PREFACE

The main task of editing papers from a Symposium original title also did not include the words “and is to ensure that they are published as soon as possible adjacent seas” but as many of the papers deal with after the meeting. However, the conclusions and species which do not occur in Arctic waters, the recommendations of this Symposium highlight the addition of a few words to the title seems more lack of knowledge of some potentially valuable fish. desirable than deletion of a number of papers. Because of this, important data have been added to For the sake of uniformity, wherever possible the some papers during editing, and several verbal reports scientific names used are those published in ICES to the meeting have been included in this volume at Bulletin Statistique, Vol. 49 for 1964 (Copenhagen 1966). the request of the Symposium. Thanks to the willing I would like to thank Dr. E.M. P o u l s e n for his help cooperation of the authors the amendments and editing and advice both at the meeting and during the editing have not unduly delayed its preparation for publi­ of this volume, and Mr. R . J. W o o d and others who cation. have helped in sorting out the discussion notes. The terms of reference excluded consideration of Finally, Miss R o se B e d f o r d and her assistants of the the herring, redfish and some other pelagic species Fisheries Laboratory must also be thanked for checking which are already exploited wherever they occur. The the typescripts and proofs. R. W. Blacker Editor and Rapporteur

INTRODUCTION

At the Statutory Meeting of the International Mr. R. W. B l a c k e r was asked to act as Rapporteur, Council for the Exploration of the Sea in 1963 the and he accepted this task. Distant Northern Seas Committee and the Gadoid Thirty-eight experts from member countries, from Fish Committee presented to the Council recommen­ Canada and USA as well as from international dations that a Symposium be organised on the organisations connected with fisheries and marine “Ecology of Pelagic Fish Species in Arctic Waters”. researches participated in the Symposium. These recommendations were renewed in 1964, and Twenty-one papers had been submitted and during Dr. E r ik M. P o u l s e n was nominated Convenor of the Symposium four additional contributions were the Symposium. A Steering Committee including the given verbatim, these latter are also included in the Convenor and the Chairmen prepared a programme present publication of the contributions. for the Symposium in which the main lines of the Furthermore, two synopses, one on Norway pout Symposium were designed as follows and the other on poutassou prepared for FAO by Mr. D. F. S. R a i t t were submitted to the Symposium (a) The significance of the pelagic fish within the for comments. These two synopses were considered food-chains in the Arctic and the role of these and comments on them were given. The Symposium species as food for the most important commer­ expressed the wish that the preparation of these highly cial fishes, useful synopses be continued by FAO to include also (b) Migration and distribution of the pelagic fish in other fish species of commercial interest in the Arctic Arctic waters and their relationship with and in adjacent regions. distribution and movements of the main commer­ The scientific papers for the Symposium were cial fishes, considered (reviewed by authors or other experts) in (c) The biological basis for fishery of pelagic fish in the following order in accordance with the Agenda: the Arctic. 1 - General (occurrence), 2 - Capelin, 3 - greater In the 1965 Statutory Meeting the Distant Northern silver smelt, 4 - smelt, 5 - Norway pout, 6 - Blue Seas Committee prepared a Preliminary Programme whiting, 7 - Polar cod, 8 - Navaga, and 9 - General for the Symposium. (food interrelations). The Recommendations on the Symposium were After each of these items a consideration and discus­ adopted by the Consultative Committee and the sion of the pertinent papers took place. Council, and the Symposium was convened on Thereafter followed a general discussion of the main September 30th and October 1st, 1966, at Charlotten- subject, as follows :— lund Castle in connection with the Statutory Meeting 1. The species as links in food-chains; discussion- of that year. leader: D. V. R adakov, USSR. 74

SECTION 4: Smelt Osmerus eperlanus (Linnaeus, 1758)

