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 it 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 a d a k o v , U S S R . 23 spawning, and since the variations in spawning dance, but it would be premature at this stage of locality also seem to be linked with changes in knowledge to suggest which factor or factors are of spawning time, i.e. late spawning always being asso­ prime importance in triggering the whole system. ciated with easterly distribution), this may further aggravate the year to year differences in living REFERENCES conditions and subsequently the survival rate of the A n o n ., 1965. “Preliminary report of the joint Soviet-Norwegian larvae. investigations in the Barents Sea and adjacent waters Septem­ However, growth rate and age of maturity in post- ber 1 9 6 5 ” . ICES CM 1965, (161) 5 pp. (mimeo). larval life of capelin may very well vary sufficiently D r a g e s u n d , O . and S. O l se n , 1965. “ O n the possibility of esti­ from year to year to be other significant causes of mating year-class strength by measuring echo-abundance of fluctuations in spawning stock abundance. Thus, some of 0-group fish” . Fisk. Dir. Skr., Ser. Havunders., 13: (8) 48-75. Hjort, J., 1914. “Vekslingerne i de store fiskerier” . Kristiania year-classes spawn mainly at the age of 3 while in 1914. others the mean age of maturity is 4 years or more. M ø l l e r , D. and S. O l se n , 1962. “Norwegian Capelin Investi­ Furthermore, there is evidence of a generally high gations. ICES C M 1962, (34) 10 pp. (mimeo). growth rate and good condition factor during the O l se n , S., 1965. “Abundance estimates o f Barents Sea capelin”. Fisk. Dir. Skr., Ser. Havunders., 13: (8) 7 6 -8 2 . feeding season in years of high abundance. The few O l se n , S., 1966. “ Rapport om loddetokt med “G. O . Sars” til years of observations so far available also indicate Barentshavet 10 november til 4 desember 1965” . Fiskets Gang, that in such years the distribution is predominantly No. 2 39-43. westerly, in the areas of transition between cold and P r o k h o r o v , V. S., 1960. “ Post-spawning survival of the Barents Sea Capelin (Mallotus villosus viltosus(Müller))” . ICES CM 1960, higher temperature, and ripening of the gonads under (165) (mimeo). these conditions probably progresses quicker than in P r o k h o r o v , V. S., 1965. “The ecology of the Barents Sea capelin years when the capelin mainly sojourn in the cold (.Mallotus villosus villosus (Müller)) and the prospects for its Arctic waters farther north and east. This may go a commercial exploitation”. Trudy PINRO, 19: 71 pp. T e m p l e m a n , W., 1948. “The life history of the capelin (Mallotus long way in explaining the apparent link between villosus villosus (O. F. Müller)) in Newfoundland waters”. Newf. early and westerly spawning in years of high abun­ Govt. Biol. Sta., Res. Bull., (17).

3. MATERIALS ON THE ECOLOGY OF CAPELIN IN THE BARENTS SEA

By

the late V. S P r o k h o r o v *

The capelin (Mallotus villosus (Müller)) is a very In spite of the abundance of capelin and its high abundant species in the Barents Sea. Ecological edible qualities the stocks are poorly fished at present studies help us to determine its significance in the food and serve as a great reserve for a fishery in the North. chains of the basin and to estimate the prospects of The published data concern mostly pre-spawning further extension of the capelin fishery. and spawning periods when capelin concentrate off the The distribution and migrations of capelin define Norwegian and Murman coasts. There are fewer data to a great extent the behaviour and migrations of on the period of their life in the open sea far from many predatory fishes of the Barents Sea (cod, shores. Till now we have had no exact idea of the haddock, redfish) which feed on capelin. migration paths of capelin in the Barents Sea, nor of

