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 oulsen 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 ood and others who cation. have helped in sorting out the discussion notes. The terms of reference excluded consideration of Finally, Miss R ose Be 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 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 ulsen 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 . 116

3. SOME DATA ON THE BIOLOGY OF POUTASSOU (RISSO) IN THE NORTH-EAST ATLANTIC

By

V . K. ZlLANOV Polar Institute of Marine Fisheries and Oceanography (PINRO), Murmansk, USSR

The genus Micromesistius Gill is of great interest for the fisheries. It includes two species with a bipolar distribution: Micromesistius australis Norman off the south-eastern extremity of South America and M . poutassou (Risso) in the North Atlantic and adja­ cent seas (Figure 6:6). Only small quantities of M . poutassou are fished annually, up to 6—20,000 t (M a r t in se n , 1965), mainly by Spain and Italy. England and Ireland fish blue whiting in the NE Atlantic, but in the statistics the catches are included in “other ” (H e n d e r so n , 1957). 60 ° Soviet fishing vessels take blue whiting as by-catch when fishing for cod and redfish with bottom trawls in the Barents Sea and herring with drifts-nets, mid-water trawls and purse-seines in the Norwegian and Greenland Seas. Sometimes the catches, 4-6 t, by a midwater trawl or purse-seine consist of only blue whiting (Z il a n o v , 1965). In 1965 the Soviet fishermen fished 149-5 t blue whiting, all by the research-scouting vessel “Atlant” during one cruise west of Ireland. In February-March and June- July 1966 another research-scouting vessel “Volgo- donsk” caught 250 t of blue whiting. The species could be of great importance in the NE Atlantic, when especially fished. In 1965/1966 three research cruises were carried out to study the distribution of adults and their spawning areas in the and westward of England. Midwater and bottom trawls with 16—14 mm mesh cod-ends were used. Field biological analyses were conducted according Figure 6:6. The distribution of Micromesistius Gill in the according to data collected in Soviet expeditions in to the standard methods for Gadidae. Over the period 1947/1966. 1 - M . poutassou (Risso); 2 - M . australis Norman. 1955 to the first half of 1966, 44,163 and 6,070 blue whiting were measured and investigated respectively. almost up to 82° N . They are common in shallow areas More than 95 °/0 of these specimens were collected in and on slopes around the Faroes and Iceland and off 1960/1966. the shores of S E and S W Greenland. As B ig e l o w and S c h r o e d e r (1955) and S c o t t (1963) report, blue THE DISTRIBUTION AND ENVIRONMENTAL whiting are met on the Georges and Browns Banks CONDITIONS OF BLUE WHITING in the N W Atlantic. In research cruises conducted Blue whiting are widely spread in the Atlantic and by the Polar Institute they were found on the New­ its adjacent areas (Sv e t o v id o v , 1948; M a r t y , 1952; foundland Bank, in the Flemish Cap area and near E h r e n b a u m , 1938; T å n in g , 1958). According to data the Labrador coast. To the south blue whiting are collected by the Polar Institute (PINRO) during post­ recorded in the North Sea, Bay of Biscay and in the war years, the eastern boundary of the distribution western . The distribution in the is in the Barents Sea up to 45°E. In the north, blue N E Atlantic and especially the penetration far to the whiting are encountered to the west of the Spitsbergen north and east are closely related to the current sy­ 117 stem and inflow of warm water in different areas. of Ireland, Hebrides and Shetland Islands (Hen­ Thus, in years with high or moderate temperatures derson, 1957, 1961, 1962); in May south-west and blue whiting are observed in the Motovsky Bay, on west of Iceland (M agnusson, M agnusson & H all- the Kildin and Murmansk Banks in the Barents Sea, grimsson, 1965) and in June in the Norwegian Sea and single specimens to 45° E. In cold years they are north-east of the Faroes (Zilanov, 1966). The de­ seldom found east of the Finnmark Bank. Considering velopment of the eggs lasts about 13-14 days at 8-9° C data on the