Victor F. Bugaev. 2011. Asian Sockeye Salmon (freshwater period of life, biological structure, population dynamics)// Petropavlovsk-Kamchstsky: Publishing House "Kamchatpress" - 292 pp.
Предисловие к англоязычному изданию
Я счастлив, что моя книга «Азиатская нерка» выходит из печати на английском языке. Она является дословным переводом моей монографии "Азиатская нерка (пресноводный период численности, биологическая структура, динамика численности)" (464 с., формата А5), вышедшей в Москве в издательстве «Колос» в 1995 г. и адресована прежде всего, для англоязычного читателя.
В России эта книга широко известна среди исследователей лососей, на нее часто ссылаются, что свидетельствует о востребованности издания. Но, к сожалению, в США, Канаде и Японии среди исследователей лососей сейчас нет ученых, которые знают русский язык и, на мой взгляд, этот интересный труд незаслуженно остался без должного внимания среди англоязычной ихтиологической общественности.
В середине 1991 г. я начал писать свою книгу и сообщил об этом нескольким своим зарубежным знакомым. В ноябре 1991 г. я, неожиданно, получил телеграмму от директора Тихоокеанской биологической станции (г. Нанаймо, Канада) доктора Дика Бимиша (Dick Beamish) “I will help you book in English please let me know when you expect to have manuscript completed and the number of pages and figures”. Эта телеграмма резко подняла мою активность в процессе написания книги. В феврале 1993 г. я эту книгу закончил и передал в Канаду для перевода на английский язык.
Перевод книги на английский язык осуществили в Department Fisheries and Oceans Government of Canada. К осени 1994 г. перевод книги в основном закончили, который был выполнен H. De (основной текст, подписи к рисункам, список литературы).
В мае 1995 г. я выезжал в Канаду, где вместе с доктором William Ricker мы произвели некоторые уточнения по тексту перевода и закрыли все вопросы, возникшие у него. Одновременно житель г. Нанаймо Ed Elliot принял участие в переводе подписей к табличному материалу. Осталась техническая работа по подготовке рукописи к печати канадской стороной.
Пока рукопись книги переводили на английский язык, с помощью директора Камчатского научно-исследовательского института рыбного хозяйства и океанографии (КамчатНИРО) доктора М. М. Селифонова, в апреле 1995 г. я опубликовал ее в России на русском языке тиражом 1000 экземпляров (который сейчас уже практически закончился – осталось около 50 экземпляров книги).
К сожалению, пока шел процесс написания книги и ее перевод, экономические обстоятельства в Канаде изменились и спонсор данного издания – Тихоокеанская биологическая станция, не смогла найти средств, чтобы ее издать и завершить проект в 1996 г.
Несколько лет ситуация была неопределенной. Время остановилось. В связи со сложившимися объективными обстоятельствами личного плана (тяжелой болезнью), я смог вернуться к вопросу о подготовке к публикации англоязычного варианта книги только весной 2004 г., которую решил опубликовать в России. Ситуация осложнялась тем, что у доктора Д. Бимиша не имелось электронного варианта рукописи (она была отпечатана на пишущей машинке), имеющиеся материалы необходимо было оцифровать и уже потом внести корректуру В. Риккера, сделанную в манускрипте.
Но вернувшись к работе над рукописью, в некоторых местах я не смог разобрать почерк В. Риккера и внести в электронный вариант все его редакторские правки. Это также затормозило работу. В 2005-2010 гг. я был сильно загружен издательской деятельностью: подготовил и опубликовал (часть из них в соавторстве) ряд научных и научно-популярных книг по биологии нерки и других тихоокеанских лососей: «Рыбы реки Камчатка» (2007), «Рыбы бассейна реки Камчатки» (2007), «Нагульно-нерестовые озера азиатской нерки» (2008) и др.
В связи с большой нагрузкой, я окончательно закончил работу над английской версией книги «Азиатская нерка» только в сентябре 2010 г. В итоге, некоторые замечания В. Риккера я все-таки внести не смог и подготовил ее для издания в том виде, насколько мне это удалось. Я понял, что если не опубликую книгу сейчас, то этого может не произойти никогда. Люди не бессмертны. Поэтому, те погрешности в тексте, которые могут быть встречены англоязычными читателями, могут быть отнесены на мое плохое знание английского языка и не связаны с редакторской правкой доктора В. Риккера.