* This summary was prepared by Professor N ik o ls k y at the request of the Symposium. 24 the causes of the changes of spawning area that occur Table 2:10. in different years. The seasonal rhythm of their Radius of the first annual ring in spring- and feeding and biological structure of the population are summer-spawning capelin (in micrometer eye-piece also not quite clear yet. In the literature we meet units; binocular MBS, object glass 4 x occular 8) contradictory data on the age composition of spawning Age of Number of capelin shoals. The effect of the peculiarities of Spawning Average spawning Sex capelin time radius capelin distribution on the behaviour and migrations fish examined of commercial bottom fish of the Barents Sea in June 1956 Males different years is little known as yet. (Summer-spawning 9-77 13 Females 10-67 134 In this paper an attemps is made to answer these capelin) questions and to estimate the possibilities of wider April 1957 Males 9-40 76 exploitation of capelin. (Spring-spawning capelin) Females 9-45 77 The material was collected on board the research June 1962 vessels of PIN R O , scouting and fishing vessels in Males (Summer-spawning 11-36 42 Females 1953-1963. Samples were taken from fixed nets, purse capelin) 11-24 119 seines and bottom trawls (a net with the 10 mm mesh April 1963 size (from knot to knot) was inserted into the cod-end). (Spring-spawning Males 10-45 38 Females A trawl-attached net was used to fish for young capelin) 10-46 113 capelin. Catches of capelin larvae were taken with egg-nets and a ring-trawl. summer-spawning capelin spawn near the Murman Capelin distribution was studied mainly by their coast east of the Kola Bay. The reproduction of the occurrence in cod stomachs, so material from field Novaya Zemlya autumn-spawning capelin takes place analyses of cod feeding, made by the PINRO scientists near Novaya Zemlya and in the Cheshskaya Inlet in from 1949 to 1959, were used in these studies. Capelin August-September. caught in the bottom trawl were also examined. Different size-compositions show that spring-spawn­ The age of fish was determined by otoliths with ing capelin are about a year older than summer- help of the binocular MBS-I using reflected light, the spawning ones (R a k h m a n o v a , 1928, P r o k h o r o v , 1963, magnification being 4x8. Back calculation was made 1965). The analysis of meristic characters does not with an empirical curve specially constructed in reveal any real differences between spring- and sum- accordance with data on fish measurements and size mer-spawning capelin (R a k h m a n o v a , 1928, K h o k h - of otoliths. LINA, 1957). Studies on capelin feeding were based on the analyses An attempt was made to discuss the problem of the of stomach contents. Several capelin stomachs were ecological independence of spring- and summer- examined by using the qualitative-weight method in spawning capelin from some other points of view. order to estimate the significance of different food Since the spawning, and consequently the hatching, objects. of summer-spawning capelin larvae occur two or two and a half months later than that of spring-spawning capelin, it follows that the growth period of the REPRODUCTION progeny from summer-spawning capelin is also two The spawning of capelin occurs over a vast area or two and a half months shorter than that of spring- along the Norwegian and Murman coasts. There are spawned capelin. The formation of the first annual some records of their spawning in the White Sea and ring in the summer-spawned fish will take place at a near Novaya Zemlya (S o l d a t o v , 1923). The spawning smaller linear size than in spring-spawned capelin. period is greatly prolonged. Off the Norwegian coasts Proceeding from the assumption of the ecological capelin spawning usually starts in March, but in some independence of spring- and summer-spawning groups years it was observed in February. Further to the east of capelin we should expect a smaller radius of the capelin spawn at a later date, and near Novaya first annual ring in summer-spawning capelin than Zemlya the spawning period is in August-September. that in spring-spawning fish. But the analysis we made R ass (1933) distinguished three groups of capelin on two year-classes showed that the radius of the first in the Barents Sea named according to their spawning annual ring in summer-spawning capelin was slightly areas - the Finnmarken, Murman and Novaya Zem­ larger than in spring-spawning fish (Table 2:10), so lya capelin. we have no grounds to consider spring- and summer- In March-May, the Finnmarken spring-spawning spawning capelin as ecologically isolated groups. capelin spawn off the Norwegian and West Murman A large radius of the first annual ring in summer- coasts as far as Teriberka. In June-July, the M urm an spawning capelin is indicative of their origin from 25 spring-spawning fish. Extra good growth of the young with the deposited eggs. The larger size as well as the during the first year of life and favourable growing stronger paired and anal fins of