distribution in the Barents Sea 1934— (Flüchter and R osenthal, 1965). Consequently it 1938, Boldovsky (1939) concludes that their maxi­ occurs much later in the north than in the south. mum migration to the east takes place during the Schmidt (1909) believes that for spawning the tem­ hydrological summer. perature should be at least 8-9° C and salinity 35-2 °/00. During a great part of their life blue whiting live In fact, such conditions are observed west of Ireland pelagically over 200-3000 m. The young and pre- late in February and in the southern Norwegian Sea spawners occur in considerable quantities also near in May. Judging by the number of larvae caught, the the bottom. One can meet M . poutassou in bottom most intensive spawning takes place west of Ireland trawl catches taken at great depths, 500-800 m, west and the Hebrides. According to H enderson (1961) of the Bear Island and in the Norwegian Sea. In the centre of larval distribution remains almost con­ catches from 700-800 m blue whiting amounted to stant in this area from year to year; it is found near 1-4 °/0. Vertical migrations of blue whiting are well 57° N and 13°W,* but the number of larvae may pronounced. In the day-time in winter the species is change considerably from year to year (H enderson, found at depths of 100-300 m (over 180-3000). At 1962). Both Schmidt (1909) and H enderson (1957) twilight they rise into the 0-30 m surface layers. In found larvae above depths greater than 200 m. Such summer the amplitude of vertical migrations is less, a distribution of larvae allowed Schmidt (1909), not exceeding 30-100 m. Although the range of depths H enderson (1957) and Svetovidov (1948) to suppose where M . poutassou live is rather wide, they are ob­ the spawning to take place over considerable depths. served in greatest numbers at 100-400 m (over 180- However, Polonsky (1966) and our scientists found 3000 m). In the Barents and Norwegian Seas at depths in March 1965 and February/March 1966, respective- of 700-800 m blue whiting are found at temperatures between 3° and — 0-03° C. The lowest temperature Table 6:10. observed while catching M . poutassou was — 0-7°C, The ratio of mature (stage of maturity of gonads - it was registered in the Barents Sea (71°26'N, 41° II-III and up) and im mature (juv. - stage II) M . p o u ­ 4 6 'E) at 225 m in January 1964. Such low temperatu­ tassou according to size classes during the spawning res are rare, as blue whiting prefer temperatures process west of Ireland (1. February-18. March, between 2° and 15°C, depending on their habitat. In 1966) September-January they concentrate in the south­ western part of the Norwegian Sea at 2-7° C in the Males Total no. Females Total no. Length Imma­ Mature of males Imma­ Mature offemales surface and at 200-300 m 0-3-5°C. Here they remain cm ture inves­ ture inves­ 0/ in waters with the temperature higher than 3°C. In °// 0 °//o tigated la / 0 tigated summer (June/August) blue whiting occur in 5-8° C. 16 100 - 1 100 - 1 South of the Faroe Shallow and west and south of 17 50 50 4 100 - 1 Ireland M . poutassou were found in great quantities 18 --- 100 - 4 19 50 50 2 _-- in temperatures of 8-10° C in January/March and 20 50 50 2 --- 12-15°C in June-August. Blue whiting is an oceanic 21 33-2 66-8 9 --- species. Thus, the observation by W heeler (1965) of 22 23-1 76-9 56 36-3 63-7 11 blue whiting in the estuaries of the Couch and Black- 23 9-0 91-0 77 33-2 66-8 96 24 16-7 83-3 60 22-4 77-6 125 water rivers is of great interest, indicating once again 25 2-1 97-9 94 13-2 86-8 120 that blue whiting can adapt itself to most different 26 2-3 97-7 85 4-8 95-2 85 conditions. 27 - 100 53 1-7 98-3 60 28 - 100 25 1-6 98-4 62 29 - 100 14 _ 100 50 SPAWNING TIMES AND AREAS 30 - 100 6 - 100 44 Blue whiting spawn in many different areas of the 31 - 100 2 _ 100 24 32 - 100 1 - 100 24 NE Atlantic (Schmidt, 1909; Ehrenbaum, 1936; 33 - 100 1 - 100 12 endersen vetovidov H , 1957, 1961, 1962; S , 1948). 34-40 ---- 100 58 During 1955/1965 larvae in early stages of develop­ ment were found as follows: in M arch in the north­ * Positions are determined by the author following the scheme western part of the Bay of Biscay; in March/May west in H e n d e r s o n ’s paper. 118