1. DYNAMICS OF SMELT POPULATIONS IN SUB-ARCTIC WATERS

By

T. N. B e l y a n i n a Institute of Animal Morphology, USSR Academy of Sciences

Species of the family Osmeridae inhabit waters of A. Populations of Group 1 different salinities and live both in seas and landlocked fresh waters. All marine species of this family are % The Rybinsk associated with coastal waters during their spawning 60 60 period, many of them entering the rivers to spawn. 40 40 Most of the species of the family Osmeridae belong to 20 20

the North Pacific along the Asiatic and American _ l I L_ coasts. Only capelin (Mallotus villosus) and smelt 1 2 3 Years 1 2 3 4 S Years (Osmerus eperlanus) are distributed almost circum- of life of life polarly. The capelin inhabits pelagic waters of the high seas. The smelt is a neritic species — in fact, it is one B. Populations of Group 2 of the main neritic fishes of Arctic and boreal seas, playing an important role ecologically and in the % The While Sea % The Yenisey river fisheries. It feeds on pelagic and nectobenthic crusta­ 60 60 ceans and young fish (among them there are such 40 40 important commercial species as white-fishes). On 20 20 the other hand, some commercial fish feed on smelt (cod and others), so do sea-birds and some mammals. 2 3 4 5 6 2 3 4 5 6 7 The smelt which is distributed over a large area Years of life Years of life including the coastal regions of the North Atlantic, Figure 4:1. Linear growth in successive years of life (in °/0 of Pacific and Arctic seas and freshwater lakes, can be maximum length) of different smelt populations. divided into several sub-species: the European smelt A. Populations of Group 1. B. Populations of Group 2. — Osmerus eperlanus eperlanus L. (the Baltic and the North Sea basins and the Upper Volga system), the grow most intensively during their first year of life; Asiatic smelt —O.e. dentex Steind. (American and then the growth rate decreases comparatively sharply Asiatic coasts of the North Pacific and Arctic to the (smelt populations of West and East European basins, White Sea) and the American smelt — 0. e. mordax excluding the extreme north, and North American (Mitchill) (Atlantic coasts of North America). Now waters) ; (2) populations whose individuals grow some authors (M cA llister, 1963; Bigelow and comparatively slowly during their first year while Schroeder, 1963) consider the last two sub-species their growth rate increases more or less sharply during to be the same. their second year of life. Then it decreases gradually Over its wide range the smelt lives under various (smelt populations of the White Sea, the Cheshskaya ecological conditions which determine the growth Bay and the Siberian coasts). Sizes of individuals of rate and maturity, the age composition of the stock, different smelt populations in successive years of life the longevity and other aspects of the dynamics of the are given in Table 4:1. Values of the linear growth different populations. Great variability in these char­ (in °/0 to maximum length) of some populations of acters is typical of the smelt. both groups are shown in Figure 4:1 a and 4:1 b. All smelt populations may be divided into two The populations of the first group live under temp­ groups based on the character of the growth rate erate climatic conditions. Their growth season lasts during ontogeny: (1) populations whose individuals six to seven months. They live in waters with a good 75

Table 4:1. Size (in cm) of fish in successive years of life, age of maturation and age-groups of spawning stock of different smelt populations

Age- Age groups Locality Age-groups of of Author ------matu- spawn- 1 23456789 10 11 12 ration ing stock

Pskov Lake 7-2 9-7 12-9 ------11-2 Fedorova, 1953 Ilmen Lake 4-7 8-2 10-7 ------1-2 1-3 D omrachev & Pravdin 1926 White Lake 6-0 8-5 11-0 ------1-2 1-3 Fedorova, 1953 Rybinsk waterbody 5-9 8-7 9-4 — — — — — — — — — 1—2 1-3 Lapin, 1955 Dadey Sea 7-1 10-7 12-2 ------11-3 W iller, 1926 Lazmiaden Sea . . . 8-2 9-3 11-8 12-7 15-6 ------2-3 2-5 W iller, 1926 Kurishes Haff: non-migrant .... 6-3 10-5 - 11-2 M arre, 1931 sea-m igrant 6-5 13-3 16-1 20-4 ------2 2—4 M arre, 1931 Onega L ake 6-3 8-8 9-4 10-6 11-0 11-3 11-8 12-3 - - - - 2-4 2-8 Stefanovskaya, 1957 Pyaozero (Karelia) - - 10-6 11-3 12-0 12-9 13-6 14-4 4-6 4-12 M elyantzev, 1946 Ladoga Lake ...... 8-0 9-5 10-7 13-6 15-8 18-3 ------1-3 2-6 Archipzeva, 1956 Elba R iver 7-1 13-4 17-3 21-2 23-8 ------2 2-5 Lillelund, 1961 Neva R iv e r 7-8 11-1 13-6 16-0 17-6 ------3-4 3-9 K ojevnikov, 1956 Michigan Lake . . . 9-2 15-7 17-1 ______2 2-3 Creaser, 1929 Huron Lake - 13-7 15-5 18-3 ------2 2-4 Baldwin, 1948 Miramichi River. . - 13-7 15-6 17-6 19-4 ------2 2-5 M cK enzie, 1958, 1964 Basin of Maine . . . - 12-2 17-2 22-0 24-0 ------2-3 2-5 R upp, 1959 W hite Sea: Onega B a y ...... 4-7 10-1 14-5 19-2 23-2 27-4 ------2-4 2-7 Balagurova, 1957 Dvina B ay 4-1 9-3 13-2 16-9 19-1 21-5 24-6 27-4 28-1 - - - 3-4 3-9 K irpichnikov, 1935 Kandalaksha Bay 4-7 12-9 18-8 22-6 25-0 27-0 ______3-4 3-8 our data Cheshskaya Bay. . . 3-5 8-1 12-5 15-2 17-7 20-5 22-2 ----- 4-5 4-7 K irpichnikov, 1935 Gulf of O b - 18-3 19-3 20-2 20-9 22-1 - - - - 4-5 4-8 Amstislavsky, 1959 Yenisey River . . . . 4-6 9-8 14-1 17-6 20-3 22-3 23-9 24-4 25-5 - - - 5-6 5-9 T yurin, 1924, N eiman, 1957, K ravchuk, 1958 Lena R iver ------19-6 23-4 26-3 27-6 28-8 30-1 7-8 7-12 Pirojnikov, 1950