males when compared conditions in subsequent years may result in some with females allow such a supposition. capelin maturing a year earlier than others of the Mass death of capelin in the post-spawning period same year-class. These fish will spawn in summer, is well recorded in the Barents Sea (Soldatov, 1923, while the bulk of capelin of this year-class will only Suvorov et al. 1931, R ass, 1933, K hokhlina, 1957, appear on the spawning grounds the following spring. Hjort, 1914, M eek, 1916) as in some other areas — Thus, summer-spawning capelin may originate from in the Japan Sea (R umyantsev, 1946), the Newfound­ spring-spawning fish and vice versa. As to the Novaya land area (Templeman, 1948) and off Greenland Zemlya capelin, these cannot be considered as an (H ansen and H ermann, 1953). But nothing is known isolated group, as only occassional spawning is about the proportion of a spawning stock that survives observed near the Novaya Zemlya coasts. For 40 years after spawning. Some authors state that males mostly after Soldatov’s data on the location of mature perish after spawning (Meek, 1916), while others capelin in the area of the Krestovaya Inlet were pub­ affirm that in general most of the spawning stock, lished (1923) no new materials on the spawning in the both males and females, die (K hokhlina, 1957). Novaya Zemlya area are available in literature. Suvorov and others believe that only females die Shaposhnikova (1937), V ladimirov (1938), Zatse­ totally. In 1959, we found that after spawning a part pin & Petrova (1939) and Baranenkova (1951) who of the capelin stock migrates to the open sea. Females studied cod feeding near Novaya Zemlya in July- predominate (79 °/0) among the capelin that survived September report nothing about cod feeding on after spawning. Males lose their breeding dress after capelin. spawning — the anal fin fits closely to the walls of the Apparently Novaya Zemlya is the easternmost limit body and the spawning ridges disappear — therefore of capelin spawning area and the occasional occurrence it is very difficult to distinguish males and females in of spawning shoals in this area seems quite natural. the post-spawning period. The sex of fish may be In coastal waters of the southern Barents Sea reliably determined only from the gonads. spawning of capelin takes place in March-April. The comparison of the age composition of pre­ While approaching the shores spring-spawning capelin spawning capelin and of the survivors after spawning form great concentrations extending for hundreds of in the same year show that the percentage of the young miles. Summer-spawning capelin do not form such is higher among the fish leaving spawning grounds large concentrations. than among the fish that came for spawning. Males Capelin migrate inshore at a depth of 40-60 m aged 4 made up 31-2 °/0 and females 27-0 °/0 among from the bottom. Having reached the spawning the pre-spawning capelin while among the fish leav­ grounds capelin sink to the bottom and deposit eggs. ing the spawning grounds 4-year-old males were They spawn in inlets and shallow waters in a narrow absent and the percentage of females of the same age coastal zone at a depth of 30-130 m (Rass 1933). was only 6-5 °/0. So we may conclude that most of the Absolute capelin fecundity averages 10,764 eggs survivors are 3-year-olds, and 4-year-old capelin perish (POZDNYAKOV, 1957). almost totally after spawning. Five-year-olds are ex­ By spawning time the gonads of females occupy tremely rare. the whole body cavity and, according to our data, The materials thus show the partial survival of may make up to 30°/0 of the body weight (23-5 °/0 on capelin after the first spawning and indicate the average). Male gonads are relatively small and by possibility of a second spawning. the period of spawning amount to only 1 -53 °/0 of the The mortality of capelin in the post-spawning body weight. The analysis of the gonads from Sep­ period is very high. All the predatory fish in the tember till the spawning period showed a slow and southern Barents Sea feed on capelin during the gradual rate of growth in females at early stages while migration to the spawning grounds. Therefore, the in March-April, sex glands develop very intensively. role of surviving capelin in the spawning stock is The development of male gonads is not accompanied insignificant. We may attribute capelin (according to with a notable growth of sex glands and their weight M onastyrsky, 1949) to the fish with the type of changes only a little from September till April when spawning population in which the number of first­ spawning takes place. time spawners greatly predominates. Capelin males stay on the spawning grounds a little longer than females, but the biological signi­ LENGTH, AGE, GROWTH RATE AND TIME OF FIRST ficance of this cannot yet be explained exactly. It SEXUAL MATURITY is possible that capelin males spawn with several The maximum length of capelin in the Barents Sea females at a time or have some functions concerned reaches 20 cm, while the weight of the largest speci- 26