3 0 -

n 492 m 24.85 20 - \ n 176 m m 26.93 \ 10 -

33 cm 22 24 26 28 30 32 34 36 Figure 6:7. The difference in the size composition of females and males of blue whiting in the Norwegian Sea - A (August- December 1961) and in the Porcupine Bank area - B (February-March 1966). ly, pre-spawning and spawning concentrations on the Porcupine Bank above depths of 180-300 m. In 1965, the area where schools were observed made up 280 - 600 square miles and in 1966, 800 square miles. The spawning started in 1965 on March 10th and on Feb­ 260 - ruary 23rd. Its peak was in mid-March in 1965 as well as in 1966. Echo-sounders show that schools of 240- pre-spawning blue whiting kept close to the bottom in the daytime when the sea surface was sunlit. During 220 - spawning blue whiting were found 10-30 m from the bottom (where the depth of the sea is 180-250 m) and 2 0 0 - only a few schools were near the bottom, migrating into midwater layers on sunny days. In the evening 180 - schools scattered and at night they were observed 80 m from the surface and sometimes 20-40 m from 160- the bottom. During the 1965 spawning the temperatu­ re was 9-6-9-7°C, salinity 35-5-35-6°/00, in 1966 140- 9-8-10-5° G. Eggs ripen at different times and the ovaries contain both the ripe transparent, easily 2 0 - running eggs (stage V according to Sorokin’s scale, 1957) and opaque, ripening eggs (stage IV). The mean diameter of a transparent egg is 1 0-1 • 1 mm, or similar 100- to that supposed by H enderson from larvae just hatched. Judging by biological analyses, the eggs in 80- blue whiting ripen in portions and spawning occurs in 2-3 periods. There are no eggs in ovaries of spent 60- blue whiting, only rarely single resorbing eggs. The sex ratio is about 1 to 1 during the spawning. Females 40- are larger than males, which rarely reach 30 cm (Figure 6:7). In the area west of Ireland M . poutassou 19 21 23 25 27 29 31 33 35 37 cm mature at 17-20 cm (Table 6:10). Males mature Figure 6:8. The average weight of blue whiting by sizes during usually at 23-24 cm and females at 25-26 cm (Table (1) the feeding period, (2) before spawning, and (3) during 6:10). The weight decreases after spawning and spawning. amounts to about 70-100 g in fishes of 24-27 cm long (Figure 6:8). on the Rockall Bank slopes, where concentrations of The slopes of the Porcupine Bank are not the only blue whiting recently spawned were found at 200- spawning locality in this area but they are undoubtedly 250 m in M ay 1966. Probably spawning occurs on the most important one. Spawning also takes place the Lousy Bank, the remotest bank south-west of the 119

7. brought with one branch of the currents to the Shet- land-Faroe-Icelandic area, and with another to the 10 northern North Sea; from the north-eastern slopes of m 28.04 the Faroe Shallow to the north-eastern Norwegian 5 Sea and western Barents Sea; the Irminger Current carries the young from the south-western to the western 0 and northern parts of Iceland and also to East Green­ land. Besides, the scattered spawning grounds and considerable differences in times of spawning suggest 5 m 28.76 that in the NE Atlantic there are several stocks. The data on size-composition from different areas con­ 0 firms this assumption.

5 m 28.35 SIZE-COMPOSITION AND SOME DATA ON AGE 0 In the Barents Sea fish between 12 and 37 cm n 1446 occurred, mean: 28-04 cm. In areas of the Bear 5 m 28.27 Island Bank, Sorkapp Deep and West Spitsbergen blue whiting are somewhat larger, averaging 28-76, 28-35 and 28-27 cm, respectively (Figure 6:9 B, C & 0 D). These differences are insignificant and the iden­ m 23.62 tity of size curves shows that these fish are of the same 5 origin. In the Barents Sea and Bear Island-Spitsber- gen Bank are fish at stages of maturity II and II—III 0 (Sorokin’s scale, 1957). When mature, M . poutassou migrate from these areas to spawn in the Norwegian Sea. Fish 26-29 cm in length, more often with the 15 n 2739 developing gonads, dominate in the south-western m 27.35 Norwegian Sea (Figure 6:9 E). So, in January 1966, 10 stages II—III—IV amounted to 46 °/0. The spawning of these fish takes place in May on the north-eastern 5 slopes of the Faroe Shallow. The Norwegian Current carries the young and larvae northward. Fish of 11- 0 23 cm averaging 23-62 cm, account for 42 °/„ in the Il 13 15 17 19 21 23 25 27 29 31 33 35 37cm north-eastern Norwegian Sea (Figure 6:9 F). Young blue whiting are also found in the Barents Sea (Figure Figure 6:9. The size composition of blue whiting in different 6:9 A). areas to the north of the Faroe-Iceland Ridge in 1963. From 1960 to 1964 was observed a gradual displace­ A — Barents Sea, east of North Cape; B — South slope of the Bear Island Bank; C - Sorkapp Deep; D - the Spitsbergen area; ment of the size-frequency peak of M . poutassou in the E - the north-eastern part of the Norwegian Sea; F - the south­ Norwegian Sea to the right by 1-2 cm (Figure 6:10). western part of the Norwegian Sea. it was due to the predominance of the 1958 and 1959 year-classes. Fish of 23-26 cm were again met in Faroe Shallow. On May 25-30, 1966 spent blue considerable numbers in samples from 1965 and the whiting were observed in great numbers at 230-300 m peak of the size frequency moved to the left. on the north-east slope of the Faroe Shallow in the Blue whiting of 14-43 cm are found in trawl Norwegian Sea. Thus, M . poutassou choose for spawn­ catches taken in the area south of the Shetland- ing the banks and slopes of shallows washed by Atlantic Faroe-Icelandic Ridge Figure 6:11. Young fish waters, depths being 180-300 m. The developing eggs (14-23 cm) were mainly observed off Iceland and are carried northward by the current and hatching south and west of Ireland, larger fish (25-42 cm) of larvae occurs over oceanic depths. Based on the south-east of Iceland and on the Lousy, Rockall, and chart of currents in the NE Atlantic and the occur­ Porcupine Banks. M ature fish are also found here and rence of larvae and yearlings, one can conclude that spawning occurs on the Rockall and Porcupine Banks. the young are carried to the Irish Shallow (Celtic In summer 1963/1964 young and mature fish, 30-33 Sea) from spawning grounds in the Bay of Biscay; cm, were observed in the Irish Shallow (Probatov from the Porcupine and Rockall Banks they are and M ikheev, 1965). 120