supply of small zooplankton on which fry and young 50-300 mg/m3. The later spawning period (May-June feed; the plankton biomass is about 300-1300 mg/m3, and even July) compared with that of the European as may be concluded from various literature sources. and American populations (March-April), the lower The earlist maturing populations of smelt are in the temperature during the feeding season, the earlier first group: for example, the smelt of some lakes of cold in autumn, the poorer food resources — all these the Baltic Sea basin (Pskov Lake and others), the factors determine the slow growth of the young smelt population of the Kurisches Haff of the Baltic and of these regions. However, the growth increases dur­ others mature during their first year of life. On the ing their second year of life and exceeds absolutely other hand, among the first group there are some that of the first year (Figure 4:1, b ). This is evidently populations maturing in their third to fourth year of a result of changes in the feeding habits: the smelt life (East Baltic smelt and others) (Table 4:2). Fresh­ begins to feed on larger crustaceans (Amphipoda, water landlocked populations mature earlier than those Mysidacea). The Kandalaksha Bay smelt (White from the sea (Tables 4:1 and 4:2). The growth rate Sea) is remarkable for the most rapid growth of the former decreases more sharply during ontogeny (linear and weight) during its second and third (Figure 4:1, a ) and their rate of weight-gain is lower year of life (Tables 4:1 and 4:3). This population (Table 4:3). lives under conditions with higher salinity (25—28 °/00) The populations of the second group live under than do all other smelt populations. The food resources severe sub-Arctic conditions. Their growth season lasts of the White Sea are richer than those of the estuaries from five (six) months (White Sea smelt) to four of Siberian rivers. The average biomass of benthos months (East Siberian populations). The average of the White Sea bays is about 10-30 g/m2 (without zooplankton biomass during the season is about Mollusca and Echinodermata on which smelt does 76

Table 4:2. Percentage age-composition of smelt populations

Age-groups Locality 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Pskov L a k e ...... 90 10 Rybinsk waterbody . . . 17 77 6 Dadey-Sea...... 74 17 8 1 Lazmiaden S ea...... 6 37 38 15 4 Onega L a k e ...... 4 28 40 20 7 1 Miramichi R iver ...... 62 32 5* Huron L a k e ...... 54 38 8 Finnish G ulf...... 1 28 42 24 3 1 1 White Sea: Kandalaksha Bay . . . 30 46 23 1 Onega B a y ...... 7 32 41 17 3 Yenisey River...... 8 20 43 23 6 Khatanga B a y ...... 3 10 10 19 28 25 4 1 Lena R iv e r...... 6 14 8 39 28 5 Anadyr Bay...... 17 21 33 13 7 4 3 1 1