Table 2:11. Age composition of spawning capelin (in °/0)

Age-groups

Year Males No. Females______N0, II i n IV V VI spec. II III IV V spec.

Spring-spawning capelin 1954 . - 75-0 25-0 - - 111 3-2 81-0 15-0 0-8 127 1955 ...... - 1-8 58-0 39-3 0-9 112 - 1-6 53-2 45-2 62 1956 - 37-5 53-1 9-4 32 69-0 31-0 - 29 195 7 . 3-8 76-5 19-2 0-5 - 390 7-2 78-8 13-6 0-4 221 1958 ...... - 87-8 12-2 72 92-3 7-7 - 26 1959 . 1-8 67-0 31-2 - - 109 2-6 70-4 27-0 - 115 1960 .... - 33-1 66-1 0-8 - 553 - 49-5 50-0 0-5 440 1961 . 0-9 6-1 90-3 2-7 - 329 - 21-6 77-6 0-8 370 1962 ___ - 67-3 24-2 24-2 0-3 691 - 25-2 65-5 9-3 226 1963 .... - 4-6 88-8 6-6 - 347 - 5-2 91-2 3-6 405

Summer-spawning capelin 1956...... 89-5 10-5 - _- 19 88-8 11-2 -- 163 1957...... 92-0 8-0 --- 13 95-0 5-0 - - 78 1961...... 11-1 61-2 27-7 -- 54 6-7 78-7 14-6 - 164 1962...... - 42-0 58-0 -- 100 - 83-2 16-8 - 143

mens very seldom exceeds 50 g. Males are slightly numbers of 5-year-old fish; 2-year-olds were not larger than females. abundant in the stock. In spring-spawning capelin shoals males in the 15-19 Summer-spawning capelin shoals include 2- and cm length group predominate, and fish 16-17 cm in 3-year-olds. In 1962 a predominance of 4-year-olds length are most numerous. Females are about 2 cm was recorded. smaller. The data on the mean length of age-groups of Summer-spawning capelin shoals consist of smaller capelin we obtained differ from the corresponding data fish, the usual length of males and females being 15 by R akhmanova and Suvorov. According to our and 1 4 cm respectively. R akhmanova (1928), data, capelin at the end of the second year of life Suvorov et al. (1931) state that capelin first reach reach the sizes these authors report for one-year-old sexual maturity at the first year of life and yearlings capelin. The lenght of capelin caught at the end of predominate in summer-spawning capelin shoals, 2- the first year of life (June 1960) varies between 5-6 and year-olds compose the main part of the spring- 8'0 cm (5-95 cm on average). All the capelin caught spawning stock. Males of 1-year-old (according to the had gonads at the juvenile stage. data given by the authors) reach about 14 cm and Apparently the above authors did not take into females 13 cm in length. The statement of these consideration the first annual ring while determining authors that capelin is a fast growing and fast the age, so they underestimated the ages by a whole ripening fish was included in a great number of text­ year, and sizes of age-groups were overestimated. books and handbooks (R umyantsev, 1946, R ass, 1949, Pozdnyakov (1959, 1961) made the same mistake in Altukhov et al. 1958). However N ikiforovskaya (1933) the age determination, but after our papers were and K hokhlina (1957) note that spring-spawning published (Prokhorov, 1963) he dropped his inter­ shoals consist of 3-year-olds mainly and of a small pretation of age. number of 2- and 4-year-olds and yearlings are absent So the maturation of capelin in the Barents Sea may in the spawning stock. Data on the age composition first occur in the second year, but mass maturity of spring-spawning capelin available for 10 years, as takes place in the third year. well as information on the age composition of summer- The age composition of spawning capelin varies spawning capelin for 4 years, indicate the fact that no with years. In 1954, 1956-1959, the spring-spawning m ature 1-year-old fish were found in the spawning capelin stock consisted mainly of 3-year-olds while in stock (Table 2:11). In the spring-spawning capelin 1955, 1960-1963 there prevailed 4-year-old fish. In shoals 3- and 4-year-olds predominated, mixed with 1955 and 1962, 5-year-old capelin made a considerable 27

Central Elevations (The latter are also known as the Great and Central Banks respectively. Euphausiids and Calanus ßnmarchicus — most abun­ dant animals in the Barents Sea — are the main food items for capelin. Amphipoda make up about 16 °/0 of the total weight. » In spite of a clear resemblance between the food spectra of capelin and herring, there is no marked competition for food between these two species, as they have different feeding grounds (Rass, 1933). The herring is a boreal form that lives and feeds mainly in the southern and south-western Barents Sea, while capelin - a boreo-Arctic species — feeds mostly in the north-western Barents Sea. The competition for food between capelin and herring may be observed only in February-March when capelin, migrating to the spawning grounds, enter the southern Barents Sea and feed before spawning. Competition between herring and capelin also arises when capelin shoals leave coastal waters after spawning and move to the north-western areas. However the competition is not significant since only a small part of capelin population survives after spawning. Because their main areas of distribution are different, Figure 2:5. Diagram of the autumn/winter migrations of capelin there is no marked competition between capelin and from the feeding area to the spawning grounds. Polar cod (Boreogadus saida) — another abundant Arctic pelagic species — whose feeding grounds are in cold waters of the eastern, north-eastern and northern­ part of the stock. In spite of the fact that only a few most Barents Sea while capelin prefer waters with age-groups are found in the spawning stock, individual more moderate temperature. and apparently rich year-classes may be traced in the spawning stock for some years: for example the year- classes of 1956 and 1957. MIGRATIONS Based on the data obtained from many years’ investigations into the seasonal dynamics of capelin FEEDING distribution, we may compose the following pattern of The feeding of capelin is an almost unknown aspect migrations of mature fish. The spawning migration of their biology. In the available literature only begins simultaneously with autumn cooling. Approxi­ occasional data on the food composition of capelin is mately in October, capelin leave the feeding grounds found (Smitt, 1895, H elland, 1905, T hielemann, near Hope Island and the Perseus Elevation (Great 1922, Boldovsky, 1936). There are data on the feeding Bank) and move southward crossing the Central of capelin in some other areas during spawning when Elevation (or Central Bank) and the Central Deep. feeding is poor (Pozdnyakov, 1957). The main In the middle of January or sometimes in the beginning feeding period of capelin has not been studied at all. of the month, capelin appear in the areas along the The data collected in 1960-1961 showed the seasonal main branch of the Murman Current. In February- rhythm of capelin feeding. Feeding is most intensive March and sometimes in April, mass approaches of in summer-autumn (from July till September). Then capelin to the Norwegian and Murman coasts for its intensity decreases and in November-January, spawning take place (Figure 2:5). Capelin that survive capelin practically do not feed. Before spawning spawning leave the coastal waters and migrate to the (February-March) the feeding intensity increases and north through the Murman Tongue, the Finnmarken then falls again in the spawning period. By the end and M urm an Banks as far as the Central Deep; then of summer feeding capelin accumulate a considerable they move north and north-west along the boundary quantity of fat (above 25 °/0) - of cold waters of the Central Deep, across the eastern The main feeding grounds are in the north­ part of the Demidov Bank towards Hope Island and western Barents Sea — the Hope Island, Perseus and the Perseus Elevation crossing the southern part of the 28

