Annotated Bibliography of Genetic Variation in the Family Salmonidae
R. E. Withler, M. C. Healey, and B. E. Riddell
Department of Fisheries and Oceans Fisheries Research Branch Pacific Biological Station Nanaimo, British Columbia V9R 51<6
June 1982
Canadian Technical Report of Fisheries and Aquatic Sciences No. 1098
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and Aquatic Sciences No. 1098
June 1982
ANNOTATED BIBLIOGRAPHY OF GENETIC VARIATION f,-:.:.,>o" ~)
IN THE FAMILY SALMONIDAE \~ ~/'.~ J ." ,,', >:;~ "-~~:j/n!l \ : ~;.:~':,7
by
R. E. Withler, M. C. Healey, and B. E. Riddell
Department of Fisheries and Oceans
Fisheries Research Branch
Pacific Biological Station
Nanaimo, British Columbia V9R 5K6 - ii -
(c) Minister of Supply and Services Canada 1982 Cat. No. Fs 97-6/1098 ISSN 0706-6457 - iii -
TABLE OF CONTENTS
Abstract •. iv
Introduction 1
Acknowledgments 3
I. Annotated Bibliography • • 4
1. Heritability of Salmonid Characteristics •••• 4
2. Genetic Variability among Populations ••• 25
3. Effects of Domestication and Propagation 52
II. List of References • • . . • • • . • 111
1. Electrophoretic, Serological and Immunological Variability . • 111
2. Isoenzyme Properties ...... 127 3. Isoenzyme Inheritance and Ontogeny · 133 Key word/Species Index . . . . · 142 Author Index ...... · 147 - iv -
ABSTRACT
Withler, R. E., M. C. Healey, and B. E. Riddell. 1982. Annotated bibliography of genetic variation in the family Salmonidae. Can. Tech. Rep. Fish. Aquat. Sci. 1098: v + 161 p.
This bibliography contains references published between 1920 and 19~J. that deal with genetic variation in the family Salmonidae. Topics covered include the heritability and intraspecific and interspecific genetic variation of morphological, physiological, and behavioral characteristics of salmonids. Publications dealing with the effects of stock manipulation and domestication on the genetics of salmonid populations are included. Cytological and cytotaxonomical studies and studies that deal exclusively with interspecific hybridization are not covered.
The bibliography consists of two parts. The citation, abs:tract, a brief comment, and key words for each quantitative genetic study are provided in Part l. In Part ll, electrophoretic, serological, and immunological studies on salmonids are listed by subject matter. A key word/species index to Part l and an author index to Parts land II are provided. Contents of this report are available in computer readable format (tape and Apple II Plus microcomputer disks with DOS 3.2 controller).
Key words: Bibliography, fish, salmon, trout, char, grayling, whitefish, genetics, genotypes, heredity, selective breeding, inbreeding - v -
Hl:':SUMl:':
Withler, R. E., M. C. Healey, and B. E. Riddell. 1982. Annotated bibliography of genetic variation in the family Salmonidae. Can. Tech. Rep. Fish. Aquat. Sci. 1098: v + 161 p.
La bibliographie enumere des ouvrages publies entre 1920 et 1981, qui traitent de la variation genetique dans la famille Salmonidae. Les sujets traites comprennent l'heritabilite et les variations genetiques intraspecifique et interspecifique des caracteristiques morphologiques, physiologiques et comportementales des salmonides. Elle renferne aussi les publications traitant des effets de la manipulation et de la domestication des stocks sur la genetique des populations de saumons. Elle ne mentionne pas les etudes cytologiques et cytotaxonomiques ni les etudes qui portent exclusivement sur l'hybridation interspecifique.
La bibliographie est constituee de deux parties. La premiere partie comprend Ie titre, Ie resume, un court commentaire et les mots-cles de chaque etude genetique quantitative. Dans la deuxieme partie, les etudes electrophoretiques, serologiques et immunologiques sont classees par ordre de matiere. Un index des mots-cles et des especes de la premiere partie et un index des auteurs des deux parties sont inclus. Le contenu de cet ouvrage est disponible sous forme lirible par un ordinateur (bande et disques de microordinateur Apple II Plus avec contrOleur DOS 3.2).
Mots-cles: bibliographie, poisson, saumon, truite, amble, omre, coregone, genetique, genotypes, heredite, accouplement selectif, croisements consanguins. INTRODUCTION
This bibliography is intended as a guide to the available literature on genetic variation within and among salmonid populations and species. Information published between 1920 and 1981 on fishes of the Salmonidae subfamilies Salmoninae, Coregoninae and Thymallinae has been covered. Cytological and cytotaxonomical studies have not been included.
References in Part 1 of the bibliography have been placed in one of three sections. Publications cited in section 1 deal with the heritability of morphological, physiological, and behavioral characteristics of salmonid populations. Studies included are generally those in which breeding studies were conducted to examine the genetic components of variance for the traits of interest in one or more populations.
Publications cited in section 2 report on intraspecific and interspecific genetic variation in morphological, physiological, and behavioral characteristics among salmonid populations. Not included are (i) studies dealing with one or more stocks that are specified as domestic (these are in section 3); and (ii) studies which have investigated primarily the genetic basis of interpopulation differentiation (section 1).
Publications cited in section 3 deal with the effects of stock manipulation and fisheries on the genetics of salmonid populations. Included are studies that (i) report on the genetic characteristics of hatchery stocks; (ii) compare genetic variation in hatchery and wild stocks; (iii) document the genetic results of introductions, transplantations and fisheries; and (iv) describe techniques intended to maintain genetic variability and natural population structure in domesticated salmonid populations.
References in Part II of the bibliography contain studies on the electrophoresis, serology, and immunology of salmonids. These citations have also been arranged in three sections. Section 1 includes investigations of electrophoretic (and serological and immunological) variation within and among salmonid populations. Section 2 includes studies which examine relationships between electrophoretic and morphological, physiological or behavioral variability in salmonids. Also included are studies of the structural and physiological properties of the isoenzymes produced by allelic variants. Section 3 includes studies dealing with the inheritance of electrophoretic variation and the ontogeny of electrophoretic patterns. In Part II, references dealing with topics in more than one section have been repeated 1n each section to which they are relevant.
The citation for each reference included in Part 1 is accompanied by the abstract, a brief commentary, and key words. For papers published without an abstract, one has been drawn from the text or prepared de novo. Some abstracts have been abbreviated for reasons of space. Abstracts that were not provided by the author or journal, or that were abbreviated, have been denoted by an asterisk. Some recent (1980-1981) or difficult to obtain references have been included without comment. - 2 -
The key words, which follow each citation, are intended to convey the following information:
t. The level at which genetic variation 1S examined: interpopulation variability: variation among populations or species. interpopulation variability: variation within populations. heritability: influence of parental genotypes on expression of polygenic traits. genetic structure: influence of breeding population characteristics on genetic variation within populations or species.
2. The traits for which genetic variation is examined: morphology: shape and size of body and body parts; meristic values. growth: growth rate and size reached. age of maturity: age reached at time of first maturity. size of maturity: size reached at time of first maturity. disease: susceptibility or resistance to pathogens. electrophoresis: allele frequencies at structural gene loci. life history: all traits not included in above categories (e.g. survival, behaviour, physiology, body composition).
3. The species in which genetic variation is examined: chinook, chum, coho, pink, sockeye, rainbow, steelhead, cutthroat, Atlantic salmon, brown trout, Arctic char, brook trout, lake trout, splake, whitefish, grayling. salmonids: indicates information derived from or applicable to many or all salmonid species.
4. The geographic regions from which samples were obtained: Canada, Europe, Japan, U.S.A., U.S.S.R.
S. Other key words and their usage include: fisheries: the genetic effects on a population caused by fishing (selective removal of individuals). founder effects: influence on genetic variability of the finite number of genomes that established a population. genetic drift: stochastic variation in allele frequencies over time due to finite population size. genotype-environment interaction: a variable effect of the environment on expression of genetic information. heterosis: hybrid vigour. inbreeding: genetic effects of the mating of fish closely related by ancestry. maternal effects: specific maternal genetic and environmental influences on offspring. propagation: genetic effects of stock manipulation. propagation?: possible genetic effects of future stock manipulation. selection: actual results or possible consequences of natural or artificial (practised by man) selection on fish populations. - 3 -
We recognize that mistakes and omissions are inevitable in the compilation of a bibliography of this nature. Additions and corrections provided by readers will be received gratefully at the address below.
This bibliography is also available on floppy disks suitable for use on the Apple microcomputer system with a commercial text processing program, Easywriter. Text of .the bibliography can also be provided on computer tape but bibliographic search and sort programs cannot be provided. We intend to keep the disk version up-to-date and, when warranted by the amount of revision, produce another printed copy.
R. E. Withler Fisheries Research Branch Pacific Biological Station Department of Fisheries and Oceans Nanaimo, British Columbia Canada V9R 5K6
ACKNOWLEDGMENTS
Ms. Heather Baker of Aquatic Environments Ltd. assisted greatly with data organization and entry. Dr. Craig Busack provided valuable advice in a critical review of the manuscript. - 4 -
I. ANNOTATED BIBLIOGRAPHY
SECTION 1. HERITABILITY OF MORPHOLOGICAL, PHYSIOLOGICAL AND BEHAVIORAL CHARACTERISTICS IN SALMONIDS , Aulstad, D., T. Gjedrem/and H. Skjervold. 1972. Genetic and environmental sources of variation in length and weight of rainbow trout (Salmo gairdneri). J. Fish. Res. Bd. Can. 29: 237-241.
Abstract: Rainbow trout of three year-classes (1967-1969) were produced from random mating, and one year-class (1970) from inbreeding. The two first year classes were fullsib groups. Intraclass correlations for body length in the 1967 year-class were: 0.16, 0.15, 0.09, and 0.17 at 90, 130, 355, and 485 days of age, respectively. The corresponding estimate for the 68 year-class was 0.25 at age 110 days. For the 1969 year-class the sire x dam interaction component was negative at ages 150 and 280 days, indicating that nonadditive gene effects were unimportant. Estimated heritabilities ranged from 0.0 to 0.40, those from the sire component being generally higher. Environmental differences between tanks were low, but not ignorable. The 1970 year-class showed significant differences between inbred and control (noninbred) for mortality of eggs and fry, but not for body weight at age 75 days.* Comment: This study provides good estimates of the heritability of growth in rainbow trout fry reared under hatchery conditions. Although the 1969 factorial experiment was hampered by poor survival, it was designed and analysed properly for the estimation of heritability values. The observed heritabilities for body length and weight are not unexpectedly low for a fitness-related characteristic such as growth. Moreover, if the indication of little nonadditive genetic variation in growth proves correct, the possibility of selectively breeding for increased growth in hatchery strains of trout is good. Unfortunately, it was not specified whether the parental fish used were from wild or domesticated stocks. Genotype-environment interactions, which might significantly affect the growth of hatchery bred fish released in the wild, were not examined. However, the differences observed among tanks were likely partly due to such interactions. Key words: heritability, growth, inbreeding, maternal effects, propagation?, selection, rainbow, Europe. - 5 -
Ayles, G.B. 1974. Relative importance of additive genetic and maternal sources of variation in early survival of young splake hybrids (Salvelinus fontinalis x~. namaycush). J. Fish. Res. Bd. Can. 31: 1499-1502. Abstract: Additive genetic and maternal effects of survival of uneyed eggs, eyed eggs, and alevins were determined from five series of matings within a splake brood stock. Average values for family h (heritability) and family m (maternal variance/total variance) were estimated. There were additive effects in alevin survival (h = 0.41) but not in uneyed or eyed egg survival. Maternal effects were greatest within the uneyed stage (m = 0.78), decreased during the eyed egg stage (m = 0.68), and were least within the alevin stage (m = 0.40). The additive genetic effect on alevin survival was attributable to genetic differences in the resistance of young splake to blue sac disease (h = 0.76). Comment: The relatively high heritability of resistance to bluesac disease displayed by splake in this study indicated that selection for resistance under hatchery conditions should be successful. The assumption that the large maternal influence on egg and alevin survival was primarily the result of environmental factors was supported by the fact that the observed effect decreased with age (ie. from uneyed egg to eyed egg to alevin). However, because of the magnitude of the maternal effect, an evaluation of possible genetic components would be valuable. Key words: heritability, disease, maternal effects, lake trout, brook trout, splake, Canada.
Bailey, J.K. and R.L. Saunders. 1978. Bimodal growth trait frequency distributions in strains of artificially reared Atlantic salmon (palmo salar) parr produced in a dial leI experiment. (Abstract Only). Can. J. Genet. Cytol. 20: 440. Abstract: The frequency distributions of length and weight, in all strains of artificially reared Atlantic salmon parr, produced by a series of diallel sets involving four New Brunswick river stocks, showed obvious bimodality during the first autumn of growth for both the 1975 and 1976 year classes produced at the North American Salmon Research Center. Although the majority of precociously mature males was concentrated in the upper tail of the lower size mode, this alone did not account for the bimodality. The degree of separation was inversely proportional to the number of mature male parr.
Key words: interpopulation variability, intrapopulation - 6 -
variability, growth, age of maturity, Atlantic salmon, Canada.
Bailey, J.K., R.L. Saunders and M.I. Buzeta. 1980. Influence of parental smolt age and sea age on growth and smolting of hatchery-reared Atlantic salmon (Salmo salar). Can. J. Fish. Aquat. Sci. 37: 1379-1386. Abstract: Hatchery-reared Atlantic salmon consistently developed bimodal length-frequency distributions by the first November following hatch. In a study of 32 hatchery populations involving two year-classes, mean length in the lower mode showed little variation among populations and was not correlated with either the smolt age or sea age at first maturity of their parents. Mean length and the proportion of individuals in the upper mode were both variable among populations and correlated with parental age variables. Large mean length in the upper mode was strongly associated with early smolting male parents and late maturing female parents. The proportion of individuals in the upper mode was more strongly correlated with the age variables of the female parent. Late smolting and early maturing female parents tended to produce relatively greater proportions of fish in the upper mode. The optimum growth rate which produced the greatest proportion of individuals in the upper mode occurred when 8-15% of the total population matured precociously as parr. A threshold size hypothesis for precocious maturation is discussed.
Comment: In this study, an examination of the effect of parental age variables on progeny mean length and length distribution was hampered by the inability to identify offspring of individual parents. No satisfactory genetic explanation was provided for the observation that females which spent a long time in freshwater and short time at sea (ie. smolted late) tended to produce a greater proportion of parr in the upper length mode (which presumably smolted early). The assumption that all individuals in the upper size mode smolt one year earlier than those in the lower size mode should be verified.
The suggestion that very fast growth at a young age (ie. before the 'decision' of precocious maturation must be made) can lead to a large percentage of precociously mature male parr and a reduced proportion of 'one year smolts' has important implications for hatchery production, as discussed by the authors. The determination of a life history stage at which the 'decision' on early maturation is made would be beneficial. Key words: heritability, interpopulation variability, intrapopulation variability, maternal effects, growth, age of maturity, life history, selection, Atlantic salmon, Canada. - 7 -
Bergot, P., B. Chevassus and J.-M. Blanc. 1976. Genetic determination of the number of pyloric caeca in brown trout (Sa1mo trutta) and rainbow trout (S. gairdneri). I. Character distribution and phenotypic variability within and between families. (English Summary). Ann. Hydrobio1. 7: 105-114. Abstract: The number of pyloric caeca was determined in various populations of brown trout and rainbow trout. This revealed: 1) An important phenotypic variability of the character within the populations (variation factor = 16 to 18 p. 100). 2) The log-normal structure of the distribution of caeca number within populations. 3) Important differences between populations issued from different environments. 4) The existence of important genetic effects in the character determinism. An upper limit for the heritability was estimated to be between 0.84 and 1.00 in brown trout and between 0.41 and 1.00 in rainbow trout. The sex does not seem to have any influence on this character in either species. In rainbow trout, a poor but significant (log-log) correlation between caeca number and fish length was demonstrated in fishes of the same age, which may correspond to an influence of caeca in growth rate. This result was not observed in brown trout. The possibility of obtaining through artificial selection batches of fish with a different mean caeca number and the ev.entua1 selective value of this character are discussed.*
Key words: heritability, interpopulation variability, intrapopu1ation variability, morphology, growth, selection, brown trout, rainbow, Europe.
Blanc, J.-M., B. Chevassus and P. Bergot. 1979. Genetic determination of the number of pyloric caeca in brown trout (Sa1mo trutta) and rainbow trout (S. gairdneri). III. Influence of the genotype and egg size on the realization of the character in brown trout. (English Summary). Ann. Genet. Se1. Anim. 11: 93-104.
Abstract: An analysis of the variation of the number of pyloric caeca in hatchery-reared brown trout showed that: 1) The sex of the animals has no significant influence. 2) An important part of variability is caused by additive genetic factors (approximate heritability 0.4). 3) There is a maternal effect which inheres to the size of eggs1 a1evins hatched from large eggs tend to have high numbers of caeca (correlation +0.5). 4) Lastly, the joined action of that maternal factor and other genetic and environmental factors apparently includes interactive effects1 further studies on that point would be - 8 -
useful.*
Key words: heritability, morphology, maternal effects, genotype-environment interaction, brown trout, Europe.
Chebanov, N.A. 1979. Behavior and mate selection among chum brood stock of different sizes with a predominance of males in the spawning grounds. Sov. J. Ecol. 10: 141-146. Abstract: The behavior of a females and 23 chum males (Oncorhynchus keta Walbaum) labelled with cloth labels was studied in spawning grounds. The predominance of males resulted in the selection of adults of similar size in comparison with spawning pairs only among average and large fish. The use of unique indices (intensity of active and inactive migration in the spawning grounds, spawning activity, incomplete utilization of sexual products, life span in the spawning ground) permitted the evaluation to a certain extent of the role of males from different size groups during spawning. Comment: In this study, behavioral differences between large and small spawning male chum salmon were described, and were interpreted as evidence for a dependence of reproductive success on size. However, spawning was not actually observed, and the actual success (fertilization of eggs) of individual males could not be verified. The effects of nonrandom mating on genetic variability in the population were not examined. Key words: genetic structure, life history, chum, USSR.
Chevassus, B., J.-M. Blanc and P. Bergot. 1979. Genetic analysis of the number of pyloric caeca in brown trout (Salmo trutta) and rainbow trout (S. gairdneri). II. Effect of the genotype, rearing environment and feeding on the realization of the character in rainbow trout. (English Summary). Ann. Genet. Sel. Anim. 11: 79-92. Abstract: Four factors liable to affect the within and between population variability of the number of pyloric caeca in rainbow trout were studied. After six months, no variation due to age was observed even after transferring the fishes from one fish farm to another. Rearing of fishes from the eyed-stage in two fish farms with very different mean temperatures (a and 16 C) induced a large difference between the mean number of pyloric caeca (55.5 at ac, 51.0 at 16C). At ac, a diet with a high level of polyholosids slightly increased the number of caeca (+2.7 p. 100 in average) as compared to one with a high level of proteins. No effect was detected at 16C. Study of the progenies of crosses between parents having a known - 9 -
number of caeca showed a high correlation (r = 0.92) between the mean parent and the mean of progenies. A quite high estimate was obtained for heritability (0.53), the non-additive genetic variance being quite low. The conjoined effect of those different factors was analysed and described by a linear additive model. It seems to be possible to obtain, by a two way selection, strains with different numbers of caeca and to analyse the effect of this trait on other quantitative ones like growth rate or nutritional parameters.* Key words: heritability, interpopulation variability, intrapopulation variability, morphology, selection, brown trout, rainbow, Europe.
Davis, H.S. 1934. Growth and heredity in trout. Trans. Am. Fish. Soc. 64: 197-201.
Abstract: Environmental factors such as food, water temperature and water chemistry have been shown to affect the growth of trout in both Europe and North America. However, inherent differences in growth capability also influence the size attained by brook trout in American hatcheries. The mean size reached by progeny of different parents raised under identical environmental conditions varies greatly. Furthermore, selection over two generations for rapid growth has resulted in the production of brook trout families in which both the maximum and minimum sizes attained by juveniles have increased dramatically. Preliminary evidence indicates that selection for an increased growth rate will also be successful in brown trout and rainbow trout.* Comment: This paper contains a review of early evidence for the influence of both environmental and genetic factors on trout growth. The author documented progress made in selection for increased growth of brook trout under hatchery conditions, but no quantitative analysis of the results was presented. Key words: heritability, growth, selection, brook trout, brown trout, rainbow, USA.
Gall, G.A.E. 1975. Genetics of reproduction in domesticated rainbow trout. J. Anim. Sci. 40: 19-28. Abstract: A population consisting of parental, Fl, F2, and backcrosses among two domestic strains of rainbow trout was used to estimate genetic parameters of reproductive performance for hatchery cultured stocks. Data were collected for post-spawning body weight, volume of eggs spawned, egg size, egg number and eggs per 100 9 body weight for a total of 1,604 two year old female progeny. Heritabilities estimated from full-sib - 10 -
comparisons were similar for all five traits and equal to about 0.20. Dominance and epistatic variance was evident for all traits except number of eggs for which genetic variation appeared to be primarily additive. The coefficient of variation was lowest for egg size, intermediate for body weight and egg number, and highest for egg volume and eggs per unit body weight. Genetic, environmental and phenotypic correlations among the traits were estimated.*
Comment: In this study, variability in the reproductive performance of female rainbow trout was examined within and among fullsib families only. As a result, the estimates of heritabilities and genetic correlations contain dominance and epistatic, and possibly maternal, effects as well as additive genetic variation. The genetic correlation between egg volume and egg number was high, and lower but positive between egg volume and both egg size and body weight. Egg number, and presumably egg volume, possessed a relatively large component of additive genetic variation, and egg volume displayed a large coefficient of variation. For these reasons, selection for egg volume might be an effective means of improving the reproductive performance of these domesticated stocks.
An interesting possibility raised by the author is that past selection for increased egg number may have modified the relationship between egg size and number in these stocks from that which prevails in natural populations. If the negative phenotypic correletion commonly observed in natural populations has a strong genetic basis, then selection in those populations for increased egg volume could lead to selection for decreased egg size, with deleterious results on fry growth and survival.
Key words: heritability, growth, life history, selection, propagation, rainbow, USA.
Gall, G.A.E. and S.J. Gross. 1978. A genetics analysis of the performance of three rainbow trout broodstocks. Aquaculture 15: 113-127. Abstract: Data on post-spawning body weight, volume of eggs spawned, egg size, egg number and fertility to the eyed stage were collected for three domesticated rainbow trout broodstocks. Heritabilities estimated from fullsib comparisons indicated male weight was more influenced by environmental stress at spawning than was female weight. Heritability estimates for egg volume, egg size and egg number, averaged for the three stocks, ranged from 0.32 to 0.52. The heritability of fertility was low and was lowest for the stock with poorest fertility. Differences between year classes isolated by 2-year spawning appeared to be genetic and demonstrated the effect of sampling the original parents. - 11 -
Genetic and phenotype correlations among the traits were estimated. It was determined that egg volume was the principal determinant of egg number and that the relationship of number to size could be negative. It is recommended that selection for egg size be included in all selection programs and that egg number be ignored in any selection program designed to increase body size.* Comment: This study illustrates the use of genetic correlations among performance characteristics of broodstock for the determination of the probable effects on other traits of selection for a single trait. Estimates of both heritabilities and genetic correlations in the study were high because they included components of nonadditive genetic variance and possibly some environmental effects. The small egg size and low fertility of one hatchery stock were attributed to inbreeding, but heritabilities of production traits other than fertility in this stock were not particularly low. The genetic differentiation between reproductively isolated year classes of a single broodstock provides an indication of considerabe genetic variation in natural populations, and demonstrates the need for hatchery stocks to be initiated with representative samples of founding populations and maintained with large effective breeding populations. Key words: heritability, growth, age of maturity, inbreeding, propagation, selection, founder effects, rainbow, USA.
Gjedrem, T. and D. Au1stad. 1974. Selection experiments with salmon. I. Differences in resistance to vibrio disease of salmon parr (Sa1mo sa1ar). Aquaculture 3: 51-59. Abstract: In this paper analyses of observed differences in resistance to vibrio disease (Vibrio angui11arum) are reported. Significant differences in resistance between river strains of salmon parr were found. The differences between localities are supposed to be partly heritable. The data were also used to estimate the heritability on an intra-river basis. The estimates were 0.12 and 0.07 based on the sire and dam component, respectively. It is concluded that selection against vibrio disease will result in genetic change. Comment: The study provides preliminary evidence for genetic variability in resistance to vibrio disease among Atlantic salmon parr from different river systems, and additive genetic variation among individuals within a single river system. However, some of the highly significant variation in mortality among locations may have been due to uncontrolled environmental factors (eg. age of parr, dosage of vibrio infection). - 12 -
The heritability estimates of disease resistance were based on intra-river diallel crosses of fish from eight different river systems. Because the heritability of any trait may vary among populations, the values presented represent average heritabilities for vibrio resistance among the eight populations examined. The significance of the sire x dam interaction, which was not presented, would have provided an indication of the presence or absence of nonadditive intra-river genetic variation.
While the authors have adapted a statistical method to analyze discrete data they proceed to utilize the proportion of fish surviving per family as the dependent variable. In the analysis of threshold or 'all or none' characters Falconer (1964. Introduction to Quantitative Genetics. Chapt. 18. Ronald Press, N.Y.) emphasizes that proportional or percentage data maybe inappropriate because on a percentage scale variances are not independent of means. The recommended scale for expression of such data is within-group standard deviation with the threshold positioned as the origin or mean within each group and with variances assumed equal between groupings. The heritability of threshold characters is treated by Robertson and Lerner (1949. Genetics 34: 395-411) and Dempster and Lerner (1950. Genetics 35: 212-236). If within-group variance cannot be assumed equal over all groups then means cannot be expressed on a common scale and, strictly speaking, valid comparisons cannot be made. Key words: heritability, interpopulation variability, disease, Atlantic salmon, Europe.
Glebe, B.D., W. Eddy and R.L. Saunders. 1980. The influence of parental age at maturity and rearing practice on precocious maturation of hatchery reared Atlantic salmon parr. ICES Mariculture Comm. C.M. 1980/F:8. (Also: N. Amer. Salm. Res. Center Rep. 4-1980).
Abstract: Matings involving various combinations of precocious parr, grilse and salmon produced 107 family groups. A survey of the incidence of precocious male parr in these groups indicated the rearing of full sibs as 1+ smolts and 2+ smolts produced similar numbers of precocious parr. The use of precocious parr as sires significantly increased the incidence of early maturation among progeny in a limited number of matings. The incidences of precocious parr resulting from all matings were highly variable (ranging from 0 to 42%) and did not appear to be related to specific sea ages at maturity. The culture implications of these results are discussed. Comment: Accelerated growth did not significantly increase the proportion of precociously mature male Atlantic salmon parr in - 13 -
this study, but the difference in length between progeny reared to produce one and two year old smolts was not large. The actual production of smolts of different ages in the two progeny groups was not examined. The heritability of precocious maturation was generally low, but variable, among Atlantic salmon strains. In two strains with relatively high incidences of early maturation, precocious male sires tended to produce more precocious male progeny than did anadromous sires. In two strains with low incidences of early maturation, precocious parr sires did not produce more precocious offspring than did anadromous sires. Genetic parameters for the incidence of early maturing males were not determined for the various strains. As the authors note, the environmental and genetic factors which control precocious parr production have yet to be identified and quantified satisfactorily. However, the variation in incidence of precocious maturation is greater among than within Atlantic salmon strains, so that the production of precocious males in hatcheries can be controlled to a large extent by the selection of appropriate strains for propagation. Key words: heritability, interpopulation variability, intrapopulation variability, age of maturity, growth, life history, propagation?, selection, Atlantic salmon, Canada.
Glebe, B.D., R.L. Saunders and A. Sreedharan. 1978. Genetic and environmental influence in expression of precocious sexual maturity of hatchery reared Atlantic salmon (Salmo salar) parr. (Abstract Only). Can. J. Genet. Cytol. 20: 444. Abstract: Consistent trends in incidence of sexually mature (dwarf) males among pure strains of hatchery reared Atlantic salmon parr and positive heterosis indicated a genetic component in this trait. Similarly, an environmental component was indicated by annual variation in the proportion of males maturing in specific strains, ie. in high growth years relative numbers of mature males were higher. Multiple regression analysis showed the contribution of these components to such maturation. The implications of this phenomenom to Atlantic salmon culture are discussed. Key words: interpopulation variability, heritability, growth, age of maturity, size of maturity, heterosis, Atlantic salmon, Canada.
Gunnes, K. and T. Gjedrem. 1978. Selection experiments with salmon. IV. Growth of Atlantic salmon during two years in the sea. Aquaculture 15: 19-33.
Abstract: Atlantic salmon were sampled from 37 rivers or river systems (strains) for three years. Each strain was represented - 14 -
by full and half-sib families. Fingerlings large enough to become l-year-old smolts were freeze-branded and smolts were transported to five salmon farms along the Norwegian coast. This paper deals with body weight and length of Atlantic salmon after two years growth in the sea. Significant differences between strains were found. The interaction farm x strain was significant but accounted for a small part of the total variation. It is concluded that genotype x environment interaction can be ignored when planning a selection program for Atlantic salmon for Norwegian farming conditions. The heritabilities for body weight and length estimated from sire components were 0.31 and 0.28. Genetic variation in body weight of Atlantic salmon is high, and about three times as high as for body length.
Comment: The estimates of heritability of growth provided by this study are particularly valuable because they are based on body weight and length measurements made on fish of a marketable age (two years). The estimates may, however, be biased by the nonrandom selection of large fish from each family for branding. In addition, estimates of mortalities in strains would have allowed comparison of the total weights of fish produced by each strain as well as the average weight of surviving fish.
It was suggested that because of the small strain x farm interaction breeding genetically different strains of fish for different Norwegian farms was unnecessary. This reasoning should not be extrapolated to Atlantic salmon bred for release to the wild: environmental variability is greater among river systems than among fish farms and genotype-environment interactions would therefore be correspondingly greater. This study illustrates the value of determining the heritabilities and amounts of genetic variation for more than one measure of growth in order to choose the best trait on which to practise selection.
Key words: heritability, interpopulation variability, growth, propagation, selection, Atlantic salmon, Europe.
Hanson, A.J. and H.D. Smith. 1967. Mate selection in a population of sockeye salmon (Oncorhynchus nerka) of mixed age-groups. J. Fish. Res. Bd. Can. 24: 1955-1977. Abstract: Anadromous Skeena River sockeye mature and spawn mainly at ages 4(2) and 5(2). Lesser numbers of 3(2), 5(3), 6(3), and 6(4) fish, and non-anadromous kokanee, may spawn in the same stream. Mate selection by the different types was studied by observing salmon of known length and using the relationship found between length and age in dead, spawned fish. - 15 -
Fish of all lengths tended to mate with similar sized fish. Small males were less successful in holding mates than were large males because they could not successfully defend redds against larger intruders. Small males spent more time alone than large ones and frequently lay in groups behind mating pairs. The term 'satellite male' is used in describing the behaviour. Small females mated with large males but spent more time alone than did large females. The genetic implications of mating within age-groups are considered. Comment: Sockeye salmon in a stream tended to spawn with mates of a similar size. There was apparently little gene flow between anadromous sockeye and resident kokanee, and some restriction of gene flow among the different size (age) classes of anadromous sockeye. However, neither the heritability of size (age) of maturity nor the effective gene flow among sockeye size groups was known. Thus the amount, if any, of genetic isolation among age-groups could not be determined. Key words: heritability, size of maturity, age of maturity, genetic structure, sockeye, Canada.
Ihssen, P. 1973. Inheritance of thermal resistance in hybrids of Salvelinus fontinalis and S. namaycush. J. Fish. Res. Bd. Can. 30: 401-408.