* The number of fish of I, V and VI age-groups together is 1 °/0. Data from Agapov, 1941; Alexandrova, 1963; Balagurova, 1957; Baldwin, 1948; Kojevnikov, 1956; Kravchuk, 1958; L uky- anchikov, 1964; McKenzie, 1964; Meshkov and Sorokin, 1952; Pirojnikov,1950; Schetinina, 1954; W ille r, 1926, and the Author’s materials. not feed), while this value for the estuaries of the freshwater lakes. Besides, both sea and freshwater Siberian rivers is only 4-5 g/m2 (G r e s e , 1957, and populations are often biologically heterogeneous ; others). Besides the Kandalaksha Bay smelt feeds within the same waterbody there are ecological forms intensively on heteronereid stages of Polychaeta, differing in size and growth rate, age-composition of mainly Nereis virens Sars (K u d e r s k y and R u s s a n o v a , the spawning stock, age and size of maturing, period 1963, and others), which is an easily accessible and of spawning, character of feeding and some other very abundant food in this region. One does not find peculiarities. This holds true for the smelt populations Polychaeta in the smelt diet of other regions. Young of the Baltic Sea bays (M a r r e , 1931; K o j e v n i k o v , fish (its own species included) form a great part of 1955), the lakes of eastern Europe (A r c h i p z e v a , the diet of the older smelt. However, zooplankton 1956; S tefanovskaya , 1957, and many others), the continues to be an important part of the diet of the Atlantic coasts of North America (K e n d a l l , 1926, older fish of the Siberian smelt populations. and others). The smaller and earlier maturing form It is typical that the smelt populations of the first is always non-migratory, the larger and later maturing group develop landlocked, early maturing forms in one usually migrates for more or less considerable

Table 4:3. Values of “n” in equation “Q = A ln” (Q — weight of fish, 1 = length, A const.) for different smelt populations

Locality n Author

White Lake ...... 2-70 Schetinina, 1954 Land­ Rybinsk waterbody...... 2-91 Schetinina, 1954 locked Kurisches H aff...... 2-87 M a rre, 1931 Great L ak es...... 2-82 L illelund, 1961

E lba R iv e r ...... 3-28 L illelund, 1961 M iram ichi R iv e r ...... 3-20 M cK enzie, 1958, L illelund, 1961 Sea- W hite Sea: m igrant K andalaksha Bay ...... 3-48 our data D vina Bay ...... 3-36 K irpichnikov, 1935 Yenisey River ...... 3-15 T yurin, 1924 and others 77

Table 4:4. Fatness of body and eggs (in °/o of wet substance), relative fecundity (number of eggs per 1 g of body weight) and average size of eggs in smelt populations of different longevity*

Population Fatness of body of Fatness of Relative Diametre of ripe spawning fish eggs fecundity eggs (mm)

Short-lived smelts of East-European lakes . .. abt. 1-5 4-8 800-1000 0-7-0-8 White Sea sm elt...... 1-7-3-6 8-9 700 0-8-0-9 Siberian sm e lts...... 4-7-S-3 12 360 1 -0-1-1

* Data from A brosov and A gapov, 1957; A mstislavsky, 1959; K leimenov, 1962; M arre, 1931, T yurin, 1924 and others, and the author’s materials.

