IARCHIVES FISHERIES RESEARCH BOARD OF CANADA Translation Ser3esA No. 181 ON THE SCALE PATTERN OF KAMCHATKA SOCKEYE OF DIFFERENT LOCAL POPULATIONS By F. V. Krogiusa Doctor of Biological Sciences, Kamchatka Branch9 Pacific Research Institute for Fisheries and Oceanography (TINRO) Original titles 0 stroenii cheshui Kamchatskoi krasnoi raznykh lokalnykh stad Froms Materialy po biologii morskovo perioda zhizni dalnevostochnykh lososeie pp. 52-63, 1958. Published by Vsesoiuznyi Nauchno-Issledovatelskii Institut Morskovo Rybnovo Khoz.iaistva 3 Okeanografii (VNIRO)9 Moscow Translated by R. Eo Foerster Distributed by the Fisheries Research Board of Ganada9 Biological Station9 Nanaimoq B. C. 1958 [b. 521 In connection with studies of the distribution and routes of migration of salmon in the northwest portion of the Pacific Ocean, conducted by the Kamchatka Division of `fllüE?.0, it became necessary to ascertain if it is possible to determine9 by some method other than tagging, from what spawning river basins the sockeye (Oncorhynchus nerka Walb) caught in the ocean origlnateo Conditions during the residence of sockeye in the spawning-nursery areas of Kamchatka and during the ocean period of their life on the routes of migration, and probably also in the marine feeding areas, are dissimilar for different stockso Thus differences arise in the periods of residences of the young sockeye in different nursery areas and in the ocean, i.e., variations occur in the rate of maturity and growth of sockeye of separate stocks. All these characteristics of life and growth of the sockeye are reflected in the pattern of their soaleso Long age.^ it was established that the scales of sonkeye, reared in different spawningGnursery a,reas, had dissimilar patterns (Gilbert, 1914m1925-, Foerster, 1929? Krogius and K.•okhin, 1956? Gerry Kiddq 19^°^6)o Howeverf, not baving a sufficiently representative knowledge of the patterns of scaleWp by which the fish, c•aughi, in the ocean, could be related to thd particular stocks produced in the different rivers, much confusion existed. With a view to investigating this question, there was undertaken, in 1955, a comparative study of the scales of sockeye originating from those different spawning areas of the Kairi,.;hatka pe^insssla, which were the best known or which were of greatest :>a gnifüoance in t.h^.^ reproduction of these salmono The length of life of young s4,ckeye, prior to descent to the sea, in different spawning.._,nut.ses`:1 areas comprises from a few months to three or sompm, times four yea.t•E.o From the r:â.ver::, and sprengs the young migrate downstream u..^^ually as yearlings and rarely a und.wx`yC,-'rrliSlgs and t?iUo°yenr°oldso In the lakes the young :ï el'!s"kin not l es4.5 than one yGar<, in many of the lakes of the K6'•mehat,ka p11Y7in;',ilrl: a ',ti.h W, young continue to feed for two to three yearso Differences in hydrological and feeding conditions in the different lakes, rivers and springs, lead to dissimilar growth of the young and, c;onse® quently9 to different scale patternss in some areas the young sockeye may have in a year only a few solerites, in others the number of sclerites may range from 15-20o However in mono-typ3o rearing areas the conditions of life cannot always cause substantial differences in rate of growth of the young and consequently in the pattern of the central part of the scaleo Such differences are not deteoted, for example, in comparing the lazabaciva°°, produced in the springs of the Kamchatka, Paratunka, V^.^rovski river systems and the sockeye from Kurile Lake (Càzernaya River system) and from Lake Azabachi (Kamchatka River system). In such cases it is necessary to base the recognition of sockeye preferably on the differences in the pattern of the ocean zone of the scaleo ^po 50 The seaward migration of young sockeye in different areas of the ocean takes place in dif fer ent months ? in some cases even prior to the commencement of spring growth, in others - not until after the resumption of new spring growth of the youngo In the latter seaward migration the freshwater zone of growth of the scales terminates in several wider scr erites, laid down after the narrow °°winter°° oneso It may terminate with narrow 00winter'° scleritesa if the seaward migration takes place before the commencement of intensive summer growtho For early seaward migrations the °°winteb °° sclerites can even be absent slnce, according to the calendar, they develop usually in the spring or even at the beginning of the sunmero - 2 - . All these features in the scale pattern can occur among young sockeye in a single area or can be noted in different yearso But9 in general9 certain characteristic scale patterns usually predominate in sockeye of any single stock, Their understanding or recognition requires observation of material over several. ,. yearso In order to differentiate the patterns of scales we have. used the following indices or criterla.