Abstract: Reciprocal Fl hybrids of brook trout and lake trout had similar times to death on exposure to several lethal high temperatures for a series of acclimation temperatures. These hybrids resembled the brook trout, the more resistant parent, more than the lake trout. The F2 hybrids were intermediate in resistance to the parent species, and the backcrosses intermediate between the F2 hybrids and the respective .parents. After acclimation to SC and 10C, F2's and backcrosses arising from the Fl hybrid of brook trout maternal origin were consistently higher in resistance than the F2 and backcrosses arising from the Fl of lake trout maternal orlgln. After acclimation to 20C and above, differences associated with the maternal origin of the Fl hybrid were not found. The number of effective factors segregating was estimated using the techniques of variance component analysis. A genetic model with two codominant factors was found to fit the data for the higher acclimation temperatures. Comment: This study demonstrates the potential of interspecific hybridization for the production of genetic variability in traits that show little intraspecific variation but significant differences between closely related species. The estimation of different numbers and types of genetic factors that determine - 16 -
thermal resistance in hybrid brook and lake trout at different temperatures indicates that genotype-environment interactions may be important. The design of effective breeding programs could benefit from consideration of the range of temperatures (and other conditions) to which the offspring would be exposed. The program might also be designed to take advantage of the observed maternal effects on thermal resistance, especially if these persist to older ages. Finally, Fl purebreds and hybrids could be compared under a range of temperatures in natural habitats to determine if the heterotic effect of hybridization persists in the wild.
Key words: heritability, interpopulation variability, life history, heterosis, maternal effects, genotype-environment interaction, selection, brook trout, lake trout, splake, Canada.
Ihssen, P. 1978. Inheritance of bluesac disease for hatchery charr of the genus Salvelinus. Env. BioI. Fish. 3: 317-320.
Abstract: Bluesac disease is one of the major causes of post hatching embryo mortality in salmonids. The incidence of blue sac is strongly inherited in splake (Salvelinus fontinalis x ~. namaycush hybrid) under hatchery conditions. Lake charr, F2 splake, F6 splake, and lake charr backcrosses of F6 splake had incidences of 7%, 23%, 5%, and 40% respectively. For the backcrosses, which are of practical interest because they are used for experimental plantings in the Great Lakes and northern Ontario inland lakes, the variation among families in the incidence of bluesac is primarily determined by the splake parent. Hence the incidence of bluesac disease in the progeny of splake and lake charr is considered to be a character of the splake parent. The heritability of this character is about 0.74. The level of bluesac in the backcrosses can, therefore, be significantly reduced in one generation by selecting as breeders those splake that produce low levels of bluesac in test backcrosses to lake charr.
Comment: The inheritance of bluesac disease was examined in both lake trout and splake, as well as in backcrosses of splake to lake trout. The high heritability of bluesac incidence found for lake trout indicated that the large additive variance that was shown in this and other studies to underlie bluesac resistance in splake was not simply the result of the splake's hybrid ancestry. Nevertheless, in progeny of F6 splake x lake trout backcrosses the genetic influences of the two parents were apparently unequal. This indicated that the genetic contribution of the splake, or the expression of that contribution, differed from that of the pure lake trout. A developmental analysis of the activation of parental genes controlling bluesac disease and other traits in the progeny of - 17 -
splake backcrosses might provide insight into the regulatory mechanisms of gene expression. Key words: heritability, disease, maternal effects, selection, propagation?, brook trout, lake trout, splake, Canada.
Kanis, E., T. Refstie and T. Gjedrem. 1976. A genetic analysis of egg, alevin and fry mortality in salmon (Salmo salar), sea trout (§. trutta) and rainbow trout ~. gairdneri) • Aquaculture 8: 259-268. Abstract: Heritabilities of mortality in eggs, alevins and fry were estimated using data from salmon, sea trout and rainbow trout. The highest heritability (average for all species and both estimation methods) based on the sire component was obtained for the eyed egg stage (0.08), followed by the alevin stage (0.05), while estimates for fry mortality did not differ significantly from zero. The maternal effect was rather large for uneyed eggs and eyed eggs, while it was low for alevin mortality. Maternal effects were also found to have a significant influence on the mortality of salmon fry. It was, however, not possible to separate maternal effects from tank effects.* Comment: This three year study compared the heritability of early life mortality (up to age nine months) in populations of three salmonid species collected from more than 50 locations. The origin of the parental fish (hatchery or wild) was not indicated. There were differences in the heritability of mortality among species, and among strains within species. However, the percentage of total variance due to year and locality (strain) effects was small. Unfortunately, the heritability estimates of mortality in offspring of fish of the same species taken from the same locality in two different years were not compared. A brief discussion of the methods of selection that can be applied to characters displaying little additive genetic variance (low heritability) and of the importance of environmental conditions under these circumstances is provided. Key words: heritability, interpopulation variability, life history, propagation, selection, maternal effects, rainbow, brown trout, Atlantic salmon, Europe. - 18 -
McIntyre, J.D. and D.F. Amend. 1978. Heritability of tolerance for infectious hematopoietic necrosis in sockeye salmon (Oncorhynchus nerka). Trans. Am. Fish. Soc. 107: 305-308.
Abstract: A hierarchical breeding design was used to demonstrate the heritability of tolerance for infectious hemanopoietic necrosi,s (IHN) in sockeye salmon. Heritability was about 30%, indicating that artificial selection may increase the number of fish that can tolerate the disease. comment: This is one of very few studies that have examined the heritability of a disease in a wild salmonid population. The significant heritability of IHN susceptibility under hatchery conditions indicated that a program of selective breeding for disease resistance may be successful. However, genotype-environment interactions likely also influence IHN tolerance, and fish bred for increased resistance in the hatchery might not show increased resistance upon release to natural conditions.
Key words: heritability, disease, maternal effects, sockeye, USA.
McIntyre, J.D. and J.-M. Blanc. 1973. A genetic analysis of hatching time in steelhead trout. J. Fish. Res. Bd. Can. 30: 137-139.
Abstract: The elapsed time from fertilization through hatching for steelhead trout was obtained from groups of eggs that were fertilized according to a factorial breeding plan in which 24 males were each mated to each of 10 females. Data were obtained from the eggs of 240 crosses held in an incubator through hatching and from replicated crosses held in an incubator for most of the incubation period, then in troughs. Estimated heritabilities for hatching time were 0 and 0.23, respectively, for these data, the differences being of additive genetic origin. Because of a significant genotype-environment interaction, it was suggested that hatching may have been controlled by different genetic mechanisms in the two environments.
Comment: This study demonstrates effectively that for anyone population the heritability of a trait is dependent on the conditions to which the offspring are exposed. Genotype-environment interactions of this type can be examined before a selective breeding program is established. This will facilitate the choice of rearing conditions in which the environmental contributions to observed variability in the traits of interest are minimized. - 19 -
Key words: heritability, life history, maternal effects, genotype-environment interaction, propagation?, steelhead, USA.
Refstie, T. and T.A. Steine. 1978. Selection experiments with salmon. III. Genetic and environmental sources of variation in length and weight of Atlantic salmon in the freshwater phase. Aquaculture 14: 221-234. Abstract: Atlantic salmon (Salmo salar) brood stock were taken from 32 strains in Norway for three consecutive years. Each year after fertilization, the offspring in each family from each strain were reared in separate egg trays and fingerling tanks. Length and weight of fish at a standardized age were significantly affected by hatching date and number of fish held in a tank. There was also a significant 'tank effect' which influenced the heritabilities estimated. Significant differences between strains were found for all three year-classes (P < 0.01). The estimates of heritabilities found for different year-classes are very consistent. When 'tank effect' was removed, the heritabilities estimated from the total material were 0.08 for weight and 0.12 for length calculated from the sire components of variance. Calculated from the dam components, the heritabilities were 0.15 for weight and 0.17 for length. The genetic correlation between length and weight estimated from the total material was 1.00. For the 'trait' condition factor there were no significant sire and dam components of variance when tank effect was removed.* Comment: This study demonstrates the significant influence of environmental factors on fish growth, and the need to remove these effects from an analysis of genetic variation within or among strains of fish. The removal of environmentally induced variability in the growth data reduced the estimates of both intra- and inter-strain genetic variation, and therefore lowered the heritability values of body weight and length. Tank effects were much greater among replicates of some full sib families than others, and the growth of some strains was variable among years. Genotype-environment interactions may have been partly responsible for these observations. Epistatic variance is included in heritabilities estimated from the sire component of variance, but epistasis is usually assumed to be unimportant. Key words: heritability, interpopulation variability, growth, propagation?, selection, maternal effects, Atlantic salmon, Europe.
Refstie, T., T.A. Steine and T. Gjedrem. 1976. Selection experiments with salmon. II. Proportion of Atlantic salmon smoltifying at one year of age. Aquaculture 10: 231-242. - 20 -
Abstract: Salmon (Salmo salar) brood stock were taken from 37 localities in Norway for four consecutive years. Each year, after fertilization, the offspring in each family from each strain were reared in separate egg trays and fingerling tanks. Percentage smoltification was significantly affected by the number of fish held in a tank, or fish density (correlation coefficient 0.03 - 0.27). Variation between locality of origin of brood stock and per cent smoltification was highly significant for each year class, and there was a high correlation (0.89 - 0.95) between smolt percentage and average weight of fish in a family. Heritabilities in per cent smoltification estimated by sire component from total data had a weighted average of 0.06 (range 0.16 - 0.01). From the dam component heritabilities ranged from 0.20 to 0.40 when tank effect was ignored, and 0.08 - 0.25 with tank effect taken into account. Variance components for locality were two to three times as high as those for sires within localities, indicating that genetic variation is greater between than within localities. Highly significant interaction sire x dam was found, suggesting a considerable nonadditive genetic variance influencing the percentage of fish smoltifying at one year of age.*
Comment: In this study, fish that were too large to pass through a 10 mm grader in March of a given year were assumed to become smolts in the spring of that year. Thus, the actual trait measured was parr size, and the resulting heritabilities provide estimates of the additive genetic variance of growth (or perhaps condition factor) in Atlantic salmon less than one year old. The extent to which this measure reflects smoltification is doubtful; genetic variation in the size at which smolting occurs likely exists among families and populations of salmonid species (eg. Thorpe, J.E. and R.I.G. Morgan. 1978. J. Fish BioI. 13: 549-556). In addition, much of the variation observed among strains may have been the result of environmental maternal effects due to variable conditions experienced by the mothers, and therefore eggs, before transfer to a common hatchery environment.
Results of the study indicated that the sire by dam interaction component contributed significantly to variability in parr growth, and therefore that the genetic control of growth may be largely nonadditive. As suggested by the authors, selection for increased growth (and therefore smoltification) under these circumstances would be most readily accomplished by the crossbreeding of strains. The analysis in this study suffers from the same inappropriate treatment of percentage data that was discussed earlier in this section in association with the Gjedrem, T. and D. Aulstad (1974) study. - 21 -
Key words: heritability, interpopulation variability, growth, life history, maternal effects, selection, propagation?, Atlantic salmon, Europe.
Riddell, B.E., W.C. Leggett and R.L. Saunders. 1981. Evidence of adaptive polygenic variation between two populations of Atlantic salmon (Sa1mo sa1ar) native to tributaries of the S.W. Miramichi River, N.B. Can. J. Fish. Aqat. Sci. 38: 321-333.
Abstract: Breeding experiments were conducted to test the hypothesis that spatial homeostasis in growth and proximate composition and geographic variation in body morphology and timing of migration in juvenile Atlantic salmon have an adaptive basis. The populations studied were Rocky Brook and Sabbies River, tributaries of the S.W. Miramichi River. Growth rates and proximate composition were very similar in the two populations under hatchery conditions. Genetic contributions to homeostasis in these traits were largely additive. The phenotypic expression of migratory behavior and the genetic control of timing were not quantifiable. A genetic basis to interpopulation variation in body morphology was demonstrated. Progeny from Rocky Brook which exhibits higher flows had more fusiform bodies and longer fins than progeny from Sabbies River when reared under identical conditions. Heritable variation in morphology and a demonstrated directional selection for greater fin size in high velocity environments support the hypothesis that these traits are adaptive. Adaptive polygenic variation between local populations stresses the need to delineate stocks on a functional basis so that species can be managed without significant loss of fitness and/or depletion of genetic variation in natural populations. Key words: heritability, interpopulation variability, growth, morphology, life history, selection, Atlantic salmon, Canada.
Ritter, J.A. and K. Newbold. 1977. Relationships of parentage and smo1t age to age at first maturity of Atlantic salmon (Sa1mo sa1ar). ICES Anadromous and Catadromous Fish Comm. C.M. 1977/M:32. Abstract: In this paper the relationships of parentage and smo1t age to age at first maturity of Atlantic salmon are examined in tagging data for hatchery reared smo1ts produced and released in southern Nova Scotia. One-year smo1ts produced fewer gri1se than two-year smo1ts, while progeny of gri1se parents produced more gri1se than smo1ts from large salmon parents. The combination of one-year smo1ts and large salmon parentage produced the fewest gri1se (28%) while two-year smo1ts - 22 -
of grilse parents produced almost entirely grilse (91%). The results point to the positive contribution that can be made to hatchery programs through the selection of multi-sea-winter salmon for broodstock and the production of one-year smolts. Mention is made of the potential damaging effects of fisheries that disproportionately harvest the older maturing salmon in a population.
C6~ment: The fact that Atlantic salmon grilse produce more proqeny that mature as grilse than do large salmon indicates an hereditary influence on age of maturity. Since smolt age is probably determined by both environmental and genetic factors, the influence on age of maturity mediated by smolt age may be affected by both the rearing regime and the parental genetic constitution. Environmental maternal effects (differences in quality of eggs produced by grilse and large salmon females) may have contributed to the differences in grilse production between the two groups. However, when large salmon females were mated with grilse males they also tended to produce a high proportion of grilse offspring. The nature of the genetic variation for age of maturity was not examined. Key words: heritability, intrapopulation variability, interpopulation variability, age of maturity, life history, Atlantic salmon, Canada.
Ryman, N. 1971. An analysis of growth capability in full sib families of salmon (Salmo salar L.). Swede Salm. Res. lnst. Rep. LFl medd. 5/1971. Abstract: Over a three year period, Atlantic salmon from the river lndalsalven were bred to produce full sib families that were raised under dissimilar environmental conditions in the Alvkarleo hatchery, Sweden. Variable numbers of each family were measured for length and individually tagged upon release. The total weight of each tagged fish of each family that was recaptured in its second or third year of ocean life was recorded. Analyses of variance for each year class of salmon indicated that up to 10% of the variation in weight of recaptured fish was the result of differences among families. Analyses of covariance indicated that part of the variation of family means was due to different lengths at release. The apparently low heritability for weight at recapture in the river lndalsalven indicated that it might be difficult to increase recapture yield through selection for high weight at recapture, at least in this population.*
Comment: As indicated by the author, this study was hampered by the fact that only full sib families were raised and by the fact that rearing conditions, including diet, varied among and within families. As a result, the contribution of environmental and - 23 -
genetic effects to variation in weight at recapture could not be determined accurately. Further study, under more favourable experimental conditions, would be required to confirm the tentative conclusion of little genetic variability among families in weight at recapture. Also of interest would be an examination of not only variation in the family mean weight of recaptured fish, but an indication of the variation in family total weight (ie. number x mean weight) of recaptured fish. Key words: heritability, growth, selection, Atlantic salmon, Europe.
Schmidt, J. 1919. Racial studies in fishes. III. Diallel crossings with trout (Salmo trutta L.). J. Genet. 9: 61-67. Abstract: Each of three male brown trout was crossed with each of four female trout to produce all 12 possible genetic combinations of offspring. The average vertebral count of 50 offspring of each cross was compared with the mean of the parental vertebral counts. For each male and female parent, the 'generative value' (genetic influence) for vertebral number was calculated. The mean vertebral number of the offspring corresponded closely to the mean of the parental generative values.* Comment: This study provides an illustration of the early use of a diallel or factorial design to study the heritability of a growth trait. It was shown that apparently different mean vertebral numbers characterized the offspring of different parental combinations raised under similar conditions, but the standard deviations of vertebral counts were not provided. The genetic components of variance and the heritability of vertebral number as presently defined were not calculated, but a 'generative' or 'breeding' value was determined for each parent. Unfortunately, the environmental rearing conditions were not described. Key words: heritability, growth, morphology, brown trout, Europe.
Thorpe, J.E. and R.I.G. Morgan. 1978. Parental influence on growth rate, smolting rate and survival in hatchery reared juvenile salmon (Salmo salar). J. Fish Biol. 13: 549-556. Abstract: The proportion of potential one-year smolts, their mean length, the mean length of potential two-year smolts, and the mortality rate in four half-sib families of Atlantic salmon, reared under four contrasted conditions of overhead cover, is shown to be influenced primarily by genetic factors (89.9%, 86.1%, 82.7% and 80.2% of total variance respectively). - 24 -
Variation· between families in smolting rate and mortality rate is influenced by both parents, but more by the male than the female. Variation in mean length is influenced almost entirely by the female parent. These results are discussed in relation to previous findings on bimodality of size distribution and inheritanc~'of growth and mortality characteristics in Atlantic salmon.
Comffl~i'1t: In this st'tlldy, the strong pater'nal and maternal influence on the proportion of individuals in the upper size mode, and the small male x female interaction effect, indicate that a large component of additive genetic variance underlies parr growth. However, these results were obtained from four families only, and the analysis was somewhat confounded by unequal mortalities among the halfsib groups. The extent to which the fraction offish in the upper size mode represented fish which become smolts in the following spring was not documented in this study. Fish from one population only were raised, and no estimate of genetic variation among strains was obtained.
The strong maternal influence on the mean length of juveniles was assumed to be primarily a genetic effect. It seems likely, however, that environmental variability experienced by the mothers contributed significantly to the observed variation in parr length.
Key wo~ds: heritability, intrapopulation variability, growth, life history, maternal effects, Atlantic salmon, Europe. - 25 -
SECTION 2. INTRASPECIFIC AND INTERSPECIFIC GENETIC VARIABILITY IN SALMONIDS
Amend, D.F. and J.R. Nelson. 1977. Variation in the susceptibility of sockeye salmon, Oncorhynchus nerka, to infectious haematopoietic necrosis virus. J. Fish BioI. 11: 567-573.
Abstract: Each of 16 mature female sockeye salmon from two river drainages were spawned with individual males, and the progeny from each pair were later challenged with virulent infectious haematopoietic necrosis (IHN) virus. At each of four monthly challenges, distinct differences were detected in the susceptibility of the fish from each family to IHN. Average percentage mortality was 98 or more in highly susceptible families, in families of intermediate susceptibility, 85, and in resistant families, 52. Furthermore, the mean time to death was only 9.8 days for fish from the susceptible families but 17.9 days for fish from the more resistant families. These results were similar at each monthly challenge. Challenging the fish at various virus-dosage levels did not change total mortality, but high dosage hastened the onset of mortality. A genetic basis for resistance is proposed to explain these results. Comment: The variability in susceptibility to the IHN virus among families raised under controlled environmental conditions does indicate a genetic basis for increased resistance (or susceptibility) to the virus, but non-genetic maternal effects may also be involved. A more structured breeding design would be required to determine the relative importance of genetic and maternal bases for resistance. Key words: interpopulation variability, intrapopulation variability, heritability, disease, maternal effects, propagation, selection, sockeye, USA.
Aspinwall, N. 1974. Genetic analysis of North American populations of the pink salmon, Oncorhynchus gorbuscha, possible evidence for the neutral mutation - random drift hypothesis. Evolution 28: 295-305. Abstract: Electrophoretic variability at three polymorphic loci, MDH-A, MDH-B and alpha-GPDH, was examined in 32 populations of pink salmon along the coasts of Alaska, British Columbia and washington. Both odd- and even-year populations from 13 Alaskan streams were sampled. There were no significant differences in phenotypic frequencies at any loci among either the odd- or even-year populations. However, phenotypic frequencies were significantly different between odd- and - 26 -
even-y€ar populations at all three loci. This is interpreted to support the neutral mutation - random drift theory of protein polymorphisms.* Comment: The major conclusion of this study is that molecular variability is not under the influence of natural selection. However, more recent work has demonstrated that functional differences often exist among electrophoretically distinct isozymes. Moreover, the correlation of isozyme frequency with environmental variables (eg. temperature) in salmonids and other organisms indicates that at least some electrophoretic variation is influenced directly or indirectly by natural sel€ction. In this study, data were provided for only 3 genetic loci, sampled once in each population. No estimate of temporal allele frequency variability within populations was available. Such data might yield a different picture of within year class variability. Moreover, the assumption that odd- and even-year populations face similar selective regimes in coastal waters and the ocean should perhaps be reevaluated, and the role of founder effects in influencing phenotypic frequencies be given more consideration.
Key words: interpopulation variability, electrophoresis, selection, founder effects, pink, USA, Canada.
Austreng, E. and T. Refstie. 1979. Effect of varying dietary protein level in different families of rainbow trout. Aquaculture 18: 145-156.
Abstract: Groups of rainbow trout fingerlings from five different families and five inbred groups were fed for 153 days on each of four diets similar in energy content, but differing in their percentage of protein. The protein contents were 24, 33, 42 and 51%, ~espectively. Significant differences between fish families were found for growth, condition factor, chemical composition of the carcass, and digestibility of protein. At the end of the experiment, interaction between diet fed and family was found close to significance for weight and relative growth rate, and significant for length and condition factor. This interaction indicates that prospects for selectively breeding strains of rainbow trout specifically better able to utilize protein are promising.* Comment: This study reveals genetic variation in fry growth rate among full sib families and inbred lines of fish. Unfortunately, no hybrid strains were produced from the available inbred lines to test for heterotic growth. No measurements were made of the heritabilities of the examined traits, nor of the relative contributions of additive and - 27 -
nonadditive genetic variances. Maternal effects might be expected to strongly influence fry growth rates over the time period monitored (to 153 days of age). The significant interaction between diet and condition factor, and near significant interaction between diet and growth indicated that at least some of the genetic variance is nonadditive. These interactions also indicated that some genotypes will perform (grow) better under certain environmental conditions (diet) while other genotypes will perform better in other environments. In any breeding program, the fish strain genotype and the diet fed should be chosen to maximize growth. Methods of selection for nonadditive genetic variability were not discussed. Key words: interpopulation variability, growth, propagation, rainbow, Europe.
Ayles, G.B. 1973. Comparative growth and survival of matched plantings of wild and domestic rainbow trout in prairie potholes. Fish. Res. Bd. Can. Tech. Rep. 382. Abstract: Matched plantings were made in May 1972 of a wild strain and of two size groups of a domestic strain of rainbow trout in 10 prairie pothole lakes of Manitoba. The trout were harvested as marketable fish (over 200 g) in the fall of 1972. The growth and survival of fish from the domestic strain was better than that of the fish from the wild strain. There was considerable variability between lakes and there was significant lake by strain interaction. The results indicate that the cross breeding of different strains would lead to the greatest increase in growth and survival of trout in thes.e lakes. Comment: This study provides strong evidence of a genetic basis for variability in growth and survival among rainbow trout strains, and among fish of a single strain raised in different habitats (genotype-environment interactions). Methods of :election for traits with little additive genetic variation and strong genotype-environment interactions are discussed well. No indication was made of the number of parents used to produce the fertilized eggs representing each strain, nor of the genetic variability for growth and survival among individuals within either the domestic or wild stock. Thus, the observed genetic variability between fish from the two geographically distinct strains may be no greater than the variation among individual fish within a single strain. In addition, because hatchery conditions (eg. temperature) for the two strains differed, environmental factors may have contributed to the differences between strains. No consideration was given to the possibility of differential effects of inter-strain competition within lakes on the growth and survival of fish of the two strains. - 28 -
~ey wards: interpopulation variability, growth, inbreeding, maternal .effects, propagation, selection, genotype-environment interaction, rainbow, Canada.
Ayles, G~B., D. Bernard and M. Hendzel. 1979. Genetic differences in lipid and dry matter content between strains of rainbow trout (Salmo gairdneri) and their hybrids. Aquaculture 18.: 253-262.
Abst·ract: Observed phenotypic differences of lipid content between strains of rainbow trout and their hybrids cultured in small Canadian prairie lakes are related to differences in the size of fish and highly correlated with differences in growth rate. As a percent of dry matter, mean lipid levels of different strains and their hybrids ranged from 32.5~ to 45.9% in one experiment and from 11.6% to 24.3% in another. There were significant additive genetic differences in lipid content between strains, independent of differences in weight, and there also appeared to be significant non-additive genotype-environment interactions. Phenotypic differences in percent dry matter were small compared to the differences in lipid content.
Comment: Genotype-environment interactions were detected for lipid content in rainbow trout raised in three different small prairie lakes. Possible effects of different stocking rates on lipid content were not examined, and the effect on the growth and lipid content of each strain exerted by the presence of other strains in the lake could not be determined. The two parental strains maintained a consistent relative ranking for lipid content in all three lakes (ie. the domestic stock had a higher lipid content than did the wild). However, the relative levels of lipid in the reciprocal hybrid strains varied among lakes. Key words: interpopulation variability, heritability, growth, life history, selection, propagation, rainbow, Canada.
Ayles, G.B. and M. Hendzel. 1978. Genetic analysis of lipid and moisture content of intraspecific hybrids of cultured rainbow trout (Salmo gairdneri). (Abstract Only). Can. J. Genet. Cytol. 20: 439. Abstract: Product composition can influence storage characteristics and consumer acceptance, and this is of considerable prac·tical importance in the commercial aquaculture of rainbow trout. Observed phenotype differences of lipid and moisture content between strains of rainbow trout could frequently be related to differences in size at harvest and were highly correlated with genetic differences in growth rate. We - 29 -
found significant additive genetic differences in lipid content independent of weight between two strains (45% vs. 34% lipids on a dry weight basis) but no significant dominance effects. Key words: interpopulation variability, heritability, growth, life history, rainbow, Canada.
Bailey, J.K., M.l. Buzeta and R.L. Saunders. 1980. Returns of three year classes of sea ranched Atlantic salmon of various river strains and their hybrids. ICES Anadromous and Catadromous Fish Comm. C.M. 1980/M:9. (Also: N. Amer. Salm. Res. Center Rep. 3-1980.)
Abstract: Three different river strains of 1974 year-class Atlantic salmon, released as small (x = 14.1 cm) l-yr smolts in 1976 produced about 2.5 times more 2-sea-winter adult returns than grilse. The same three strains plus all six possible hybrid combinations planted in 1977 as large (> 20 cm) 2-yr smolts returned approximatly eight times more grilse than larger salmon. Four river strains and all 12 hybrid combinations of 1975 year-class salmon released as large (> 18 cm) l-yr smolts in 1977 returned about 1.4 times more grilse than larger salmon. The same four river strains and 12 hybrid combinations were produced in the 1976 year-class and released as l-yr smolts in 1978. The 1976 year-class returned a much higher proportion as grilse than the 1975 year-class. One river strain, Big Salmon River, has accounted for approximately 47% of the identifiable grilse returns. Of the 505 marked grilse which have returned to date, 405 or 80% have been derived from crosses in which at least one parent was of Big Salmon River origin. Smolt age, size, quality and genetic origin appear to influence the size of returning grilse and grilse-larger salmon ratio. Comment: This study demonstrates the influence of both genetic and environmental factors on age of maturity in Atlantic salmon. Genotype-environment interactions may be important, but were not investigated. The genetic basis of age of maturity was not analyzed because offspring of individual parents were not identified. Nevertheless, some of the genetic heterogeneity among stocks was likely the result of additive genetic variance, because both the maternal and paternal parentage affected age of maturity, and values for interstrain hybrids tended to be intermediate to those for pure strains. The large difference in grilse-larger salmon ratio among rivers is probably adaptive. The selective forces that operate differentially on the stocks of various watersheds should be identified to facilitate choosing the appropriate strain of Atlantic salmon for propagation on the basis of the environmental conditions to which the fish will be exposed.
Key words: interpopulation variability, age of maturity, size - 30 -
of maturity, Atlantic salmon, Canada.
Bailey, J.K. and R.L. Saunders. 1979. Preliminary report on releases and returns of two year-classes of Atlantic salmon smolts from various pure strains and strain crosses. ICES Anadromous and Catadromous Fish Comm. C.M. 1979/M:2l. (Also: N. Amer. Salm. Res. Center Rep. 5-1979). Abstract: Three different river strains of 1974 year-class Atlantic salmon, released as small (x = 14.1 cm) one-year smolts in 1976 produced about two times more two-sea-winter adult returns than grilse. The grilse from this release averaged 55.0 cm fork length. The same three strains plus all six possible hybrid combinations planted in 1977 as large (> 20 cm) two-year smolts returned a much higher proportion of grilse. The mean length of the grilse returns was 59.6 cm. Four river strains and all 12 hybrid combinations of 1975 year-class salmon released as large (> 18) one-year smolts in 1977 returned few medium sized (x = 56.6) grilse. Smolt age, size, and genetic origin appears to influence the size of returning grilse and the grilse-Iarger salmon ratio. Comment: See comment for Bailey, J.K., M.I. Buzeta and R.L. Saunders. 1980.
Key words: interpopulation variability, age of maturity, size of maturity, Atlantic salmon, Canada.
Barns, R.A. 1976. Survival and propensity for homing as affected by presence or absence of locally adapted paternal genes in two transplanted populations of pink salmon (Oncorhynchus gorbuscha). J. Fish. Res. Bd. Can. 33: 2716-2725.
Abstract: An experiment was carried out on pink salmon (Oncorhynchus qorbuscha) at the Tsolum River, Comox Bay, B.C., comparing an introduced pure donor stock with a hybrid stock created by crossing females from the donor with males of the local residual stock~ Progeny of both treatments were raised in gravel incubators and released as unfed fry. Upon return from the ocean, marked fish were recaptured from catch and escapement.
At the fry stage times of emergence differed, but mean fry lengths, weights, and stages of development were the same in both treatments. Survivals from fry to returning (coastal) adult were identical and comparable to that of other years, as was timing of adult migrations. Large differences occurred in returns to the river. At the hatchery stream the expected relative rate of return of the hybrid was p = 0.53, observed p = - 31 -
0.91. Returns to the river below the hatchery stream also favored the local genotype, but less strongly so. The results demonstrated that (1) imprinting alone brought back some pure donor stock, (2) addition of the local male genetic complement improved return to the natal river system to a normal level, and (3) the male complement alone was not sufficient to achieve normal accuracy of return to the natal tributary within the system. "Hybrid" transplants may hold considerable potential for salmon rehabilitation and enhancement, but genetic and managerial implications should be carefully evaluated. Possibilities exist of seriously affecting fitness and abundance of other stocks and ecosystems.
Comment: This study is particularly valuable because it provides an indication of genetic differentiation among pink salmon stocks that is of adaptive value under natural conditions. Confirmation of the postulated maternal and paternal effects on fry and adult migration and homing would benefit management decisions. The discovery that a large proportion of 'hybrids' that returned to the coastal region failed to locate the natal river system, and apparently strayed to other streams, was of considerable importance. The genetic impact of such strays on an invaded population would depend on their successful contribution to the resident gene pool: and that process would be difficult to measure, or even detect. Key words: interpopulation variability, life history, propagation, pink, Canada.
Bowler, B. 1975. Factors influencing genetic control in lakeward migrations of cutthroat trout fry. Trans. Am. Fish. Soc. 104: 474-482. Abstract: Progeny from inlet-spawning cutthroat trout (Salmo clarki) in Yellowstone Lake move downstream and progeny from outlet-spawning adults move upstream to enter the lake to rear. I examined the role of genetic control, rheotactic acclimation (acclimating swim-up fry to water current and no water current), constant and fluctuating water temperatures, and changing water source in directing migrations of Yellowstone Lake fry by testing them in simulated stream channelS. Genetic control influenced upstream and downstream movement of Inlet and Outlet fry, but rheotactic acclimation significantly altered the direction of migration of inlet fry. Fry moved under genetic control in constant and fluctuating water temperatures and in tests of changing water source, but Outlet - 32 -
fry that were tested in a water source other than that used for incubation and acclimation moved downstream in higher numbers than those tested in the same water source used for incubation and acclimation. Tests of parental influence were inconclusive but some tests yielded migration patterns similar to those of the female parent. Hatchery operations that include rearing fry in open raceways, exposing them to water current, can alter the behavior of newly emerged fry. Commen't: This study confirmed the existence of genetically controlled differences in fry migratory behaviour between inlet and outlet spawning populations of cutthroat trout. In addition, environmental modification of the heritable directional responses was shown to differ for the two populations tested. As in previous studies, the genetic basis of the behavioral response was not determined: hybridization of inlet and outlet fish yielded inconclusive results. Because a minimum of ten females and five males were used to produce the fry of each group, the offspring tested can be considered repre,sentative of the inlet and outlet populations. Intrapopulation variability in behaviour among families was not measured. Key words: interpopulation variability, life history, propagation?, cutthroat, USA.