distances from feeding to spawning grounds. The ground is usually not large. Eggs are spread irregularly, existence of these ecological forms promotes the more often in lumps. Larvae hatch in fifteen to twenty complete use of food supply and spawning grounds. days and are immediately carried down the river. As a rule such landlocked, non-migratory forms Survival of eggs and larvae increases in years when the and ecological heterogeneity are not characteristic water level is high. Lillelund (1961) who has of sub-Arctic populations. Only one landlocked form thoroughly studied the smelt of the river Elba notes is known among the smelt populations of these waters, that the survival of a year-class is determined mainly which inhabits lakes of the Pechora river system by temperatures and food supply during the first four (K u c h i n a , 1956). Fish of the sub-Arctic populations weeks after hatching. Evidently, these factors influence mature during their third to eighth years of life (Tables identically the survival of smelt fry in different basins, 4:1 and 4:2). Among them the White Sea smelt is as the fluctuations in the abundance of the same year- the earliest maturing (during the third to fourth classes are often synchronous; for example, the 1957 year) Eastwards the age of maturation increases; year-class was of middle density in the White Sea the Cheshskaya Bay smelt matures during the fourth smelt (our data) and the elba river smelt (Lillelund, to fifth year of life, the Yenisey smelt during the fifth 1961); the 1958 years-class was of high density in the to sixth year of life, the populations of the Khatanga White Sea smelt, the Elba smelt, the smelt of the Bay, the Lena river, the Anadyr Gulf during their White Lake and the Upper Volga system (M oro- seventh to eighth year of life (Tables 4:1 and 4:2). s o v a , 1960) ; the 1959 year-class was poor in the White Correspondingly, the age composition becomes more Sea smelt, the smelt of some Karelian lakes and the complicated, the longevity increases, and some other Kurishes Haff smelt. K udersky (1962) notes synchron­ characters change : fatness of the body increases, egg- ous fluctuations in the abundance of different smelt sizes and their fatness increase too, while the relative populations living in fresh-waters of the north-western fecundity (i. e. egg-number per 1 g of body-weight) USSR. decreases (Table 4:4). The average smelt catch in USSR is about 15,000 t The smelt stays near the shores almost throughout yearly and evidently may be increased. However, in the year. The most intensive feeding takes place order to take into account the great variability of the during summer and autumn. In winter the feeding age of maturation and age structure of stocks in this intensity declines or ceases completely and the smelt species it is necessary to know the probable effect spends winter in the estuaries till spawning migration of a fishery on a discrete smelt population. For in spring. The extent of migration depends on the example the spawning stock of the short-lived popu­ location of suitable spawning places and it varies lations consists of fish of 1-2 age-groups, so the repro­ from about several hundred metres (some landlocked duction depends on the changes in the recriutment populations) or several kilometres (the White Sea abundance, i. e. on the density of one or two year- smelt) to hundreds of kilometres (some Siberian classes. Such populations may recover their density populations). Spawning begins when the temperature very rapidly due to their early maturation and high of the water reaches about +4°C. The peak of the individual reproductive capacity (relative fecundity). spawning usually lasts several days. The smelt has But in years when the recruitment abundance is low bottom-adhering eggs, which are laid on stones and and the main spawning stock consists of older fish other submerged things and vegetation. Spawning the number of which is relatively small, then the grounds are usually situated in a current at depths fishery should be limited (L a p i n , 1960). Reproduc­ from 15-20 cm to several metres, and the spawning tion of long-lived populations is more stable and dep­ 78 ends to a smaller degree on fluctuations in the abun­ Bigelow, H.B. & Schroeder, W. C., 1963. “ Family Osmeridae. dance of separate year-classes. However, the fish of Fishes of the western North Atlantic”. Sears Found. Mar. Res., 1: (3) 553-97. New Haven. these populations mature later and their individual Creaser, G. W., 1929. “The smelt in Lake Michigan”. Science, reproductive capacity is lower (Table 4:4). Such 69 (1798). populations recover their density more slowly, and D omrachev, P. F. & I. F. Pravdin, 1926. “ Fishes of the Ilmen an intensive fishery may consequently result in over­ Lake and the Volkhov river and their economic importance”. Studies of fishery of the Ilmen Lake and the Volkhov river, fishing. p. 2, Leningrad. Fedorova, G. V., 1953. “The White Lake form of freshwater