!ARCHIVES . FISHERIES, RESEARCH BOARD:OF CANADA' Translation Series ,No. 112 WHITEFISH GENUS -- COREGONUS By G.V.Nikolsky .From: - Chastnaia Ikhtiologiia ! Moscew, 195 -. Translation pf pp. 1604,63 ! •Preliminary- translation 1).y Donald E Wohlschlag Stanford -University. 1 (Checked .by Mrs . Lisa Lanz). •istributed by Fisheries , Research Board; of Canada Arctic Unit, •50 5 Pine AVenue W. 1 Montr ea 1 1 P Whitefish Genus -- Coregonus by GV.Nikolsky These differ fromthe beloribitsa (Stenodus leucichtbm.) by having smaller mouths and are usually rather depressed on the sides of the body. The scales are coarser than those of salmon. The colouration on the sides is usually uniform, silvery; the back is darker. Eggs, in contrast to the eggs of other salmon014,, are small. It is a widely distributed arctic genus including " many forms populatiag basins of the Arctic Ocean, northern Atlantic and Pacific Oceans both in Europe and in Asia, and in North America. Biologically whitefish are very diversified: among them there are migratory, river, and lake fish. In manner of feeding they are likewise diversified: there are among them plankton feeders, benthos feeders, and carnivores on small ani- mais. Systematically whitefish are as yet very badly worked out. It is possible to divide all the whitefish into three groups, distinguished by the position of the mouth: (1) whitefish with superior mouth -- riapushka Coregônus albula (L.) and Coregonus sardinella Val.; (2) whitefish with terminal mouth -- omul Coregonus autumnalis (Pall.), tugun Core5onus tugun (Pall.), peled Coregapus neled (Gmel.), etc.; (3) whitefish with inferior mouth-- chir Coregonms nasus (Pall.), muksun corelonm muksun (Pall.), all the diverse forms of species of Coregonus lavaretis (L.) and balok Coregonus nylindraceus (Pall. and Penn.) (fig. 106). Whitefish with superior mouths -- schooling fish, predominantly feed on plankton. In our waters there are two species: Baltic riapushka Coregonus albula (L.) and Siberian riapushka or zeld Coregonus sardinalla Val. Baltic, or European, riapushka Coreg.2aus albula (L.) is distributed from Ireland and England to the basins of the Baltic Sea. It is in certain,lakes in the Volga basin (Plesh- cheyevo or Pereal.avskoe' Lakes ,), The sizes of the riapushka ,Liapushka, tugun, omul, peled are included in the subgenus Leucichthys. Chir, the Ussur sig, hadar, muksun, and ordinary sig are included in the subgenus Coregonus. Balok (C.gylindraceus) is referred to the subgenus Prosopium. -2- range to 46 cm. The riapushka (occurs as a) semi-anadromous or lake form. From the Gulf of Finland, the riapushka in schools at the end of August entett; -into th3Neva and stop, not getting up to Lake Ladoga. 'Th the Ladoga, Onega, Pereslavl and other lakes, there are lacustrine formà of riapushka. In these lakes in the summer the riapushka occurs in schools, usually located out from shore, but at night it (the riapushka) breaks up into small strings. Summer migrations of riapushka both in lakes and in the Baltic Sea are connected with the dilstribution of its food, mainly peagiccTusUceans. In Lake Onega the principal position is occupied b,ipBosmina and DaDhpia in the feeding of riapushka. In Lake Pereslavl Pmf4h2Irep_hes, followed further by Diaptomus and Çmçloos,. In 24 hours a riapushka 16 cm. long (known for Lake Plensk in Germany) eats up 35,200 cladoceran ceastaceans and 25,000 copepod crustaceans during the time of nagul (wandering). The riapushka feeds most intensively in summer, but feeding persists in winter. Completely, the feeding of the riapushka stops at the time of spawning. The riapushka in Ladoga, Onega, and Pereslavl Lakes grows rather rapidly. GROWTH OF THE RIAPUSHKA IN DIFFERENT LAKES 11 12 13 14 1 5 16 L.Pereslavl 10.8 17.2 23.2 26.4 28.8 30.6 L.Ladoga (ripusa) -- 19.9 24.1 25.1 (data with growth increments 2+3+4+) L.Onega 11.4 13.2 14.5 16.1 ditto In Lakes Ladoga and Onega there are two forms of riapushka: fast growing -- ripus, or kiletz, and the slow growing (form). The ripus grows to maturity later (than is) typical of riapushka at the age of 3+, 4+, but the riapushka matures at the age of 2+.. Spawning of the riapushka proceeds in the autumn. In Lake Pereslavl, it spawns eggs at the end of November until the middle of December. Spawning proceeds on sandy bottoms at a temperature rather higher than 0° (Borisov, 1924). In Lake Onega the riapushka spawns on the twentieth of October to 15 November; it starts spawning usually at a temperature around 5° C. It spawns ongrerolly and sandy bottoms. The small Onega riapushka produces about 720 to 7779 little eggs. The average produced is around 3000 eggs. The large Ladoga4Onega riapushka is more fecund. The average produced by the Neva (River) riapushka is about 5000 little eggs. Larvae emerge from