0 0 Central Elevation. By July-August, the majority of 20° 30 ° 4050° 60 spring-spawning capelin reach their feeding grounds (the Hope Island area and the Perseus Elevation). In summer and in the first half of autumn, feeding capelin move gradually to the north and some shoals reach the ice edge. By October, capelin reach the northern limits of their distribution and turn to the south

(Figure 2:6). 70 ° Depending on the temperature regime in different years capelin change their spawning area: in cold years capelin spawn in western parts of the spawning area, and in warm years they spawn in eastern parts. This peculiarity is characteristic of capelin not only in the Barents Sea, but also off the eastern coasts of America (Dunbar, 1954), Greenland, Iceland (J en­ sen, 1939) and in the Japan Sea (Rumyantsev, 1946). G lebov (1941) showed a relationship between the peculiarities of capelin approaches to shores and the features of the hydrological regime observed in winter-spring in the open sea and in coastal waters. 69° Analysis of the data on the approach of capelin to the coasts for the last 13 years supports the general rule determined by G lebov and indicates some variations. 66° Thus, in winter-spring 1953 and 1962 the water temperature in the southern Barents Sea was very low Figure 2:6. Diagram of the spring/summer feeding migrations of the capelin. but capelin approaching the Murman coast were very abundant, while in 1959 no intensive water cooling was observed in winter-spring but catches of capelin females on the feeding grounds make up 60°/0 and near the Murman coast were the lowest for the 13 40 °/0 respectively. years. The analysis of sex composition of capelin on the In our point of view the character of capelin feeding grounds made according to their age shows approaches to shores in spring are in a good agree­ that the sex ratio of fishes at the second year of life, ment with the temperature regime of the Barents Sea i.e. fishes that have not yet participated in the re­ observed for the last three months of the previous production, is 1 :1 (Table 2:12). calendar year. The temperature in the 0-200 m layer In 3-year-old capelin the sex ratio changes and on the section along the Kola Meridian was taken as males become dominant. The percentage of males an index for temperature conditions in the Barents further increases with years. So when a spawning Sea. Low temperature of the water masses in the stock consists mostly of older fish there is observed a Barents Sea at the end of the previous year is respon­ significant predominance of males. sible for the displacement of spawning capelin con­ Thus, in 1962 males made up 90 °/0 of the spring- centrations towards the Norwegian coast. Mild spawning capelin stock that included 4- and 5-year- hydrological conditions contribute to abundant capelin olds; this fact disrupted the natural structure of the approaches to the Murman coast. The regularity capelin population and adversely affected the results determined allowed us to make fair forecasts of of spawning. capelin approaches to shores during the last 4 years. As a rule, females predominate in summer-spawning capelin shoals consisting of younger fish. This is the

THE STRUCTURE OF THE CAPELIN POPULATION Table 2:12. Females ripen earlier than males; therefore, females Sex ratio of capelin on their feeding grounds (in °/0) predominate among younger age-groups while males Age-group Males Females No. of spec. predominate in older age-groups. An earlier ripening 1 + ...... 50-0 50-0 136 and death of females may be fairly well traced by the 2 + ...... 57-2 42-8 355 structure of capelin population on their feeding 3 + ...... 60-7 39-3 699 grounds. The material collected for a four-year period 4 + ...... 81-1 18-9 164 show that the relative numbers of capelin males and Average...... 6L2 38-8 29

Table 2:13. Calculated length of mature capelin (in cm)

Males Females Age- Year group No. No. k h ^3 U h spec. h k k u k spec.

