Translation Series No

[4,_RCHIVES7 P FISHERIES RESEARCH BOARD OF CANADA Translation Series, No. 142 CONCERNING THE CAUSES OF A PECULIARITY OF THE PINK SALMON OF THE SEA OF JAPAN By I. B. Birman (Amur Division of the TINRO) Original title: 0 prichinakh odnoi osobennosti iaponomorskoi gorbushi [Oncoriumhus ggiole.scha (Walb.)] From: Zoologicheskii Zhurnal, Vol. 35, No. 11, pp. 1681-1684, 1956. Preliminary translation by W. E. Ricker Distributed by the Fisheries Research Board of Canada, Biological Station, Nanaimo, B. C. 1958 -2- Throughout the whole basin of the Amur, pink salmon since long ago have been numerous in the even years, and as a rule tUey are very scarce in the odd years, which is the time of the abundant runs of gorbusha in the rivers of the Strait of Tartary. [page 1682] Up to very recent years the general abundance of the Amur gorbusha was considerabry greater than that of gorbusha in the Sea of Japan, but only in the even-numbered years; in odd years considerably fewer gorbusha were taken in the Amur estuary than on the two sides of the Strait of Tartary. For example, from 1946 to 1948 (a period having an average level of stock of Amur gorbusha) the gorbusha taken in the Amur estuary were 63,000 centners more than in the Maritime Province and on the western coast of southern Sakhalin. But by individual years the situation was thisg in 1946 and 1948 the catch of gorbusha in the Amur estuary was 2.5 and 4 times greater, respectively, than in the Gulf of Tartary, but in 1947 it was 8 times less. In the Maritime Province the adjacent year-classes of gorbusha are not so sharply distinguished from each other, in respect to abundance, as on the Amur; nevertheless they are not the same in their qualitative characterss in the Strait of Tartary the gorbusha are heavier in odd years, that is, when the pink salmon of the Amur basin are less numerous and in= Tsee the Figure). This can scarcely be a coincidence. In any event, if the gorbusha of any other stock does have an effect upon the rate of growth of the Maritime Province and western Sakhalin.gorbusha 9 that stock must be the gorbusha of the Amur basin. As is well known, the times of the spaivning migration of gorbusha in the Amur estuary, In the northern part of the Maritime Province and on the western coast of southern Sakhalin for the most part coincide, and at the same time are quite different from the times of the spawning migration of gorbusha in other regions of the Far East. For example, on the two coasts of the Strait of Tartary pink salmon begin to enter rivers a little earlier than at the mouth of the Amur, but the duration of the run in all three regions is approximately the same. Thus, in the northern part of the Maritime Province and western Sakhalin the run of gorbusha ordinarily begins during the first decade [10-day period] of June and ends in the third decade of July, and in the Amur estuary the run begins in the second decade of June and ends near the close of July or early in August. Does this not indicate that the pink salmon of the Maritime Province, of west Sakhalin and of the Amur begin their migration to the rivers simultaneously, and from neighbouring regions of the sea? Simultaneous readiness for migration naturally would imply uniformity of the conditions which govern migration. We must suppose also that back in the Quaternary Period the Amur River discharged not into the Sea of Okhotsk, but had its outlet through the territory now covered by the waters of the Sea of Japan, and flowed through it far to the south, including As is well known, among pink salmon there is a well-marked inverse relationship between the rate of growth of the fish and the size of the corresponding year-class: when spawning stocks are small the salmon are of a larger average size than when stocks are comparatively abundant, although under both conditions the individuals are one and a half years old (1+). The cause of this is generally considered to be that when stocks are sparse the availability of food for each individual is greater, and when stocks are abundant it becomes less. An exception to this is afforded by the pink salmon which enter the rivers of the Maritime Province and along the western coast of southern Sakhalin for spawnings these achieve a larger size in the years when their abundance on the feeding grounds is great. All investigators have regarded this peculiarity of the pink salmon of the Sea of Japan as a very puzzling phenomenon." It is true that A. G. Kaganovsky (1949) considers that the large size of the Maritime Province gorbusha in the years of their abundance • can be explained on the basis of the comparatively small stock present in the Sea of Japan, resulting in a condition where "insufficient food does not occur, or it loses its influence to a large extent". However, the same author observes that in such event it is impossible to account for the small size of the gorbusha of the less numerous year-classes. Let us try to explain this phenomenon. The fact is, appar- ently, that pink salmon of the Maritime Province and the west coast of Sakhalin do their feeding along with pinks from a number of neighbouring spawning regions, which latter are more numerous and have their high productivity during years when a weak year- class is produced in rivers of the Japan Sea basin. It is known that everywhere the strong and the weak spawning runs of pink salmon alternate, year after year, a fact which is associated with their always maturing› in the second year of life after hatching from the egg. In some regions the strong runs are present in the even years, and in other, regions in the odd years. Regions of massive production of pink salmon lying close to the Strait of Tartary are the eastern coast of Sakhalin, the southern Kuril Islands, and the basin of the Amur River, including the rivers which drain into the Amur estuary. Along the eastern coast of Sakhalin and in the southern Kuril Islands the large migrations of gorbusha are in the odd years (just as they are on both coasts of the Strait of Tartary), and the size of the fish is greater in the even years. If we compare gorbusha from the rivers draining into the Straitof Tartary with the Amur gorbusha, we observe the following. a r e R01- 2\ 6 \'‘ yo L -49 lt ) VO - -48 'It; i j / . / oi... x- Y k -47 %1 v % -46 4g JO - . 1 _ e. e 70 45 e c; çàk k 60 / \ 44 50 ‘ 1 et ék. 1 e gi- 6.: l ei / 1 JO 1 . 1- / 41 \ / \ 20 ! 'v. 1 1 101- a 1.947e.‘ 1948e. 1949e. Sequence of changes in abundance of the spawning runs of pink salmon, end the length of thé fish, in the Amur basin and in the Maritime Province. 1 -- size of catches in the Amur estuary (d) and in the Maritime Province (6), 2 -- mean length of pink salmon of thé Amur end of the Maritime Province (6) (Bay of Datta, from data of N. F. Pushkereva). [Left-hnnd scale--catches in thousands of centners (i.e., hundreds of metric tons); right-hand scale-- menn fish length in centimeters.] 0 f. -3- in its system all the rivers'of the Maritime Province, western Sakhalin and western Hokkaido (Lindberg, 1946, 1953; Melioransky, 1936). Consequently, not so long ago the gorbusha •of the Maritime Province, west Sakhalin and the Amur River comprised a single stock with one spawning and feeding range. It is certainly not impossible, as I have earlier postulated for the autumn chum salmon of the same rivers, that after the break-up of the united river system of the Palaeoamur into separate [page 1683] parts isolated from each other by the sea, the feeding grounds of the gorbusha of all these parts remained as before. In the northern part of the Strait of Tartary the gorbusha undoubtedly arrive from the southern waters of the Sea of Japan (Derzhavin, 1933; Kaganovsky, 1949). In the opinion of R. Sato (1938), it is from this direction that gorbusha approach the Amur River. Their path to the Amur is pictured by Sato as going through the Strait of Tartary. Whether or not this is true, I am not in a position to say. It is possible that the gorbusha of the Amur (or part of them) and of the Maritime Province, just like the autumn keta of the same rivers, move from one and the same foraging region to their places of spawning by different routes. For our purposes here it is important to know only whence they come, not what exactly are the paths they follow. In the opinion of A. G. Kaganovsky (1949) 9 the larger size of Sea of Japan gorbusha in their years of abundance, and their reverse alternation of years of abundance and scarcity in the spawning migration—these are facts which preclude the possibility of the Amur gorbusha coming from *the same marine region as the former. However, it is known that the alternation of strong and weak runs of gorbusha in various regions can become reversed. For example, along the northwest coast of the Sea of Okhotsk during 1917-1935 the big runs of gorbusha were observed in even-numbered years, but after this period they were in odd years.

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