the eggs in March to April, absorption of the yolk sac proceeds in 3 to 4 days, after which the fish transforms into the active feeding stage. A- great amount of eggs and larvae of riapushka are destroyed by predatory fish. 1 -3- The riapushka is an important item of commerce; it is caught by us in the Gulf of Finland and Neva (River), in Karelian lakes, in Pereslavl and other lakes. Exploitation is carried out with the use of seining, weirs of netting and fykes (a trap type of large fyke). CATCHES OF RIAPUSHM IN DIFFERENT LAKES (in centners) (1 centner = 50 kg.) 1936 1937 1938 1939 Southern part of Lake Ladoga 1,666 1,315 1,285 1,078 Lake Onega 13,180 10,126 9,322 7,822 Pskovsko-Chudskoye Lake 1,164 767 6,748 7,612 A cyclic fluctuation on catches has been observed for riapushka in a series of basins. It has been noted by P.G.Borisov (1924) for Lake Pereslavl, V.V.Pokrovski (1938) for Lake Onega and for a series of similar basins. The source of this periodi- city is not as yet clear. The riapushka was successfully ac- climated in some Ural lakes where it became ahcbject of commer- cial exploitation. In the Urals the ripus is acclimatized both in deep lakes with comparatively cold waters (for example, Lake Wilda) and in shallow, highly warmed (lakes) (Lake Shartash). In the Ural lakes the ripus has a significantly more rapid growth and is already mature in the second year of life (in year-class 1+). In certain Ural lakes the ripus changed into feeding on benthos (larvae of chironomids). The ripus appears to be a good object for pond ilâming, and in the same way as ac- climatized (introduced fish) in lowland lakes and reservoirs. The riapushka has been successfully acclimatized in certain reservoirs of the Moscow canal. The Siberian riapushka. -- Core- _minus sardinella Val0 is widely distributed over the littoral of the Arctic Ocean from the Béloye (White) Sea to North America. Sizes up to 42 cm., weight -- up to 500 g0(1500 g0 would seem more realistic. D.E.W.) At the limits of areal (distribution) there are evolved a series of geographical races. The Siberian riapushka are semi-anadromous or fresh- water fish, inhabiting lower parts of rivers, and lakes not located far from the sea. -4- The principal places (of occurrence are as wandering riapushka (in marine coastal waters) spawning (riapushka) in Siberian rivers, (riapushka)'occürring usually•in regions near river mouths, often at junctures of fresh and brackish waters. Immature individuals stay near shore more than the adults. The Siberian riapushka feeds the same as the Eurepean (riapushka) on plankton crustaceans. In the downstream-(lower) Ob, its principal items of food are BosminaBvthotrephes, Diaptomus., and related crustaceans; in the lower Yenesei it eats chiefly'the crustacean daphnids, diatoms, mysijs e (Podlesnyi, 1945) 1 Individuals, which stay in a river, feed partially on benthos (lar.ïrue of mosquitoes and caddis flies) and terrestrial insects (ivanchinov, 1935). Mature Siberian riapushka in different • waters do not grow at the same rates. The earliest ripening , L riapushka is in the lower Ob; here males spawn in 3 - years, • females -- 4 -- 5 years. The most retarded in ripening is the Lena riapushka, where males grow to maturity in 6 years, and females -- in 7 years. The movement of riapushka in the Ob begins in June and is completed at the beginning of September. Approximately at these times, the riapushka migrates in the Yenesei. In the Lena it enters a little later, in August and September, and the.movem4nt is continued until October. Spawning in the Ob basin (Shchuchya River (ca. 67 0 N 68° 15' E)) proceeds at the end of September to the beginning of October at the time of temperature of 1 - 2° C. Eggs are deposited on the bottom on a gravel or sand substrate. In the Yenesei spawning proceeds in the second half of October. In the Kolyma, the riapushka spawns at the end of September. Fecundity of the Ob riapushka is about 7,011 to . 18,281 eggs;• Yenesei -- about 2,500 to 23,600 eggs; Lena, on the average, 17,000 eggs; that is more than for the European(form). After spawning is completed, the riapushkk drifts downstream. A fraction of the individuals of Siberian riapushka are lost after spawning. The hatching of larvae from thp, eggs in the Ob occurs in:May, and they as yet have not absorbed the yolk sac and are carried• downstream where they wander around. The Siberian riapushka grows usually with somewhat the rapidity of the European riaPushka. The limiting age of the western Siberian riapushka, eVidehtly, is 8+, of the eastern Siberian (riapushka) -- 11+ 0 In the lower parts, of Siberian rivers, the riapushka- appears to be one of the most important commercial fishes, Occupying among the whitefishes in the catches the third or fourth place (after omul and muksun).