1960... . 3 6-6 12-1 16-3 41 6-3 10-9 15.0 52 4 5-6 10-9 14-2 17-2 - 54 4-0 9-7 12-6 16-7 - 36 1961. . . . 3 7-1 11-2 16-0 _ 7 6-2 11-5 14-9 „ 42 4 5-8 10-5 14-1 16-6 - 131 5-1 9-8 12-8 : ■ _ 147 5 4-8 9-8 13-2 15-4 17-4 3 3-6 9-3 11-7 14-2 16-5 1 1 9 6 2 .... 3 5-7 11-9 16-2 — 26 6-8 11-5 14-3 __ 16 4 5-0 10-7 13-9 17-1 - 125 4-0 10-2 12-5 15-3 - 24 5 4-2 9-2 12-9 15-2 17-8 60 3-7 8-4 11-9 13-7 16-2 3

result of their earlier ripening when compared with cod shoals move to the west and become more easily males. available for the Norwegian “loddetorsk” fishery. If On the whole we may consider that sex ratio is capelin spawning takes place near the Murman coast, about 1:1. then the cod that follow the migrating capelin are In spite of the fact that after the first spawning a heavily fished in Russian coastal waters. partial survival of capelin is observed, and the The changes of migration paths and spawning possibility of repeated spawning remains, the variations grounds have some influence upon the location as well in the age composition in different years and the as the productivity of the fishery in coastal waters occurrence of several age-groups in the spawning stock and of the trawl fishery in the southern Barents Sea. is due to irregular ripening of fish in various years and In years when capelin migrate to the Murman coast, non-simultaneous maturing of capelin belonging to the the trawl fishery is most important in winter-spring in same year-class. the central Barents Sea. When the main spawning As stated earlier the rate of maturation usually capelin concentrations move towards Finnmarken the depends on the growth rate. Fast growth leads to the trawl fishery concentrates in the western Barents Sea. increase of the rate of maturing as well as of the re­ Table 2:14 gives the ratio of catches of bottom productive ability of the stock. Slow growth rate delays fishes taken in the central and western areas of the maturation. Barents Sea. In 1954-1956, when capelin approaches Back calculation of the growth rate in capelin to the Murman coast were extremely good, most of the clearly shows that the growth rate of fish that reached total catch of demersal fish was taken in February- maturity at a younger age is higher than that of fish May in central areas, while in the same period of the which reached maturity at an older age. So the next three years the Soviet trawling fleet operated abundance of spawning capelin stock depends both mainly in the western Barents Sea; the central areas on the strength of the year-class and the rate of its were of no importance as capelin and “capelin cod” maturation. (loddetorsk) migrated to the Norwegian coasts in the main. In 1960, capelin shoals moved slightly to the east and the role of central areas in the trawl fishery INFLUENCE OF PECULIARITIES OF DISTRIBUTION increased. But in 1961, capelin approaches to the AND MIGRATIONS OF CAPELIN UPON THE LOCA­ Murman coast were poor and the catches of bottom TION AND PRODUCTIVITY OF DEMERSAL FISHERIES fish in the central areas sharply decreased. Mass IN THE BARENTS SEA capelin migrations to the Murman coast recorded in A number of Soviet and foreign authors (Danilev­ 1962 gave sharp increase of catches of bottom fishes s k y , 1862, Smitt, 1895, Hjort, 1914, R ass, 1933, in the central Barents Sea. In 1963, there was observed M arty, 1939, G lebov, 1941, M aslov, I960, M iro­ a mass capelin spawning off Murman but it took nova, 1961) noted a direct relationship between the place only in the westernmost parts of the Soviet productivity of the inshore cod fishery and the abun­ coast. dance of capelin near the Murman and Finnmarken The important point is that capelin migrations coasts. The data for the last decade show that in the westward to the Norwegian coast cause a decrease of years when capelin approach the Norwegian coast, Soviet fishery intensity, not only in the central and 30