- 1o A count of the number of sc5erites, laid down during each year of life of the fish in fresh water or in the seao In the ocean zone of the scale the wide ("summer°°) and narrow ("winter") sclerites were counted separatelyo 2. A determination of the size of the scale at the end of each period or year of life (from the beginning to the end of the band of narrow fi1win-kert9 sc ^.er^,tes) 0 This made it possible to estimate the mean w^.dth of the sclerites (measurements made by ocular micrometer with constant magniflcatzon)o 3o A notation of the character of the scierites9 which can have either straâght, cr.ooked, broken or forked formo In the ocean zone of growth the transition or change from wide sclerites to narrow and again to wide can be sudden or gradual. It was sometimes difficult to determine the narrowest Bclerites. The presence or absence of "winter" sclerites or sclerites of second summer growth in the freshwater zone region of the scale was also notedo 4o The shape of the sockeye scale 5._= not always the samee it can be either oval or more _ezrcealara It is necessary to consider this feature carefully since the form of the scale-changes vary considerably even a short distance from that place on the body of the fish where the scales are usually collected ( from the left side of the fish above the lateral gâ.ne, somewhat anterior to the dorsal fin). Our studies have included sockeye sGales from the following river vystemss Kamch,atka, Py^.ga (Apuka river system) and Parattanka (east coast)9 Ozernayag Bolshaya and Palana (west coast) and also Kukhtua,(north coast of Okhotsk Sea)o The characteristic features of the sockeye scales of the Rivers 4zernayag Bolshayas Kamchatka and Paratunka and of Lakes Dalnee and Blizhnee have been determined on the basis of studies of material collected over several recent yearso The characteristics of the sockeye scales from other rivers (Palana9 Kukhtua9 Pylga) were revealed from a collection of only one year for each river, but the collections were made in different yearso The material examined is still insufficient for a complete understanding of the characteristic features of the scale pattern of sackeyea produced in these various river systems,but it does give an idea of the chief types of different patternso Some idea of the differences are shown in the following tableso With reference to the fish caught in the ocean9 belonging to one or other of the stocks9 it is necessary to use both tableso In the tables we do not at present include the data on the dimensions of the scales since these datag with rare exceptions9 do not reveal sufficiently the real dlfferences9 except with the use of statistical methods of vari.ationo However even the information contained in the tables and in the description of the scales is still insufficient for all cases of determ?.natlono For this purpose an atlas is required of photographs of sockeye scales from different areas of the penznsula9 ïncà.udzngfl for each of themg samples for all age groupso 3 [p° 56] Let us summarize briefly the characteristics of the scale J patterns of sockeye from some of the main KamGhatka River spawning groundso Kamchatka Rûvero The Kamchatka River system occupies the greatest areaô its spawning-nursery basins, in which sockeye are reared (riversa springs and lakes) are very dlversifledo It is apparent that in this river system are produced several local stocks of sockeye whose characteristic differences are found not only during the freshwater period of life but also during the ocean pe.riodo A large part of the sQckeye population migrates to the Karnchatka system at an age of 41+ years, l.oea9 has one year of freshwater lifeo Moreover9 a considerable part of the population remains for 2 years in fresh water9 for the most part - these sockeye are reared in the lakeso They return to spawn at ages 42+ and 52¢o These sockeye consist of two typess one with a fast growth^, the other with a delayed growth. For Kamoha`cka River sockeye typical scales have an elongated oval form with uniform9 continuous sclerltes9 rarely Wplit or irregular (orooked). On the sockeye scales from the Kamchatka Rivero as distinct from sockeye from the rivers on the west coast of the Peninsula (©zernaya9 Bolshaya9 Palana), the first sclerites laid down after seaward migration from the rivers are poorly distinguished in width from the remaining sclerites laid down in the first summer spent in the oceano They are auite narrower than in the scales of sockeye from the rlv-ers on the west coast of Kamohatka, in which the first ocean sclerites are wider than the suwsequent, oneso 0°Wis3ter" sclerlt.es, which are considerably narrower than 20siummer°° sc'l^erites are sharply separated off from the latter.