В заключение, я хочу выразить свою искреннюю благодарность специалистам, осуществивших перевод моей книги с русского языка на английский язык: Х. Де (H. De), Эду Элиоту (Ed Elliot) и ныне покойному доктору Збигневу Кабате (Zbignev Kabata) (принимавшего участие в переводе некоторых трудных мест в рукописи), а также сотруднице КамчатНИРО Виктории Плищенко, подготовившей оцифрованный вариант книги.
Особую признательность и благодарность я хочу выразить ныне покойному известнейшему канадскому ученому доктору Вильяму Риккеру (William Ricker), и доктору Р. Бимишу (Richard Beamish) проделавших большую редакторскую работу по литературной обработке английского варианта рукописи.
Я надеюсь, что публикация моей монографии «Азиатская нерка» на английском языке будет способствовать сближению ученых многих стран, использующих лососевые ресурсы Тихого океана.
Но надо подчеркнуть, что публикация данной книги сейчас не была бы возможна без решения директора Камчатниро д.б.н С. Г. Коростелева и его заместителя по научной части к.б.н. Е. А. Шевлякова опубликовать эту книгу на английском языке, понимавших важность такой публикации. Они смогли решить все финансовые вопросы, связанные с изданием. Книга вышла небольшим тирафом – 200 экз. и предназначена только для англоязычных читателей. Конечно, небольшую часть тиража КамчатНИРО распространит по научным библиотекам рыбохозяйственных институтов и ведущих университетов России, как образца уникального издания российско-канадского сотрудничества.
SUMMARY
This book represents a generalization of long-term observations on the Asian sockeye, and is based on the 20-year results of the author's research of the species. The need for this type of generalization became apparent long ago, for researchers often could not obtain the necessary information on the biology of the Asian sockeye due to the complete absence or obsolescence of such data, and often to the incompatibility of the methods used to derive these data.
We have attempted to make maximum use of the oldest archival data available to us, and to interpret them from the positions of our own practical experience in researching the biology and population dynamics of this species. We do not lay claim to exhaustive information on all the aspects of sockeye biology in this book; we limited ourselves mainly to the study of the freshwater period of its life cycle, though we understand perfectly that the biological characteristics of the sockeye are made up of complex cause-and-effect relationships that exist between the freshwater and sea periods of this species' life cycle.
The Asian sockeye is found in greatest abundance on the Kamchatka Peninsula, where approximately 90-95% of all the Asian sockeye is harvested in some years the watersheds of the Kamchatka and Ozernaya rivers.
As a result of our study of the scale structure in the juvenile and adult sockeye, the incidence of its infection by the indicator parasite Diphyllobothrium sp., as well as the migrations and growth of juvenile sockeye in the Kamchatka R. watershed, we have come to distinguish the following local second-order stocks and their groups.
1. A group of local second order stocks of the tributaries in the upper and middle reaches of the Kamchatka R., the young of which migrate downstream to the sea as underyearlings (“S”).
2. A group of local second order stocks of the tributaries in the upper and middle reaches of the Kamchatka R., the young of which spend their first year in the vicinity of the spawning grounds and migrate seaward the following year (“V”).
3. A group of local second order stocks of the tributaries in the lower and to some extent
middle reaches of the Kamchatka R., the young of which migrate as underyearlings to forage in Azabach L., and migrate seaward the following year (“E”).
4. The local second order stock of Azabach L., the young of which forage together with the young of group “E”, and spend mostly two winters in the lake (“A”).
5. The local second order stock of Dvukhyurtochnoye L., the young of which spend
mostly two years in the lake (“D”).
6. The local second order stock of the brackish Nerpichye L, and a group of local stocks from the tributaries of the lower Kamchatka R., the young of which migrate to Nerpichye L. to forage (these structural components are indistinguishable in the catches); the young of the stock and group spend one winter in the lake (“N”).
7. The local second order stock of Kursin L., the young of which spend mostly one year in the lake (“K”).
All of these stocks and some of the groups have an early (spring) and late (summer) seasonal race of the sockeye (“E”, “A”, “K”, “N”, “D”). Some groups are represented by virtually one seasonal race, e.g. group “S” by an early race only, and “V” by a late race; as a whole, they reproduce in the same area. In the case of the sockeye, we regard the seasonal races as structural components of local sub-stocks.
