 2.9 B.C. 23.4 164.5 4.7 415 17.7 2.5 23.8 I60.8 4.4 360 15.1 2.2 25.7 207.2 4.5 579 22.5 2.8 Shawnigan Lk. 28.0 296.2 4.9 1086 38.8 3.7 28.8 347.5 4.9 1258 43.7 3.6 29.0 340.7 5.1 963 33.2 2.8 30.8 375.9 5.2 1077 34.9 2.9 Salmo 42.5 1127 4.7 1877 44.2 2.0 eairdneri 44.0 1264.7 4.3 2238 50.9 2.0 J.C.Lyons & 47.5 1357.3 4.4 2014 42.4 1.7 P.A.Larkin 47.5 1534.3 4.5 2744 57.8 2.0 (unpub) 48.0 1524.5 4.5 2527 52.7 1.9 Peterhope Lake Znouff Lake 28.0 286.4 3.6 750 26.8 2.9 30.5 393.1 3.5 2064 67.7 5.-9 44.5 1036.5 4.3 2170 48.8 2.5 4-7.5 1293.5 4.3 2067 43.-5 1.8 48.0 1449.0 4.3 3090 64.4 2.5 50.0 1608.4 4.3 2330 46.6 1.7 52.0 1783.0 4.2 3905 75.1 2.6 Jacko Lake 61.5 2849.5 4.0 6313 102.7 2.6 63.0 3000.0 4.3 4831 76.7 1.8 63.0 3700.0 4.3 6941 110.2 2.2 70.0 3999.7 4.4 6991 99.9 2.0 Appendix 1. Cont'd. Fecundity data of some British Columhia fish arranged in phylogenetic order. Species Fork Egg Egg Egg No. Egg No. Length Weight Diameter Number Per cm. Per gm. (cm) (gm) (mm) Salmo eairdneri 28.5 260.8 3.4 884 31.0 3.9 J.C.Lyons & 32.0 622.9 4.1 1121 35-0 2.0 P.A.Larkin 33.0 5*0.2 3.9 979 29.7 2.1 (unpulO 35.0 393.2 3.9 838 23-9 2.4 Paul Lake 35.0 619.0 4.3 1306 37.3 2.5 35.5 479.9 3.8 1621 45.7 4.0 36.0 575.8 4.0 1326 36.8 2.7 36.0 563.2 4.0 1556 43.2 3.3 36.0 451.4 3.9 1451 40.3 3.9 38.0 729.7 4.0 2111 55.6 3,-5 4o.O 619.5 3.9 1204 30.1 2.2 41.0 712.3 4.0 800 19.5 1.2 41.0 887.6 4.3 1957 47.7 2.6 41.5 962.5 4.3 2485 59.9 3;. 2 42.5 820.8 4.6 1058 24.9 1.5 43.0 723.3 3.6 1788 41.6 2.8 43.0 936.5 3.8 2298 53.^ 2.8 44.0 999.8 4.2 2326 52.9 2.7 44.0 842.3 4;:2 1395 31.7 1.9 44.0 1158.1 4.0 2919 66.3 2.9 44.5 1159.8 4.4 2350 52.8 2.4 45.0 1090.3 4.2 2423 53.. 8 2.7 47.0 1260.0 4.4 2121 45.1 1.9 47.0 1051.7 3.6 4970 105.7 5.9 48.0 1275.5 4.7 1581 32.9 1.4 49.0 1249.7 4.1 2623 53.5 2.4 Catostomus 28.6 297.4 I.60 8600 300.7 28.9 catostomus 29.0 304.5 1.50 12765 440.2 41.9 30.7 371.2 1.70 15132 592.9 40.8 Shelley 31.5 399.3 1.64 18098 574.5 45.3 Slough 32.2 416.0 17603 546.7 42.3 32.4 418.3 1.61 18544 572.3 44.3 32.5 498.8 — 24978 768.6 50.1 32.6 378.5 1.74 12033 369.1 31.8 33.0 426.2 1.55 18544 572.3 44.3 33.3 551.2 1.72 19593 588.4 35.5 34.0 545.6 1.50 20300 1067.6 66.5 -71-Appendlx i . Cont'd. Fecundity data of some British Columbia fish arranged in phylogenetic order. Species Fork Egg Egg Egg No. Egg No. Length Weight Diameter Number Per cm. Per gm. (cm) (gm) (mm) Catostomus 34.5 544.7 1.61 18,000 521.7 33.0 catostomus 34.5 460.8 1.49 15,800 457.9 34.3 Shelley 35.0 528.8 1.66 22,833 652.4 43.2 Slough 35.0 510.5 — — 20,787 593.9 40.7 Catostomus 39.0 741.2 2.01 17,963 460.5 24.2 macrocheilus 41.5 1,085-5 2.41 13,669 329.3 12.6 41.5 930.0 2.20 15,463 372.6 16.6 42.2 1,040.0 2.16 20,667 489.7' 19.9 Wolf Creek 43.0 1,044.0 2.28 14,900 346.5 14.3 45.0 l,156:o 2.23 21,11? 