Brannon, E.L. 1967. Genetic control of migrating behavior of newly emerged sockeye salmon fry. Int. Pac. Salmon Fish. Comm. Prog. Rep. 16.
Abstract: Genetic control of migrating behavior in response to current was investigated in newly emerged sockeye salmon fry. Fertilized eggs from three races, representing stocks from outlet streams, inlet streams and lake incubation areas of the Fraser River system, were hatchery incubated under controlled conditions very different from their natural environments. The resulting alevins and fry were tested to determine their preferred direction of migration, and each race responded to current with the same behavior pattern exhibited in its natural environment. Although the innate response to current was not influenced by age of the fry or by temperature, the source of water (lake or creek) was shown to have a marked effect on the response of certain races. The implicatons of a genetic control of fry migrating behavior are discussed with regard to fisheries management. Comment: The nature of the genetic variation underlying observed differences in sockeye salmon fry migratory behaviour was not examined in this study. However, hybrid fry produced from males of an inlet spawning and females of an outlet spawning stock displayed an intermediate migratory response - 33 -
similar to, but more variable than, the response of fry from a lake spawning stock. This indicates a relatively large component of additive genetic variation. However, the differential response among stocks to lake water also indicates that genotype-environment interactions may affect fry behaviour. For this reason, the failure of fry from one stock to respond to changes in test water temperature does not preclude the possibility that temperature is an important environmental cue for fry of other populations. Key words: interpopulation variability, life history, propagation?, sockeye, Canada.
Chilcote, M.W., B.A. Crawford and S.A. Leider. 1980. A genetic comparison of sympatric populations of summer and winter steelheads. Trans. Am. Fish. Soc. 109: 203-206.
Abstract: The 1973 and 1974 year classes of adult, wild summer and winter steelheads (Salmo gairdneri) were genetically compared at five polymorphic enzyme loci: alpha-GPOH-l; LOH-4; MOH-3,4; SOO-l; and PHI-3. Overall genetic difference between summer and winter steelhead groups was not significantly greater than genetic differences observed for 1973 and 1974 year classes compared within each group. These findings, in conjunction with field observations of known summer-winter steelhead spawning pairs, suggests that summer and winter steelheads in the Kalama River are not at present reproductively isolated. Comment: This study demonstrates the importance of sampling more than one year class of fish to determine the allele frequency variation within a population. Significant differences in allele frequencies were found at two of five polymorphic loci between adjacent year classes of Kalama River steelhead.
Although the data provided no evidence for genetic isolation of t summer , and 'winter' steelhead runs from a single river, the possibility of genetic distinction was not eliminated. Apparent genetic similarity at 5 polymorphic loci does not exclude the possibility of differentiation at other loci. Misidentification of summer and winter fish was possible. The observation of 'interracial' spawning gave no indication of the reproductive success of offspring of these crosses. Key words: interpopulation variability, intrapopulation variability, electrophoresis, life history, steelhead, USA.
Child, A.R., A.M. Burnell and N.P. Wilkins. 1976. The existence of two races of Atlantic salmon (Salmo salar L.) in the British Isles. J. Fish BioI. 8: 35-43. - 34 -
Abstract: Sera from approximately 10,000 Atlantic salmon collected from rivers in the British Isles have been analysed. Polymorphism at the transferrin locus was observed and the distribution of the transferrin alleles provides further evidence supporting the presence of two races of salmon first postulated by Payne et ale (197la) .
Comment: The suggestion made in this study of two races of Atlantic salmon in the British Isles was based on electrophoretic variation at a single locus. Breeding studies were not conducted to confirm the genetic interpretation of observed transferrin patterns. If the presence of the Tf2 band is under genetic control, the significant difference in the frequency of this band between the 'celtic' and the 'boreal' populations is indicative of some degree of genetic isolation. The historical theory of geographically isolated 'races' of Atlantic salmon provides a r~asonable explanation for the distinction of the two groups, but other possibilities have not been eliminated. Differences in selective regimes between the areas occupied by celtic and boreal populations may have brought about or may presently maintain the transferrin phenotypic variability.
Support for the racial theory of ice age isolation might be obtained from an examination of transferrin patterns in more Atlantic salmon populations along the east coast of Britain and in continental Europe, and from patterns of genetic variation at other electrophoretic loci. Key words: interpopulation variability, electrophoresis, Atlantic salmon, Europe.
Donaldson, L.R., D.O. Hansler and T.N. Buckridge. 1956. Interracial hybridization of cutthroat trout, SalmQ clarki, and its use in fisheries management. Trans. Am. Fish. Soc. 86: 350-360. Abstract: Two races of coastal cutthroat trout were hybridized and the resultant first generation hybrids were compared with the two parent races. In both laboratory and field studies the hybrids showed evidence of hybrid vigor. The catch of sports fishermen, during two seasons at Echo Lake, Washington, where both parent and hybrid trout were planted, was composed of three to six times as many fish of the hybrid stocks as of the parent races.
Comment: In this study, the greater catch of hybrid than of purebred cutthroat trout on the first day of angling in the year following introduction was interpreted as evidence for greater overwinter survival of hybrids. However, no attempt was made to - 35 -
sample the unfished population, and the possibility that hybrids were simply more susceptible to angling was not discounted. Fish of one of the parental strains, the University of Washington stock, grew faster than hybrids under both laboratory and field conditions except, perhaps, at very young ages. Thus, very little solid evidence was produced to support the contention of hybrid vigour. Maternal effects, which may have had a greater influence on growth rates, were not examined. Key words: interpopulation variability, growth, life history, propagation?, heterosis, cutthroat, USA.
Friars, G.W., J.K. Bailey and R.L. Saunders. 1979. Considerations of a method of analyzing dia11e1 crosses of Atlantic salmon. Can. J. Genet. Cyto1. 21: 121-128. Abstract: Inferences derived from a proposed mixed model analysis of a dia11e1 cross involving four stocks of Atlantic salmon (Sa1mo sa1ar) are illustrated with growth data on weight and length. Variation between stocks was more apparent when samples represented darns as opposed to sires, thus stressing the relative importance of maternal effects. However, the ranking of stocks was not altered when either the means of sire sources or the means of darn sources were considered. No heterotic effects were found for the growth traits studied. Comment: The analytical method proposed in this study provides valuable information on heritable differences among populations, but gives little indication of the nature of the observed variability. The inability to separate environmental maternal effects from genetic differences among populations detracts from the utility of the design. The view of a salmon stock as a genetic source that represents a fixed effect may be open to some question, long-term spatial and temporal genetic stability in sa1monid 'stocks' has not been established. Selection, genetic drift and straying among populations may separately or together result in directional genetic alteration of sa1monid populations over time.
Key words: interpopulation variability, heritability, growth, life history, heterosis, maternal effects, Atlantic salmon, Canada.
Glebe, B.D., T.D. Appy and R.L. Saunders. 1979. Variation in Atlantic salmon (Sa1mo sa1ar) reproductive traits and their implications in breeding programs. ICES Anadromous and Catadromous Fish. Comm. C.M. 1979/M:23. (Also: N. Amer. Sa1m. Res. Center Rep. 4-1979).
Abstract: Analysis of variance of inter- and intra-strain - 36 -
crosses of Atlantic salmon from four New Brunswick rivers indicated a strong maternal influence on progeny size. The reproductive traits, egg size and energy content and fecundity, were investigated as possible causes of this effect. The lack of a significant difference (p > .75) in energy content of unit weights of ova from each stock suggested similar proximate compositions. However, significant differences in egg diameter (p < .01) existed as did a significant correlation (p < .01) between egg size and progeny mean length. No correlation between egg size and juvenile survival was detected. The calculated energy content per ovum ranged from 1066 J (SD = 215) for the Magaguadavic stock to 1576 J (SD = 140) for salmon of Rocky Brook origin. Increased egg size may have contributed to a significant depression in fecundity of Rocky Brook females. The importance of understanding the relative influence of maternal effects associated with reproductive traits in salmon breeding studies is discussed.
Comment: Maternal effects can mask additive genetic variance for egg and fry production traits in salmonids. In this study, the genetic variation between two strains of Atlantic salmon for the production of precocious parr remained significant after the removal of maternal effects mediated by egg size variability. The need to reduce maternal effects in the analysis of within and between strain genetic variability is discussed.
Key words: interpopulation variability, growth, life history, maternal effects, Atlantic salmon, Canada.
Henricsson, J. and L. Nyman. 1976. Introgression: The last obstacle in char speciation. (Abstract Only). Zool. Scr. 5: 187.
Abstract: The three or four species of anadromous Arctic char that invaded the headwaters of the post-glacial Scandinavian rivers did not have enough time to achieve complete reproductive isolation. This fact is realized in certain bodies of water where either man has changed the environment to force two sympatric species of char in close contact, or, where a limited number of spawning grounds or other environmental prerequisites preclude the segregation of two or more sympatric species. This has resulted in introgression, ie. the gradual incorporation of genes from one species into the gene pool of another. Very often the gene flow has acted both ways and thus changed both species involved. Depending on environmental factors the rate of gene flow has been different in a series of inter-connected lakes and thus produced various stages of introgression. The effect of this long-term hybridization was studied by a variety of techniques such as a protein polymorphism, ecological data, growth data and various statistical methods. - 37 -
Key words: interpopulation variability, growth, life history, electrophoresis, Arctic char, Europe.
Ihssen, P. and J.S. Tait. 1974. Genetic differences in retention of swimbladder gas between two populations of lake trout (Salvelinus namaycush). J. Fish. Res. Bd. Can. 31: 1351-1354. Abstract: Lake trout derived from two populations differed in retention of swimbladder gas. The two. reciprocal interpopulation crosses were intermediate to the parent populations. The two Fl hybrids obtained by crossing fish from each lake trout population with brook trout (S. fontinalis) were also found different in retention. Gas retention was correlated with depth distribution of the parent populations, high retention being associated with deeper distribution. Comment: This study provides a rare demonstration of genetically controlled variation in a physiological trait between two salmonid populations. To confirm the selective role of depth in determination of gas retention by lake trout, a prediction of swimbladder gas retention ability in other lake trout populations based on their observed depth distributions could be made and tested. Such a demonstration of physiological adaptation among lake trout populations would lend support to the common suggestion that in transplantation efforts, donor salmonid populations should be genetically matched to the recipient environment if maximum success is to be achieved. Key words: interpopulation variability, heritability, life history, lake trout, brook trout, splake, Canada.
Klupp, R., G~ Heil and F. Pirchner. 1978. Effects of interaction between strains and environment on growth traits in rainbow trout (Salmo gairdneri) • Aquaculture 14: 271-275.
Abstract: Three strains and their three crosses were tested in two environments, floating nets and ponds. The genetic growth potential was reduced considerably in the much poorer pond environment. In addition, interactions independent of the average performance of the particular genotype were observed for weight and length but not for height and head length. Comment: This preliminary study of the importance of genotype-environment interactions to growth of trout in captivity was based on small sample sizes and no replication. Each pure or hybrid strain was represented by the offspring of 5-6 females and 4-5 males: neither strain origin (hatchery or wild) or mating design was specified. Genetic and - 38 -
genotype-environment variability in growth among individuals within a strain was not examined. Environmentally induced variation in growth among nets was not removed from the calculation of genetic variance among nets (strains). Probability levels to indicate the significance of variance components were not provided. However, despite the preliminary nature of the experiment, the results indicated a need to examine strain-environment interactions when choosing fish for propagation efforts.
Key words: interpopulation variability, heritability, growth, propagation?, genotype-environment interaction, rainbow, Europe.
Kristiansson, A.C. and J.D. McIntyre. 1976. Genetic variation in chinook salmon (Oncorhynchus tshawyts~ha) from the Columbia River and three Oregon coastal rivers. Trans. Am. Fish. Soc. 105: 620-623. Abstract: Genetic variation in chinook salmon from ten hatcheries along the Columbia River drainage and the Oregon coast was described from results of starch gel electrophoresis. Highly significant differences were found between spring and fall chinook in the Columbia River watershed. It was suggested that frequencies of malate dehydrogenase, tetrazolium oxidase, and phosphoglucomutase phenotypes may be influenced directly or indirectly by selective forces.
Comment: In this study, the electrophoretic allele frequencies of 100 juvenile chinook salmon collected from each of 10 hatcheries were assumed to be representative of the natural spawning populations from which they were derived. However, no indication is given of the number of parents used in each set of hatchery crosses, of the locations from which brood stock for each hatchery were obtained, of possible historical egg transfers to any of the hatcheries, or of the possible effects of propagation (eg. inbreeding) on the observed allele frequencies. In addition, allele frequency variability within or between years for a single run was not measured. Although the allele frequencies of hatchery reared juveniles may be representative of the present and historical natural runs of spring and fall chinook salmon in the region, and differences among the hatchery populations may be the result of natural selection in the wild populations, these possibilities cannot be properly assessed without some consideration of the time span and methodology of hatchery operations. Key words: interpopulation variability, electrophoresis, selection, propagation, chinook, USA. - 39 -
Lynch, J.C. and E~R. Vyse. 1979. Genetic variability and divergence in grayling (Thymallus arcticus). Genetics 92: 263-278.
Abstract: In North America there are two distinct forms of grayling, Montana and Arctic, which have been separated for approximately 75,000 to 100,000 years. Electrophoretic analysis of thirty-six protein loci in these forms has revealed: (1) levels of gene duplication comparable to other salmonids, (2) a level of heterozygosity similar to other salmonids, (3) a fast and a slow evolving set of proteins, and (4) no obvious relationship between genetic variability and enzyme function. The genetic divergence between these populations may warrant subspecific designations for these two forms. Comment: In this study, levels of genetically controlled electrophoretic variation within, and differentiation between, two geographically disjunct groups of grayling were based on a single sample from each of four locations. One of the 'Arctic' populations was sampled from Fuse Lake, Montana, to which it had been transplanted in the 1950's. A low level of heterozygosity in this population indicated the possibility of a genetic diversity reduced through founder effects, although the relatively small sample size (20 fish) may also have contributed to the low variability observed. Historical gene exchange between the two Yellowstone Park 'Montana' grayling populations had likely occurred. Therefore, the assumption that the populations examined were representative of the genetic variation within and between the Arctic and Montana forms of grayling requires verification. Confirmation of the proposed genetic basis of observed electrophoretic patterns through breeding studies, and the inclusion of other Arctic and Montana grayling populations in an electrophoretic survey would be required before any satisfactory conclusions regarding the subspecific status of the two forms could be drawn. While the genetic distance between the Arctic and Montana populations observed is no more than among distinct populations of some species, it is similar to the distance between sympatric brown trout populations that inhabit a single lake but are completely reproductively isolated (Ryman, N. et ale 1979: Genetics 92: 247-262). Key words: interpopulation variability, electrophoresis, grayling, USA, Canada.
Okazaki, T. 1978. Genetic differences of two chum salmon (Oncorhynchus ketal populations returning to the Tokachi River. Far Seas Fish. Res. Bull. 16: 121-128. - 40 -
Abstract: This investigation examines two peaks of chum salmon returning to the Tokachi River in 1977 relative to the allelic frequencies of polymorphic proteins of collections from both peaks, and the timing of runs and allelic frequencies of chum salmon populations from other rivers that have been introduced to the Tokachi River. Prior to 1973, the chum salmon run of the Tokachi River exhibited a single peak during late September and early October. Both the timing and the allelic frequencies of isocitrate dehydrogenase (ICD) variants of the second peak during late November and early December correspond with chum salmon runs from the Abashiri and Yubetsu rivers: transplantations from both of these rivers to the Tokachi River were made in 1970. Both lines of evidence independently support the hypothesis that the second peak of salmon return to the Tokachi River is largely a reflection of these transplantations. The significance of timing as a major variable to be considered in transplantations and the value of gene frequency data in monitoring the success of transplantations is discussed. comment: This analysis provides a straightforward illustration of the use of biochemical allele frequencies as markers to monitor the success of a transplanted population. However, methods of identifying separate stocks (eg. native and transplanted) in a mixed sample are not discussed because in this case the two stocks could be sampled independently. The data also indicate that time of return in chum salmon is under genetic control. Late-run salmon transplanted to a river containing a native early-run stock maintained their late time of river entry into a second generation. Although not discussed by the author, allele frequency data presented indicate a possible reduction in genetic variability in an introduced population relative to the donor stocks. Although differences in allele frequencies were not significant between the introduced and donor populations, at two of the four polymorphic loci examined the transplanted stock lacked a rare allele of the donor populations. The loss of these alleles could be due to founder effects, genetic drift or natural selection. Key words: heritability, interpopulation variability, life history, electrophoresis, propagation, chum, Japan.
Raleigh, R.F. 1967. Genetic control in the lakeward migrations of sockeye salmon (Oncorhynchus nerka) fry. J. Fish. Res. Bd. Can. 24: 2613-2622.
Abstract: Eggs of sockeye salmon taken from tributary, outlet, and beach spawners at Karluk, Alaska, were treated identically from time of egg fertilization through time of testing as fry in a laboratory. Test lots were released during the day and at - 41 -
night in a central release pool from which the fry could migrate either upstream or downstream through simulated stream channels. Oxygen-saturated water at 50F (lOC) was pumped through the 40-ft (12.2 m) gravel-bottomed simulated stream at about 0.3 ft/sec (9.1 cm/sec). Test results showed that directions (upstream and downstream) and times (day or night) of migration differed substantially between fry from the tributary and those from the outlet. Fry from beach spawning reacted in a manner similar to that of the tributary fry. These differences were concluded to be of genetic origin. The possible interaction of innate behavior and environment in controlling the migratory movements of salmonid fry is discussed along with the significance of choosing a donor stock with appropriate innate responses to make best use of a new environment.
Comment: See comment for Raleigh, R.F. 1971.
Key words: interpopulation variability, life history, propagation?, sockeye, USA.
Raleigh, R.F. 1971. Innate control of migrations of salmon and trout fry from natal gravels to rearing areas. Ecology 52: 291-297.
Abstract: The upstream and downstream directional responses of demes of sockeye salmon (Oncorhynchus nerka) fry from inlet and outlet streams hatched and reared under controlled identical conditions were tested in the laboratory. The tests compared innate directional responses of fry from the two sources to variables of water source and temperature. Both variables influenced the directional responses of the fry. The direction of migration (upstream for outlet fry or downstream for inlet fry) and response to changes in the test variables differed substantially between fry from inlet or outlet streams1 this response difference held for populations of sockeye salmon from different geographical locations (Canada and Alaska). The differences were concluded to be innate in origin. Single tests of fry of rainbow (Salmo gairdneri) and cutthroat (~. clarki) trout from inlet and outlet streams indicated that directional responses of fry from these species are also innately influenced. The significance of matching the innate responses of donor stocks of fish to the characteristics of a recipient environment is discussed. Comment: The genetic basis of the heritable directional response of fry from different populations was not examined. The numbers of fish used to produce the fry representing each 'deme' were not specified, and variability in fry response among - 42 -
families within demes was not measured. However, the fact that the effect of environmental variability (eg. water temperature, water source) differed among populations indicated that genotype-environment interactions were important.
Key words: interpopulation variability, genotype-environment interaction, life history, propagation?, rainbow, sockeye, cutthroat, Canada, USA.
Refstie, T. and A. Kittelsen. 1976. Effect of density on growth and survival of artificially reared Atlantic salmon. Aquaculture 8: 319-326. Abstract: Groups of salmon (Salmo salar) from two localities were kept at five different densities during the initial feeding period of 42 days and a subsequent growth period of 205 days. They were then kept at the same density for 95 days. Differences in mean weight between fish from different localities were found as early as the end of the initial feeding period. No marked differences were found between mean weights of fish held at different densities during the initial feeding period, while the mortality rate of fry decreased with higher densities for both strains. At the end of the 205-day growth period the differences in mean weight between strains and between density groups within a strain were large. Significant interaction between locality and density was also found. Part of this interaction is due to scale effects. When groups were kept at the same density, those originally at high densities showed the highest relative growth, and also had the highest K-factor at the end of this period. It is concluded that high densities depressed the growth rate, and that compensatory growth occurred when the densities were standardized. It is important to take density into account when ranking families or progeny groups for growth performance in selective breeding trials. Comment: In this study, the nature of the genetic difference in growth between Atlantic salmon strains could not be determined because no interstrain hybrids were produced. The average egg size of each stock was not specified, but the much larger size of fry from one strain than from the other strain indicated that maternal effects may have been important. The interaction between locality (strain) and density indicated the presence of genotype-environment effects as well. The number of females of each strain from which eggs were obtained and the degree of replication (to measure tank effects) were not specified. The discussion of the actual, as opposed to estimated, number of smolts produced at each density seemed incomplete. Key words: interpopulation variability, growth, life history, - 43 -
propagation?, genotype-environment interaction, Atlantic salmon, Europe.
Reinitz, G.L, L.E. Orme and F.N. Hitzel. 1979. Variations of body composition and growth among strains of rainbow trout. Trans. Am. Fish. Soc. 108: 204-207. Abstract: Fish from six strains of rainbow trout (Salmo gairdneri) were fed the starter diet SD7 until reaching an average weight of 1.5 g. In the second segment of this trial, 1.5-g fish from the six strains were fed the experimental diet X263 for 180 days. At the end of both trial segments, body composition varied significantly among the strains of fish. After 180 days of diet X263, growth and feed conversion also differed significantly among strains. Changes in body composition averaged for all strains combined after 180 days of the diet X263 were as follows: crude protein decreased 8.2%; moisture decreased 5.7%; ash increased 6.2%. Data from the first segment of this trial give the strongest support to the hypothesis that variations of body composition of rainbow trout are influenced by genotype.
Comment: This study provides strong evidence for variability in growth, feed conversion and body composition among rainbow trout genotypes. However, the numbers of and relationships among the parental fish used to produce the offspring of the various hybrid strains were not specified. If a single fish of either or both sexes was used to produce the offspring representing each strain, and if the various hybrid strains had no parents in common, then the observed genetic variability should not be assumed to represent variation among strains rather than among individuals within a strain. Key words: interpopulation variability, growth, rainbow trout, USA.
Riddell, B.E. and W.C~ Leggett. 1981. Evid~nce of an adaptive basis for geographic variation in body morphology and time of downstream migration of juvenile Atlantic salmon (Salmo salar). Can. J. Fish. Aquat. Sci. 38: 308-320. Abstract: Differences in growth rate, proximate composition, body morphology, and time of downstream migration between two populations inhabiting tributaries of the Miramichi River, N.B. that differed in distance from the head of the tide, temperature, and flow velocity were studied. Rocky Brook, located 132.6 km above the head of tide, had lower temperatures and higher average flow velocities than Sabbies River, located 42.5 km above tide. Growth rate and proximate composition were similar between populations but body morphology and time of - 44 -
downstream migration differed significantly between populations. Individuals from Rocky Brook had more fusiform bodies and larger paired fins than their counterparts in Sabbies River. Rocky Brook fish also left the tributary in the fall rather than in the spring as was the case in Sabbies River. The generality of the flow regime - body morphology relationship observed was test,ed and confirmed by predicting differences in morphology of juvenile salmon in other rivers based on knowledge of their flow regimes. It is suggested that early migration by the Rocky Brook fish is related to the higher energetic costs of overwintering in that stream. We hypothesize that the phenotypic similarity in growth rate and proximate composition and geographic variation in body morphology and timing of migration have an adaptive basis.