Unlike the sockeye of the Kamchatka R, which spawns and forages throughout the tributaries and certain lakes of the river watershed, the sockeye of the Ozernaya R. reproduces strictly in the Kuril L. watershed. The small Etamynk L. from which the Etamynk R. flows into Kuril L. is the second spawning and foraging ground of the sockeye in the Ozernaya R. watershed, but the abundance of this species in Etamynk L. is very low and can hardly be compared with that of Kuril L. Two seasonal races of the sockeye exist in the Ozernaya R. watershed, but one of them (the early race) constitutes only about 1-2 % of the total numbers, and therefore it was believed that the sockeye of Kuril L. was homogenous in composition and had no seasonal races.
We have discussed the July–November migration of underyearling sockeye from the tributaries of the lower and middle reaches of the Kamchatka R. to Azabach L. (group “E”). The average size of the juveniles migrating in July–beginning of September is slightly smaller than of those migrating later on. In the underyearlings that migrate to the lake, a zone of adjacent sclerites, which is not an annulus, forms on the scales after their migration to the lake watershed. In Azabach L., the overwintered young of group "E" and stock “A” (all age groups) resume their growth virtually at the same time.
In the overwhelming majority of cases, the juvenile sockeye migrate downstream from Azabach L. with two zones of adjacent sclerites (ZAS) on their scales. The young of group “E” migrate downstream from the lake at age 1+ and the young of the Azabach L. stock at age 2+. The yearling smolts of group “E” have two ZAS on their scales (the first a supplementary one, and the second an annulus); the two-year-old smolts of the Azabach L. stock do not usually have supplementary ZAS. A method for identifying fish of the Azabach L. stock and group “E” among the downstream migrants has been developed on the basis of the definition of the ZAS and, to a smaller extent, the number of sclerites in the existing zones of scale growth, as well as the incidence of infection by plerocercoids of the genus Diphyllobothrium and the number of gill rakers.
Unlike Azabach L. where up to 50-70 % of all the juvenile sockeye of the Kamchatka R. feeds and grows, the brackish Nerpichye L. (one of the largest lakes of NE Asia) is not a very important foraging ground for the juvenile sockeye from the tributaries of the Kamchatka R. We believe the instability of the forage base during the salinization of Nerpichye L. to be the cause of the insignificant migration of juvenile sockeye to the lake in comparison with the situation in Azabach L., Nerpichye L. belongs to the shallow lakes where depths of 4-5 m predominate. In freshwater lakes of this type, the forage base for juvenile sockeye fluctuates. Therefore, even during the freshwater periods of Nerpichye L., it probably is not a prime foraging ground for young sockeye of the Kamchatka R. watershed. However, in our opinion, the importance of Nerpichye L. as a foraging ground for juvenile sockeye from the tributaries of the Kamchatka R. increases during the freshening period.
The structure of the scales in smolts (body length) of the aboriginal (stock “A”) and transitory (group “E”) juvenile sockeye migrating from Azabach L., as well as the central part of the scale in adult sockeye of stock “A”, which corresponds to the growth of the young during the freshwater period, undergoes regular changes that depend on the level of the forage base in the lake, the water temperature and the abundance of parent fish.
The central part of the scale in adult sockeye from Kuril L., which corresponds to the growth of the juvenile sockeye during the freshwater period (body length of smolts), changes according to the level of the forage base and water temperature in the lake. The strongest relationship is noted between the number of sclerites on the scales of age 2.2 and 2.3 individuals during the first and second years and the abundance of Cyclops scutifer in the lake in August–October. The latter indicates that August–October is the main period of growth for the young of the sockeye here. The relationship between the number of sclerites and the water temperature in the lake is a subordinate one. Analysis of the influence of water temperature on the spacing of the sclerites (with subdivision into years of high and low abundance of juveniles in the lake) has shown high reliable correlations with water temperature at certain depths. The interannual variability in the thermal stratification of the near-surface and abyssal waters of Kuril L. can affect the growth of juvenile sockeye. With the abundance of Cyclops in the lake down to a certain level, the young of the sockeye grow better with small temperature gradients, but with an increase of Cyclops abundance above this limit, they grow better with higher temperature gradients.
Our study of the food interrelations of the fish foraging in the pelagic zone of Azabach L. now makes it possible to draw certain conclusions regarding the factors that determine the changes in the abundance of some species of fish in the watershed of Azabach L. and the Kamchatka R. We believe that the recently observed increase in the abundance of the freshwater form of the threespine stickleback (leiurus morph) in Azabach L. is related to the specialized fishery of the anadromous form (trachurus morph) in the lower reaches of the Kamchatka R. during 1979-1984, which was stopped in 1985 due to overexploitation. Prior to overfishing, the migratory form of the threespine stickleback spawned extensively in Azabach L.