Table 6:11 shows the growth rate in the Norwegian Sea. The data are similar to those reported by Sae- mundsson (1929) from west Iceland.

FEEDING OF M. POUTASSOU AND POSSIBLE 1960 COMPETITION WITH HERRING

M . poutassou live half pelagically, feeding mainly on 793 planktonic Crustacea and young fish (Table 6:12). 25.38 According to the occurrence (in °/0 of stomachs with food) Euphausiids are most important (78-5 °/0), followed by fry and young fish, mainly Myctophum glaciale, Maurolicus miilleri, young cod, herring, and sand eel. Copepoda and Amphipoda are essential 10 - food items. 1961 The comparison of food in different areas of the m 26.65 NE Atlantic shows that fry are an important food west of Ireland (the Porcupine Bank) and especially in the Barents Sea (Table 6:12): herring and cod predominate in the Barents Sea, Maurolicus and Myctophum glaciale west of Ireland (up to eighteen spe­ 1963 cimens of M . miilleri were found in some stomachs). The next important food in the Norwegian Sea is m 26.92 Copepoda, among which Calanus finmarchicus prevail, particularly in July/August (Zilanov, 1964). The main fattening is in spring and summer (Zilanov, 1964). In winter the feeding activity 1964 n 2883 decreases to some extent. In the pre-spawning period m 28.53 M . poutassou feed on the spawning grounds but during the spawning process many are empty. Spent blue whiting feed intensively. Fat concentrates in the liver, the weight of which is greatest in July/September: 1965 average 7-6-9-1 °/o °f the weight of a fish and up to 15-16 °/0 in single fish. During the spawning process m 26.83 the weight of the liver decreases to 3-1—5-5 °/0. Till recently the main feeders on plankton and small fishes in the NE Atlantic were whales. Since whales were exterminated the rich food resources are 15 17 19 21 23 25 27 29 31 33 35 37 cm mainly used by herring (M arty, 1956) and, as recently Figure 6:10. The size composition of blue whiting in the Nor- shown, by blue whiting (Zilanov, 1964). The distri- wegian Sea in 1960/1965.

Table 6:11. Size-composition of M. poutassou according to age in the Norwegian Sea in 1961

L■ength in cm No. of Average length Age 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 spec- (cm)

1 + 33-3 - 3-33 _ 33-3 3 21-05 2 + 1-0 2-0 4-2 9-6 23-5 38-4 16-0 5-3 94 23-47 3 + 0-9 1-4 14-9 43-3 30-7 8-4 0-4 215 26-33 4 + 10-9 26-0 31-2 16-8 10-9 3-4 0-8 119 28-09 5 + 4-8 - 14-3 14-3 4-8 19-0 23-7 4-8 4-8 21 30-81 6 + 100 1 34-05 1 1 3 4 12 25 68 122 102 58 24 14 8 6 2 2 1 453 25-4 «/„ 0-2 0-2 0-6 0-9 2-7 5-5 15-0 27-0 22-5 12-9 5-3 3-1 1-8 1-3 0-4 0-4 0-2 100-0 121