I Ryman, N., F.W. Allendorf and G. Stahl. 1979. Reproductive isolation with little genetic divergence in sympatric populations of brown trout (Salmo trutta). Genetics 92: 247-262. Abstract: Two reproductively isolated demes of brown trout coexist in a small Swedish mountain lake, Lake Bunnersjoarna. We electrophoretically examined 102 specimens from the lake for 27 enzymes encoded by 54 loci. The two demes are fixed for different alleles at a lactate dehydrogenase locus (LDH-l)1 statistically significant allele frequency differences at five other loci further support the complete lack of gene flow between these demes. There are significant differences in growth rates between fish in the two demes, but no further morphological differentiation has been detected. In light of these findings, the genetic distance between these populations is surprisingly small (Nei's I = 0.975). These demes represent one of the least genetically divergent, reproductively isolated sympatric pair of vertebrate populations that have been identified. The results are discussed from both an evolutionary and ecological perspective. Comment: This study demonstrates the utility of electrophoretic variation in detecting intraspecific genetic subdivision among fish displaying little morphological differentiation. Gene exchange between the two sympatric brown trout "demes" was apparently extremely low or absent, but an electrophoretic examination of trout less than three years old would be required to ascertain that no hybridization occurred. Determination of the mechanism of reproductive isolation will likely require sampling of the two demes throughout their life cycles, from fry to spawning adults. - 45 - Unfortunately, attempts to hybridize trout from the two demes under hatchery conditions were unsuccessful: the production of hybrids would have confirmed the genetic interpretation of electrophoretic banding patterns. Samples from two consecutive years indicated that allele frequencies were stable within demes, but repeated sampling of the mUlti-year-class populations would increase the reliability of the estimate of temporal stability. Key words: interpopulation variability, intrapopulation variability, electrophoresis, growth, brown trout, Europe. Saunders, R.L. and A. Sreedharan. 1977. The incidence and genetic implications of sexual maturity in male Atlantic salmon parr. . ICES Anadromous and Catadrom0us Fish. Comma C.M. 1977/M:2l. (Also: N. Amer. Salm. Res. Center Rep. 2-1978) • Abstract: There were differences in the incidence of sexually mature (dwarf) males among purebred and hybrid strains of Atlantic salmon reared in a hatchery with spawn taken from wild salmon collected in several New Brunswick rivers and fertilized according to a diallel mating scheme. Dwarf males developed in both young-of-the-year, which had been hatched and reared at elevated temperatures during the winter, and those in their second year following hatching and rearing at prevailing ambient temperatures. Mature males were usually smaller than immature males and females and grew more slowly during August-November. Total lipid decreased and moisture content increased in dwarf males during late summer and autumn: immature parr had increasing lipid and decreasing moisture during this period. Consideration is given to the energetic effects of this early sexual maturation and the genetic implications. Comment: This preliminary examination of the incidence of precocious maturation in male Atlantic salmon parr provided evidence of genetic variation in early maturation among Atlantic salmon stocks. However, the genetic basis of precocious maturation was not examined, and the genetic variability in precocity among families within strains was not determined. Key words: interpopulation variability, age of maturity, size of maturity, life history, propagation?, Atlantic salmon, Canada. - 46 - Schorn, C.B. and. E.. Hal.fon. 1978. Kin selection: Can it explain a portion of the variability of salmonid families? (Abstract Only). Cafl. J. Genet. Cytol. 20: 454. Abstract: variability in salmonid families has been attributed to either genes or environment, with families bimodal. Kin select-ion has been S.uggfilsted as a possible explanation, defined to, be depend~nt on inc~,usive fitness (individual fitness plus a OOftlPOltEnt contribut'ed by kin). Here reported are results from a cOmPu'ter model settin'C) outside limits on isolation, migration and differences in tbe number of individuals of high and low fitness;:- defined as re$istance to predation - required for kin selectiOft to be advantageous. Specifically, if families are isolated for a period of time, 200 days, it is an advantage to have- groups with different fitnesses, one of 0.5 or less and the other of'l. The optimum proportions range from 950 to 550 out of 1,000. Migration reduces but doesn't eliminate the advantages as only when families mix immediately are the advantages lost.* Key words,: interpopulation var iabili ty, intrapopulation variability, selection, salmonids, Canada. Smith, S.B:. 1969. Reproductive isolation in summer and winter races of steelhead trout. p. 21-38. In: Symp. on Salmon and Trout in Streams. MacMillan Lect. in Fish. UBC. Vancouver. Abstract:: Wide differ.ences occur in times of migration and st-ate of' sexual maturation in steelhead trout entering spawning stre.ams f-rom salt- water. Steelhead in a sexually immature state, enterinq streams largely between June and September are designated as 'summer' fish and those entering in a sexually mature state, are designated as 'winter' fish. Progeny from summer and from winter fish from Capilano River, British Columbia we,re reared together, in order to determine the extent to which taxonomic and physiological characteristics are heritable. Some taxonomic characteristics are heritable to the extent that meristic series, such as numbers of vertebrae, gill rakers and parr-marks in Fl yearling fish can be used to separate summer and winter stocks', but not individuals of the two stocks. No intergrades were found between summer and winter steelhead with respect to physiological characteristics, such as rate of maturation in salt water and level of storage fat, both in juvenile and adult fish. Artificial fertilizations, including reciprocal crosses, indicated that summer and winter stocks are mutually viable. However, detailed examination of migratory behaviour and - 47 - taxonomic and physiological characters in Capilano River steelhead strongly indicate that the two races do not interbreed in that stream: samples from wild populations from six other rivers provided data consistent with the same hypothesis. The available evidence suggests that reproductive isolation probably has occurred, but relatively recently, because of mutual viability of reciprocal crosses and also because of relatively small differences in taxonomic characters. Comment: In this study, meristic differences between summer and winter Capilano River steelhead reared under similar hatchery conditions supported the suggestion of a genetic basis for morphological distinction between natural summer and winter steelhead populations. However, non-genetic maternal effects likely contributed to the differences observed between offspring of the two Capilano populations. A diallel crossing design, including reciprocal crosses between summer and winter fish, would have enabled partitioning of the genetic variances into additive and nonadditive components, and the estimation of maternal effects. Although significant differences were demonstrated between· a number of wild summer and winter steelhead populations for traits shown to be heritable in the Capilano populations, the designation of summer and winter 'races' of steelhead should be made with caution. Any genetic similarity among winter or summer steelhead populations for morphological traits of likely adaptive value could be the result of natural selection. Thus, the genetic similarity may well reflect similar selective regimes rather than close taxonomic relationships. Key words: interpopulation variability, heritability, morphology, life history, steelhead, Canada, USA. Swarts, F.A., W.A. Dunson and J.E. Wright. 1978. Genetic and environmental factors involved in increased resistance of brook trout to sulfuric acid solutions and mine acid polluted waters. Trans. Am. Fish. Soc. 107: 651-677. Abstract: Several strains of hatchery-reared brook trout, Salvelinus fontinalis (Mitchill), were exposed to low pH in the laboratory (sulfuric acid solutions) and in the field (mine acid polluted waters). Wild brook trout were also used in some field tests. Tests were both acute and chronic (up to 2 mo.). Pronounced strain differences in survival ability were detected among embryonic, juvenile, and adult brook trout in laboratory tests, and among juvenile brook trout in field tests. However, in one case a strain difference in resistance times detected in field tests was not evident in several laboratory studies. A single selection of NYSV strain brook trout for high resistance to sulfuric acid solutions did not yield Fl progeny of greater - 48 - resistance. wild brook trout survived longer at lethal field pH levels than hatche'r'y fish which were tested immediately upon transport from the hatcheryr there was no difference if the h~tchery fish were-held, prior to testing, in nonacidic field environments. Developm''E!nt of the embryonic brook trout was d~layed in sulfuric acid solutions of low pH. Larger and older fish tended to survive longer although size was not strongly correlated with resistance times within narrow size categories of equal age fish. Th~re was no difference between the sexes in survival times at loft' pH. The most important factors in, erih~rtee~~nt of acid re~tstance in hatchery brook trout were the heiedit~ry re~istanceof a given strain and the acclimation of fish to n6riacidic stream or laboratory conditions prior to acid exposure~ The establi~hment by selection within strains of one superior in acid tolerance will probably require many generations; screening for a tolerant strain from among extant strains may accomplish the goal more quickly.* Comment: Significant differences among strains in tolerance of acidic waters, and perhaps also in the ability to become acclimated to acidic conditions, confirmed the presence of genetic variation for this trait among brook trout brood stocks. Individuals from a limited number of families within each strain were tested, so that no reliable estimate was produced of genetic variation for acid tolerance within the outbred trout strains used. The genetic basis of acid tolerance in brook trout was not examined. Failure of one strain to respond to a single generation of selection for tolerance may have been due to a low heritability of this trait. However, as suggested by the authors, experimental conditions (eg. low selection pressure, inadequate testing procedures) may have been partially responsible. The inconsistencies observed in strain performance among different laboratory experiments, and between lab and field tests in some experiments, illustrated the difficulties associated with producing fish that display the desired characteristics in the environment to which they will be exposed. Key words: interpopulation variability, growth, life history, selection, brook trout, USA. Todd, T.N., G.R. Smith and L.E. Cable. 1981. Environmental and genetic contributions to morphological differentiation in ciscoes (Coregoninae) of the Great Lakes. Can. J. Fish. Aquat. Sci. 38: 59-67. Abstract: Laboratory-produced progeny of Coregonus alpenae, c. zenithicus, ~. hQyi, and~. ~ and their wild parents were used to examine the contributions of genotype and environment to - 49 - morphology. Morphological differences between parents and offspring were generally greater than those between species, indicating strong environmental effects. The phenotypic effects on most characters can probably be attributed to different developmental temperatures and perhaps to stresses in the hatchery not encountered in the Great Lakes. Genetic differences were inferred from morphological differences between offspring of different species raised under identical conditions. Genetic differences were demonstrated between C. hoyi and~. kiYi but not between~. alpenae and~. zenithTcus which suggested that our samples of ~. alpenae and ~. zenithicus represented only a single species. The presence of unique stocks of coregonines in the Great Lakes, as well as of several species, suggests that management strategies should focus on both levels of diversity. Key words: interpopulation variability, intrapopulation variability, heritability, morphology, whitefish, USA. Trojnar, J.R. and R.J. Behnke. 1974. Management implications of ecological segregation between two introduced populations of cutthroat trout in a small Colorado lake. Trans. Am. Fish. Soc. 103: 423-430. Abstract: Ecological differences reflected in food and habitat preference and angling vulnerability were investigated between two introduced sympatric populations of cutthroat trout, Salmo clarki. The Pikes Peak cutthroat fed to a large extent on Daphnia (68% by volume), whereas the Snake River cutthroat fed primarily on terrestrial insects (68% by volume). Other food habit differences were observed in the brook trout, Salvelinus fontinalis, and rainbow trout, Salmo qairdneri, populations. The Snake River cutthroat trout was more vulnerable to angling than the Pikes Peak cutthroat. This was due in part to the opportunistic and surface feeding behavior of the Snake River cutthroat and angling restrictions which resulted in most fishermen angling on or near the surface. The Pikes Peak cutthroat had a high mortality rate during August and September. This coincided with the period of greatest competition with the longnose sucker, Catostomus catostomus, for Daphnia. The results illustrate the practical application of intraspecific variability in fisheries management programs. The establishment of interacting populations of the same or different species can result in more efficient use of the food resources of a lake and greater fish production. It is urged that every effort be made to preserve the remaining genetic diversity in polytypic species such as S. clarki. Comment: In this study, the breeding and rearing techniques - 50 - employed to produce fry of the two cutthroat trout subspecies for planting were not described. Any differences in treatment may have contributed to the behavioral differences observed between the two introduced populations. Nevertheless, the results did support the contention of signficant intraspecific genetic variation, although the nature of the genetic differentiation was not investigated. The possible longterm success of the two populations if intu:oduced into an en.i'I,f'ironment wi th sui table spawning habitat was not examined. The, ecological segregation reflected in food pr-eferences would not necessarily ensure reproductive isolation of the two forms. One form might outcompete and eventually eliminate the other. Alternately, hybridization between th~ two forms might occur, despite the fact that the Snake River cutthroat in its native habitat is resistant to introgression. The ultimate genetic and ecological consequences of hybridization could not be predicted. Key wor-ds: interpopulation variability, life history, cutthroat, propagation; USA. Utter, F.M., D. Campton, S. Grant, G. Milner, J. Seeb and L. Wishard. 1980. Population structures of indigenous salmonid species of the Pacific Northwest. p. 285-304. In: Salmonid Ecosystems of the' North Pacific. (W.J. McNeil and D.C. Himsworth, eds.). Oregon State Univ. Press and OSU Sea Grant College Program. Corvallis. Abstract: General consistencies of allelic and phenotypic frequencies at many electrophoretically detected loci have been observed within closed salmonid populations (1) throughout life cycles; (2) over· successive generations; and (3) among year classes where overlap occurs. These data support the assumption that patterns' of genetic variation observed among populations of these species' tend to reflect life history rather than environmental variables. This assumption is the basis for interpreting known patterns of variation in seven salmonid species indigenous to the Pacific Northwest (sockeye, chum, pink, chinook and coho salmon, and rainbow and coastal cutthroat trout). Each species has a characteristic and unique pattern of variation and it is therefore inappropriate to generalize with regard to population structure between even such closely related forms as the two trout species. A major factor affecting the patterns and amounts- of genetic variation is the effective population size. This parameter is, in turn, affected by a number of variables such as discrete or variable year classes, single or multiple spawnings, preferred spawning habitat, degree of anadromy, degree of immigration and emigration, population stability, location of population relative to conspecific populations and time since divergence of two populations. The - 51 - tendancy to form distinct populations in a particular drainage appears to be strongest in the coastal cutthroat and weakest in the pink salmon. Key words: interpopulation variability, intrapopulation variability, electrophoresis, life history, genetic structure, sockeye, pink, chum, chinook, coho, rainbow, cutthroat, USA, Canada. - 52 - Sf:CTI0N 31. GENE1!':DC EFFECTS OF DOMESTICATION, PROPAGATION AND FISHERIES ON SALM0NI'DS Allendorf, F.W., ~.M. E~peland, D.T. Scow and S.R. Phelps. 19-80. C0e·xistence of native and introduced rainbow trout in the Kootenai River dr ainage. Froc. Mont. Acad. Sci. 39: 28-36. Ahs·tnact: Rainbow t:Il:Gut (Salmo qairdner i) have been suspected to be nat i ve to sO.me Montana dr ainages, although previous reports have indica~ed the contrary. We collected and electrophoretically examined 281 rainbow trout from six sampling locati: Comment: This study illustrates the use of electrophoretic data to idenhify genetically distinct populations of different origin. Baseline electrophoretic data do not exist for the putative native Kootenai rainbow trout populations. However, the genetic similarity of two Kootenai populations to coastal hatchery rainbow trout stocks provides convincing evidence of the presence of two distinct groups within the drainage system. The intermediate Ldh allele frequencies of one Kootenai population may have resulted from hybridization of the two types of rainbow, as suggested by the authors. However, selection, founder effects or genetic drift in a native population could also have produced the observed gene frequencies. Complementary morphological and karyological studies among and within the Kootenai River rainbow trout populations will facilitate the interpretation of electrophoretic results. Key words: interpopulation variability, electrophoresis, propagation, rainbow, USA. Allendorf, F.W. and S.R. Phelps. 1980. Loss of genetic variation in a hatchery stock of cutthroat trout. Trans. Am. Fish. Soc. 109: 537-543. Abstract: We have detected significant reduction in genetic - 53 - variation at isozyme loci in a hatchery stock of west-slope cutthroat trout (Salmo clarki) in comparison to the wild stock from which it was derived 14 years earlier. This conclusion is supported by (1) a 57% reduction in the proportion of polymorphic loci, (2) a 29% reduction in the average number of alleles per locus, (3) a 21% reduction in the average heterozygosity per individual, and (4) significant changes in allelic frequencies between age-classes. This loss of variation is attributed to both a limited number of founders of the hatchery stock and the effects of genetic drift in the maintenance of the hatchery stock. Comment: This study provides a valuable illustration of the effect of hatchery procedures on genetic variability in domesticated salmonids. Although some genetic information was undoubtedly lost as result of the low numbers of fish used to establish the stock, founder effects apparently did not account for the total observed reduction in genetic heterogeneity. The evidence of ongoing erosion of variation under hatchery conditions demonstrates the need to avoid inbreeding in hatcheries through the maintenance of large effective population sizes, and the occasional infusion of gametes from wild fish. The significant differences observed in this study in allelic frequencies between hatchery and wild fish, and among year classes of hatchery fish, were attributed entirely to hatchery production techniques. Unfortunately, genetic variation among year classes of wild fish was not measured, and therefore was unavailable for comparison. Key words: interpopulation variability, intrapopulation variability, electrophoresis, propagation, selection, inbreeding, genetic drift, founder effects, cutthroat, USA. Allendorf, F.W. and F.M. Utter. 1980. Population genetics. p. 407-454. In: Fish Physiology Vol. VIII. (W.S. Hoar, D.J. Randall and J.R. Brett, eds.). Academic Press. New York. Abstract: The relative amount of genetic variation in a particular population within a species may be an indicator of the potential of that stock to undergo genetic change in a program of artificial selection. A review of the amount of genetic variation based on our own studies shows that (1) different species of salmonids have significantly different amounts of genetic variation as measured by average heterozygosity, (2) populations within a species have remarkably similar levels of heterozygosity, and (3) hatchery management procedures, in at least one case, have resulted in the loss of genetic variation in artificially cultured stocks. We also emphasize the role of limited population size in causing the - 54 - loss of genetic variation in hatchery populations of fish. Protein variations have been applied to define genetically some populations of fishes in much greater detail than had previously been possible. Biochemical identification of species can frequently be made on samples where morphological criteria are not us~ful. Identification of population groups provides data for management base'd on the genetic structures of these populations. Proportions of component populations of mixed fisheries can be detfJrmined if known differences in frequencies of isozyme variants &xist among these populations. Biochemical genetic differences among hatchery populations can be maximized through selection for specific protein variants. Such genetic marking can be done without affecting performance characteristics of a particular stock. This procedure has considerable potential as a tool in the management of fish populations.* comment: This paper provides a detailed review of the methodology, interpretation and application of biochemical genetic information. One important topic not dealt with, however, is temporal variation of allele frequencies within populations. Key words: interpopulation variability, propagation, selection, electrophoFesis, salmonids, USA, Canada. Aulstad, D. and A. Kittelsen. 1971. Abnormal body curvatures of rainbow trout (Salmo gairdneri) inbred fry. J. Fish. Res. Bd. Can. 28: 1918-1920. Abstract: In an inbreeding experiment with rainbow trout, a special type of deformed fry was found. The deformity appeared after one generation of fullsib mating in one of nine fullsib groups. The deformed fry were observed soon after the resorption of the yolk sac and showed different forms of body curvatures. The deformity was lethal. Significant differences between inbred groups and the non inbred control groups indicate that the deformity is at least partly heritable. Comment: This study illustrates the difficulty in quantifying the environmental and genetic contributions to the production of anomalous fry under hatchery conditions. The observed deformity was to some degree heritable, but the genetic basis of deformity was not established and any gene-environment interactions were not measured. The production of a second generation of inbred fish from survivors of crosses suffering deformity would probably have facilitated determination of the genetic basis of deformity. Key words: heritability, growth, morphology, propagation, - 55 - inbreeding, rainbow, Europe. Ayerst, J.D. 1977. The role of hatcheries in rebuilding steelhead runs of the Columbia River system. p. 84-88. In: Columbia River Salmon and Steelhead. Am. Fish. Soc. Spec. Publ. No. 10. Abstract: The Skamania steelheaa hatchery, located on the West Fork of the Washougal River in Washington, was started with a broodstock of 153 fish in 1957. Over a seven year period, selection of early spawning fish resulted in the advancement of the mean date of egg take by two months. In later years, selection of large adults for use as broodstock may also have increased size of returning Skamania hatchery summer-run and Cowlitz hatchery winter-run steelhead.* Comment: This is a non-quantitative review of some apparently genetic changes that have taken place in washington. state hatchery steelhead stocks since domestication. Unfortunately, the genetic and environmental effects on the Skamania stock have not been distinguished. Moreover, no measurement was made of important variables (ie. selection coefficients, effective population size, gene flow) which might be used to estimate the amount and rate of genetic alteration. Key words: heritability, age of maturity, size of maturity, life history, selection, propagation, steelhead, USA. Ayles, G.B. 1975. Influence of the genotype and the environment on growth and survival of rainbow trout (Salmo gairdneri) in central Canadian aquaculture lakes. Aquaculture 6: 181-188. Abstract: Strains of rainbow trout were evaluated for suitability for use in extensive aquaculture operations in central Canada. Matched plantings were made of three strains of trout in a number of small, shallow, eutrophic, winterkill lakes. Growth and survival were measured at the time of harvest. There were significant effects of the genotype and the environment and significant genotype-environment interactions in the differential growth and survival of the trout. Comment: See comment for Ayles, G.B. 1973. (Part I, Section II) • Key words: interpopulation variability, growth, propagation, genotype-environment interaction, rainbow, Canada. - 56 - Bergot, P., J.-M~ Blanc and A.M. Escaffre. 1981. Relationship between number of pyloric caeca and growth in rainbow trout (Salroo gairdneri Richardson). Aquaculture 22: 81-96. Abstract: The relationship between fish length and number of pyloric caeca was studied in full-sib families, with different caeca number, which were obtained through genetic selection and reel'eo in two different hatcheries. At- Lee,s-Athas hatche-ry a significant positive correlation between caeca number" and size of fish of the same age was demonstrated, both within and between families. An influence of rear ing' cond it ions upon th is relat ionship was also observed as no significant correlation was found in Donzacq hatchery with the same families. In' both hatcheries, families with many caeca exhibited better food conversion ratios than families with fewer caeca, the former showing either lower feed intake for the same growth rate or greater weight gain, for the same feed intake. Two non-exclusive hypotheses could account for the growth-caeca number relationship: the caeca number could be either an indicative character reflecting initial growing conditions or a causal character, acting on intestinal morphology and food utilization. In either case, caeca number seems to be an interesting criterion in trout selection. Key w0rds: heritability, morphology, growth, selection, genotype-environment interaction, rainbow, Europe. Busack, C.A. and·G~A.E~ Gall. 1980. Ancestry of artificially propagated California rainbow trout strains. Calif. Fish Game 66: 17-24. Abstract: An historical treatment of the ancestry of the nine strains of rainbow· trout artificially propagated by the California Department of Fish and Game is presented: Pit River, Eagle Lake, Junction Kamloops, Davis, Mt. Shasta, Virginia, Hot Creek, Mt. Whitney, and Coleman. The first three strains listed are descendants of collections from single populations: the other six are the result of mixing or deliberately crossing strains. Comment: The broodstock histories provided in this paper will facilitate· greatly the'prediction and interpretation of genetic variation within and'among Californian rainbow trout hatchery stocks. As the authors mention, it may also be possible to trace the occurrence of diseases (and other factors under genetic influence) from present day hatchery strains back to - 57 - particular founding stocks of trout. Key words: interpopulation variability, life history, propagation, selection, rainbow, USA. Calaprice, J.R. 1969. Production and genetic factors in managed salmonid populations. p. 377-388. In: Symp. on Salmon and Trout in Streams. MacMillan Lect. in Fish. UBC. Vancouver. Abstract: Fisheries management methods include transplanting organisms, applying restrictions on the catch, and supplementing natural reproduction by various means. The relative successes or failures of most of these measures have been attributed to method, or to specific interactions among organisms in the ecosystem. In the following, attention is focused upon the probable pattern of genetic variation in salmonids, some means whereby current management practices may modify these patterns, and the related heritable aspect of production. Comment: This paper provides a review of some theoretical and actual genetic consequences of fishing, hatchery breeding practices and introductions on salmonid populations. The large potential for radical genetic alteration of hatchery stocks through conscious or unintentional selection of broodstock and resultant inbreeding is emphasized, and the possible deleterious effects of these domesticated fish on wild stocks is considered. Key words: interpopulation variability, intrapopulation variability, age of maturity, growth, life history, inbreeding, selection, propagation, rainbow, salmonids, USA. Cooper, E.L. 1961. Growth of wild and hatchery strains of brook trout. Trans. Am. Fish. Soc. 90: 424-438. Abstract: Various growth characteristics of the brook trout (Salvelinus fontinalis) were investigated by comparing the performance of three wild populations with five hatchery groups. Wild populations attained a total length at the end of two years of about six inches, which was less than half the size of the hatchery trout in the same period. Differences in weight between wild fish and hatchery fish for the same period were of the order of ten times. Unfavorable temperature and lack of food were chief causes of slow growth of wild populations. Among the hatchery groups, inbreeding caused a decrease in growth. Randomly bred groups were very similar in size at all times up to 20 months of age. Different mathematical models were applied to growth data from the hatchery groups. The concept of Parker and Larkin appeared to describe adequately the growth curves obtained and was useful in measuring differences - 58 - due to genetic factors. weight-length curves were similar for fish of different strains grown under similar environmental conditions. Inbred groups had markedly different weight-length curves from those of randomly bred groups. A modification of LeCren's relative condition factor, derived from the weight-length data of the hatchery groups of brook trout, is proposed. It compares the observed weight of a fish with the weight expected to promote the optimum rate of growth of the species. Examples of its use for wild and hatchery groups are given.* Comment: Environmental and genetic contributions to the observed differences in growth between wild and domestic brook trout strains could not be distinguished in this study because the two groups reared in dissimilar habitats. However, the deleterious effect of one generation of inbreeding on the growth of domestic fish indicated a genetic influence on growth rate. The fish representing each domestic strain were offspring of only four parents (two males and two females) and no estimate of within strain variability in growth rate was obtained. Nevertheless, the similarity in growth between the two randomly bred domestic strains, and the lack of het( :osis displayed by the hybrid strain, were indicative of little genetic dissimilarity in growth between domestic strains. This may have resulted partially from the independent selection exerted on both stocks for rapid growth under hatchery conditions. A controlled experiment in which the genetic differences among and between domestic and wild stocks were examined would have provided more information on levels of genetic variation in growth among natural brook trout strains. Key words: interpopulation variability, growth, propagation, inbreeding, brook trout, USA. Cordone, A.J. and S.J. Nicola. 1970. Harvest of four strains of rainbow trout, Salmo gairdneri, from Beardsley Reservoir, California. Calif. Fish Game 56: 271-287. Abstract: Four strains of rainbow trout, a wild strain of Kamloops rainbow and three domestic strains utilized in California's catchable trout program, were planted as fingerlings in Beardsley Reservoir, Tuolumne County, from 1961 through 1966. Kamloops and Shastas, the most recently developed domestic strain, were decidedly superior to Whitneys and Virginias, two strains domesticated since near the turn of the century. The best time of the year to plant Kamloops was in April and May when they were 1.0 to 3.2 per ounce. Shastas planted in July and August from 2.5 to 6.2 per ounce were most successful. Comparing groups of these strains planted only at these times we found that Kamloops were harvested at a - 59 - significantly higher rate than Shastas. Shastas, however, had a higher average ratio of pounds caught to pounds planted, and a lower average cost per pound in the creel. Kamloops displayed a greater tendency to leave the reservoir during periods of spillway discharge, and were less available to shore anglers than the domestic strains. Moreover, they were more difficult to raise in the hatchery. The performance of Shastas we believe, could be greatly improved if they were available for planting at a larger size in the spring. Comment: In this study, environmental and genetic factors undoubtedly both contributed to variation in growth, catchability and migratory tendencies among repeated plantings of the four' strains of trout. All planted trout were reared in the same hatchery, but at different times (season and year) and for variable periods before release. In addition, the effects on each strain of the presence in the reservoir of other trout strains were not examined. Nevertheless, consistent differences among strains in percentage harvest, time of harvest, and weight obtained by harvest indicated genetic differentiation among the rainbow trout strains. The nature of this genetic variability was not determined. However, the study indicated that long domestication histories resulted in hatchery strains of trout that were poorly adapted for growth and survival in a fluctuating and highly competitive environment. Key words: interpopulation variability, growth, life history, propagation, rainbow, USA. Davis, H.S. 1931. The influence of heredity on the spawning season of trout. Trans. Am. Fish. Soc. 61: 43-47. Abstract: Brook trout in the Pittsford, Vermont hatchery are spawned from late October through November, but fullsib offspring of a single female ripen over a much shorter time period (one week or less). One rainbow trout strain raised in the hatchery matures in winter (December - January), but a second strain matures in spring (April - May) • These data suggest that heredity, rather than temperature, is the primary factor that determines the date at which trout will spawn. Advantages for fish culture include the opportunity to select for a reduced spawning period, an altered spawning season, and other desirable production traits.* Comment: Evidence collected under hatchery conditions for the genetic control of time of spawning in brook and rainbow trouts was briefly outlined. No experimental work was reported. Selective breeding for desirable characteristics in hatchery salmon ids was suggested, but the possible deleterious consequences of selection (eg. inbreeding) were not discussed. - 60 - Key words: heritability, interpopulation variability, intrapopulation variability, life history, brook trout, rainbow, USA. Dollar, A.M. and M. Katz. 1964. Rainbow trout brood stocks and strains in American hatcheries as factors in the occurrence of hepatoma. Prog. Fish Cult. 26: 167-174. Abstract: There is mounting evidence to support the idea that disease susceptibility in fish and other organisms is to some degree under genetic control. This paper provides a preliminary review of the origins and histories of domestic rainbow trout stocks in the U.S.A. Little selection for disease resistance has been practised in these fish, and the complex history of most stocks makes the effect of strain on disease resistance difficult to evaluate. It is possible that selection for other traits (fecundity, growth rate, spawning season, etc.) in hatcheries has resulted in the inadvertent selection of stocks which are more susceptible to a liver tumor known as hepatoma.* Comment: This paper provides a valuable summary of available information on the historical development of rainbow trout broodstocks used in American hatcheries, and on some of the selective practices to which they have been subjected. The authors suggested that genetic variation in hepatoma resistance may exist among the one hundred or more stocks maintained, but provided no data to support this contention. Key words: heritability, interpopulation variability, disease, propagation, selection, rainbow, USA. Donaldson, L.R. and D. Menasveta. 