Underyearlings of the migratory form (trachurus morph) migrate from Azabach L. to the sea in masses at the end of August–September. Underyearlings of the two forms of the threespine stickleback have a high degree of food similarity in the lake. We expect that before the specialized trachurus fishery got underway (this morph spawns slightly earlier than leiurus), the high abundance of underyearling trachurus suppressed and limited the numbers of leiurus through food competition during the first summer. This created more favourable foraging conditions for the young of the sockeye. A sharp increase in the numbers of leiurus, observed by us since 1984 and coinciding with the overcrowding of the spawning grounds in the Azabach L. watershed in 1982-1985, may have been one of the major causes of the decrease in the present numbers of the group “E” sockeye, which, based on the average long-term data, amounted to more than 40 % of the total numbers of the Kamchatka R. sockeye. The increase in the abundance of leiurus did not have the same catastrophic effect on the abundance of stock “A” sockeye because the numbers of the latter were greatly limited by the area of the spawning grounds in the Azabach L. watershed. Later, more profound and detailed research into the fish community of this river will be required as recommendations for bioamelioration are developed.
We have also discussed the methods of age determination in the sockeye, as well as methods by which the supplementary ZAS on its scales, which do not reflect the seasonal rhythm of growth of the fish, can be identified.
Analysis of the periods of formation of annuli and the periods of scale initiation in young sockeye salmon from the same waters has shown that the young of the year in all the bodies of water studied resume their seasonal growth (the formation of annuli) before their scales begin to appear, or, in rare cases, the resumption of growth and scale initiation take place at the same time in underyearlings. Therefore, if the number of sclerites in the first zone of scale growth is greater than in the second, we can expect to find supplementary ZAS there.
For more accurate age determination, a knowledge of sockeye biology during the freshwater period can be helpful in some cases. Therefore, the most accurate determination of the length of time spent in fresh (brackish) waters by individuals caught at sea is possible only if we know the waters or the type of river or lake in which the fish grew, or at least its origin (Asian or American sockeye). In the sea period of their life cycle, some sockeye may develop supplementary ZAS on their scales during certain years.
We have examined the age structure of mature fish from 38 Asian stocks of the sockeye. Individuals of age 1.3 predominate in the sockeye on the western coast of the Kamchatka Peninsula, except for the sockeye of the Ozernaya and Palana rivers where spawners with two freshwater years of growth predominate (of age 2.2-2.3 and 2.3 respectively). In the sockeye on the eastern coast of the Kamchatka Peninsula, the age structure is more varied as a whole, but individuals of age 1.3 predominate in the river stocks. Most of the Kamchatka R. sockeye from the catches of the USSR (Russia) are of age 1.3, and less commonly 2.3 and 0.3. In the sockeye of the same stocks and groups, we observe differences in the age composition of the fish caught by drift nets in the river and trap nets at sea, as well as differences in the timing of the spawning migration. The age structure of fish from catches differs significantly from the age structure of the reproductive part of the sockeye stock of the Kamchatka R., which is related to the effect of the fishery on its structure. Having determined the ratio of the spawned out stocks and groups (on the basis of aerial survey data from 1957 to the present) and knowing the age at which most of the fish attain sexual maturity, we derived the age composition of the reproductive part of the stock since 1957. The results of our research have changed the traditional concept of age structure in the sockeye of the Kamchatka R., and are now being used successfully to predict the abundance of its spawning runs. A highly unusual age composition is noted in the individuals from the Ananapylgen R. where we encounter a large number of fish with 4-6 freshwater years of growth. The age structure of the Asian sockeye can be affected by various factors (population abundance, availability of food, type of river or lake, etc.). As a whole, a negative relationship between the average duration of the freshwater and sea periods is noted for the Asian sockeye.
The changes observed in the size characteristics (analysis of weight characteristics unfeasible due to lack of material) of mature sockeye within our study areas (from Iturup Is. to Eastern Chukotka) indicated a correlation with the geographic latitude at which the river estuary inhabited by the sockeye is located.
Our analysis of the interannual variability of the body length and weight of mature male and female individuals of the Ozernaya sockeye in the most abundant age groups (2.1, 2.2, 2.3, 2.4, 3.2 and 3.3) in some cases showed reliable correlations between the abundance of the pink salmon and that of the sockeye during 1970-1991.