Table 6:12. Food composition of M. poutassou (in °/o of the occurrence) in different areas of north-east Atlantic

Food The Norwegian The Barents The Porcupine components Sea 1961 Sea 1963 Bank 1966 Euphausiids .... 78-5 38-6 70-0 Copepoda ...... 21-4 -- Them isto...... 6-8 8-7 _ Sagilta...... - m 24.63 0-2 0-8 Pandatus...... - 3-1 - Pisces...... 3-6 56-7 30-0 O thers...... - 10-2 0-1

Fish investigated 709 175 2,106

and herring is observed in spring and summer and 3447 their main food is the same: Euphausiids, Copepoda, 28.64 Amphipoda and young fish. Unlike herring, the feed­ ing of which was not intensive in October and Nov­ ember (Rudakova, 1956), the feeding of blue whit­ ing remains intensive and thus they feed on the winter stock of plankton influencing its abundance in sum­ m 27.96 mer (Boldovsky, 1939). Therefore, competition is quite possible between M . poutassou and herring in different areas of the NE Atlantic. Blue whiting is a food for shark, cod, hake, coalfish, halibut and the appearance of blue whiting in the continental shelf waters means an increase of food for these species.

m 26.05

REFERENCES 20 - B ig e l o w , H. B. & W. C. S c h r o e d e r , 1955. “ Occurrence off the middle and North Atlantic United States of the offshore hake Mertuccius albidus (Mitchill) 1818, and of the blue whiting Gadus (Micromesistius) poutassou (Risso) 1826” . Bull. Mus. comp. Zool. Harv., 113: 205-26. Bo l d o v sk y , G. W., 1939. “Warm-water Gadidae in the Barents n 19197 Sea” . Dokl. Akad. Nauk SSSR, 29 (3). m 24.42 E h r e n b a u m , E ., 1936. “Naturgeschichte und Wissenschaft- Bedeutung der Seefische Nordeuropa” . F’l ü c h t e r , J. & H. R o s e n t h a l , 1965. “Beobachtungen über das Vorkommen und Laichen des Blauen Wittlings (Micromesistius poutassou (Risso)) in der Deutschen Bucht” . Helgoländer wiss. Meeresunters., 12: 149-55. m 16.22 H e n d e r s o n , G. T. D., 1957. “Continuous plankton records: the distribution of young Gadus poutassou (Risso)” . Bull. Mar. Ecol., cm 4 (35). Edinburgh. H e n d e r s o n , G. T. D., 1961. “Continuous plankton records, 1948- Figure 6:11. The size composition of blue whiting in different 1956: Contributions towards a plankton atlas of north-eastern areas to the south of the Faroe-Iceland Ridge in 1965/1966. Atlantic and the North Sea” . Bull. mar. Ecol., 5 (42). Edin­ A - South-west Iceland, June 1965; B - South-east Iceland, burgh. December 1965-January 1966; C - Lousy Bank, January 1966; H e n d e r s o n , G. T. D., 1962. “Young stages of blue whiting over D - Rockall Bank, January 1966; E - Porcupine Bank, February/ deep water west of the British Isles” . Annls biol., Copenh., March 1966; F - Irish Shallow, January 1966. 19: 59-60. M a g n u sso n , J., S. M ag n u sso n & I. H allgrimsson , 1965. “The bution of M . poutassou in the Norwegian, Greenland ÆGIR redfish larvae expedition to the Irminger Sea in May 1961” . Rit Fiskideild., 4: (1) 35 pp. and 4: (2) 86 pp. and Barents Seas resembles that of herring (M arty, M a r t y , Y u . Y u ., 1952. “ Blue whiting. Commercial fishes in the 1956; Zilanov, 1964). The fattening of M . poutassou Barents and White Seas” . 161-2 pp. Leningrad. 122