1961. Selective breeding of chinook salmon. Trans. Am. Fish. Soc. 90: 160-164. Abstract: Selective breeding of plants and animals has been carried on for hundreds of years. Few attempts, however, have been made to breed salmon that have characteristics which would better fit the fish for the needs of modern salmon management. Experiments started in 1949 at the University of Washington to develop a selected stock of chinook salmon have shown progress in producing fish better adapted to the environment available to them. Selected stocks grow faster, are more resistant to high temperatures and disease, mature earlier, and have a higher survival rate than the non-selected stocks. Comment: This study provides only circumstantial evidence for the genetic control of age at return in chinook salmon. No experimental design was followed which would allow quantification of the heritability of this trait, or of the intensity of selection practised. Eggs from four consecutive - 61 - year classes of a hatchery stock were used to establish a run of chinook to a pond at the College of Fisheries, Seattle. No indication was given of the numbers of fertilized eggs used to establish the run, nor of the number of parents used to produce them. No mention of the possibility of a native run of chinook in the river system was made. Fish of one year class that returned in significant numbers at age three apparently showed a greater tendency to produce early returning offspring than fish of the same and other year classes that returned at age four. No evidence was provided for the suggestion that "selected" stocks grew faster and were more resistant to high temperatures and disease than "unselected" stocks. All the fish of this study were of the same stock. All year classes had likely experienced strong selection prior to and during the experiment in the hatchery. Key words: heritability, disease, growth, age of maturity, propagation, selection, chinook, USA. Eckroat, L.R. 1971. Lens protein polymorphisms in hatchery and natural populations of brook trout, Salvelinus fontinalis (Mitchill). Trans. Am. Fish. Soc. 100: 527-537. Abstract: Lens protein phenotype and allele frequencies of three autosomal loci were anal~zed by acrylamide gel electrophoresis for 1,164 speclmens from four hatchery populations of brook trout, each representing combined progenies from random matings of hundreds of parents. A deficiency of heterozygous genotypes at one locus, according to Hardy-weinberg analysis, may indicate a degree of inbreeding in the hatchery environment. Allele frequencies of the lens protein variations appeared to be relatively stable from year to year within a particular hatchery. Gene frequency analyses for the lens protein variations disclosed that brook trout populations from some of the different hatcheries were distinguishable from each other. Analyses of the lens proteins for 547 specimens from nine natural populations of brook trout revealed no genetic divergence in these small isolated populations. A length-frequency analysis of one population indicated that allele frequencies were independent of length classes. Evidence was presented suggesting that a distance greater than 300 yards may act as an isolating mechanism leading to genetic divergence of a brook trout population in one small stream. Gene frequency analyses for the lens protein variations disclosed that some of the brook trout natural populations from different areas sampled were distinguishable from each other. Comment: In this study, allele frequency differences between - 62 - two brook trout samples taken from Marsh Creek indicated a need for more extensive examination of the spatial and temporal allele frequency variation in wild populations. The generally low frequencies of rare alleles at eye lens protein loci in wild populations suggest that natural selection favours the common alleles at these loci. High frequencies of variant alleles in some hatchery populations may result from a relaxation of natural selective forces under artificial conditions. A general deficiency of heterozygotes at one locus in hatchery populations indicated that inbreeding may have occurred, but genotypes at other loci were apparently in Hardy-Weinberg equilibrium. The heterozygote shortage may have resulted from a misc1assification of phenotypes. Key words: interpopulation variability, intrapopu1ation variability, electrophoresis, propagation, selection, genetic drift, inbreeding, brook trout, USA. Ehlinger, N.F. 1964. Selective breeding of trout for resistance to furunculosis. N.Y. Fish Game J. 11: 78-90. Abstract: A program of selective breeding has been carried on to develop strains of brook trout and brown trout resistant to furunculosis. Diverse geographical strains of these species, obtained from stations in the United States and Canada, were intensively exposed to Aeromonas sa1monicida, the etiological agent, and the less resistant individuals were removed by mass selection. Survivors were retained as brood fish for the next generation which was similarly exposed to disease, etc. Hybridization through crossing more promising strains in some instances improved resistance. Typical data are presented to demonstrate the variation among fingerlings and yearlings of resistant strains and to compare them with control strains. Resistant strains were also compared with regular hatchery stock under actual hatchery conditions. Results obtained thus far indicate that resistance to furunculosis is being achieved. The work is continuing. Comment: Increased resistance to furunculosis in brook and brown trouts was achieved in this study through selection of best performing strains, mass selection of resistant individuals within strains, and hybridization between resistant strains. Although the genetic basis of furunculosis resistance was not examined, the fact that selection within strains and crossbreeding between strains were both successful indicates that the genetic variance may contain both additive and nonadditive components. Unfortunately, selection intensities could not be determined for the various strains used. A measure of strain response (increase in resistance) divided by the selection differential would have enabled a calculation of the - 63 - heritability of furunculosis resistance in each strain. Key words: heritability, interpopulation variability, disease, selection, brook trout, brown trout, USA. Ehlinger, N.F. 1977. Selective breeding of trout for resistance to furunculosis. N.Y. Fish Game J. 24: 25-36. Abstract: Results, subsequent to those previously published~ concerning efforts to develop furunculosis resistance in strains of brook trout (Salvelinus fontinalis) and brown trout (Salmo trutta) are reported. Crossing resistant strains produced no further significant increase in the level of resistance, so techniques employing individual matings were attempted. Limited field testing of resistant strains was generally encouraging but suggested that a selected furunculosis-resistant strain of brook trout may be more susceptible to gill disease. Project setbacks from flooding and extraneous diseases, as well as difficulties in efforts to field test resistant strains, are discussed. Comment: In this study, an examination of the genetic components of variance for resistance to furunculosis in brook and brown trouts would have given an indication of the potential success of alternate breeding methods (ie. crossing within or between strains). The observed high susceptibility to gill disease among the selected brook trout strains may have reflected unintentional selection for gill disease susceptibility, pleiotrophic effects of the genes conferring furunculosis resistance, or inbreeding. Similarly, the unusually severe consequences of a fungal outbreak among the brook and brown trout stocks may have resulted from genetic alteration brought about by the program of artificial selection. Further studies might examine the genetic and environmental basis of susceptibility to these and other diseases in trout strains bred for furunculosis resistance. Breeding programs designed to reduce disease susceptibility in fish may benefit from simultaneous selection for resistance to several pathogens. Key words: heritability, interpopulation variability, disease, selection, brook trout, brown trout, USA. Favro, L.D., P.K. Kuo and J.F. McDonald. 1979. Population genetic study of the effects of selective fishing on the growth rate of trout. J. Fish. Res. Bd. Can. 36: 552-561. Abstract: A mathematical model that simulates the effect of selective fishing on the size distributions of populations of - 64 - trout is presented. The model assumes that the growth rate is genetically controlled by a small number of major genes. Empirical numbers for the growth and mortality rates of brown trout (Salmo trutta) in the Au Sable River of Michigan are used as input data. A computer is used to calculate the changes in the population subject to various degrees of fishing pressure for various size limits. Results are presented for periods of time ranging from 5-30 years. The observed changes in the population over the period 1959 to 1977 in a test stretch of the Au Sable River agree quite well with the computations. Comment: See comment for Favro, L.D., P.K. Kuo and J.F. McDonald. 1980. Key words: heritability, growth, fisheries, selection, brown trout, USA. Favro, L.D., P.K. Kuo and J.F. McDonald. 1980. Effects of unconventional size limits on the growth rate of trout Salmo trutta. Can. J. Fish. Aquat. Sci. 37: 873-876. Abstract: A computer model was used to study the genetic effects on a trout population that was subjected to selective fishing with unconventional size limits; both a mInlmum and maximum size were specified. The model predicts that such window size limits will not have their intended effect, ie. to increase the percentage of larger fish in the population. Comment: The predictions of the model are of interest from a fisheries management viewpoint, but require experimental substantiation. Very few data underlie the model parameterization (eg. the genetic control of growth, the seasonal variation in growth, the degree of dependence of fishing mortality on growth) and thus the results are theoretical at best. Key words: heritability, growth, selection, fisheries, brown trout, USA. Flick, W.A. and D.A. Webster. 1962. Problems in sampling wild and domestic stocks of brook trout (Salvelinu~ fontinalis). Trans. Am. Fish. Soc. 91: 140-144. Abstract: In the spring of 1959 two wild stocks and a domesticated stock of brook trout were planted as fingerlings in Bear Pond in the northern Adirondack Mountains of New York. A resident population of brook trout of domesticated parentage was also present. Differences in behavior between the four groups affected the catch by angling and trap-netting. During the summer of 1960, when all four groups were approximately the same • - 65 - length, over 30 percent of the domesticated stocks were taken by fly fishing, while only 12 percent of the two wild stocks were recovered. The stocked domestic group was found to be much more vulnerable to trap-netting than the other groups. During the first 24 hours of netting, 46 percent of the trout estimated at large from this stock were recovered. At the end of three weeks of trap-netting, 84 percent of the stocked domestic, 64 percent of the resident domestic, 66 percent of the Long Pond Stream wild, and 44 percent of the Honnedaga Lake wild brook trout were recovered. Gill-netting was not found to be selective for any of the four groups. Comment: Fish of two wild strains and one stocked domestic strain raised in the same environment and released into the same pond displayed different behavioral responses (and therefore vulnerability) to angling. This most likely resulted from the unintentional genetic alteration of domesticated fish through selection. Although the stocked hatchery strain might be suitable for use in a 'put and take' fishery, it would be less likely to establish a self-sustaining population in a water body subjected to heavy fishing pressure. The genetic basis of the behavioral differences and the effect of density ·on behaviour were not examined. In addition, the presence of other strains may have affected the behaviour of fish of each brook trout strain. It is possible that fish of the domesticated stocked strain would display more adaptive behaviour in the absence of competition from other strains. Keywords: interpopulation variability, life history, propagation, brook trout, USA. Flick, W.A. and D.A. Webster. 1964. Comparative first year survival and production in wild and domestic strains of brook trout, Salvelinus fontinalis. Trans. Am. Fish. Soc. 93: 58-69. Abstract: Brook trout from three wild populations were compared with domesticated hatchery strains with respect to growth, survival, and production in semi-natural environments (drainable ponds) . Eggs from all strains were hatched and reared in the hatchery and planted as spring or fall fingerlings. Over-summer survival consistently favored wild strains (65 to 76 percent compared with 43 to 53 percent survival for domestic strains). Over-winter survivals were not different, although the effect may have been masked by other overriding factors in the test waters. Domestic strains maintained the initial size advantages held at planting. Larger size at planting was due to faster growth rate during hatchery existence. Net production, based on recovery weight less stocking weight, was similar for wild and - 66 - domestic groups during the over-summer period (higher survivals in wild strains balanced by size advantage of domestic), but domestic groups generally showed lower production or net losses in the over-winter period. Comment: See comment for Flick, W.A. and D.A. Webster. 1976. Key words: interpopulation variability, growth, life history, propagation, brook trout, USA. Flick, W.A. and D.A. Webster. 1976. Production of wild, domestic and interstrain hybrids of brook trout (Salvelinus fontinalis) in natural ponds. J. Fish. Res. Bd. Can. 33: 1525-1539. Abstract: Hatchery-reared wild and domestic strains of brook trout were released in natural lakes, and survival and growth estimated at semiannual intervals throughout the life span. Angling was restricted. Four experiments with two year-classes involved three different Adirondack Mountain (New York) wild strains and two domestic strains, a fifth experiment included two wild strains from James Bay, Quebec and a hybrid between one of these (Assinica Lake) and a New York domestic strain. Wild and hybrid strains consistently exhibited greater longevity (5-7 yr) compared with domestic (few recovered after 3 yr). Climax sizes were not much different, except the Domestic x Assinica hybrid that was substantially larger than either of the two parents. Gross production and yield to angling of any given strain cohort was correlated (r = 0.93) and life-span gross production was 50% greater for wild and hybrid groups per unit fish stocked. Biomass stocked per recruit was much larger for domestic strains, and taking this into account, the ratio of gross production to weight stocked was about 6 times greater. Increased costs of rearing nondomesticated strains, if any, must be taken into consideration in an economic evaluation, but use of wild and/or hybrid strains of trout offers significant benefits under management conditions of these experiments. Comment: Wild brook trout from Quebec as well as native wild trout survived longer than did domestic trout introduced into Adirondack waters. This indicated that a lack of adapatation to Adirondack conditions per se was not the sole determinant of poor survival in domestic strains. Poor egg quality may have resulted in a large environmental maternal effect that contributed to the observed differences in survival between domestic and wild fish. However, eggs from one of the domestic strains were used to produce the domestic x wild hybrids which showed heterotic growth and survival. This indicated that the domestic eggs did not suffer a large nutritional deficiency. - 67 - Inbreeding may have reduced genetic variation in the domestic strains, but no evidence of inbreeding depression (eg. slow growth) was observed in the hatchery environment. Instead, it seems probable that selective breeding for adaptation to hatchery conditions during a long history of domestication has resulted in the genetic alteration of domestic strains. Key words: interpopulation variability, growth, life history, propagation, heterosis, brook trout, USA, Canada. Fraser, J.M. 1981. Comparative recoveries of matched plantings of domestic and wild or semi-wild stocks of brook trout in lakes of Algonquin Park, Ontario. Can. J. Fish. Aquat. Sci: in press. Abstract: Matched plantings of domestic strain and semi-wild strain hybrid (or wild strain) brook trout (Salvelinus fontinalis) were made annually in nine small Precambrian Shield lakes during 1973-1977. Recoveries of planted fish were made by gillnetting and/or angling during 1974-1980. In six study lakes, semi-wild hybrids (and wild strains) were recovered at rates two to four times greater tlEn the domestic strain; in three lakes recoveries were similar. Most domestic strain trout were caught in the year following planting whereas recoveries of semi-wild hybrids and wild strains were spread over three - four years. Each kg of hybrid (or wild) strain planted yielded 5.6 kg (1.2 - 12.3); each kg of domestic strain planted yielded 0.8 kg (0.2 - 2.1). Lakes containing only minnows and sticklebacks yielded the highest returns of brook trout; lakes containing competitive species yielded low returns. Rapid growth of brook trout occurred in lakes containing only minnows and sticklebacks; slowest growth was noted in lakes supporting white suckers (Catostomus commersoni). Domestic strain brook trout and the matched hybrid grew at approximately the same rate within a lake and in seven of the nine lakes ate the same food. The performance of the semi-wild hybrids (Nipigon x domestic, Dickson x domestic) qualify them for consideration as replacements for the domestic brook trout presently planted in Ontario lakes. Key words: interpopulation variability, life history, growth, propagation, brook trout, Canada. Gall, G.A.E. 1969. Quantitative inheritance and environmental response of rainbow trout. p. 177-184. In: Fish in Research. (O.W. Neuhaus and J.E. Halver, eds.). Academic Press. New York. - 68 - Abstract: Some factors influencing the genetic composition and structure of a domesticated fish population were reviewed. Genetic differences in reproductive performance among four domesticated and one wild rainbow trout strains were related to differences in their breeding histories. One domestic strain of trout grew faster at low densities, while another grew faster at high densities. This type of genotype by environment interaction may be common in fish, and can be used in research programs to separate genetic lines of fish or to alter responses in a single line.* comment: The variation in growth and egg production among four domesticated stocks of rainbow trout provided an indication of the effect of breeding methods on the genetics of populations. Unfortunately, the amount of genetic differentiation among the strains could not be quantified, nor was it possible to determine the importance of various factors (founder effects, selection, genetic drift, inbreeding) in producing the genetic differentiation. The demonstration of an interaction between fish strain and density in determining growth indicates the importance in a selective breeding program of choosing broodstock from fish that perform well in the environment for which the offspring are intended. Key words: interpopulation variability, propagation, inbreeding, heterosis, selection, growth, genotype-environment interaction, rainbow, USA. Gall, G.A.E. 1972. Phenotypic and genetic components of body size and spawning performance. p. 159-163. In: Progress in Fishery and Food Science. (R.W. Moore, ed.). Univ. washington Publ. Fish., New Ser. 5. Seattle. Abstract: An evaluation of the biological components of the reproductive process was made for two domestic strains of rainbow trout maintained by the California Department of Fish and Game. Data were collected on body weight, egg volume, egg size and egg number for age two spawners from the two strains and their reciprocal crosses. Variation existed among strains and their crosses for the three measures made on eggs spawned. These differences were probably genetic in origin since environmental variables were controlled as far as possible.* Comment: The differences demonstrated between the two strains examined in this study for egg production traits were likely a reflection of genetic distinction, although environmental effects were not eliminated. Much of the genetic differentiation between the two populations may have been brought about by methods of hatchery propagation. The nature of the genetic variation was not determined, which makes it - 69 - difficult to assess the potential for changing these traits through selective breeding. Because the production of eggs is a 'fitness related' characteristic, it might be expected to possess little additive genetic variance. The fact that the number , size and volume of eggs produced by reciprocal hybrids were not intermediate to parental values supports the suggestion that the additive variance is small. Key words: interpopulation variability, intrapopu1ation variability, growth, life history, propagation, maternal effects, rainbow, USA. Gall, G.A.E. 1974. Influence of size of eggs and age of female on hatchability and growth in rainbow trout. Calif. Fish Game 60: 26-35. Abstract: The egg production of two and three year old rainbow trout females and the growth of their progeny to 75 days of age were studied in two consecutive years to evaluate the effect of egg size and age of female on size and growth of fingerlings. Age two females produced smaller eggs than age three females making it difficult to separate the two effects. There were significant differences between years and ages of females in egg volume, egg size, and egg number per female. There was also a significant year by age interaction which was attributed to differences between the two genetic stocks used in the study. Age three females gave a higher percent eyed eggs, and larger, more rapidly growing fingerlings. The age of female effects on fingerling size could be accounted for by regression on egg size. Fingerling growth was affected by both age of female and egg size. Comment: In this study, fingerling growth was measured to 75 days of age only, so that much of the variability in fingerling size and growth between the offspring of two and three year old females was possibly due to maternal effects. Persistence of the growth superiority of larger fingerlings should be monitored. The two genetic stocks used in this study were both maintained at the Hot Creek hatchery and were presumably of similar genetic origin. Propagation under hatchery conditions has likely brought about the observed genetic differentiation. Founder effects, genetic drift, selection or inbreeding may have altered gene frequencies in one or both populations. Key words: interpopulation variability, intrapopu1ation variability, growth, life history, propagation, selection, maternal effects, rainbow, USA. - 70 - Gjedrem, T. 1975. Possibilities for genetic gain in salmonids. Aquaculture 6: 23-29. Abstract: A review of the literature concerning phenotypic and genetic parameters for economic production traits in salmonids shows that very few estimates are available. However, based on present knowledge the possibilities for genetic gain in, for example, growth rate are extremely good even if conservative estimates are considered. The high genetic gain may be obtained primarily because of high fertility, a large phenotypic variance and a moderate length of the generation interval. There is a great need to start selection in order to get a more productive animal which is better adapted to captivity. Comment: This review deals with methods of selective breeding that might be used in salmonid populations which are raised entirely in captivity. Under these conditions, the selection of broodstock possessing desirable production characteristics at any life history stage is feasible. Less success might be expected in a selective breeding program applied to fish that are released to the wild to reach maturity. Under these conditions, natural selection may work in opposition to the artificial selection imposed on the stock, and reduce both survival and the amount of genetic alteration achieved. In addition, more of the phenotypic variation observed in adult characteristics that might be of interest for selection (size, fecundity, flesh colour, etc.) would likely be a result of environmental variability experienced by the fish during growth under natural, but uncontrolled, conditions. This would hinder identification of genetically superior individuals for broodstock purposes. Key words: heritability, growth, selection, inbreeding, propagation?, salmonids, Europe. Gjedrem, T. 1976. Possibilities for genetic improvements in salmonids. J. Fish. Res. Bd. Can. 33: 1094-1099. Abstract: No systematic breeding work has been done so far with salmonids except for some attempts with rainbow trout and Pacific salmon. The possibilities for obtaining genetic change are particularly dependent on selection intensity, heritability, phenotypic variance, and length of generation interval. The very high fertility in salmonids makes it possible to practice an intensive selection for fish in captivity and a more moderate selection in wildlife cultivation. Very few estimates of heritability have been calculated for production traits in salmonids and most of them are based on limited data. The few estimates for heritability of growth rate are moderately large (0.1 - 0.2). For most production traits studied, a remarkably - 71 - high phenotypic variance has been found, and the coefficient of variation is two to four times as high as for production traits in farm animals. The length of generation interval varies from one species to another and with the production system applied; two to five years will be the usual. To make a selection program possible, one must control the whole life cycle of the fish. Therefore, hatching, fingerling production, and cheap and efficient tagging methods are necessary requirements. Because of the high fertility, the large variation and a moderately long generation interval, it should be possible to obtain much higher genetic gain per time unit in salmonids than in farm animals. Comment: This paper provides a brief review of heritability estimates for various Atlantic salmon traits of actual and potential economic importance. Genetic variation among Atlantic salmon strains and methods of selection are also discussed. However, the potential hazards of large scale selective breeding programs to domestic and, more importantly, wild stocks are not examined. Key words: heritability, interpopulation variability, growth, disease, life history, selection, propagation?, Atlantic salmon, Europe. Gjedrem, T. 1979. Selection for growth rate and domestication in Atlantic salmon. Z. Tierz. Zuchtungsbiol. 96: 56-59. Abstract: At the research stations for salmonids at Sunndalsora and Averoy a selection program is being carried out. Selection for body weight is based on strain, full ann half sib groups, and individual information. Strongest selection was applied on weight after two years in the sea. The first generation response of salmon fingerlings to selection for high weight at 190 days old was as much as 30%. This response is higher than expected and cannot be explained wholly as a direct selectiort response. It is thought that part of this response is a domestication effect. Comment: The large increase in Atlantic salmon juvenile size observed in this study as the result of selection applied to adults is hypothesized to be predominantly the result of selection for 'domesticity' rather than for faster growth. Selection for domesticity, ie. good performance in captivity, must occur to some extent in every fish population which is maintained under hatchery conditions. In populations which are to be kept captive until harvest, selection for increased domesticity likely results in greater productivity. However, increased domesticity of fish which are to be released may result in decreased growth and survival, and hence productivity, - 72 - under natural conditions. The author's proposed examination of the heritability of domesticity in Atlantic salmon should provide valuable information on an important trait that is difficult to measure. Key words: heritability, interpopulation variability, growth, life history, selection, propagation, Atlantic salmon, Europe. Gjedrem, T. and H. Skjervold. 1978. Improving salmon and trout farm yields through genetics. World Review of Animal Production 14: 29-38. Abstract: Salmonid farming is a young industry in Norway and so far has relied almost entirely on wild salmon stocks and stocks of rainbow trout kept in captivity for only a few generations. Increased production may be achieved on salmonid farms by use of selective breeding programs based on established genetic principles. The salmonid characteristics of high fertility, external fertilization and successful interspecific hybridization will facilitate the Norwegian selective breeding program, which consists of six stages. These include a comparison of performance among species and among strains within species, selection within strains, crossbreeding between inbred strains, crossbreeding between species, and chromosomal engineering. The results and potential achievements of this program for various Norwegian salmonid species are dicussed.* Comment: this paper provides a basically nonquantitative review of the Norwegian selective breeding program for salmonids, and the genetic information on which it is based. Few strains have been subjected to selection over a sufficient number of generations to permit evaluation of the program results. Key words: interpopulation variability, intrapopulation variability, heritability, growth, disease, life history, age of maturity, size of maturity, heterosis, selection, propagation, Atlantic salmon, rainbow, brown trout, Arctic char, pink, Europe. Glebe, B.D., R.L. Saunders and C.B. Schorn. 1981. Implications of precocious maturation for the culture and selective breeding of Atlantic salmon. (Abstract Only). Can. Conf. Fish Res. Jan. 1981, Montreal. Abstract: The incidence of precocious sexual maturity among hatchery-reared parr was stock specific. High incidences adversely affected strain performance by a reduction in growth and lipid reserves of maturing individuals. Similarly the smoltification rate among the high incidence groups was depressed. The genetic and environmental influence on precocious maturation was investigated by comparing the - 73 - incidence of precocious parr within paternal and maternal half-sib family groups and between full-sibs reared at different temperatures from matings involving various combinations of precocious parr, grilse and two-sea-year salmon. The incidence of precocious parr at the family level was highly variable (0-84%) and not related to parental age at maturity 0r experimental rearing temperatures. Survival and growth rate of parr sired groups was similar to that of families sired by anadromous parents. The results suggest precocious parr sires may be used to reduce generation time in salmon breeding programs thus accelerating genetic gains for traits measurable at the parr stage. Key words: interpopulation variability, intrapopulation variability, heritability, age of maturity, life history, propagation?, Atlantic salmon, Canada. Green, D.M., Jr. 1964. A comparison of stamina of brook trout from wild and domestic parents. Trans. Am. Fish. Soc. 93: 96-100. Abstract: Eggs from one domestic strain and two wild strains of brook trout were reared under similar, but not identical, batchery conditions. Stamina tests on 50 fish from each strain at two different flow rates were conducted. Within each strain, stamina increased with fish length. Fish of the two wild strains demonstrated significantly more stamina than domesticated fish of the same length. Reduced stamina in the domestic strain may have a genetic or nutritional basis.· Comment: In this study, the author suggests that the significant differences in stamina between wild and domestic strains of brook trout may result from the genetic alteration of the hatchery strain through selection, or from the lower nutritive value of the eggs produced by hatchery reared females. Reciprocal hybridization of the wild and domestic strains would provide an indication of the relative importance of maternal effects (genetic and nutritive) and additive genetic variation. The heritability of stamina in the wild and domestic strains could be determined by an examination of intrapopulation variability. Key words: interpopulation variability, life history, growth, propagation, brook trout, USA. Greene, C.W. 1951. Results from stocking brook trout of wild and hatchery strains at Stillwater Pond. Trans. Am. Fish. Soc. 81: 43-52. Abstract: In 1948 and 1949, 1,000 fingerling brook trout of a - 74 - wild strain and 4,500 fingerlings of a hatchery-developed strain were stocked in Stillwater Pond, a 55-acre pond in Putnam County, New York. All fingerlings were fin-clipped for recognition. Returns from plantings in both years followed similar patterns. Yields from the wild strain were disproportionately low in the first season after planting and disproportionately high in the second season. Field observations indicated that individuals of the two groups were consistently different in appearance and generally could be separated by characteristics of body shape and color. Length-weight data, expressed as condition factors, illustrate morphological differences in trout of the two groups after they had been in the pond for 18 months. Angling returns indicate that better angler satisfaction may be obtained here from stocking trout of both strains together than from stocking either one alone. It is concluded that differences in these two strains of trout exhibited in this situation are hereditary (racial) and are of sufficient magnitude to be important in management of a brook trout fishery. Comment: In this study, all sampling of the introduced wild and domestic brook trout was done by angling, which may not have provided a representative indication of the pond population. Nevertheless, as in other studies, survival of wild fish to the second and third fishing seasons after stocking appeared to be greater than survival of domestic fish. Although a genetic basis for the differential survival was indicated, the nature of the genetic variation within or between strains was not examined. Environmental maternal effects may also have contributed to the differences in growth and survival between brook trout strains. Key words: interpopulation variability, growth, life history, morphology, propagation, brook trout, USA. Gunnes, K. and T. Gjedrem. 1981. A genetic analysis of body weight and length in rainbow trout reared in seawater for eighteen months. Aquaculture 24: 161-174. Abstract: Data from four year-classes of rainbow trout were analysed. The brood fish originally carne from different Norwegian fish farms, but all are considered to belong to the same population. During the freshwater period each full-sib family was reared separately and each group was given as equal environmental conditions as possible. At an age of one year fingerlings from each family were sampled and transported to different fish farms along the Norwegian coast. This paper deals with the traits body weight and length at slaughter after about 18 months in net cages in the sea. Fish farm x sire interaction was significant, but accounted for - 75 - a relatively small part of the total phenotypic variance. It is concluded that genotype x farm interaction can be ignored when planning a selection programme for rainbow trout under Norwegian farming conditions. A significant interaction was found between sire and dam, implying the presence of non-additive genetic variation. The heritabilities for body weight and length estimated from sire components were 0.17 and 0.23, respectively. The genetic correlation between body weight and length was close to unity. Genetic variation in body weight of rainbow trout is high, about three times as high as for body length. The heritabilities estimated for condition factor were small and none of the sire components were significant. It is concluded that the combination of weight and length used to calculate the K factor has little genetic basis.* Comment: In this study, rainbow trout collected over a four year period from several Norwegian fish farms were treated as members of a single population. The origins and breeding histories of trout on different farms were not given. Large variation in the heritabilities of length and weight calculated from the data provided by different year classes was attributed to the small numbers of sires used within year classes. However, genetic heterogeneity among fish farms likely contributed to the inconsistency of heritability estimates. The demonstration of a non-additive genetic influence on adult size has implications for the method of selection that should be employed to produce larger fish. The efficiency of mass selection (selection of the largest individuals for broodstock regardless of family or strain) will be decreased to the extent that the genetic control of growth is non-additive. As the authors suggest, alternative selection procedures such as family selection and the hybridization of inbred lines may be required. Key words: heritability, growth, selection, propagation, rainbow, Europe. Hansen, M.J. and T.M. Stauffer. 