Table 2:14. At present, the total catch taken by Soviet and The ratio of bottom fish catches in the central and Norwegian trawlers exceeds 2 million centners only in western Barents Sea in February-May 1954-1963 the most favourable years. To our mind the annual (in °/0) catch of capelin may reach up to 10 million centners, Total catch of without decreasing the stocks. Weight of bottom Weight of bottom bottom fish in Capelin stocks in the Barents Sea are large and Year fish catches fish catches the central and (in °/0) taken in (in °/0) taken in western areas little exploited and serve as a reserve for fisheries in central areas western areas (in thousand the North. centners*) REFERENCES 1954.. 77-3 22-7 1254-1 1955.. 68-5 31-5 1353-6 A l t u k h o v , K .A . el cd. 1958. “Fisheries of the White Sea” . Petro­ 1956.. 55-0 45-0 1851-7 zavodsk. 1957.. 7-0 93-0 918-3 B a r a n e n k o v a , A. S., 1951. “ Results of ichthyological investiga­ 1958.. 4-0 96-0 722-2 tions of scientific expeditions carried out near the Novaya 1959.. 0-1 99-9 415-0 Zemlya Island on board the trawler “Keta” in August-Sep- 1960.. 23-0 77-0 830-4 tember 1950” . Promyslovyi Bulleten, Murmansk 4 (7). 1961.. 17-8 82-2 898-9 B o l d o v s k y , G. V., 1936. “Feeding of capelin in the Barents Sea”. 1962.. 66-5 33-5 1446-6 Za Rybnuyu Industriyu Severa, (4). 1963.. 14-0 86-0 1350-4 D a n il e v s k y , N. Y a., 1862. “ Investigations into the state of fishery in Russia”, 6. * A Russian centner = 100 kg D u n b a r , M. J., 1954. “A note on climatic change in the sea”. Arctic, 7 (1). G l e b o v , T. I., 1941. “Ecology of the M urm an cod” . Priroda coastal areas, but also in the whole southern Barents (4). Sea. It may be explained by the fact that more H a n s e n , P. M. & F. H e r m a n n , 1953. “Fisken og havet ved Grøn­ intensive fishing in other areas cannot completely land” . Danm. Fisk.- og Havunders. Skr., (15) 128 pp. compensate the loss of fishery importance in such H e l l a n d , A., 1905. “Norges land og folk”. Finnmarkens amt XX. H j o r t , J., 1914. “ Fluctuations in the great fisheries of Northern productive areas as the central and coastal ones Europe”. Rapp. P.-v. Réun. Cons. perm. int. Explor. Mer, (K onstantinov, 1964). 20: 228 pp. J e n s e n , A. S., 1939. “ Concerning a change of climate during the recent decades in the Arctic and Subarctic regions”. Det kgl. PROSPECTS FOR INCREASING THE CAPELIN FISHERY Dansk, videnskabernes selskab biologiske-meddelelser, 15 (8). Near the Murman and Norwegian coasts the fishery K h o k h l in a , N. S., 1957. “The distribution and migrations of capelin in the Barents Sea in 1945-1952”. Tr. PINRO, vyp. 10, based on capelin approaching the shores for spawning 212-29. has been carried out since historic times. Near the K onstantinov , K . G., 1964. “Effect of water temperature on Murman coast the fishing season is between March fish resources in the Barents Sea”. Vop. Ikhtiol., t. 4, vyp. 2 and July and the maximum catch is usually taken in (31), 255-69. M a r t y , Y u. Y u., 1939. “Materials on cod biology off the M urm an April. In Norwegian coastal waters fishing is carried coast” . Tr. PIN RO, vyp. 3, 38 pp. out from February to May, and the peak is in March— M a s l o v , N. A., 1960. “ The state o f stocks and the abundance o f April. The productivity of fishing varies, depending cod in the southern Barents Sea”. Trudy Soveshch. ikhtiol. upon the capelin spawning places. Fishing for capelin kom., vyp. 10, 106-16. M e e k , A., 1916. “ Migration of fish” . London. with a midwater trawl will be quite reasonable and M ir o n o v a , N. A., 1961. “ Migrations of immature cod and reasons make fluctuations in fishing productivity less con­ of their variability” . Trudy murmansk. biol. Inst. vyp. 3 (7), siderable; its use will also give us an opportunity to 198-219. prolong the fishing season and to catch capelin in the M o n a s t y r s k y , G. N., 1949. “ On types of spawning fish popula­ tions. Zool. Zh., 28: (6) 535 pp. open sea while they are approaching the spawning N ikiforovskaya , T. D., 1933. “Races of capelin off the Murman grounds. coast”. Trudy gos. okeanogr. Inst., 4, vyp. 1: 55-64. In summer-autumn, great concentrations of fat­ P o z d n y a k o v , Yu. F., 1957. “The fecundity of capelin in the tening capelin are observed in the north-western Barents Sea” . Dokl. Akad. Nauk SSSR, 112: (4) 777 pp. P o z d n y a k o v , Y u. F., 1959. “ Spawning of capelin in an aqua­ Barents Sea. In these feeding areas the fat content of rium ” . Izv. karel’. kol’. Fil. Akad. Nauk, SSSR (3). capelin is very high (over 25 °/0) and this fishery will P r o k h o r o v , V. S., 1963. “Some features of the ecology of capelin produce capelin of high edible quality. (.Mallotus villosus (Müller)) in the Barents Sea”. Tr. PINRO, The density of capelin concentrations and the depth vyp. 15, 163-76. P r o k h o r o v , V. S., 1965. “ The ecology of capelin in the Barents of their distribution make it possible to fish for capelin Sea and perspectives of the fishery”. Trudy PINRO, 19. in north-western areas with a purse-seine. Freezing R a k h m a n o v a , S. I., 1928. “On the Barents Sea capelin”. Tr. Inst. should be the main method of capelin preservation. Rybn. Khoz-va, 8 (2). Canned capelin is also a very good food product. R ass, T. S., 1933. “ Spawning of the Barents Sea capelin (Mallotus villosus (Müller))”. Trudy gos. okeanogr. Inst., 4: (1) 3-35. Salted capelin are of low edible quality and are R ass, T. S., 1949. “ Capelin. V Sb. “ Promyslovye ryby SSSR” .” unlikely to be in much demand. Pishchepromizdat, M. 31