After the Western Kamchatkan pink salmon attained an extremely high level of abundance and the spawning grounds became overpopulated in 1983, the abundance of the even- and odd-numbered year-classes of the Western Kamchatkan pink salmon began to change in 1985, and has continued to change up to the present day. As a result, the abundance of the Western Kamchatkan stocks and the pink salmon of Northeastern Kamchatka began to fluctuate in the opposite phase. This taken into consideration we examined the interannual variability of size in the Ozernaya sockeye for two periods. For the period 1970-1984, we noted the highest negative relationships between the body length and weight of the Ozernaya sockeye and the abundance of the Western Kamchatkan pink salmon, and slightly lower values of length and weight dependence on the abundance of Ozernaya and Kamchatka R. sockeye. We did not at any time note any reliable correlations with the abundance of the Eastern Kamchatkan pink salmon, as we examine 1985, a very brief period of observations, we also note reliable correlations in some cases, both with the abundance of Western Kamchatkan pink salmon (positive), and with the abundance of Northeastern Kamchatkan pink salmon (negative). Considering the fact that the sockeye and the pink salmon are food competitors in the sea, we can assume that the change in the abundance of the even- and odd-numbered year-classes of the Western Kamchatkan pink salmon was probably responsible for the change in the food competition of these species of salmons since 1984. These data suggest that the abundance of Western Kamchatkan pink salmon has had some influence on the size of the sockeye from the Bolshaya, Kamchatka and Khailyulya rivers (material on other rivers not discussed). The absolute fecundity of the Asian sockeye depends primarily on the size of the females. The changes in fecundity are also discussed for individuals of age groups.
Analysis of the population dynamics of two major Asian stocks of the sockeye, the Ozernaya R. and Kamchatka R. stocks, has shown that the first is a highly abundant stock at the present time, while the second is at a very low level of abundance.
Over the past few years, the spawning grounds in the Ozernaya R. watershed (Kuril L.) have been continuously overpopulated. The high abundance of this stock is due to a number of factors, namely fertilization, improvement of survival conditions and reduction of the Japanese high seas fishery.
In the Kamchatka R. watershed, because of the differences in the biology of the freshwater period, the known local sockeye stocks and sub-stocks have their own specific dynamics of abundance. The overall dynamics of abundance of the Kamchatka R. sockeye is considered to be the sum of the fluctuations in the abundance of each of its components. In the Azabach L. watershed, we periodically observe the overcrowding of spawning grounds by adult sockeye, which has a detrimental effect on the population dynamics of not only stock “A”, but also group “E”. This is due to the fact that the individuals of stock “A” and group “E” are food competitors.
The fluctuations in the abundance of sub-stocks of the Asian sockeye on the Kamchatka Peninsula are characterized mainly by the data on the overpopulation of spawning grounds, due to the absence of fishery statistics for individual rivers.
The abundance of the sockeye sub-stocks of Western Kamchatka fluctuates synchronously with that of the Ozernaya R. sockeye, i.e. the abundance of the latter increases concurrently with the abundance of sockeye in the small rivers. Only the sockeye stock of the Palana R. is an exception to this rule.
As we examine the prospects of natural and artificial reproduction of the sockeye in Asia, we must proceed from the fact that these prospects are limited because this region does not have a great number of lakes that would be suitable for the foraging of the young prior to their downstream migration. Fertilization of certain bodies of water and rational utilization of the sockeye stocks are the resources by which the abundance of the Asian sockeye can be increased. The freshening of the brackish waters of Nerpichye L., which is not at all a difficult task, could increase the abundance of sockeye in the Kamchatka R. watershed.
The situation concerning sockeye abundance on the Kamchatka Peninsula could be altered considerably by creating a stock of anadromous sockeye using the Kronotskoye L. stock of kokanee (freshwater form of sockeye) as a base. However, the fact that Kronotskoye L. is located on the territory of the Kronotsky State Biosphere Reserve, where all hunting and fishing activity is prohibited, prevents us from doing so.
In a complex, the Asian sockeye is a component of the ecosystem of the northern part of the Pacific watershed, as is each of the components of its populations. In the interests of the fishing industry, the local stocks of the Asian sockeye should be maintained in such a way as to enable them to utilize the resources of their environment more fully and to preserve the best population structure from the economic point of view. A knowledge of the biological characteristics of the species makes it possible, at least theoretically, to visualize the negative consequences of changes to the population structure of the stocks, and to prevent situations in which the probability of these negative consequences would be particularly high.