1971. Comparative recovery to the creel, movement and growth of rainbow trout stocked in the Great Lakes. Trans. Am. Fish. Soc. 100: 336-349. Abstract: In this study we planted 132,973 tagged rainbow trout during 1955-59 at 29 locations along Michigan shores of the Great Lakes and Burt Lake. Three stocks of two to three year old trout were used: (1) progeny of Michigan hatchery brood stock, (2) progeny of Great Lakes run rainbow trout and (3) progeny of sea-run rainbow (steelhead) trout from the State of Washington. Matched plants were used to study four factors that might have influenced recovery rates, namely; (1) month of planting, (2) stock of trout, (3) size of trout, and (4) location of planting (stream versus lake). We used only records - 76 - on fish which had grown 3 inches or more since planting. These fish added up to 1.2% of the total planted; the rates ranged from 0.0 to 9.3% among the many plantings. For the factors studied, we found: (1) May plantings produced the highest returns, (2) the three stocks did not differ consistently in returns, (3) larger fish gave better returns than smaller fish, and (4) lake planting of the Michigan hatchery stock produced better returns than stream planting.* Comment: Although no difference in total recovery was noted among the one domesticated (of Great Lakes origin) and two wild (Lake Michigan and Washington State) rainbow trout stocks planted in the Great Lakes during this study, time before recapture and amount of straying did vary among stocks. Planted fish of the domestic stock were recaptured within two years of stocking, and were the most abundant fish recaptured in the first year after release. Fish of the two wild stocks were recaptured up to five years after stocking, and were more abundant in second year recaptures than were domestic fish. The rearing conditions of the study were not described, but presumably the environments of all three stocks were as similar as possible. Thus, the variability noted above may indicate some genetic distinction between the domestic and wild stocks in life span or vulnerability to angling, and in migratory tendencies. In addition, domestic fish grew faster than wild fish in the hatchery, but wild fish overtook domestic fish after release to natural conditions. This likely reflects genotype-environment interactions. Key words: interpopulation variability, propagation?, life history, growth, rainbow, USA, Canada. Hershberger, W.K. 1978. Salmonid genetic study. Washington Dep. of Fish. Completion Rep. Proj. l-lOl-R. Univ. of Washington. Seattle. Abstract: This study was designed to assess three strains of coho salmon that are reared and managed by the Washington Dep. of Fisheries by monitoring genetic differences in the early life history that would be advantageous to hatchery management. The following conclusions were made: early mortality (through shocking) indicated consistent differences in the 1974 and 1975 crosses based on origin of male and female parents. Growth and food conversion efficiency measurements through three months of rearing indicated significant differences between the three populations utilized. In hybrid crosses, growth and food conversion efficiency were generally better than in either of the pure line crosses. Differences in susceptibility to low temperature disease were evident, with crosses involving parents - 77 - from the Simpson stock showing the greatest incidence of the disease. Genetic differences in serum transferrins were found to 'mark' resistance levels to three common fish pathogens. This offers some limited potential for utilization in breeding programs to enhance disease resistance. comment: This study revealed significant genetic variation among three discrete, domesticated salmon stocks returning to a relatively small geographic area. Unfortunately, the origin and domestic history of each of the stocks was not provided. Characteristics of the Green River stock, especially, (high egg mortality, slow growth and low disease resistance) were indicative of an inbred line of fish. The heterotic growth of Green River and Simpson hybrids supports the contention that one or both stocks were highly inbred. Different transferrin genotypes displayed greater resistance to different pathogens. Unfortunately, the stock(s) from which the different transferrin genotypes were taken for testing was not specified. If the transferrin genotypes that displayed differential resistance to a pathogen were sampled from different stocks, the relationship between transferrin genotype and level of pathogen resistance might have been spurious. If, however, consistent differences in resistance were observed among transferrin genotypes within stocks, then transferrin genotype may indeed provide a genetic 'marker' for disease resistance. A particularly encouraging aspect of this study is the intention to monitor each of the three strains and their hybrids for returns to the fishery and to the hatchery. This will enable a comparison of the performance of each stock in early hatchery life with its performance in the wild. The ability of hybrids to survive and possibly maintain their heterotic growth can also be determined. Key words: interpopulation variability, growth, life history, disease, electrophoresis, genotype-environment interaction, heterosis, selection, coho, USA. Hjort, R.C. and C.B. Schreck. 1981. Phenotypic differences between stocks of hatchery and wild coho salmon (Oncorhynchus kisutch) in Oregon, Washington and California. Fish. Bull: in press. Abstract: Phenotypic similarities between 35 stocks of coho salmon from Oregon, Washington, and California were compared by using agglomerative and divisive cluster analyses. The phenotypic characters evaluated include isozyme gene frequencies, life history characters and morphological characters. Coho salmon stocks from similar environments were - 78 - phenotypically similar. Five groups of stocks were identified by the agglomerative cluster analysis: (1) wild stocks from the northern Oregon coast; (2) wild stocks from the southern Oregon coast; (3) stocks from hatcheries that used wild coho salmon for an egg and sperm source; (4) stocks from large stream systems; and (5) hatchery stocks from the northern Oregon coast. Three trends were indicated by the clustering patterns: (1) stocks that are geographically close tend to be phenotypically similar; (2) stocks from large stream systems were more similar to each other than to stocks from smaller stream systems, independent of geographic proximity; and (3) hatchery stocks were more similar to eac~ other than to wild stocks, and wild stocks were more similar to each other than to hatchery stocks. These trends may be useful to fishery managers for selecting donor stocks from hatcheries for transplanting to stream systems or transferring to other hatcheries. Individual phenotypic characters were correlated with characters of the stream systems. Results of two agglomerative cluster analyses, one of certain characters of the stocks and one of certain characters of the stream systems demonstrated a lack of correspondence between stream types and stock phenotypes. Key words: interpopulation variability, intrapopulation variability, morphology, electrophoresis, life history, propagation, coho, USA. Ihssen, P. 1976. Selective breeding and hybridization in fisheries management. J. Fish. Res. Bd. Can. 33: 316-321. Abstract: Selective breeding of fish using quantitative genetic techniques is discussed. Fish offer advantages over other livestock for selective breeding procedures because of their relatively high productive potential and low reproductive barriers. Maintaining fish stocks in artificial environments can cause undesirable genetic changes such as loss in heterozygosity due to inbreeding and loss in fitness. Methods to minimize inbreeding are given. The study of cross breeds of inbred lines, and hybrids among strains or even species, to produce high levels of heterozygosity and heterosis or hybrid vigor is suggested. Comment: This paper provides a discussion of factors that reduce genetic variation and determine the rate at which information is lost in artificially propagated fish populations. Hybridization of genetically distinct strains or species is suggested as a method to maintain or even enhance genetic variability in domesticated salmonid stocks, but possible deleterious consequences (eg. loss of coadapted gene complexes, disruption of gene regulation and expression) are not examined. Key words: interpopulation variability, heritability, - 79 - propagation?, inbreeding, genetic drift, founder effects, heterosis, salmonids, Canada. Kaya, C.M. 1978. Thermal resistance of rainbow trout from a permanently heated stream and of two hatchery strains. Prog. Fish Cult. 40: 138-142. Abstract: Resistance times to high temperatures were determined for fingerling and juvenile rainbow trout (Salmo gairdneri) from the Firehole River, Yellowstone National Park, and from the Ennis and Winthrop hatchery strains, after acclimation to 5, 9, 13, 17, 21 and 24.5 C. Firehole and hatchery trout acclimated to 21 and 24.5 C had similar median resistance times and upper incipient lethal temperatures. After acclimation to the lower temperatures of 5, 9, 13, and 17 C, Firehole trout had longer median resistance times and slightly higher upper incipient lethal temperatures than did the hatchery trout. The ultimate upper incipient lethal temperature for the Firehole trout and for both hatchery strains was about 26.2 C. Rainbow trout inhabiting and reproducing in the heated waters of the lower Firehole River do not appear to have developed the ability to acclimate to higher temperatures. Comment: This study provided no evidence for a genetically controlled facility in the Firehole rainbow trout to acclimate to high water temperatures. This does not preclude a genetic basis for other apparently adaptive characteristics of the Firehole trout population (eg. delayed spawning). How€"er, much or all of the altered behaviour and physiology of Firehole trout may be the result of a phenotypic flexibility which enabled the trout to accomodate high temperature conditions and therefore avoid natural selection for warm water genotypes. Key words: interpopulation variability, life history, selection, rainbow, USA. Kincaid, H.L. 1976. Inbreeding in rainbow trout (Salmo gairdneri). J. Fish. Res. Bd. Can. 33: 2420-2426. Abstract: Effects of inbreeding on rainbow trout were evaluated by a comparison of differences between inbred and outbred half-sib families reared as contemporaries during the first year of life. Attention was focused on two levels of inbreeding expressed as inbreeding coefficients: F = 0.25, one generation of brother-sister matings, and F = 0.375, two generations of brother-sister matings. Although inbreeding at the F = 0.25 level in fall-spawning populations had no effect on egg hatchability, it significantly increased the frequency of crippled fry and significantly decreased feed conversion efficiency, fry survival to 147 days, and growth rate to 147 and - 80 - 364 days. Effects of inbreeding at F = 0.375 were more pronounced; significant differences included increased frequency of crippled fry and decreased feed conversion efficiency, fry survival to 147 days, and growth rate to 147 and 364 days. Application of the total effects of inbreeding on the number of fish remaining and the weight of fish remaining in a production lot at one year of age indicated losses of 17.4 and 36.6% after one generation, and 47.9 and 65.4% after two generations of brother-sister mating. Similar studies on a spring-spawning population produced similar results. General breeding methods that minimize the rate of inbreeding accumulation are discussed.* Comment: This analysis provides a conservative indication of the detrimental effects of one generation of inbreeding on the growth and survival of young hatchery reared trout. The data demonstrate a reduction in both the total number and total weight of offspring from full sib crosses. No information on growth beyond one year is provided, although an analysis of growth to maturity and of reproductive success would facilitate a more complete assessment of inbreeding effects. The study of the effects of increasing homozygosity on growth and survival at higher levels of inbreeding was hindered by difficulties in rearing the highly inbred crosses. Key words: heritability, intrapopulation variability, life history, growth, inbreeding, propagation, maternal effects, selection, rainbow, USA. Kincaid, H.L. 1976. Effects of inbreeding on rainbow trout populations. Trans. Am. Fish. Soc. 105: 273-280. Abstract: An approach for measuring inbreeding depression on the basis of differences between inbred and outbred half-sib family groups is described. using this method, estimates of inbreeding depression in populations of rainbow trout (Salmo gairdneri) following one generation of brother-sister mating were calculated for three production traits. Estimates for fry survival and fry weight at 150 days were significant (P < 0.01) while egg hatchability estimates were nonsignificant. Following one generation of full-sib mating, the calculated effect of inbreeding on the number of live fish and total weight of fish at 150 days of age showed a reduction of 16.1 and 24.4% in female families and 22.1 and 31.4% in male families, respectively. The difference between inbreeding depression estimates derived from male and female half-sib groups provides a measure of the maternal influence. Generalized trends of increasing depression with increasing levels of inbreeding from F = 0.125 to F = 0.50 were significant for weight at all ages from 77 to 150 days, but were nonsignificant for percent hatchability or percent fry survival.* - 81 - Comment: See comment for Kincaid, H.L. 1976 (above). Key words: heritability, life history, growth, propagation, inbreeding, maternal effects, selection, rainbow, USA. Kincaid, H.L. 1977. Rotational line crossing: An approach to the reduction of inbreeding accumulation in trout brood stocks. Prog. Fish Cult. 39: 179-181. Abstract: A system is presented for maintaining trout brood stocks for long periods with levels of inbreeding accumulation lower than that experienced in random mating populations of equal size. The system requires the formation of three or more distinct breeding lines. Brbod stock generations are advanced by a systematic mating scheme in which females of each line are mated to males of a different line. Eggs for hatchery production may be obtained from matings either within a single line or between lines. An opportunity for improving the breeding population is provided through selection of individual fish to be used in the production of the next brood stock generation. The requirement for increased handling of brood stock is not considered to be serious. Comment: The method outlined for the reduction of inbreeding in hatchery maintained salmonid stocks requires the identification of three different strains, and. multiple year classes and age groups within each strain, under hatchery conditions. However, fish do not have to be marked by family, and breeding records for individual fish do not have to be maintained. For each cross made in the creation of the next broodstock generation, one male is mated to one female and no fish is used twice, so that equally large numbers of males and females are required. In older age groups which do not contribute to succeeding generations, an excess of females can be kept to meet hatchery egg production requirements. Key words: intrapopulation variability, propagation, inbreeding, selection, rainbow, USA. Kincaid, H.L. 1979. Development of standard reference lines of rainbow trout (Salmo qairdneri). Trans. Am. Fish. Soc. 108: 457-461. Abstract: Two separate lines of rainbow trout have been developed for use as standard reference lines in genetic research being conducted at the United States Fish and Wildlife Service Fish Genetics Laboratory, Beulah, wyoming. Lines (one fall-spawning and one winter-spawning) were developed from the mixing of unselected strains during the 1968 and 1969 spawning - 82 - seasons and have been maintained since by a modified random mating scheme. Production data on egg hatchability, fry survival, and growth performance for the 1972-1977 year classes show a high degree of uniformity within each year class and significant year-class differences (P < 0.05) in all traits. The use of standard reference lines, such as these, allows the researcher to remove the effects of environmental variation from long-term studies extending over multiple spawning seasons. Comment: Reference lines maintained with minimal annual variability in genetic composition are a valuable tool for fisheries research. The care taken to preserve the various genetic components of the fall and winter spawning lines (early and late season spawners, two and three year old spawners) is in sharp contrast to usual hatchery practice. The domesticated strains of trout used to produce the two standard lines had undoubtedly been subjected to selection prior to this study, but the use of more than one strain in the creation of each reference line maximized the available genetic variability. Key words: intrapopulation variability, propagation, growth, life history, rainbow, USA. Kincaid, H.L., W.R. Bridges and B. von Limbach. 1977. Three generations of selection for growth rate in fall-spawning rainbow trout. Trans. Am. Fish. Soc. 106: 621-628. Abstract: A selection program to improve the growth rate of rainbow trout (Salmo gairdneri) was begun in 1967 with random samples of fall-spawning fish from the Manchester and Wytheville National Fish Hatcheries. All matings were made as one male to one female, and selection was based on family mean fish weight of the progeny at 147 days post-fertilizaton. The selected families in each year class were mated in all combinations at two years of age (age II) and three years of age (age III). Selection was applied only to the age II progeny. During the three cycles of selection studied, mean 147-day weight of progeny from age II parents increased from 2.02 g in the first generation to 5.28 g in the fourth generation, a gain of 161%. Of the 3.26 g total gain during the study, net genetic gain in weight from selection was 0.98 g or 30.1%. The rest of the gain (69.9%) resulted from improved rearing conditions. Gains in percentage hatch and percentage fry survival to 147 days were not significant. Differences in the performance of progeny from the age III parents, as compared to that of progeny of age II parents from 1970 to 1974 showed an advantage for the age III parents in all three traits.* Comment: Two hatchery stocks of rainbow trout were used to provide the base population for this selective breeding program. - 83 - Directional selection and inbreeding prior to the beginning of this experiment may have reduced the level of genetic variation below that characteristic of wild stocks. Nevertheless, significant genetic improvement in growth rate was made on the basis of family selection ~ver three generations. This is one of few studies that have provided quantitative experimental results from a selection program that could be compared to gains predicted on the basis of heritability estimates. The fact that expected and realized genetic gains in growth corresponded closely suggests that heritability measurements of traits of interest do provide a good indication of the potential for genetic improvement under relatively uniform environmental conditions. Key words: heritability, selection, propagation, growth, life history, rainbow, USA. Kinunen, w. and J.R. Moring. 1978. Origin and use of Oregon, USA rainbow trout brood stocks. Prog. Fish Cult. 40: 87-89. Abstract: An historical analysis of Oregon's brood stocks of rainbow trout (Salmo qairdneri) revealed six distinct strains now in use within the state. Three spawn in spring, and three in fall. At least four strains originated from McCloud River trout, which have been transferred around the country and genetically altered over the past 100 years. Current use of these strains includes special applications, such as the use of Ceratomyxa shasta-resistant Deschutes River rainbow trout in areas with bacterial disease problems, Eagle Lake trout in alkaline waters, and Cape Cod trout in waters where it is essential that downstream movements be limited. Comment: This historical outline of broodstock development will facilitate greatly the prediction and interpretation of genetic variation within and among domestic rainbow trout stocks in Oregon. Variability in life history and other traits among stocks is apparently under genetic influence, but the underlying genetic variation has not been quantified. Key words: interpopulation variability, life history, growth, age of maturity, selection, propagation, rainbow, USA. Kirpitschnikow, W.S. and K.A. Faktorowitsch. 1969. Genetic control methods of fish disease. Fish. Res. Bd. Can. Transl. Sere No. 21967. Abstract: Susceptibility to abdominal dropsy was monitored in - 84 - four strains of carp and their hybrids over a period of four years. The percentage of fish affected varied among strains. In all strains, some fish died of dropsy and others with abdominal scars were removed. Selection reduced the carp populations to betwen 1% and 10% of the initial levels. These fish will be used as stock from which dropsy resistant varieties will be developed. The incidence of alimentary liver disease varies between five pure and hybrid strains of rainbow trout. Selection for a strain of trout with a tendency for normal liver development is being established.* Comment: A literature review of heritable resistance to disease in fish is provided. In the experimental work, offspring of the carp selected for dropsy resistance had not yet been tested for resistance, so the response to selection was not determined. No control lots of carp in which selection was not carried out were mentioned. In addition, the number of families representing each strain and the intensity of selection imposed on each strain were not specified. It appears that a quantitative genetic analysis of the results will be difficult to achieve. The selection program for rainbow trout was not outlined. Key words: heritability, disease, selection, rainbow, USSR. Krueger, C.C. and B.W. Menzel. 1979. Effects of stocking on genetics of wild brook trout populations. Trans. Am. Fish. Soc. 108: 277-287. Abstract: The study was undertaken to evaluate the long-term genetic impact of maintenance stocking upon wild brook trout populations in Wisconsin. Trout were collected from streams of the Wolf and Fox River drainages and from the Osceola State Trout Hatchery. The stocking histories of the streams ranged from unstocked to heavily stocked for many years. The hatchery stock was genetically distinct from most wild populations at two loci. variation of Tf allelic frequencies among wild populations suggested an undisturbed natural geographic pattern. There were significant correlations between Ldh-B allelic frequencies and stream stocking histories, however, with the wild type allele decreasing in importance as stocking intensity increased. This relationship does not seem to reflect interbreeding between wild and hatchery trout. Rather, it may indicate alteration of selective pressures induced by ecological interactions between the two stocks.* Comment: This study provides important preliminary evidence which indicates that planted fish of the same or different species may affect the gene pools of native salmonids, even in the absence of interbreeding. The analysis suffered from a lack - 85 - of data on the spatial and temporal variation in allele frequencies in the hatchery and stream populations. Differences in allele frequencies were found between locations on the one stream that was sampled at three different stations, which raised the possibility of considerable genetic variation within as well as between streams. Thus, the clusters of streams with similar allele frequencies might be the result of sampling error rather than of uniform and stable genetic similarity. As suggested by the authors, an examination of functional differences among the LDH-B allele products, and an extension of the survey to other polymorphic loci would be useful. Key words: interpopulation variability, electrophoresis, propagation, brook trout, USA. Lannan, J.E. 1980. Adaptive and behavioral responses to artificial propagation in a stock of churn salmon, Oncorhynchus keta. p. 309-312. In: Salmonid Ecosystems of the North Pacific. (W.J. McNeil and D.C. Himsworth, eds.). Oregon State Univ. Press and OSU Sea Grant College Program. Abstract: Hatchery produced churn salmon fry in whiskey Creek, a tributary of Netarts Bay, Oregon, migrate from the stream to estuary earlier in the spring than do naturally produced fry. The number of thermal units until emergence required by hatchery fry increased significantly between 1972 and 1977. Rapidly maturing hatchery fry may be selected against because of their early seaward migration. Thus, the increased incubation time can be interpreted as an adaptation to the hatchery environment. The time interval over which adult churn salmon returned to Whiskey Creek was reduced between 1972 and 1977. This apparently reflects the selective use in the hatchery of gametes from early returning fish.* Comment: This study provides an indication of the wide range of genetic effects that artificial propagation may have on a salmonid population, even over a short period of time. The genetic basis of the changes in time of adult return and egg incubation period was not established. However, selective forces which were likely operating to bring about the observed changes were identified. Experimental manipulation of hatchery production is required to confirm the interpretation of adaptive genetic alteration. Key words: intrapopulation variability, interpopulation variability, life history, propagation, selection, churn, USA. - 86 - Mason, J.W., O.M. Brynildson and P.E. Degurse. 1967. Comparative survival of wild and domestic strains of brook trout in streams. Trans. Am. Fish. Soc. 96: 313-319. Abstract: Survival and growth of progeny of domestic, domestic x wild, and wild strains of brook trout were compared after these trout were released during the fall as fingerlings 9 to 10 months old in selected sections of streams. One group of the wild strain was hatched and reared in the wild. Other groups were hatched and reared in the hatchery. The domestic strain had the highest over-winter survival in three of five streams. In only one stream did the wild strain have the highest over-winter survival. In the four streams investigated during the fall, the wild strain had the highest summer survival. Survival of the domestic and domestic x wild strains through the summer fishing season was generally too low to evaluate survival of these strains through the second winter. The domestic strain grew most rapidly in the hatchery followed by the domestic x wild strain. This growth advantage was not maintained after release into streams. Brook trout of the domestic strain were harvested early in the fishing season and did not contribute to the late-season catch, whereas the domestic x wild and wild strains were harvested throughout the fishing season. Comment: This study illustrates clearly the dangers of using offspring of hatchery maintained and selected salmonids for distribution to natural habitats. Because of important genotype-environment interactions, broodstock should consist of fish that show good survival and growth in the environment for which the offspring are intended. In this case, 30 years of deliberate and unintentional selection under hatchery conditions had produced a domestic strain of brook trout that survived and grew better than wild strains under hatchery conditions, but could not maintain a reproductive population in natural streams subjected to heavy fishing. Unfortunately, no estimates of the genetic variability within or between the wild and domestic strains were made under the controlled hatchery conditions of early growth. The fact that, both in the hatchery and in the wild, hydrid fish displayed behaviour and growth intermediate to the parental types indicated that much of the genetic variation between the strains was of the additive type (which is most easily affected by selection). However, maternal effects (egg size) also appeared to be important. Key words: interpopulation variability, propagation, selection, maternal effects, heritability, growth, life history, genotype-environment interaction, brook trout, USA. - 87 - McIntyre, J.D. 1980. Selection to increase yield of coho salmon, Oncorhynchus kisutch. p. 305-308. In: Salmonid Ecosystems of the North Pacific. (W.J. McNeil and D.C. Himsworth, eds.). Oregon State Univ. Press and OSU Sea Grant College Program. Abstract~ A program was initiated at Big Creek Hatchery, Oregon to evaluate the potential for increasing returns of adult coho salmon via selective breeding. Returns from 60 1968 brood year full and half sib families, tagged and released from the hatchery in April 1970, were monitored (as jacks and as three year olds taken in the fishery and at the hatchery). In 1971, 30 pairs of fish from the 19 families with the highest yields (ie. greatest number of adults recovered per 1000 smolts released) were mated to produce 30 full sib families. These 'select' and 15 nonselected 'control' families were reared, tagged and released. Returns to each family were monitored and in 1974, a second generation of selection resulted in the production of 29 select and 12 control families. Returns from the 1974 brood year indicated a significantly greater yield of both two (jacks) and three year old coho from the select group of families.* Comment: Two generations of selection have apparently increased yield in the Big Creek Hatchery coho stock. Returns from the 1977 brood year will provide data necessary for confirmation of the higher productivity of selected coho parents. The environment experienced by the juvenile coho after release to the ocean could not be controlled or monitored, and some of the variability in yield among families was undoubtedly due to factors other than genetic differentiation. Environmental effects may have contributed to the apparent lack of response to selection for increased yield in the 1971 year class. A difference in selection intensity may also account for some of the differences in response to selection between brood years, but the data required to calculate selection intensity were not provided. Hopefully, the ancestries of all fish used in the control and select groups are being recorded, so that in future years the effects of different levels of inbreeding on yield can be examined. Key words: intrapopulation variability, life history, age of maturity, propagation, selection, coho, USA. McIntyre, J.D. and A.K. Johnson. 1977. Relative yield of two transferrin phenotypes in coho salmon. Prog. Fish Cult. 39: 175-177. Abstract: Experimental groups of coho salmon (Oncorhynchus kisutch) of transferrin types AA and AC were compared to - 88 - determine relative growth and survival before release, yields from the fishery, and returns of fish· to the hatchery as two and three year olds. In the hatchery, growth was faster and survival higher in the AA than in the AC types. However, yields of AA and AC types were equal, although the yield of AC types as three year olds was greater than that of AA types because more of the AA males matured in two years. We concluded that it would be futile to attempt to increase the yield of coho salmon by maximizing the frequency of biochemical phenotypes that display only a temporary advantage over other types. Comment: The correlation demonstrated in this study between the genotype at a single locus and a complex physiological process such as growth is unusual. However, since the AA coho transferrin genotype is apparently characterized by greater susceptibility to bacterial kidney disease infection as well as by increased growth and survival under hatchery conditions, the elimination of the C allele is undesirable. Under these circumstances, electrophoresis of blood samples should be conducted to ensure that genetic variability is maintained at this locus in fish chosen for broodstock. Key words: intrapopulation variability, growth, electrophoresis, life history, selection, propagation, coho, USA. McIntyre, J.D. and R.R. Reisenbichler. 1977. An effect of interbreeding hatchery and wild anadromous salmonids. p. 93-94. In: Columbia River Salmon and Steelhead. Am. Fish. Soc. Spec. Publ. No. 10. Abstract: Test mating of hatchery x hatchery (HH), hatchery x wild (HW), and wild x wild (WW) fish were made with Deschutes River summer steelhead trout in Oregon. In streams, WW offspring had the highest survival, and HW offspring the highest growth rates when significant differences were found. In the hatchery pond, HH offspring had the highest survival and growth rates. We concluded that the hatchery fish were genetically different from wild fish and when they interbreed with wild fish may reduce the number of smolts produced. Comment: See comment for Reisenbichler, R.R. and J.D. McIntyre. 1977. Key words: interpopulation variability, growth, life history, propagation, steelhead, USA. Millenbach, C. 1973. Genetic selection of steelhead trout for management purposes. p. 253-257. In: Int. Atl. Salm. Symp. Spec. Publ. Vol. 4. {M.W. Smith and W.M. Carter, - 89 - ed s . ) . Abstract: The selection of the earliest spawning summer steelhead trout to produce smolts for planting a hatchery river has advanced the mean date of egg-take by nearly two months. The longer growing period for fingerlings, improved diets, and new fish cultural techniques now aid the production of smolts to mesh with the natural seaward migration period of April and May. A program that started with 153 wild summer steelhead in 1956 now provides an annual sport catch of 25,000 summer steelhead, involving 20 major steelhead rivers. In addition to the sport catch, natural reproduction is supplemented, and spawn has been supplied to other state, federal, and international programs. Comment: This study provides strong evidence of successful selection for early spawning steelhead in a hatchery maintained population over a 14 year period. No quantitative estimate of the response to selection could be made because the intensity of selection and heritability of spawning time in the population were not known. In addition, for some years both returning hatchery and wild fish may have been included in the broodstock. Environmental stimuli also contributed to the advancement of spawning time. The extent to which the genetic alteration of hatchery fish has reduced their fitness under natural conditions is not known. The loss of 'wildness' in hatchery raised fingerlings indicates that selection for traits other than time of spawning has occurred, despite the use of large numbers of broodstock in later years. Although surplus hatchery fish apparently spawn in the wild, survival of their offspring has not been monitored. No data are provided on the effects of hatchery production on additional life history traits (eg. amount of residualism, age structure of returning fish). Key words: intrapopu1ation variability, selection, propagation, life history, steelhead, USA. Miller, R.B. 1953. Comparative surival of wild and hatchery-reared cutthroat trout in a stream. Trans. Am. Fish. Soc. 83: 120-130. Abstract: Gorge Creek was used in a test to measure survival and weight changes in hatchery-reared cutthroat trout (Salmo clarki) • A resident population of this species exists in the stream. Groups of trout were introduced into enclosures 1/2 to 3/4 mile long: each trout in ~ group was given a numbered Petersen tag and weighed before planting. Recapture by angling and reweighing were carried out throughout the season of planting and also in later summers. Six lots of pond-reared, one lot of stream-reared, and one lot of transplanted wild - 90 - cutthroat trout were studied. Pond-reared fish exhibited very low survivals over the first (0 to 4.9%) and second (0 to 3.1%) winters. Survival was largely independent of age. Transplanted wild trout showed survivals of 46.0 to 29.0% to the second and third summers, respectively. Stream-reared hatchery fish gave an intermediate value (17.2% to the second summer). All lots of trout lost weight for some 30 or 40 days when superimposed on a resident population. This loss was more severe and was regained more slowly in pond-reared trout than in transplanted wild trout. It is held that the low survivability of hatchery fish is due to the absence of natural selection at early stages in the life history.