R u m y a n t s e v , A. I., 1946. “Capelin in the Japan Sea”. Izv . T e m p l e m a n , W., 1948. “The life history of the capelin (Mallotus TINRO, 22: 35-74. villosus (O. F. Müller)) in Newfoundland waters” . Bull. Newf. S haposhnikova , A. I., 1937. “ Cod feeding off the western coast Gov. Lab. (17). of the Novaya Zemlya Island”. Trudy arkt. antarkt. nauchno- T h ie l e m a n , M., 1922. “Wissenschaftliche Ergebnisse einer Unter­ issled. Inst., 100. suchungsfahrt des Reichsforschungsdampfers “Poseidon” in das S m it t , F., 1895. “History of Scandinavian fishes” . Stockholm. Barentsmeer in Juni and Juli, 1913” . Die Fische. Wiss. Meeres- S o l d a t o v , V. K., 1923. “Materials on the ichthyfauna of the unters. Abt. Helgoland, N.F. 13: Heft 2, 185-228. Kara Sea and the southern Barents Sea”. Trudy plov. morsk. V l a d im ir o v , V . I., 1938. “ Biology of the Novaya Zemlya cod” . nauch. Inst., vyp. 3 (1). Uchen. Zap. perm. gos. Univ., 3, vyp. 1. S u v o r o v , E . K . , V a d o v a , L.A. & S y n k o v a , A .I., 1931. “ Capelin Z a t s e p in , V. I. & N. S. P e t r o v a , 1949. “ Feeding of cod shoals biology” . Tr. Leningradskogo Nauchno-issled. Ikhtiolog. Inst., 2. in the southern Barents Sea”. Tr. PINRO, 18.

4. O N T H E OCCURRENCE OF CAPELIN LARVAE IN ICELANDIC W A T E R S IN RELATION TO TEMPERATURE

By

J utta M agnusson Marine Research Institute, Reykjavik, Iceland *

The paper presented at the Symposium was based A comparison of the distribution and abundance of on a longer paper which has now been published in capelin larvae in July for the years 1962,1960 and 1964, “Rit Fiskideildar” (M agnusson, 1966).Therefore, only illustrated clearly the relation of temperature and abun­ a summary is given here. dance of the capelin larvae. The year 1962 represented It was shown that there are considerable yearly and a year with water temperatures close to the mean and monthly variations in the abundance of capelin larvae. “normal” larvae distribution, 1960 was a year with Although the larvae were very abundant during May water temperatures above average, and 1963 with wa­ off the west coast in all years, there were relatively few ter temperatures below average. July 1964 shows larvae off the north coast in some years. These fluctua­ clearly the effect of a cold-water influx on the larval tions in the abundance of capelin larvae off the north distribution and abundance. and east coasts of Iceland during the summer months It was finally mentioned, that not only are the adult proved to be directly linked with the water tempera­ capelin a very important food of, e.g. cod, but also the tures. As this region is a border area for Atlantic and capelin fry are food for herring. It is a well known fact Arctic water masses, it is frequently overcome by con­ that in some years the capelin larvae occur in such siderable movements in the location of the cold water quantities off the north coast of Iceland that this has an front. The investigations showed that this is of vital in­ unfavourable influence on the herring fishery, since fluence on the survival of capelin larvae. Thus, when the herring feeding on capelin larvae are not found in shoals water temperature was above average off the north suitable for purse-seining. coast during the summer months, the capelin larvae were very abundant in the area, while in water tempe­ REFERENCE ratures below average, there were relatively few larvae. M ag n u sso n , J., 1966. “ On capelin larvae (Mallotus villosus O. F. Müller) in Icelandic waters during the years 1960 to 1964, * Present address: UNDP, P.O. Box 1864. United Nations with some notes on other fish larvae”. Rit Fiskideildar, 4(4), Ave, Manila, Philippines. 36 pp.