M a r t y , Y u . Y u ., 1956. “ Main stages o f the life cycle o f the S v e t o v id o v , A.N., 1948. “ The Fauna of the USSR. ” . Atlanto-Scandian herring”. Trudy PINRO, 9: 5-61. Izd. Akad. Nauk SSSR. 9: (4) 221. M a r t in s e n , G. V., 1965. “ World fishery in figures (according to S o r o k in , V. P., 1957. “Ovogenesis and annual development of FAO data, 1963)”. Sbornik nauchno-techn. inf. VNIRO, ;i, the ovaries of cod (Gadus morhua morhua L.)”. Trudy PINRO, 1965. 10: 125-44. P o l o n s k y , A. S., 1962. “Blue whiting on the Porcupine Bank” . T å n in g , A. V., 1958. “ Observations on supposed intermingling Ryb. Khoz., 2. or a certain connection between some stocks of boreal and P r o b a t o v , A. N. & B. I. M ik h e e v , 1965. “Atlantic fish with subarctic demersal food fishes of the eastern and western good prospects for fisheries” . Ryb. Khoz., 9: 3-5. Atlantic” . Spec. Pubis Int. Commn NW Atlant. F ish., 1: 313-25. R u d a k o v a , V. A., 1956. “ Data on the feeding of Atlanto- W h e e l e r , A., 1965. “The occurrence of the blue whiting in the Scandian herring”. Trudy PINRO, 9. southern North Sea”. Ann. Mag. nat. Hist., Ser. 13, 8: 155-59. S a em u n d s so n , B., 1929. “ On the age and growth of the coalfish Z il a n o v , V. K., 1964. “On feeding competition between poutas­ (Gadus virens L.) the Norway pout (Gadus esmarki, Nilsson) and sou and herring in the Norwegian Sea”. Mater, rybokhoz. the poutassou (Gadus poutassou, Risso) in Icelandic waters” . Issled. Severn. Bass., 4. Meddr. Kommn Ha vunders., Ser. Fiskeri, 8: (7) 37 pp. Z il a n o v , V. K., 1965. “The distribution of blue whiting and S c h m id t , J., 1909. “The distribution of the pelagic fry and the prospects for their fishery in the Norwegian Sea”. Ryb. spawning regions of the Gadoids in the North Atlantic from Khoz., 4. Iceland to Spain”. Rapp. P.-v. Réun. Cons. perm. int. Explor. Z il a n o v , V. K., 1966. “The biology and prospects of blue whiting Mer, 10: (4) 229. Micromesistius poutassou (Risso) in the northern Atlantic Ocean” . S c o t t , W. B., 1963. “A note on Micromesistius poutassou (Risso) Mater. Sessii Uchcnogo Soveta PIN R O po Resultatam Isslcdo- from western Atlantic waters” . J. Fish. Res. Bd Can., 20 (3). vanii, 1964, H.

4. OCCURRENCE OF MICROMESISTIUS POUTASSOU (RISSO) LARVAE IN THE NORWEGIAN SEA IN JUNE 1961

By

V. K. Zilanov Polar Institute of Marine Fisheries and Oceanography (PINRO), Murmansk, USSR

In the north-east Atlantic the spawning grounds that fingerlings taken in summer in the Ireland of M . poutassou are known to be in the Bay of Biscay, Shallows are 8—10 cm. A drift of fry to the Barents in the regions to the west of Ireland and Great Bri­ Sea and the areas to the west of Spitsbergen from the tain, to south and south-west of Iceland, and also in spawning grounds off Ireland and Great Britain is the Mediterranean Sea. (Schmidt, 1909, A ndriya- most improbable because these regions are about shev, 1954, H enderson, 1959; M agnusson, M ag­ 2,000 miles apart and in covering this distance the nusson and H allgrimsson, 1965). In spring one can fry would have grown larger. The occurrence of meet here both larvae and one-year-old fish. Fry M . poutassou fry in the Barents Sea and the Spitsbergen from 5 to 15 cm were found by Boldovsky (1939) in areas is understandable, if one assumes that there are the Barents Sea, and by Borodatov (according to spawning grounds in the Norwegian Sea. H ender­ A ndriyashsev 1954) west of Spitsbergen. According son (1957) assumed this but confirmed data were to PIN R O data, during recent years in these regions obtained only lately. specimens 12-16 cm long were met frequently. Judg­ In June 1961 on board R. V. “T unets” (head of ing by their size most of them are fingerlings and expedition: T. K. Sisoeva) ichthyoplankton samples yearlings. For M . poutassou from the Iceland region were gathered over great depths in the western part the length of the yearlings was reported by Saemunds­ of the Norwegian Sea. In these samples M . poutassou son (1929) to be 16 cm. In the southern and central larvae were found. parts of the Norwegian Sea Zilanov (1966) found a For ichthyoplankton sampling the following pelagic size of 19 cm. Probatov and M ikheev (1965) report gear was used: silk egg-net (gauze No. 140) with an