* comment: The suggestion made in this study that a lack of natural selection among hatchery (pond) reared cutthroat trout was responsible for the low survival of these fish upon release into Gorge Creek seems reasonable. However, environmental conditions imposed by domestication (little exercise, unnatural feeding regimes) may also have contributed to the low survival of pond reared fish. In addition, if the hatchery cutthroat were not of Gorge Creek stock, the poor survival may have resulted from a lack of adaptation to Gorge Creek conditions. Unfortunately, the origin and numbers of parental fish used to produce the hatchery fish planted during the study were not specified. The only slightly better survival of hatchery produced cutthroat exposed to semi-natural conditions in Bighill Creek before transplantation to Gorge Creek may also have indicated a lack of natural selection during early life, or a lack of adaptation of this stock to the the Gorge Creek environment. Key words: interpopulation variability, growth, selection, propagation, cutthroat, Canada. Miller, R.B. 1957. Have the genetic patterns of fishes been altered by introductions or by selective fishing? J. Fish. Res. Bd. Can. 14: 797-806. Abstract: This paper is a review of some of the literature dealing with changes in freshwater fish populations following exploitation or after introduction of exotic species. The object of the review was to look for changes that could be attributed to alterations in the gene pools of the affected populations. Very little concrete evidence could be found, either because the investigations reviewed were not looking for genetic changes, or because such changes did not occur. Changes in some salmonids may be assigned to introgressive hybridization, particularly where rainbow and cutthroat trout have been put together on the Eastern Slopes. In many cases, - 91 - however, exotics have apparently failed to contribute to the gene pool of the resident population, and most hybrids, when they occur, have been of low fertility. Fishes have a remarkable ability to respond to changes in population density by altered growth rates and times of maturity. These changed characters are not necessarily due to genetic changes and may be explained by assuming that fishes are pre-adapted to a wide range of conditions. There is a rather speculative suggestion that angling may select less intelligent fish, leading to an upgrading in intelligence of the fish. The general conclusion is that in the light of the existing evidence, great caution must be used in attributing to man-induced changes in fish populations changes in the genetic pattern. Comment: This survey of the effects of manipulation on fish stocks illustrates the difficulty in distinguishing genetic and environmental responses to disturbance. At the time of this review, little evidence of intraspecific genetic variability in fishes, or of genetic alteration attributable to propagation or selective removal of a phenotypically uniform segment of a fish population was available. More recent studies have revealed relatively large heritabilities for growth, morphological traits, size and age of maturity, and other characteristics in some salmonid populations. Large amounts of biochemical genetic variation have been demonstrated within and among populations. In addition, significant alterations of isozymic gene frequencies have been monitored under hatchery conditions. These data indicate that significant intraspecific variability does exist in fishes, and that a reevaluation of the effects of man on the genetics of fish stocks is required. Key words: heritability, growth, age of maturity, propagation, fisheries, salmonids, Canada. Milner, G.B., D.J. Teel and F.M. Utter. 1979. Electrophoretic survey of protein variation in eight strains of rainbow trout (Salmo gairdneri) from the u.s. Fish and Wildlife Service Genetic Laboratory. USFWS and NOAA. Rep. of Research. Seattle. Abstract: Protein variation was used to genetically characterize and measure the genetic variation of rainbow trout from the U.S. Fish and Wildlife Service's Fish Genetics Laboratory. Estimates are given for the levels of variation occurring both within the strains and among the strains. A comparison of these values and estimates of the amount of genetic variation within and among steelhead populations of the Columbia River drainage indicated that (1) the within strain variation is approximately the same for the two groups but that - 92 - (2) the among strain variation of the Fish Genetics Laboratory strains is lower than that of the Columbia River stee1head. Genetic similarities were measured and are in the range expected for conspecific strains. The lowest similarities were exhibited by pairs that included New Zealand, the most divergent strain. Consideration is given to possible causes of the excessive number of genotype distributions that departed from Hardy-Weinberg proportions. Potential breeding and management applications of e1ectrophoretica11y detected protein variations are discussed.* Key words: interpopulation variability, intrapopu1ation variability, propagation, electrophoresis, genetic structure, rainbow, USA. Milner, G.B., D.J. Tee1 and F.M. Utter. 1980. Columbia River stock identification study. USFWS and NOAA. Final Rep. of Research. Abstract: Wild and hatchery populations of chinook salmon and stee1head trout from the Columbia River drainage system were surveyed using electrophoresis for biochemical genetic variation that could be used for estimating the composition of mixed stock fisheries. Samples were collected from 62 spring, summer and fall run chinook stocks, and from 36 summer and winter run stee1head stocks. For many stocks, more than one brood years were sampled. Considerable genetic differentiation was found among many of the stocks of both species. A method for obtaining Maximum Likelihood estimates for the composition of mixed stock fisheries was outlined, and hypothetical examples of its use were provided. The appropriateness of the method and the size of sample required from the mixed fishery analysis depend on a) which stocks contribute to the fishery, b) what their genetic profiles are, and c) which contributing stocks are of interest. An increase in sample size (to a certain point) and in th~ number of polymorphic loci used both reduced the standard deviations of the estimates. We recommend that the method be used to address Columbia / Snake River management prob1ems.* Comment: In this study, gene frequencies varied among different brood years of single stocks. The instability was attributed to current management practices which involve transplantation, alteration of migratory patterns, and consequent straying. However, natural selection, genetic drift and straying may also result in temporal instability of gene frequencies in undisturbed populations. Since use of the maximum likelihood method to determine stock composition of mixed fisheries is dependent on gene frequency constancy over time, or on annual sampling of all contributing stocks, the degree of temporal - 93 - stability that characterizes gene frequencies in disturbed and undisturbed wild and hatchery stocks deserves further attention. The maximum likelihood method outlined in this report is an iterative process which in most cases will require relatively large sample sizes (N=lOOO) to provide reliable estimates of component stock contributions, especially if these are small. In addition, substantial electrophoretic differentiation among stocks is required. Key words: interpopulation variability, electrophoresis, chinook, steelhead, USA. Moav, R. 1976. Genetic improvement in aquaculture inustry. p. 610-622. In: FAO Tech. Conference on Aquaculture. Abstract: Selective breeding and supporting genetic research in aquaculture throughout the world are reviewed, including: intrapopulation selection (including selection for disease resistance and behaviour characters), biometrical analysis of quantitative characters, intraspecific hybridization, interspecific hybridization including sterile and monosex hybrids, genotype x environment interactions, genetic markers as tools in aquacultural genetic research and breeding, gynogenesis, polyploidy and mutagenesis. The review reveals that adequate genetic studies have not been undertaken, even with the most extensively studied fish such as common carp and trout. Investigations into the genetics of carp indicate a wide intrapopulation genetic variation of a rather complex nature: the most conspicuous expressions of this complexity being absence of response to mass selection for fast growth rate and a strong heterosis in Fl crossbreds. The large majority of organisms raised in aquaculture are also unselected wild stocks, while many of the hatchery bred stocks are highly inbred and probably suffer from the negative effects of inbreeding depression. Present knowledge indicates that relatively simple steps may result in large-scale genetic improvement of commercial breeding stocks. Most promising of these are: crossbreeding to benefit from heterosis, exploration and testing of new genetic stocks, interspecific hybridization to produce monosex and sterile hybrids, and the establishment of genetically sound and properly executed and controlled programmes of selective breeding.* Comment: This study provides an excellent review of available techniques to monitor and manipulate genetic variation in and among fin and shell fish species. Particularly valuable is the analysis of experimental attempts to alter growth and - 94 - reproductive traits in salmonid fishes through selective breeding programs. Potential and realized pitfalls of the commonly employed selection techniques are discussed. Key words: interpopulation variability, intrapopulation variability, heritability, growth, disease, age of maturity, size of maturity, morphology, electrophoresis, life history, selection, inbreeding, genotype-environment interaction, heterosis, propagation, fisheries, salmonids, Europe, Japan, USA, USSR. Moav, R., T. Brody and G. Hulata. 1978. Genetic improvement of wild fish populations. Science 201: 1090-1094. Abstract: A plan for the genetic improvement of commercially exploited wild animals is presented. It consists of crossing wild with domesticated breeds to produce heterotic hybrids and to upgrade the wild stocks. Empirical evidence is presented from experiments with the carp. Procedures for monitoring the manipulated populations are outlined. The suggested plan is ecologically reasonable and would counteract the negative genetic changes caused by excessive commercial exploitation of many species. Key words: heritability, interpopulation variability, growth, life history, fisheries, propagation, selection, heterosis, salmonids. Moring, J.R. and D.V. Buchanan. 1978. Downstream movements and catches of two strains of stocked trout. J. Wildl. Manage. 42: 329-333. Abstract: Downstream movements and angler catches of two strains of planted yearling rainbow trout were monitored for two years in a small Oregon stream, Mill Creek. The Roaring River strain showed a tendency for rapid downstream movement, while the Cape Cod strain tended to remain in the planted area for a longer period and were also caught in higher numbers. As many as 37.2 percent of the Roaring River trout moved out of the stream, compared to a maximum of 18.2 percent of the Cape Cod trout. Comment: This study provides important preliminary evidence for genetically controlled variation in salmonid behaviour that may affect the success of stocking efforts for a 'put-and-take' fishery. The genetic basis of the differing tendencies for downstream movement of planted fish of the two strains was not examined. A study of the migratory behaviour of hybrids of the two strains would have provided some information on the genetic control of migration (ie. the extent to which the variation was - 95 - a result of additive genetic variance). Although the study demonstrated that fish of both strains that stayed in the study area (did not migrate downstream) were readily caught, the possibility of genetic differences in catchabi1ity (unrelated to migratory behaviour) was not ruled out. The importance of genotype-environment interactions was not examined thoroughly, especially the possibility of changes in migratory behaviour at different stocking densities. However, the same strain of trout showed a greater tendency for downstream migration in both a small and a large stream. As discussed by the authors, it was not possible in the absence of controls to determine the effect, if any, of the presence of fish of one strain on the migratory tendency of the other strain. Key words: interpopulation variability, propagation, life history, rainbow, USA. Nickerson, R.B. 1979. Separation of some pink salmon, Oncorhynchus gorbuscha, subpopu1ations in Prince William Sound, Alaska by length-weight relationships and horizontal starch gel electrophoresis. Alaska Dep. Fish Game. Info. Leaflet No. 181. Abstract: The generation of a comprehensive salmon hatchery program (public and private) in Alaska necessitates implementation of certain controls to maintain genetic integrity of local indigenous stocks. Controls achieved by identification and classification of potential hatchery donor stock, environmental matching through categorization of stream-types, and coordination with an appropriate genetic policy are deemed essential. Prince William Sound pink salmon stocks (within and among systems) were separated to some extent by length-weight criteria, however, greater refinement of separations was accomplished with starch gel electrophoresis. Thirty-seven subpopu1ations of even-year pink salmon were reduced, by Roger's coefficient of genetic similarity, to seven stock types. Several protein variants were observed in this study which had never previously been observed in pink salmon. Key words: interpopulation variability, morphology, electrophoresis, pink, USA. P1osi1a, D.S. 1977. Relationship of strain and size at stocking to survival of lake trout in Adirondack lakes. N.Y. Fish Game J. 24: 1-24. Abstract: Experimental stockings of over 206,000 Seneca Lake strain and over 209,000 Upper Saranac Lake strain lake trout - 96 - were made in nine lakes in northeastern New York from 1964 to 1968. They comprised fall fingerlings, spring yearlings and fall yearlings and were fin clipped to identify the strain and age at stocking. Recoveries of marked fish obtained by gill netting, trap netting, angling and pond reclamation were used to measure survival. A total of 1,812 lake trout from these lakes were examined from 1965 to 1973 among which were 495 that had been stocked for this study. The Upper Saranac Lake strain comprised 94.3 per cent (467), while the Seneca Lake strain constituted 5.7 per cent (28) of the recoveries. Relative survival for all lakes combined was 15.9: 1 in favor of the Upper Saranac Lake strain. The ratio of survival according to age at stocking (fall fingerlings: spring yearlings: fall yearlings) for all lakes combined was~l: 9.5: 8.7. Strain was more important than the size of the fish or the season of the year when stocking was done in determining survival. It was concluded that the Seneca Lake strain is not suitable for stocking Adirondack lakes. For lake trout stocking programs in these waters, spring yearlings of the Upper Saranac Lake strain or other Adirondack stock should be used. Comment: In this study, only 495 of over 400,000 stocked lake trout of two strains were recovered in the sampling program. This indicates that survival was very low, or that sampling was limited. Nevertheless, a hatchery strain derived originally from Adirondack stock survived almost ten times better when planted in the Adirondack lakes than did a hatchery strain derived from a stock native to the Finger Lakes region of New York. In spite of the possible genetic alteration of both stocks under hatchery conditions, the Upper Saranac stock had maintained its superior adaptation to Adirondack lake environmental conditions. Unfortunately, domestication histories of the two strains were not provided. Fish of both strains were raised in the same hatchery for use in this study, but the Seneca strain hatched earlier and probably grew faster. Despite their larger size at release, Seneca trout apparently survived poorly. Size differences may have affected relative sampling success of the two strains, with larger fish more readily caught by gill nets and angling. However, fewer of the larger Seneca lake trout were captured and the greater recovery of the Upper Saranac trout more likely reflects greater survival than a sampling artifact. Key words: interpopulation variability, life history, lake trout, USA. Reisenbichler, R.R. and J.D. McIntyre. 1977. Genetic differences in growth and survival of juvenile hatchery and wild steelhead trout, Salmo gairdneri. J. Fish. Res. Bd. Can. 34: 123-128. - 97 - Abstract: Relative growth and survival of offspring from matings of hatchery and wild Deschutes River (Oregon) summer steelhead were measured to determine if hatchery fish differ genetically from wild fish in traits that can affect the stock-recruitment relationship of wild populations. Sections of four natural streams and a hatchery pond were each stocked with genetically marked (lactate dehydrogenase genotypes) eyed eggs or unfed swim-up fry from each of three matings: hatchery x hatchery (HH), hatchery x wild (HW), and wild x wild (WW). In streams, WW fish had the highest survival and HW fish the highest growth rates when significant differences were found: in the hatchery pond, HH fish had the highest survival and growth rates. The hatchery fish were genetically different from wild fish and when they interbreed with wild fish may reduce the number of smolts produced. Hatchery procedures can be modified to reduce the genetic differences between hatchery and wild fish. Comment: This study illustrates the potentially great genetic change that can be brought about in salmonid populations over short periods (two generations) of domestication. The hatchery-produced steelhead used as parents in this study may have originated from streams other than those to which the wild parental fish were returning. Thus, some of the genetic differences between hatchery and wild fish may have been due to stream of origin rather than to domestication. However, the fact that offspring of wild fish survived better in natural streams while offspring of hatchery fish survived and grew better in hatchery ponds supports the suggestion that domestication was responsible for genetic alteration of the hatchery steelhead. The question of whether or not the heterotic growth of hatchery-wild hybrid offspring under natural conditions is maintained in later life deserves further study. A discussion of the potential effects on smolt production of hybridization of hatchery and wild steelhead is provided. Further research would benefit from a study of the extent to which and the conditions under which hatchery produced and wild fish hybridize on natural spawning grounds. Key words: interpopulation variability, growth, life history, electrophoresis, propagation, heterosis, steelhead, USA. Robinson, G.D., W.A. Dunson, J.E. Wright and G.E. Mamolito. 1976. Differences in low pH tolerance among strains of brook trout (Salvelinus fontinalis). J. Fish BioI. 8: 5-17. Abstract: Survival time of brook trout at low pH was directly related to size, and inversely related to temperature. Between pH 2.50 and 3.25 an increase in pH by increments of 0.25 each - 98 - led to two to three fold increase in survival time. At higher pH's (3.25 - 3.75) elevations each produced a three to five fold increase. Brook trout tested at pH 3.25 and 3.50 showed maximum survival times in June - August. Members of seven inbred lines of brook trout were tested for acid tolerance: the lines involving either intercrossed or backcrossed offspring of tolerant or intolerant parentals demonstrated intermediate survival in 12.5% of all experiments and heterosis in 66.7% of the tests. Differences in survival of inbred lines were the most marked at pH 3.25. Exposure for 1 week at pH 3.75 resulted in a 20 - 25% decrease in survival time of 18 fish tested at pH 2.50 and 3.00. Out of a total of 24 trout (17 g) tested at pH 3.75 two highly tolerant individuals were still alive after 6.1 weeks. Thus it is likely that a strain resistant to a pH below 4.1, the previously recorded lower limit, can be developed by selective breeding. Comment: In this study, significant differences among brook trout strains indicated considerable genetic variation for survival in acidic waters. However, size of fish effects, variability in the performance of some strains at different pH levels, and large 'seasonal' effects indicated that environmental conditions affected acid tolerance, and must be carefully controlled in experimental situations. If physiological mechanisms of acid tolerance differ at different pH levels, the genetic basis of tolerance may also vary and selection for tolerance at one pH may not lead to increased tolerance at another pH. Increased inbreeding apparently did not reduce survival in acidic waters, but hybrids between inbred lines often showed heterotic acid tolerance. The genetic basis of variation for acid tolerance within and among brook trout strains must be determined before the best methods of producing acid tolerant trout can be determined. Selective breeding of especially tolerant individuals within strains and crossbreeding of tolerant inbred strains both may be effective. Key words: interpopulation variability, heritability, life history, inbreeding, heterosis, brook trout, USA. Rosentreter, N. 1977. Characteristics of hatchery fish: Angling, biology, and genetics. p. 79-83. In: Columbia River Salmon and Steelhead. Am. Fish. Soc. Spec. Publ. No. 10. Abstract: Comparisons are made between naturally produced 'wild' and artificially propagated 'hatchery' steelhead. - 99 - Differences in growth, age of maturity and other biological characteristics are the result of both genetic and environmental influences. The implications for anglers of the observed differences between wild and hatchery fish are discussed.* comment: Included in this paper is a brief discussion of the effects of artificial selection under hatchery conditions on steelhead trout for such characteristics as age of maturity and time of return. Historical ~xamples are presented but few data are provided. Key words: interpopulation variability, propagation, growth, age of maturity, life history, steelhead, USA. Ryman, N. 1970. A genetic analysis of recapture frequencies of released young of salmon (Salmo salar L.). Hereditas 65: 159-160. Abstract: A preliminary comparison was made of recapture frequencies of hatchery reared Atlantic salmon from inbred and noninbred families produced between 1958 and 1965. The recapture frequencies of fish frllTI inbred families were lower than recapture frequencies from noninbred families. Different recapture frequencies among half sib noninbred families indicated that part of the interfamily variation was of additive genetic origin.* Comment: The families monitored in this study were hatchery reared for two years before release, and undoubtedly experienced variable environmental regimes among years and tanks. For this reason, it was not possible to partition interfamily variation into genetic and environmental components. The variability among half sibs was also confounded by environmental effects. However, the lower recapture frequencies among inbred families indicated that genetic differences were important, because there is no reason to believe that all of the inbred or all of the noninbred families occupied similar environments. Further studies might examine possible effects of family size and unequal or selective fishing pressures on recapture frequencies. Controlled experimentation would allow quantification of the effect of inbreeding on recapture frequencies. Key words: interpopulation variability, intrapopulation variability, inbreeding, life history, propagation, Atlantic salmon, Europe. - 100 - Ryman, N. 1972. Mortality frequencies in hatchery-reared salmon (Salmo salar L.). Hereditas 72: 237-242. Abstract: The variation of mortalities in salmon in different families and environments has been analysed. The material consisted of a set of hatchery-reared full and half-sib families of varying geographical origin. The mortality measured occurred during a period when a specific type of gill disease sometimes results in extremely high mortalities~ Part of the variation of mortalities seems to be explained by genetic variation. Comment: This study provides valuable preliminary evidence for a genetic influence on hatchery mortality rates both among and within Atlantic salmon populations. Among families, genetic and environmental contributions to variation in mortality could not be distinguished because: (1) each family was raised separately for up to two years prior to the experiment, and (2) the causes of mortality were not controlled nor diagnosed, so that· all families did not necessarily experience equal exposure to mortality inducing agents. However, there was also significant variability among groups of families of common ancestry (parents from the same geographic location). Because families within each group did not experience a common environment before or during the experiment, this provides evidence of genetic variability in hatchery mortality among populations. Larger variation in mortality rates might have been observed if mortality had been monitored from a younger age. The offspring of domesticated (hatchery produced) parents suffered lower mortality than the offspring of wild parents of the same geographic origin, either as a result of inbreeding or adaptation to the hatchery environment. Key words: interpopulation variability, intrapopulation variability, disease, propagation, inbreeding, Atlantic salmon, Europe. Ryman, N. and G. Stahl. 1980. Genetic changes in hatchery stocks of brown trout (Salmo trutta). Can. J. Fish. Aquat. Sci. 37: 82-87. Abstract: Preservation of the genetic characteristics of a population is one of the primary objectives of many fish stocking programs. Using starch gel electrophoresis we have tested for temporal gene frequency stability at two polymorphic loci coding for alpha-glycerophosphate dehydrogenase and creatine phosphokinase. Three Swedish hatchery stocks of brown trout and field samples from natural populations corresponding to two of these stocks were analyzed. Highly significant allele frequency changes at both loci indicated considerable lack of - 101 - intra-stock genetic homogenity. In the light of these findings we emphasize the importance of using large numbers of actual as well as effective parents to avoid inadvertent genetic changes and inbreeding. No stock should be founded or perpetuated using less than approximately 30 parents of the least numerous sex in any generation. Comment: This analysis provides strong evidence that allele frequencies can be significantly altered by genetic drift and founder effects due to the use of too few parents in hatchery propagation. A good discussion is also provided of the actual and effective population sizes of brood stock required to maintain genetic variation in hatchery populations, and of the importance of preserving the genetic structure of natural populations. Allele frequency variability between hatchery fish and the natural populations from which they were derived, and between year-classes of hatchery fish, were attributed to hatchery propagation. However, variation over time (among years classes) in natural populations, although believed to be low, was not examined. Long-term hatchery effects could not be determined because all three hatchery stocks examined were relatively young (the oldest was founded in the early 1960' s'). In addition, brood stock for two of the three 'hatchery stocks' consisted of 'wild' spawners. Conversely, one sample of a 'natural' population may have included hatchery reared fish. Moreover, The effects of an altered selective regime in the hatchery on allele frequencies could not be distinguished from the effects of genetic drift and founder effects. Key words: intrapopulation variability, interpopulation variability, propagation, electrophoresis, genetic structure, inbreeding, genetic drift, founder effects, selection, brown trout, Europe. Saunders, R.L. 1979. Sea ranching: A promising way to enhance populations of Atlantic salmon for angling and commercial fisheries. N. Amer. Salm. Res. Center Rep. 8-1979. Abstract: Sea ranching involves release of salmon at the smolt stage, their migration to sea where they feed and grow and their return to the stream in which they were released as smolts. Examples are given of successful attempts at salmonid sea ranching. Consideration is given to ways in which stock selection and genetic manipulation might be used to reduce loss to commercial fisheries. Selection for maturation as one-sea-winter (grilse) rather than two-sea-winter salmon would prevent loss to the Greenland fishery. Further, it may be possible to select stocks which undertake limited sea migration thus avoiding specific commercial fisheries such as that around - 102 - Newfoundland. Delayed release of salmon would result in non-migration and a residual stock available to local commercial and angling fisheries. The possible application of this delayed release technique is suggested for Bras d'Qr Lake and the Bay of Fundy.* Comment: This paper provides a discussion of the production of Atlantic salmon strains suitable for sea ranching through manipulation of the salmonid genetic constitution and of environmental conditions. Emphasis is placed on the use of strains native to waters to which the sea ranched fish are to be released and must return. Key words: interpopulation variability, life history, age of maturity, propagation, selection, Atlantic salmon, Canada. Saunders, R.L. and J.K. Bailey. 1980. The importance of genetics in Atlantic salmon management. p. 182-200. In: Atlantic Salmon: Its Future. (A.J.E. Went, ed.). Fishing News Books. Farnham, Surrey, England. (Also: N. Amer. Salm. Center Rep. 1-1980). Abstract: The concept of salmon stocks is defined and discussed in relation to their diversity and the importance of this concept in the management of salmonid fisheries. The evidence for a genetic basis for stock differences among salmonids is documented for various traits including age and size at sexual maturity, survival at various life stages, growth rate, seasonal pattern of return to fresh water and migratory patterns at sea. Cropping of Atlantic salmon is best done in recognition of the stock concept so as to provide sufficient broodstock in each breeding population. Rehabilitation and enhancement projects should take account of specific salmon traits with attempts to match rivers with salmon possessing special characteristics which best fit them to recipient rivers. Examples of Atlantic salmon restoration attempts are given. Comment: This paper provides an excellent review of the evidence for and measurements of genetic variation in physiological, morphological and behavioral traits among Atlantic salmon stocks. The differences between breeding and production techniques required for the restoration or creation of self-sustaining runs and those appropriate for aquacultural operations are discussed. Key words: interpopulation variability, heritability, growth, age of maturity, size of maturity, life history, morphology, disease, electrophoresis, propagation, selection, inbreeding, Atlantic salmon, Canada, Europe, USA. - 103 - Smith, M.H., H.O. Hillestad, M.N. Manlove and R.L. Marchinton. 1976. Use of population genetics data for the management of fish and wildlife populations. Trans. N. Amer. Wildl. Nat. Resources Conf. 41: 119-133. Abstract: Modern wildlife management practices such as setting of harvest regimes, habitat improvement, stocking, and predator control often result in inadvertent manipulation of the genetic structures of populations. Starch gel electrophoretic techniques can be used to obtain genetic information useful in wildlife management. In this paper, we outline ways in which electrophoretic data can be applied to common management problems.* Comment: This paper provides a good review of the use of electrophoretic data in measuring spatial and temporal intraspecific genetic variation. However, severe deficiencies in the application of electrophoretic information to management decisions have not been overcome. Electrophoretic gene frequencies provide a rough measure of genetic variability at structural gene loci, but do not give any indication of the importance of this variability to the species in question. Do gene frequency differences between geographically disjunct populations arise primarily as a result of natural selection, or simply as a result of genetic drift in the absence of gene flow? What is the relationship, if any, between variability at isozymic loci and loci controlling traits of more obvious adaptive value (eg. growth, reproductive capability)? How much electrophoretic variability must be observed among populations before management on a separate basis is required? Answers to these questions are hard to come by, and may vary considerably between species. Nevertheless, without this knowledge the use of electrophoretic data in solving management problems will be limited. Key words: interpopulation variability, electrophoresis; salmonids, USA. Snieszko, S.F. 1957. Disease resistant and susceptible populations of brook trout (Salvelinus fontinalis). U.S. Fish. Wildl. Spec. Sci. Rep. 208: 126-128. Abstract: Hatchery strains of brook trout, including one with a history of selective breeding for furunculosis resistance, were reared under similar conditions and observed during natural and induced outbreaks of furunculosis and ulcer disease. Differences in mortality were observed among strains subjected to mixed infections of Aeromonas salmonicida and Hemophilus piscium. The Bellefonte strain of trout, bred for furunculosis resistance, suffered more than seven times less mortality than - 104 - two nonselected strains during replicated tests in which fish of the three strains were kept in common and in separate troughs.* Comment: Factors other than genetic variation in disease resistance among strains likely contributed to the variability in brook trout mortality observed in this study (eg. intra-strain variation, size of fish tested, dosage of pathogen received) . However, the vastly superior performance of the Bellefonte strain in replicated tests indicated that selection for furunculosis resistance in this strain had been successful. Although, as the author suggested, a strain of fish resistant to a certain disease may retain its resistance as long as it is not crossbred with more susceptible strains, this is not necessarily true. More often, a resistant strain will revert to a near normal susceptibility level unless continually subjected to selection for disease resistance. Key words: interpopulation variability, disease, brook trout, USA. Thorgaard, G.H. and G.A.E. Gall. 1979. Adult triploids in a rainbow trout family. Genetics 93: 961-973. Abstract: Six triploid individuals were found in a full-sib family of 11 adult rainbow trout (Salmo gairdneri) from a domesticated hatchery stock. The triploid individuals were normal in size and external appearance, had underdeveloped gonads, and showed no evidence of 3n/2n chimerism or mosaicism. XXY triploids were males, suggesting that the Y chromosome is male determining in trout. Because they may avoid production losses associated with sexual maturation in normal fish, triploid trout and salmon could potentially be useful in fish culture. Comment: The apparently normal viability of triploid rainbow trout under hatchery conditions indicated a potential for the production of triploids for use in fish culture operations when maturation is undesirable, and perhaps for release to natural conditions when reproduction is undesirable. However, the specific environmentaYand/or genetic factors which led to the high incidence of triploidy in one family have not yet been identified. Key words: intrapopulation variability, life history, propagation, rainbow, USA. Utter, F.M. 1981. Biological criteria for definition of species and distinct intraspecific populations of anadromous salmonids under the U.S. Endangered Species Act of 1973. Can. J. Fish. Aquat. Sci: in press. - 105 - Abstract: The validity of most recognized species of salmonids under the biological species concept is supported by evidence from diverse sources. However, the specific status of a number of recently diverged populations remains uncertain. In the United States, it is particularly important to consider the possibility of unrecognized reproductively isolated populations for protection under the U.S. Endangered Species Act of 1973 (ESA) • Innate life history differences among species as well as numerous uncertainties within species preclude the use of a generalized model based on homing as the sole or primary means of defining discrete population segments of anadromous salmonid species. A process involving successive samplings, analyses, and syntheses of data from populations of a particular area is suggested. Transplanted and hatchery populations complicate the identification and management of anadromous salmonid populations under the ESA. Some evidence is cited that indicates a potential or actual adverse genetic effect of hatchery or transplanted fish on some native populations, and current studies designed to measure such effects are mentioned. The technical and economical feasibility for measuring these effects suggest that such measurements should be a requisite for new or extended transplantation and hatchery operations. Further data are needed to determine whether or not threatened or endangered species and populations can be artificially perpetuated and still retain the capability to adapt to wild environments upon reintroduction to native habitats.* Key words: interpopulation variability, life history, propagation, electrophoresis, salmonids, USA. Vincent, R.E. 1960. Some influences of domestication upon three stocks of brook trout (Salvelinus fontinalis Mitchill) • Trans. Am. Fish. Soc. 89: 35-52. Abstract: Three stocks of brook trout - domestic, wild, and first generation removed from wild stock - were tested and observed for effects of domestication. The domestic stock had been selectively bred for 90 years, whereas the wild stock came from an isolated lake in the Adirondack Mountains. To reduce differential environmental influence to a minimum, the three lots were reared from eggs in adjacent rearing troughs at the same water temperature. After one year under these hatchery conditions the domestic fish were 5.2 inches in length and the wild 3.6 inches. Throughout the rearing domestic stock were tamer and exhibited less fright than wild-stock fish. Laboratory tests showed that wild stock could stand a greater - 106 - con~entration of accumulated metabolites, that they could endure higher water temperature, and that domestic stock had a surface response whereby they moved to the surface of a rearing trough or a tall aquarium. Domestic fish also lacked the desire to conceal themselves. Stamina tests showed that the wild stock had greater stamina throughout the size range tested. Surv~val trials in a small stream and a pond indicated that wild fish experienced less mortality and had growth rate similar to or better than domestic fish in both habitats. After being in a pond for nearly four months, the domestic stock had acquired little wariness.