smelt”. (Personal comm,). G rese, V. N., 1957. “Food resources of the Yenisey river and their using”. Izvest. VNIORKh, 41. SUMMARY K endall, W. C., 1926. “The smelts” . Bull. Bur. Fish., Wash., 42: The smelt - Osmerus eperlanus (L.) — plays an 216-375. important role in the ecology of waters of the northern K irpichnikov, V. S., 1935. “Biologo-systematic study of the smelt of the White Sea, the Cheshkaya Bay and Pechora River”. hemisphere ; on the one hand, as a consumer of pelagic Trudy VNIRO, 2. and nectobentic crustaceans, on the other, as a prey Kleimenov, I. Y a ., 1962. “ Chemical and weight composition of of some commercial fish and other animals. The smelt fish of USSR waters and foreign countries”. Moscow. K ozhevnikov, G. P., 1955. “ Ecological peculiarities of the Neva is an im portant commercial fish there. river smelt”. Vop. Ikhtiol., 3: 126-8. The great variability of the growth rate, the age- K ozhevnikov, G. P., 1956. “ Prognosis of the spawning migration composition of the stock and other characters determ­ and catches of the Neva river smelt”. Nauch.-Tekh. Biull. ining the dynamics of the separate populations are VNIORKh, 1-2. K ravchuk, V. A., 1958. “The Asiatic smelt - Osmerus eperlanus typical of the smelt. These peculiarities should be dentex Steind”. Izvest. VNIORKh, 44. taken into account when fishing. K uchina, E. S., 1956. “Peculiarities of ichthyofauna of the Comparison of the characteristics of the various Pechora river within the Ust-Usinky region”. Trudy Komi. smelt populations of Europe, Asia and America is Fil., Akad. Nauk SSSR, (4). K udersky, L. A., 1962. “On fluctuations in abundance of main made. From the northern part of eastern Europe commercial short-lived fish species in some waterbodies of the eastwards to the East Siberian shores the growth rate north-west USSR”. Inst. Zool. Bot., Akad. Nauk Estonsk. SSR, of the smelt populations gradually decrease, the age Hydrobiol. Invest., Gidrobiol. Issled., 3. Tartu. of maturation and longevity increases, the age struc­ K udersky, L. A. & M. N. R ussanova, 1963. “Bottom fishes diet in the west part of the White Sea”. Sei. Papers of Karelian ture of the stock becomes complicated, some other Pedagogical Inst., 15. characters change. L apin, Yu. E., 1955. “ On the method of smelt scale-reading” . Brief data are given on the ecology and the repro­ Trudy biol. Stants. Borok, 2. duction of the smelt. Synchrony of fluctuations of Lapin, Y u . E., 1960. “On peculiarities of population dynamics in short-lived fishes (for example - freshwater smelt)” . Zool. year-class abundance in different basins is noted. Zh., 3» (9). Lillelund, K., 1961. “Untersuchungen über die Biologie und Populationsdynamik des Stintes, Osmerus eperlanus eperlanus (Linnaeus 1758) der Elbe” . Arch. Fischwiss., 12: (1) 127 pp. Lukyanchikov, F. V., 1964. “ Abundance of the most important commercial fishes of the Khatanga River and ways of their REFERENCES increasing”. Izvest. GosNIORKh, 57. A brosov, V. N. & Yu. D. A gapov, 1957. “ On self regulation of M arre, G., 1931. “Fischereiwissenschaftliche Untersuchungen the smelt abundance in Zizitskoye lake”. Vop. Ikhtiol., 8: über die Grundlagen der Stintefisherei im Kurischen Haff”. 160-78 (in Russian). Z. Fish., 29: 443-512. A gapov, Yu . D., 1941. “ Fish and fishery of the Anadyr Bay” . M cAllister, D. E., 1963. “ A revision of the smelt family, Works of Sei. Inst. Polar. Agricult., Cattle-breed. and Industr. Osmeridae” . Nat. Mus. Canada, Bull., No. 191, Biol. Ser., Manag., <>. (71). Alexandrova, T. N., 1963. “ Biological characteristic of the M cK enzie, R. A., 1958. “Age and growth of smelt, Osmerus spawning stock of the Onega Lake smelt”. 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PiROjNiKOV, P. L., 1950. “Data on biology of Asiatic smelt”. Stefanovskaya, A. F., 1957. “The smelt as an object for increas­ Dokl. Akad. Nauk SSSR, 74 (5), (Biol. Ser.). ing of fish productivity in Karelian lakes”. Ryb. Khoz. Ka- R u p p , R . S., 1959. “ Variation in the life history of the American relli, 7. smelt in inland waters of Maine”. Trans. Am. Fish. Soc., 88: T yurin, P. B., 1924. “To Asiatic smelt study” . Works of East- 241-52. Siberian Sei. Fish. Stat., 2 (1). Schetinina, L. A., 1954. “The Rybinsk waterbody smelt” . Zool. W iller, A., 1926. “Untersuchungen über den Stint (Osmerus Zh., 33: 1336-43. eperlanus (L.)} in Ostpreussen”. Z. Fish., 24: 521-58.

2. DISCUSSION

P o u l s e n asked if there was any relation between be shorter-lived than the northern ones. In reply to the maximum size and age of smelt and the size of T e m p l e m a n , N ik o l s k y said that there was no simple the water body in which they live. N ik o l s k y replied age and maturity relation (B e l y a n i n a shows the wide no, but that often there were two populations in lakes, range of the age of spawning stocks in Tables 4:1 one short-lived and the other long-lived. On the whole and 4:2). there was a tendency for southern lake populations to