469.2 18.3 46.0 1.349.5 2.27 22,662 492.7 16.8 Little Bull B. 46.0 1,648 2.62 20,000 434.8 12.1 Catostomus 32.0 465-7 1.84 11,825 369.5 25.4 commeraonl 38.5 733.2 1.89 17,405 452.1 23.7 Mylochellus 24; 0 218.5 1.59 10,974 457.2 50.2 caurinum 24.5 225 <0 1.58 12,381 505.3 55.0 24.7 226.7 1.66 11,972 484.9 52.8 White Lake 25.1 237.0 1.62 11,786 469.6 49.7 25.2 247.5 1.59 14,170 562.3 57.3 25.6 246.6 1.61 13,933 544.2 56.5 26.1 264.7 1.68 17,261 661.3 65.2 26.2 246.7 1.66 13,585 518.5 55.1 26.2 266.4 1.68 13,796 526.5 51.8 26.3 265.9 1.63 13,030 495.4 49.0 26.8 282.7 1.62 17,268 644.3 61.1 Hansard Lake 19.6 1*1.3 1.48 5,222 266.4 64.2 19.6 79.0 1.48 4,643 236.9 58.8 19.9 80.5 1.53 4,335 217.8 53.9 20.7 92.2 1.48 6,664 326.7 72.3 21.2 86.1 1.59 5,256 247.9 61.0 -72-Appendix i . Cont'd. Fecundity data of some British Columbia fish arranged in phylogenetlc order. Species Fork Egg • Egg Egg Ho. Egg Ho. Length Weight Diameter Dumber Per cm. Per gm. (cm) (go) (mm) Mylocheilus 21.2 119.3 1.56 7,884 371.9 60.9 - caurinum 24.7 194.7 1.55 13,376 541.5 68.7 Terrace 24.8 219.3 1.55 13.261 534.7 60.5 Bhinichthys 9.9 14.5 1.38 520 52.5 35.9 cataractae 9-9 14.0 1.53 775 78.3 55.4 10.0 15.7 1.35 773 77.3 49.2 10.9 21.3 1.51 890 81.7 41.8 Tulameen B. 11.3 20.0 1.38 756 66.9 37.8 11.4 25.0 1.40 1,102 96.7 41.8 Bichardsonlus 9.9 13.9 1.26 1,198 121.0 86.2 balteatus 10.1 14.5 1.18 1,182 117.0 81.5 10.2 15.9 1.21 1,071 105.0 67.4 Shelley 10.7 17.8 0.84 1,694 158.3 95.2 Slough 10.8 18,7 1.24 1,334 123.5 71.3 10.9 18.6 1.21 . 1,243 114.0 66.8 11.0 18.3 1.12 1,539 140.0 84.1 11.5 22.7 1.34 l,4o4 122.1 6I.9 11.6 20.6 1.24 1,279 110.3 62.1 12.4 30.7 1.20 2,205 177.8 71.8 Trembleur 9.2 10.9 1.22 1,404 153.6 128.8 Lake 9.2 9.7 1.24 1,688 183.4 174.0 9.3 10.6 1.33 958 103.0 90.4 11.1 20.0 1.10 2,327 209.6 66.4 11.2 20.1 1.28 2,568 229.3 127.7 11.5 19.5 1.23 2,472 214.9 126.8 11.7 23.1 1.43 1,508 128.8 65.3 12.7 24.6 1.20 3,384 266.5 137.6 Paul Lake 8.3 7.7 0.93 778 101.0 93.7 9.3 11.9 1.04 827 88.9 69.5 9.4 11.7 1.12 1,066 113.4 91.1 9.4 12.8 1.17 1,129 120.1 88.2 9.5 11.1 1.30 880 92.6 79.3 9.7 13.2 1.29 1,166 120.2 88.3 9.8 11.7 — 1,000 102.0 85.5 -73-Appendlx 1. Cont'd. Fecundity data of some British Columbia fish arranged in phylogenetic order. Species Pork Length (cm) Weight (gm) Egg Diameter (mm) Egg Number Egg Ho Per cm. Egg Ho. Per gm. Richardsoniua bal teat/us. Paul Lake 10.2 10.3 11.5 15.4 15.3 18.1 1.12 1.16 0.99 1,372 i,5oo 1,216 134.5 145.6 105-7 89.1 98.0 67.2 Lota lota Dutch Creek (Kootenay) 36.5 37.0 361 399.2 0.65 0.70 295,000 395,000 8,082 10,675 817.2 989.4 Cottus asner Bella Coola 12.4 21.2 27.1 178.9 1.23 1.21 1,571 14,655 4o4.5 691.2 69.9 81.9 Appendix i i . Mean fecundity data of some British Columbia fish. Fork Egg Egg Egg Ho. Egg Ho. Number Species Length Weight Diameter Number Per cm. Per gm. in (cm) (gm) (mm) Sample Prosopium williamsoni 28.2 306.6 2.80 3,570 125.8 11.7 6 Thymallus arcticus signifer 28.1 — 2.51 — — — 5 Oncorhynchus nerka kennerlyl 22.3 134 4.28 35^ 10.8 2.4 37 Salmo gairdnerl 43.7 1,171.3 4.13 2,389 51.4 2.6 42 Catostomus catostomus 32.6 444 1.60 8,361 569.6 4 l.l 15 Catostomus macrocheilus 43.0 1124 2.23 18,305 424.4 16.9 8 Catostomus commersoni 35.2 599 1.85 1 ,^615 410.8 24.5 2 Mylocheilus caurinum 23.8 194 1.57 11,095 453.3 58.1 19 Bhinichthys cataractae 10.5 18.4 I.35 802 75.6 44.0 6 Appendix i i . Cont'd. Mean fecundity data of some British Columbia fish. Species Pork Length (cm) Weight (gm) Egg Diameter (mm) Egg Number Egg No Per cm. Egg No. Per gm. Number in Sample Blchardsonlus balteatus 10.5 16.2 1.15 1,453 137.0 90.1 29 Lota lota 36.8 380 0.68 345,000 9,378.5 903.3 2 Cottus asper 16.8 103 1.21 8,113 404.5 70.0 2 


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