* Comment: This study demonstrates that long periods of domestication can result in the alteration of numerous morphological, physiological and behavioral characteristics of salmonid populations. The inferior performance of domestic offspring under 'harsh' natural conditions emphasizes the need to prevent radical genetic alteration of hatchery stocks that are to be reintroduced into natural environments. The genetic basis of the observed differentiation between the domesticated and wild stocks of brook trout in this study was not determined. Non-genetic maternal effects may have contributed to differences in growth, stamina and temperature tolerance between the stocks, especially in very young fish. Reciprocal hybridization between the wild and domesticated stocks would facilitate partitioning of the environmental, and additive and non-additive genetic contributions to differentiation. Key words: interpopulation variability, growth, life history, age of maturity, propagation, selection, genotype-environment interaction, brook trout, USA. Wilkins, N.P. 1981. The rationale and relevance of genetics in aquaculture: An overview. Aquaculture 22: 209-228. Abstract: The application of genetics to the breeding and management of cultivable aquatic organisms is likely to result in considerable improvement as it has with domesticated mammalian and avian livestock. Because aquatic organisms are still largely undomesticated and relatively little is yet known about many basic features of their genetic constitution, genetic improvement studies have wider implications in aquaculture than in agriculture. Analysis of existing variability must be carried out on wild stocks to determine levels of genetic variability and to investigate those aspects of reproductive biology not encountered in terrestrial livestock. In breeding studies, both the traditional selective breeding strategies of established animal breeders, and the more novel schemes of gynogensis, self-fertilization, sex manipulation and induced - 107 - polyploidy may be feasible. Because aquatic organisms are ectothermic and lack the sophisticated endogenous homeostasis of mammals and birds, it is more than ever necessary that genetically altered stock be adequately tested and monitored und~r a variety of conditions representative of the great range of environments characteristic of intensive and extensive culture systems.* Comment: This review covers a broad spectrum of genetic methodology available for use in aquaculture, with emphasis on some relatively unexplored technology particularly suitable for the culture of invertebrates and poikilothermic vertebrates. The summary of available information on the genetic structure and potential for selective alteration of aquatic stocks illustrates a general paucity of research on these subjects. Techniques which provide the potential for extremely rapid genetic alteration of populations are outlined in general terms, and the dangers of extensive breeding operations (eg. inbreeding, alteration of wild stocks) are discussed. Key words: interpopulation variability, intrapopulation variability, selection, propagation?, inbreeding, heritability, ~lectrophoresis, heterosis,life history, morphology, disease, salmonids. Winter, G.W., C.B. Schreck and J.D. McIntyre. 1980. Resistance of different stocks and transferrin genotypes of coho salmon, Oncorhynchus kisutch, and steelhead trout, Salmo gairdneri, to bacterial kidney disease and vibriosis. Fish. Bull. 77: 795-802. Abstract: Juvenile coho salmon and steelhead trout of different stocks and three transferrin genotypes (AA, AC, and CC), all reared in identical or similar environments, were experimentally infected with Corynebapterium sp., the causative agent of bacterial kidney disease, or with Vibrio anguillarum, the causative agent of vibriosis. Mortality due to the pathogens was compared among stocks within a species and among transferrin genotypes within a stock to determine whether there was a genetic basis for resistance to disease. Differences in resistance to bacterial kidney disease among coho salmon stocks had a genetic basis. Stock susceptibility to vibriosis was strongly influenced by environmental factors. Coho salmon or steelhead trout of one stock may be resistant to one disease but susceptible to another. The importance of transferrin genotype of coho salmon in resistance to bacterial kidney disease was stock specific: in stocks that showed differential resistance of genotypes, the AA was the most susceptible. No differences in resistance to vibriosis were observed among transferrin genotypes. - 108 - Comment: Results of this study indicate that genetic differences among stocks and among genotypes within stocks influence resistance to disease. However, environmental conditions also appear extremely important, and may determine which stock is more susceptible to a particular infection at any given time. In addition, large doses of a pathogen may result in heavy mortality in all genotypes or stocks and thus obscure genetic differences in resistance among them. Stocks that display increased resistance to one infectious organism often appear to be more susceptible to other diseases so that selection of a disease resistant stock for hatchery purposes may be of dubious value. A further complication in the choosing or development of a disease resistant stock which is not considered in this study is the likelihood of genetic variability among strains of the infectious agent. A stock of fish selected for resistance to one strain of a pathogen might show no increased resistance, or even increased susceptibility, to a genetically distinct strain of the same organism. Key words: interpopulation variability, intrapopulation variability, disease, electrophoresis, coho, steelhead, USA. Winter, G.W., C.B. Schreck and J.D. McIntyre. 1980. Meristic comparison of four stocks of steelhead trout (Salmo gairdneri) . Copeia 1980: 160-162. Abstract: Numbers of vertebrae and lateral series scales were compared among four Oregon State hatchery stocks of steelhead reared in a common environment. To determine possible effects of environmental factors, the meristic traits of each stock reared in two different locations were also compared. With one exception, the four stocks raised in a common environment differed significantly for vertebral number and lateral scale counts. For all four stocks, differences in vertebral number between the fish reared in two different locations were significant. Lateral series scale numbers did not differ between locations. Genetic and environmental contributions to the observed meristic variability were discussed.* Comment: This study provided evidence for genetic variation in numbers of both vertebrae and lateral series scales among hatchery stocks of steelhead. No adaptive value was attributed to this variability. The domestication histories of the four stocks were not provided, and the possible effects of propagation on the genetics of the observed traits were not discussed. Key words: interpopulation variability, morphology, steelhead, USA. - 109 - Wishard, L., J. Seeb, F. Utter and D. Stefan. 1981. Relationships of redband trout populations of Idaho. Copeia: in press. Abstract: Samples from eight populations of native (presumably 'redband') trout in Idaho from tributaries of the Owyhee River and adjacent streams flowing directly into the Snake River were analyzed by starch gel electrophoresis (1) to seek evidence of introgression from plantings of hatchery rainbow trout, (2) to determine the relationships among these populations, and (3) to identify possible ancestors of these populations from data of other investigations. Average heterozygosities over 29 loci (range 0.048 - 0.074) were well within the range reported for outbred rainbow trout populations suggesting that successions of severe 'bottlenecks' had not occurred in these populations, in spite of the harsh environmental conditions. There was no evidence of hatchery introgression, rather, different measures indicated relationships based entirely on geographic variables with genetic similarity decreasing as linear stream distance increased. The native trout populations of Idaho were closely related to a population of native trout from Chino Creek, Nevada, in the Owyhee River drainage as well as to steelhead populations of the Snake River. The Idaho populations were not closely related to hatchery rainbow trout (presumably derived from McCloud River ancestry), to coastal steelhead populations, or to 'redband' trout native to southeastern Oregon and northeastern California. Morphological and physiological similarities to the latter group were attributed to convergent evolution. It was recommended that the term 'redband' trout be retained to describe non-anadromous populations of rainbow trout adapted to harsh, arid environments, but that the term not necessarily infer taxonomic relationships among such populations. Key words: interpopulation variability, electrophoresis, propagation, rainbow, USA. Wright, J.E. and L.M. Atherton. 1970. polymorphisms for LDH and transferrin loci in brook trout populations. Trans. Am. Fish. Soc. 99: 179-192. Abstract: Seven hatchery populations and seven of eight wild populations of brook trout sampled were polymorphic for both the LDH-B and the transferrin loci. The degree of variations of allele frequencies as well as the amount of heterozygosity was generally greater among hatchery fish than those from natural populations. Calculations of interpopulation heterogeneities of allele frequency differences permitted distinguishing all of the hatchery strains, but not all of the small wild populations, from each other. While gross intra-population heterogeneity was - 110 - found, an assessment of the breeding structure of wild brook trout in a stream was not possible. Electrophoretic variants were found in wild populations for two other LDH polypeptides and for one other serum protein. From assumptions that five loci were polymorphic in 13 total loci studied, the estimate of proportion of polymorphic loci in wild brook trout is 38.4%. The similar estimate for hatchery strains is 15.4%. Comment: The relatively high levels of heterozygosity and constant allele frequencies over adjacent year classes that characterized hatchery brook trout populations indicated that inbreeding had not occurred. These stocks were apparently ~aintained with large 'effective population sizes': and their hybrid ancestries combined with occasional introductions from other st.ocks may have enhanced levels of genet ic var ia t ion. Alternately, high frequencies of rare alleles in hatcheries may simply have resulted from a relaxation of natural selective forces. The absence of very rare alleles in the domestic stocks may have been due to founder effects during the establishment of hatchery populations. Key words: interpopulation variability, intrapopulation variability, electrophoresis, propagation, inbreeding, brook trout, USA. - 111 - II. LIST OF REFERENCES SEC~ION 1. ELECTROPHORETIC, SEROLOGICAL AND IMMUNOLOGICAL VARIABILI~Y IN SALMONIDS Allendorf, F.W. 1973. Genetic variation, inheritance and preliminary population distribution of some proteins of Salmo gairdneri. M.Sc. Thesis. Univ. of Washington. Seattle. Allendorf, F.W. 1975. Genetic variability in a species possessing extensive gene duplication: Genetic interpretation of duplicate loci and examination of genetic variation in populations of rainbow trout. Ph.D. Thesis. Univ. of Washington. Seattle. Allendorf, F.W. 1978. Electrophoretic distinction in rainbow (Salmo qairdneri) and cutthroat (S. clarki) trout. (Letter). J. Fish. Res. Bd. Can. 35: 483. Allendorf, F.W., D.M. Espeland, D.T. Scow and S. Phelps. 1980. Coexistence of native and introduced rainbow trout in the Kootenai River drainage. Proc. Mont. Acad. Sci. 39: 28-36. Allendorf, F. and N. Mitchell. 1977. Genetics of Alberni Inlet sockeye salmon populations. Final Rep. to Pacific Biological Station. Nanaimo B.C. Allendorf, F.W., N. Mitchell, N. Ryman and G. Stahl. 1977. Isozyme loci in brown trout (Salmo trutta L.): Detection and interpretation from population data. Hereditas 86: 179-190. Allendorf, F.W., N. Ryman, A. Stennek and G. Stahl. 1976. Genetic variation in Scandinavian brown trout (Salmo trutta L.): Evidence of distinct sympatric populations. q~reditas 83: 73-82. Allendorf, F.W. and F.M. Utter. 1974. Biochemical genetic systematics of the genus Salmo. (Abstract Only). Anim. Blood Grps. Biochem. Genet. 5: 33 (Suppl. 1). Allendorf, F.W. and F.M. Utter. 1979. Population genetics. p. 407-454. In: Fish Physiology Vol. VIII. (W.S. Hoar, D.J. Randall and J.R. Brett, eds.). Academic Press. New York. Altukhov, Y.P. 1975. Population genetics of fish. Fish. Res. Bd. Transl. Sere No. 3548. - 112 - Altukhov, Y.P., A.I. Pudovkin, E.A. Salmenkova and S.M. Konovalov. 1975. Stationary distribution of frequencies of lactate dehydrogenase and phosphoglucomutase genes in population system of a local fish stock, Oncorhynchus nerka Walb. II. Random genetic drift, migration and selection as factors of stability. SOY. Genet. 11: 455-461. Altukhov, Y.P., E.A. Salmenkova, S.M. Konovalov and A.I. Pudovkin. 1975. Stationary distributions of frequencies of lactate dehydrogenase ann phosphoglucomutase genes in population system of a local fish stock, Oncorhynchus nerka Walb. I. Stability of the stock in generations under simultaneous variability of subpopulations making up their structure. SOY. Genet. 11: 447-454. ~ltukhov, Y.P., E.A. Salmenkova, V.T. Omelchenko, G.D. Sachko and V.I. Slynko. 1972. The number of mono- and polymorphic loci in a population of the tetraploid salmon, Oncorhynchus keta. SOY. Genet. 8: 181-188. Altukhov, Y.P., E.A. Salmenkova, G.D. Ryabova and N.I. Kulikova. 1980. Genetic differentiation of churn salmon, On~orhYnchus keta (Walb.), populations and effectiveness of some acclimatizative measures. (English Summary). Biologiya Morya 1980(3): 23-38. Amano, H. and H. Tsuyuki. 1975. Studies on myoglohins of salmonids. Bull. Jap. Soc. Sci. Fish. 41: 885-894. Aspinwall, N. 1974. Genetic analysis of North American populations of the pink salmon, Oncorhynchus gorbuscha: Possihle evidence for the neutral mutation - random drift hypothesis. Evolution 28: 295-305. Bouck, G.R. and R.C. Ball. 1968. Comparative electrophoretic patterns of lactate dehydrogenase in three species of trout. J. Fish. Res. Rd. Can. 25: 1323-1331. Braman, J.C., C.B. Stalnaker, G.T. K1ar and T.M. Farlev. 1980. Hemoglobin polymorphism in adult cutthroat trout, Salmo clarki. J. Exp. Zool. 211: 411-413. Brandes, W.F. 1978. The taxonomic status of tIle brook trout, Salvelinus fontinalis, in the Great Smoky Mountains National Park based on electrophoretic dnta. M.Sc. ~hesis. Tennessee Tech. Univ. Cookeville. Busack, C.A. 1977. Genetic variation among populations of Paiute trout (Salmo clarki seleniris). M.Sc. Thesis. Univ. of California. Davis. - 113 - Busack, C.A., R. Halliburton and G.A.E. Gall. 1979. Electrophoretic variation and differentiation in four strains of domesticated rainbow trout, Salmo gairdneri. Can. J. Genet. Cytol. 21: 81-94. Busack, C.A., G.H. Thorgaard, M.P. Bannon and G.A.E. Gall. 1980. An electrophoretic, karyotypic and meristic characterization of the Eagle Lake trout, Salmo gairdneri aquilarum. Copeia 1980: 418-424. Bushuev, V.P., V.T. Omelchenko and E.A. Salmenkova. 1975. Species specificity and intraspecific constancy of electrop~oretic properties and thermostability of hemoglobins in some fishes of the order Clupeiformes. Zh. Obshch. BioI. 36: 569-578. Calaprice, J.R. and J.E. Cushing. 1967. A serological analysis of three populations of golden trout, Salmo aguabonita Jordan. Calif. Fish Game 53: 273-281. Campton, D.E. 1980. Genetic structure of sea-run cutthroat trout {Salmo clarki clarki} populations in the Puget Sound region. M.Sc. Thesis. Univ. of Washington. Seattle. Chilcote, M.W., B.A. Crawford and S.A. Leider. 1980. A genetic comparison of sympatric populations of summer and winter steelheads. Trans. Am. Fish. Soc. 109: 203-206. Child, A.R. 1977. Biochemical polymorphism in char, Salvelinus alpinus, from Llynnau Peris, Padarn, Cwellyn and Bodlyn. Heredity 38: 359-365. Child, A.R. 1980. Identification of stocks of Atlantic salmon {Salmo salar L.} by electrophoretic analysis of serum proteins. Rapp. P.-v. Reun. Cons. into Explor. Mer. 176: 65-67. Child, A.R., A.M. Burnell ann N.P. Wilkins. 1976. The existence of two races of Atlantic salmon {Salmo salar L.} in the British Isles. J. Fish BioI. 8: 35-43. Clayton, J.W. and W.G. Franzin. 1970. Genetics of multiple lactate dehydrogenase isozymes in muscle tissue of lake whitefish {Coregonus clupeaformis}. J. Fish. Res. Rd. Can. 27: 1115-1121. Clayton, J.W., W.G. Franzin and D.N. Tretiak. 1973. Genetics of glycerol 3-phosphate dehydrogenase isozymes in white muscle of lake whitefish {Coregonus clupeaformis}. J. Fish. Res. Bd. Can. 30: 187-193. Cross, T.F., J.A. Healy and F.J. O'Rourke. 1978. Population - 114 - discrimination in Atlantic salmon from Irish rivers using biochemical genetic methods. ICES Anadromous and Catadromous Fish Comm. C.M. 1978/M:2. Cross, T.F. and R.H. Payne. 1977. NADP-isocitrate dehydrogenase polymorphism in the Atlantic salmon, Salmo salar. J. Fish BioI. 11: 493-496. Dehring, T.R., A.F. Brown, C.H. Daugherty and F.W. Allendorf. 1981. Genetic variation among eastern Lake Superior lake trout populations. Can. J. Fish. Aquat. Sci: in press. Diebig, E. and J.-N. Meyer. 1977. Starch gel electrophoretic studies of carbonic anhydrase in rainbow trout. (Abstract Only) . Anim. Blood Grps. Biochem. Genet. 8: 24 (Suppl. 1) • Donnelly, R.F., K.R. Johnson, W.K. Hershberger and D.E. Bevan. 1978. Identification of Kodiak Island pink salmon populations based on biochemical genetic variation. Final Rep. Alaska Dep. Fish Game. Contract No. 3813. Dufour, D. c 1d D. Barrette. 1967. Polymorphisme des lipoproteines et des glycoproteines seriques chez la truite. (English Summary). Naturaliste Can. 94: 305-313. Eckroat, L.R. 1971. Lens protein polymorphisms in hatchery and natural populations of brook trout, Salvelinus fontinalis (Mitchill). Trans. Am. Fish. Soc. 100: 527-537. Eckroat, L.R. and J.E. Wright, Jr. 1969. Genetic analyses of soluble lens protein polymorphism in brook trout (Salvelinus fontinalis). Copeia 1969: 466-473. Engel, W., J. Schmidtke and U. Wolf. 1971. Genetic variation of alpha-glycerophoshate dehydrogenase isoenzymes in clupeoid and salmonoid fish. Experentia 27: 1489-1491. Fairbairn, D.J. 1979. Evidence for the underestimation of the proportion of North American salmon in the West Greenland feeding aggregate. ICES Anadromous and Catadromous Fish Committee. 1979/M:19. Ferguson, A. 1974. The genetic relationships of the coregonid fishes of Britain and Irelan(~ indicated by electrophoretic analysis of tissue proteins. J. Fish BioI. 6: 311-315. Ferguson, A. 1977. Protein polymorphisms in the Pollan Osteichthyes Coregonidae. (Abstract Only) . Anim. Blood Grps. Biochem. Genet. 8: 24 (Suppl. 1). Ferguson, A., K.-J. M. Himberg and G. Svardson. 1978. - 115 - Systematics of Irish pollan (Coregonus pollan Thompson): An electrophoretic comparison with other Holarctic Coregoninae. J. Fish BioI. 12: 221-233. Franzin, W.G. and J.W. Clayton. 1977. A biochemical genetic study of zoogeography of lake whitefish (Coregonus clupeaformis) in western Canada. J. Fish. Res. Bd. Can. 34: 617-625. Gall, G.A.E., C.A. Busack, R.C. Smith, J.R. Gold and B.J. Kornblatt. 1976. Biochemical genetic variation in populations of golden trout, Salmo aguabonita. J. Bered. 67: 330-335. Gold, J.R. 1977. Systematics of western North American trout (Salmo) with notes on the redband trout of Sheepheaven Creek, California. Can. J. Zool. 55: 1858-1873. Goldberg, E., J. Kerekes and J.P. Cuerrier. 1971. Lactate dehydrogenase polymorphism in wild populations of brook trout frQm Newfoundland. Rapp. P.-v. Reun. Cons. into Explor. Mer. 161: 97-99. Grant, W.S., G.B. Milner, P. Krasnowski, and F.M. Utter. 1980. Use of biochemical genetic variants for identification of sockeye salmon (Oncorhynchus nerka) stocks in Cook Inlet, Alaska. Can. J. Fish. Aquat. Sci. 37: 1236-1247. Gray, R.W. and J.A. McKenzie. 1970. Muscle protein electrophoresis in the genus Salmo of eastern Canada. J. Fish. Res. Bd. Can. 27: 2109-2112. Haen, P.J. and F.J. O'Rourke. 1969. Comparative electrophoretic studies of the water-soluble muscle proteins of some Irish freshwater fishes. Proc. Roy. Irish Acad. 68B: 101-110. Henricsson, ,T. anr'l L~ Nyman. 1976. The ecological and genetical segregation of two sympatric species of dwarfed char (Salvelinus alpinus L. species complex). Rep. Inst. Freshw. Res. Drottningholm 55: 15-37. Hershberger, W.K. 1978. Salmonid genetic study. washington Dep. Fish. Completion Rep. Proj. l-lOl-R. Univ. of Washington. Seattle. Hjort, R.C. an1 C.B. Schreck. 1981. Phenotypic differences between stocks of hatchery and wild coho salmon (Oncorhynchus kisutch) in Oregon, Washington and California. Fish. Bull: in press. Hodgins, H.O. 1972. Serological and biochemical studies in - 116 - racial identification of fishes. p. 199-208. In: The Stock Concept in Pacific Salmon. MacMillan Lect. in Fish. UBC. Vancouver. Hongins, H., W. Ames and F. Utter. 1969. Variants of lactate dehydrogenase isozymes in sera of sockeye salmon (Oncorhynchus nerka) . J. Fish. Res. Bd. Can. 26: 15-19. Hodgins, H.O. and F.M. Utter. 1971. Lactate ~ehydrogenase polymorphism of sockeye salmon (Oncorhynchus nerka). Rapp. P.-v. Reun. Cons. into Explor. Mer. 161: 100-101. Hoffman, A.D. 1966. Determination of transferrin types in brook trout by means of polyacrylamide disc electrophoresis. M.Sc. Thesis. Pennsylvania State Univ. Huzyk, L. and H. Tsuyuki. 1974. Distribution of LDH-B" gene in resident and anadromous rainbow trout (Salmo gairdneri) from streams in British Columbia. J. Fish. Res. Bd. Can. 31: 106-108. Imhof, M. 1977. Population genetic structure of lake whitefish (Coregonus clupeafo,rmis), in Green Bay and northern Lake Michigan, as assessed by electrophoresis of lactate, glycerol 3-phosphate and malate dehydrogenase isoenzymes. M.Sc. Thesis. Univ. of Wisconsin. Stevens Point. Imhof, M., R. Leary and H.E. Booke. 1980. Population or stock structure of lake whitefish, Coregonus clupeaformis, in northern Lake Michigan as assessed by isozyme electrophoresis. Can. J. Fish. Aquat. Sci. 37: 783-793. Johnson, K.R. 1979. Genetic variation in populations of pink salmon (Oncorhynchus gorbuscha) from Kodiak Island, Alaska. M.Sc. Thesis. Unlv. of Washington. Seattle. Johnson, K.R., R.F. Donnelly, W.K. Hershberger and D.E. Bevan. 1978. Identification of Kodiak Island pink salmon populations based on biochemical genetic variation. Univ. of Washington ColI. Fish. Rep. FRI-UW-7801. Keese, A. and H.J. Langholz. 1974. Electrophoretic studies for population analysis on trouts. Z. Tierz. Zuechtungsbiol. 91: 109-124. Khanna, N.D., R.K. Juneja, B. Larsson and B. Gahne. 1975. Electrophoretic studies on proteins and enzymes in the Atlantic salmon, Salmo salar. Swen. J. Agric. Res. 5: 185-192. - 117 - Khanna, N.D., R.K. Juneja, B. Larsson and B. Gahne. 1975. Electrophoretic studies on esterases in the Atlantic salmon, Salmo salar L. Swed. J. Agric. Res. 5: 193-197. Kijima, A. and G. Fujio. 1977. Genetic control of isocitrate dehydrogenase isozymes in chum salmon. Tohoku J. Agric. Res. 28: 96-102. Kijima, A. and G. 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Goldberg. 1973. Glucose 6-phosphate dehydrogenase from brook, lake and splake trout: An isozymic and immunological study. Biochem. Genet. 10: 121-134. Yamauchi, T. and E. Goldberg. 1974. Asynchronous expression of glucose 6-phosphate dehydrogenase in splake trout embryos. Dev. BioI. 39: 63-68. - 142 - KEYWORD / SPECIES INDEX Use of the keywnr~s which follow each annotate~ citation in Part I of the text is descrihe~ in the Introduction. ~his index indicates location of keywor~s by page number. liGE OF ;-'~A'rURI'J'Y 5-6, 6, 11, 13(2), 15, 22, 29-30,45, 55, 57, 61, 72, 73, 83, 87, 91, 94, 99, 102(2), 106. A'T'L.z\NTIC SALMON 5-6, 6, 12, 13(2), 14, 17, 19, 21(2), 22, 23, 24, 29-30, 30, 34, 35, 36, 42-43, 44, 45, 71, 72(2), 73, 99, 100, 102(2). ARCTIC CHAR 37,72. BROOK 't'ROU't' 5, 9, 16, 17, 37, 48, 58, 60, 62, 63(2), 65, 66, ()7(2), 73, 74, 85, 86, 98, 104, 106, 110. RRm-m TROU'T' 7, 8, 9(2), 17, 23, 45, 63(2), 64(2), 72, 101. CANADA 5, 5-6, 6, 13(2), 15, 16, 17, 21, 22, 26, 28(2), 29, 29-30, 30, 31, 33, 35, 36, 37, 39, 42, 44, 45, 46, 47, 51, 54, 55, 67(2), 73, 76, 78-79, 90, 91, 102(2). CHINOOK SALr.lO\: 38, 51, 61, 93. CHm~ SAL~ON 8, 40, 51, 85. COHO S.l\LMON 51, 77, 78, 87, 88, 108. COREGONUS SPP. See ~.vh it e f ish. CU 'T''T'H RO,\ T TROUT 32, 35, 42, 50, 51, 53, 90. DISEASE 5, 12, 17, 18, 25, 60, 61, 63(2), 71, 72, 77, 84, 94, 100, 102, 104, 107, 108. - 143 - ELEC"'ROPTIORESIS 2(;, 33, 34, 37, 38, 39, 40, 45, 51, 52, 53, 54, 62, 77, 78, 85, 88, 92, 93, 94, 95, 97, 101, 102, 103, 105, 107, 108, 109, 110. EUROPE 4, 7, 8, 9, 12, 14, 17, 19, 21, 23(2), 24, 27, 34, 37, 38, 42-43, 45, 54-55, 56, 70, 71, 72(2), 75, 94, 99, 100, 101, 102. F IS~1'ERIES 64(2),91,94(2). FOUNDER EFFF.C'T'S 11, 26, 53, 78-79, 101. GENETIC DRIF'1' 53, 62, 78-79, 101. GENETIC STRUCTURE 8, 15, 51, 92, 101. GENOTYPR-ENVIRON~lENT INTERACTION 8, 16, 19, 28, 38, 42, 42-43, 55, 56, 68, 77, 86, 94, 106. GRAYLING 39. GRm'7TH 4, 5-6, 6, 7, 9, 10, 11, 13(2), 14, 19, 21(2), 23(2), 24, 27, 28(2), 29, 35(2), 36, 37, 38, 42-43, 43, 44, 45, 48, 54-55, 55, 56, 57, 58, 59, 61, 64(2), 66, 67(2), 68, 69(2), 71, 72(2), 73, 74, 75, 76, 77, 80, 81, 82, 83(2), 86, 88(2), 90, 91, 94(2), 97, 99, 102, 106. HERITABILITY 4, 5, 6, 7, 8, 9(2), 10, 11, 12, 13(2), 14, 15, 16, 17(2), 18, 19(2), 21(2), 22, 23(2), 24, 28, 29, 35, 37, 38, 40, 44, 47, 49, 54-55, 55, 56, 60(2), 61, 63(2), 64(2), 70, 71, 72(2), 75, 78-79, 80, 81, 83, 84, 86, 91, 94(2), 97, 99, 102, 106. HETEROSIS 13,16,35(2),67,68,72,77,78-79,94(2),97,98,107. DJBREEDING 4, 11, 28, 53, 54-55, 57, 58, 62, 68, 70, 78-79, 81(2), 94, 98, 99, 100, 101, 102, 107, 110. IN';"ERPOPULATION VARIABILITY 5-6, 6, 7, 9, 12, 13(2), 14, 16, 17, 1Q, 21(2), 22, 25, 26, - 144 - 27, 28(2), 29, 29-30, 30, 31, 32, 33(2), 34, 35(2), 36, 37(2), 38(2), 39, 40, 41, 42, 42-43, 43, 44, 45(2), 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57 (2), 58, 59, 60 (2), 62, 63(2), 65, 66, 67(2), 68, 69(2), 71, 72(2), 73(2), 74, 76, 78, 78-79, 79, 83, 85 (2), 86, 88, 90, 92, 93, 94 (2), 95 (2), 96, 97, 98, 99(2), 100, 101, 102(2), 103, 104, 105, 106, 107, 108(2), 109, 110. PJ'T'RAl?OPULA"'IO~ VARIARILI'l'Y 5-6, fj, 7, 9, 13, 22, 24, 25, 33, 45, 46, 49, 51, 53, 57, 60, 62, 69(2), 72, 73, 78, 80, 81, 82, 85, 87, 88, 89, 92, 94, 99, 100, 101, 104, 107, 108, 110. JAPAN 40, 94. LAKE 'T'~OU'" 5, 16, 17, 37, 96. LIFE HISTORY 6, 8, 10, 13, 16, 17, 19, 21(2), 22, 24, 28, 29, 31, 32, 33(2), 35(2), 36, 37(2), 40, 41, 42, 42-43, 44, 47, 48, 50, 51, 55, 57 (2), 59, 60, 65, 66, 67 (2), 69 (2), 71, 72 (2), 73(2), 74,76,77,78,79,80,81,82,83(2),85,86, 87, 88(2), 89,94(2),95,9697,98,99(2),102(2),104, 105, 106, 107. MATERNAL EFFEC~S 4, 5, 6, 8, 16, 17(2), 18, 19(2), 21, 24, 25, 28, 35, 36, 69(2), 80, 81, 86. MORPHOLOGY 7, 8, 9, 21, 23, 44, 47, 49, 54-55, 56, 74, 78, 94, 95, 102, 107, 108. ONCORHYNCHUS GORBUSCHA See Pink Salmon. ONCORHYNCHUS KETA See Chum Salmon. ONCORHYNCHUS KISUTCH See Coho Salmon. ONCQEHYNCHUS NERKA See Sockeye Salmon. ONCQ_RHYNCHUS TSHAWYTSCHA See Chinook Salmon. PINK S.z\Lf.'101\l 26, 31, 51, 72, 95. - 145 - PROPAGA'rION 10, 11, 14, 17, 25, 27, /.8(2), 31, 38, 40, 50, 52, 53, 54, 54-55, 55(2), 57(2), 58, 59, 60, 61, 62, 65, 66, 67(2), 68, 69(2), 72(2), 73, 74, 75, 78, 80, 81(2), 82, 83(2), 85, 87, 88(2), 89, 90, 91, 92, 94(2), 95(2), 97, 99(2), 100, 101, 102(2), 104, 105, 106, 109, 110. PROPAGATION? 4, 13, 17, 19(2), 21, 32, 33, 35, 38, 41, 42, 42-43, 45, 70, 71, 73, 76, 78-79, 85, 86, 107. RAINBOW TROtT'T" 4, 7, 9(2), 10, 11, 17, 27, 28(2), 29, 38, 42, 43, 51, 52, 54-55,55, 56,57(2), 59,60(2),68,69(2),72,75,76,79, 80, 81(2), 82, 83(2), 84, 92, 95, 104, 109. SALMO CLARKI See Cutthroat Trout. SALMO GAIRDNERI See Rainbow Trout and Steelhead. SALMO SALAR See Atlantic Salmon. SALMO TRUTTA See Brown Trout. SALMONIDS 46, 54, 57, 70, 78-79, 91, 94(2), 103, 105, 107. SALVELINUS ARCTICUS See .1\rct ic Char. SALVELINUS FONTINALIS See Brook 'rrout. SALVELINUS NAMAYCUSH See Lake Trout. SELECTION 4, 6, 7, 9(2), 10, 11, 13, 14, 16, 17(2), 19, 21(2), 23, 25, 26,28(2),38,46,48,53,54,55,56,57(2),60, 61, 62, 63(2), 64(2), 68, 69, 70, 71, 72(2), 75, 77, 79, 80, 81(2),83,84,85,86,87,88,89,90,94(2),101, 102(2), 106,107. SIZE OF f'.lA'1'URITY 13, 15, 29-30, 30, 45, 55, 72, 94, 102. SOCKEYE SALMO~1 - 146 - 15, 18, 25, 33, 41, 42, 51. SPLAKE 5, 16, 17, 37. STEELHEAD 19, 33, 47, 55, 88, 89, 93, 97, 99, 108(2). TIIYMALLUS ARCTICUS See Grayling. U.S.A. 9, 10, 11, 18, 19, 25, 26, 32, 33, 35, 38, 39, 41, 42, 43, 47, 48, 49, 50, 51, 52, 53, 54, 55, 57(2), 58, 59, 60(2), 61, 62,63(2),64(2),65,66,67,68,69(2),73, 74, 76, 77, 78, 79, 80, 81(2), 82, 83(2), 85(2), 86, 87, 88(2), 89, 92, 93, 94, 95(2), 96, 97, 98, 99, 102, 103, 104(2), 105, 106, 108(2), 109, 110. U.S.S.R. 8, 84, 94. WHITEFISH 49. - 147 - AU'T'HOR INDEX This in~ex inclu~~s authors cite~ in both Part I (annotated references) and Part II (citation list) of the bibliography. Location of author names is given by page number. ABREU-GROBOIS, A. 135 AITKIN, N.R. 136 ALABAS",ER, ..1. S. 133 ALLEt-1DORF , F.Y-I. 44 52(2) 53 111 114 118 122 124 125 131 133 137 140 ALTUKHOV, Y.P. 111 112 AMANO, H. 112 127 AMEND, D.F. 18 25 MmS, ~.;r • 116 124 A~JNAND, r.. 120 138 APPLEGA",E, R.A. 129 APPY, T.D. 35 T? ARAI, ,'\. . 133 ASPIWNALL, N. 25 112 134 A'!'HERTO;\i, L.M. 109 126 132 135 140 AULSTAD, D. 4 11 54 AUS'T'RENG, E. 26 AYERST, J.D. 55 AYLES, G.B. 5 27 28(2) 55 BAILSY, G.S. 127 1~ 134 137 BAILEY, Ll. K. 5 6 29 30 35 102 BALDHIN, J. 127 - 148 - BALTJ , R.C. 112 127 BAr"S, R.A. 30 BANNON, M.P. 113 BARRETTE, D. 114 BF.IINKE, R. ,1 • 49 BELAND, K.F. 117 BENDSR, E.A. 127 BERGO'l', P. 7 (2) 8 56 BERGS'T'R0r..y , E. 117 127 137 l3ERNARD, D. 28 BEVAN, D.E. 114 116 BILLECK, B.N. 134 BLANC, J.-N. 7 (2) 8 18 56 BOOKE, H.E. 116 ROSSA, F. 127 BOUCK, G. R. 112 127 BOh'LER, R. 31 BRAMAN, J.C. 112 132 141 BRANDES, ~!J • F • 112 136 BRA~INON , E.L. 32 BRAUNE, M.O. 128 BRIDGES, H.R. 82 BRODY, T. 94 BROWN, A.F. 114 BRUNDAGE, R. 131 BRYNILDSON, () • !'vI. 86 - 149 - BUCHANAN, D.V. 94 RUCKRTnGE, T.N. 34 BURNELL, A.M. 33 113 RUSACK, C.A. 56 112 113 115 BUSHUEV, V.P. 113 127 BUZETA, M. I. 6 29 CABLE, L.E. 48 CALAPRICF., J.R. 57 113 CAMPTON, D.E. 50 113 124 CARDENAS, J.M. 129 CEOERBAUM, S.D. 134 CHEBANOV, N.A. 8 CHEVASSUS, B. 7 (2) 8 CHILCOTE, ~1. w. 33 113 CHILD, A.R. 33 113 121 CLARKE, L. h'. 123 CLAYTON, J.W. 113 115 118 134 COCKS, G.T. 127 134 COOPER, E.L. 57 CORDONE, A. ~l • 58 CORY, R.P. 128 CRAWFORD, B.A. 33 113 CROSS, "r.F. 113 114 135 CTJERRIER, ~l • P. 115 135 CUSHING, J.E. 113 121 DAUGTiERTY, C.H • 114 • - 150 - DAVIS, H.S. 9 59 DAVISSO~, ~~. T. 135 DEGURSE, P.E. 86 DEHRING, T.R. 114 DIEBTG, E. 114 135 DOLLAR, A. :'1. 60 DONALDSON, L.R. 34 60 DONNELLY, H.F. 114 116 DUFOUR, D. 114 DUKE, E. ,1 • 128 136 DUT~SOl'J , \!y.A. 47 97 DURA'LL, G.L. 121 DURBIN, F.J. 133 ECKROA"" L.R. 61 114 135 EDDY, ~,1, . 12 EBLINGER, N.F. 62 63 ELLENDER, R.D. 131 ENGEL, w. 114 135 139 140 EPPENBERGER, H.lVI. 128 130 ESCAFFRE, A.M. 56 ESPELAND, D • r-l • 52 III EVANS, J.e. 117 137 FAIRBAIRN, D. ,1 • 114 FAKTOROliHTSCH, K.A. 83 FARLEY, T.M. 112 128 129 132 141 FAUST, J. 140 - 151 - FAVRO, L.D. 63 64 FERGUSON, A. 114 FLICK, v·7.A. 64 65 66 FORREST, A. 121 FRANZIN, H.G. 113 115 118 134 FRASER, J.H. 67 FRIA~S, G.N. 35 FU,TIO, G. 117 136 GAHNE, B. 116 117 129 GALL, G.A.E. 9 10 56 67 68 69 104 113 115 118 GILES, M.A. 135 GJFDRE]\~ , T. 4 11 13 17 19 70 (2) 71 72 74 GLEBE, B.D. 12 13 35 72 ~LOnEK, P. 135 GOLn, J.~. 115 GOLDBF.RG, E. 115 122 128 131 132 135 139 141 GRAf..1T, V·J. S. 50 115 122 124 GRAY, R. IV. 115 GREEN, D.H. 73 GREENE, C.w. 73 GROSS, S • ~,. • 10 ~UNNES, K. 13 74 GUYOMARn, R. 136 HAEN, P. L"T • 115 136 HALFON, E. 46 - 152 - T) HALT,I:8UR'],ON, ~ \ . 113 H.7\LVER, .T. E. 127 134 HANSEN, 1\~ • J • 75 HANSLER, D.D. 34 HN'JSON, A.J. 14 HARRIS, 'I.! • ~1J • 136 HASHH10'T'O, K. 126 128 136 HEALY, ,T. A. 113 HEARN, J. 128 136 HECKMAN, J.R. 128 132 140 11F.IL, G. 37 HENDZETJ, M. 28 (2) HENRICSSON, J. 36 115 HERSHBERGER, ~v. K . 76 114 115 116 128 HILDEBRl\~D , A.C. 123 HILLESTAD, H.O. 103 HIMBERG, M. 114 HI"t'ZEL, F.N. 43 HITZEROTH, H. 136 H,TORT, R.C. 77 115 HO, F.C. 140 HO~HACHKA, P.H. 128 130 138 HODGINS, H.O. 115 116 124 125 140 HOFF~1AN , A.D. 116 HULA':.'A, G. 94 HUZYK, L. 116 - 153 - IHSSEN, P. 15 16 37 78 134 n1HOF, M. 116 ISHIHARA, Y. 126 IUCHI, r. 128 136 IVANOVA, I • r·1 • 117 JA!-fN'KE, G. 138 ;rOHNSON, A.G. 125 140 JOHNSON, A.K. 87 130 JOHNSON, C.L. 127 136 .JOHNSON, K.R. 114 116 .:rOYCE, P. 128 136 .]UNEJA, R.K. 116 117 129 KACHMARCHIK, E.V. 139 KANIS, E. 17 KAO, Y ••J • 128 129 132 KA'T'Z, r-1. 60 KAY, R. ~1. 129 KAYA, C.~. 79 KEESE, A. 116 KELLY, ;.. , . 128 136 KERF.KES, J. 115 KHA't--1llJA, N.D. 116 117 129 KIJIHA, A. 117 136 KINCAID, H.L. 79 80 81 (2) 82 KINUNEN, N. 83 KIRCHEIS, F .''17. 117 - 154 - KIRKPl\'T'RICK, M. 117' KIRPICHNIKOV, V.S. 117 KIRPI'1'SCHNIK0W, r,r. S • 83 KI1'CHIN, -q. r,,. 118 KI'1'TELS:::N, A. 42 54 KLAR, G.T. 112 117 129 132 141 KLONZ, G.~'!. 121 KLOSE, .T. 136 KLUPP, R. 37 KOCH, H.J.A. 117 127 137 KONOVALOV, S.M. 112 KORNBLATT, 13.J. 115 KORNFIELD, I. 117 KRASNOt-JSKI, P. 115 KRIS'!'IAT'mSON, A.C. 38 117 118 KRUEGER, C.C. 84 KURL, P. 135 139 KULIKOVA, N. I. 112 KUO, P.K. 63 64 KUO, Y.J. 141 LANDREY, S.R. 129 LANGHOLZ, H. ~T • 116 LANKI~JE~ , P. 125 LANNA1-J, J.E. 85 LARSSON, B. 116 117 129 LEARY, R. 116 118 - 155 - LEE, G. r.lf. 141 LEGGETT, w.c. 21 43 LEIDER, S.A. 33 113 LEPPINK, ,-1. D. 118 LEWIS, J.K. 128 LI, ~\,.-H. 137 LIEBELr:"', LoT. E. 118 LIM, S.T. 127 129 137 LINDSEY, C.C. 119 LOCH, J.S. 118 LOUDENSLAGER, E.J. 118 LY]\~CH , J.C. 39 118 125 MACCRIMMON, H. 119 MAKSHI0V, V. 'A. 120 MAMOLITO, G.E. 97 MANLOVE, ~.N. 103 MARCHIN'T'ON, R.L. 103 MARKER"!', c. IJ. 130 137 :·lARUYAMA, T. 139 MASON, ,-ToN. 86 !>lASSARO, B. \.1 • 129 130 137 MATSU~IYA, Y. 120 138 MATSUMOTO, C. 121 MATSUURA, F. 126 128 136 MAY, B. 118 123 124 133 137 139 140 141 r.l!CCART, P. ,-1 • 119 - 156 - r·1CDONALD, ,T. F. 63 64 ~ICGLADE , J. 119 MCINTYRE, IT • D. 18(2) 38 87(2) 88 96 107 108 118 130 131 132 HCKEN7.IE, J.A. 115 119 122 MEl'!ASVETA, D. 60 MENZEL, B • till • 84 [VlEYER, ,T. -N • 114 135 MIG~11:~LL , J.L. 125 140 MILLENRACH, c. 88 ~HLLER, R.B. 89 90 MILNER, G.B. 50 91 92 115 119 124 MITCHELL, N. III MOAV, R. 93 94 ~1OLLER, D. 119 139 MOON, T.H. 130 138 MORGAN, R.LG. 23 MORING, LT. R. 83 94 117 MORRISON, w. ,1. 119 138 NELSON, J.R. 25 NEHBOLD, K. 21 NICKERSON, R.B. 95 119 NICOLA, S.J. 58 NISHIDA, M. 119 NORTHCOTE, 'J'.G. 120 NOVIKOV, G.G. 120 - 157 - NUM..ACHI, K. 120 138 NYGREN, A. 138 NYMAN, O.L. 36 115 120 130 138 ODENSE, P.R. 120 138 OHNO, S. 122 136 OKAZAKI, T. 39 121 OMELCRENKO, V.T. 112 113 121 127 139 OPT HOF, J. 135 ORME, L.E. 43 O'ROURKE, F.J. 113 115 135 136 PAIH, U. 119 PARKINSON, E. 121 PAYNE, R.H. 114 121 130 PERRIARD, J.-C. 130 PHELPS, S.R. 52(2) III PIPPY, J.R.C. 120 PIRCH\lER, P. 37 PLOSILA, D.S. 95 POULTER, R. 'T' • ~1 • 134 PRA'T'SCHNER, G.A. 130 PUDOVKIN, A. I. 112 RALEIGH, R.F. 40 41 REDDING, J.M. 130 REED, K.C. 127 REFSTIE, T. 17 19(2) 26 42 REICHENBACH-KLINKE, H.H. 121 - 158 - RF. PJI 'r z , G.L. 43 121 130 138 REISENBICHLER, R.R. 88 96 RIDDELL, R.E. 23 43 RIDG"TAY, G HI. 121 RI",'rER, J.A. 21 136 ROBERTS, E. 123 140 ROBERTS, P.L. 122 ROBINSON, G.D. 97 RONALD, A.P. 131 ROPERS, H.E. 139 ROSENTRETER, N. 98 RUTH, R.C. 131 RYABOVA, G.D. 112 RYMAN, N. 22 44 99 100(2) III 122 131 SACHKO, G.D. 112 SALMENKOVA, E.A. 112 113 127 139 SANDERS, B.G. 122 139 SATO, R. 120 138 SAUNDERS, I,. H. 122 SAUNDERS, R.L. 5 6 12 13 21 29 30 35 (2) 45 72 101 102 SAVVAITOVA, K.A. 120 SCHMIDT, E. 136 SCmUDT, J. 23 SCHMIDTKE, J. 114 135 139 SCHOLL, A. 128 130 SCnOl-l, C.B. 46 72 - 159 - SCHRECK, C.R. 77 107 108 115 130 131 132 SCOW, D.T. 52 111 SEEB, J. 50 109 122 124 125 126 SELANDBR, R.K. 117 S Et-iE NOVA , S.K. 139 SHA\'J, D.H. 130 SHUBIN, P.N. 122 139 SKJERVOLD, H. 4 72 SLYNKO, V. I. 112 122 139 SMITH, A.C. 139 SMITH, G. R. 48 SMI'T'F, H.D. 14 SMITH, M.H. 103 SMITH, R.C. 115 SMITH, S.B. 45 SNIESZKO, S.F. 103 SOJA, D. t-~ • 131 SREEDHARAN, A. 13 45 STAHL, G. 44 100 III 122 131 STALNAKER, ~.B. 112 117 129 141 STAUF'FER, T. l-1. 75 STEFAN, D. 109 126 STEGEMAN, ,1 •.J. 122 131 139 STEINE, T.A. 19 (2) STENNEK, A. 111 STILLINGS, G.A. 123 139 - 160 - STO('TCoJELL, P.A. 134 STOtJEKHI(; , r-1 • 123 137 139 141 SU'T"T'ERL IN, A.M. 120 138 SUZUMO'T'O, B.K. 131 SVARDSON, G. 114 123 SVENSSO~1 , K. 138 St'l7A~TS , F.A. 47 'l'AI't', ~) . s. 37 'I'AKAHASHI, Y. 119 TAKl'1.HA'T'A, N. 139 'rEEL, D.J. 91 92 119 THORGAARD, G.H. 104 113 THORPE, J.E. 23 THURSTON, R.V. 123 131 TODD, 'I'.N. 48 123 TRE'T'IAK, D.N. 113 134 TROJNAR, J.R. 49 TSUYUKI, H. 112 116 120 123 125 127 131 134 140 URSPRHJG, H. 128 137 U'T'HR, J.F. 123 U'T''T'ER, F • t·; • 50 53 91 92 104 109 III 115 116 118 119 124 125 126 133 137 140 VANSTONE, 1\, • E. 123 135 140 VINCENT, R.E. 105 VON LHmACH, B. 82 VUORINEN, ,T • 125 - 161 - VYSE, F.R.. 39 118 125 NAGNER, D ••] • 123 WARD, .] . c. 135 WARD, R.D. 135 NEBS'T'ER, D.A. 64 65 66 NES'T'ER, W. 131 WESTMAN, K. 140 v-rHITMO'RE, D.H. 131 132 NILKINS, N.P. 33 106 113 125 140 tV! LL I SCROFT , S.N. 120 125 131 WILMOT, R.L. 125 WILSON, A.C. 127 134 r-'1IN'T'ER, G. ~v. 107 108 132 HISHARD, L. 50 109 122 124 125 126 HOHNUS, ,J.F. 122 \\]OLD, F. 128 131 NOLF, U. 114 135 136 139 140 v-JRIGHT, J.E. 47 97 109 114 119 122 123 126 132 135 137 138 139 140 141 NUN'T'CH, T. 132 WYDOSKI, R.S. 118 132 141 YAMAGAr.lI , K. 136 YAf-1AGUCHI, K. ).26 128 YAMANAKA, H. 126 YAHAUCHI, T. 132 141 YA~AZAKI, F. 133 YONEDA, T. 126 YOSHIDA, A.• 134