Assessment of stock, spatial distribution, and recruitment of walleye pollock in the northern and eastern Bering Sea

Abundance and biomass of walleye pollock Theragra chalcogramma in the Bering Sea exceeded the mean values in 2015 owing to the high-abundant year-classes of 2008 and 2012 and several medium-abundant year-classes (of 2006, 2009-2011, 2013, and 2014). In contrast to rather stable distribution on its spawning grounds, distribution of feeding pollock in the northern Bering Sea is very variable and depends on both biomass of the population and long-term and short-term variations of environments, as water temperature and zooplankton abundance. In some years including recent times (2005-2007 and 2010-2014), the pollock migrated earlier and faster into the northwestern Bering Sea and returned back to the eastern shelf also early: in late summer - early autumn. This scenario is supposedly conditioned by low zooplankton abundance over the Bering Sea that forces pollock to active feeding migrations, particularly a deficit of preferable food (large-sized zooplankton) on the north-western feeding grounds could be a reason for its leaving this area in late summer. Strength of pollock year-classes is highly variable, too, and depends mostly on young-of-the-year fish survival in winter. As usual, favorable conditions for reproduction and progeny survival, when strong year-classes appear, are observed in the years or short periods of transition from one state of marine environments to another, whereas long periods of either «warm» or «cold» regime are not favorable for forming of high-abundant year-classes of the Bering Sea pollock.

walleye pollock, Bering Sea, spatial distribution, seasonal migration, year- class strength, stock assessment, recruitment

1. Волков А.Ф. Зависимость питания тихоокеанских лососей от состояния их кормовой базы (по результатам работ экспедиции BASIS в 2003-2012 гг.) // Бюл. № 8 изучения тихоокеанских лососей на Дальнем Востоке. - Владивосток : ТИНРО-центр, 2013. - С. 58-67.

2. Волков А.Ф. Состав и распределение зоопланктона и питание тихоокеанских лососей в западной части Берингова моря и СЗТО в осенний период 2002-2008 гг. (результаты съемок по программе «BASIS») // Изв. ТИНРО. - 2009. - Т. 159. - С. 226-242.

3. Волков А.Ф. Структура планктонного сообщества в восточной части Берингова моря летом-осенью 2012 г. // Бюл. № 7 изучения тихоокеанских лососей на Дальнем Востоке. - Владивосток : ТИНРО-центр, 2012. - С. 112-119.

4. Волков А.Ф., Кузнецова Н.А., Слабинский А.М. Структура планктонного сообщества Берингова моря в летне-осенний период (итоги 3-летней работы российско-японско-американской экспедиции по программе «BASIS») // Изв. ТИНРО. - 2005. - Т. 143. - С. 219-239.

5. Волков А.Ф., Кузнецова Н.А., Фарли Е.В., Мёрфи Д.М. Состав и распределение зоопланктона и питание тихоокеанских лососей в восточной части Берингова моря в осенний период 2003-2008 гг. (результаты съемок по программе «BASIS») // Изв. ТИНРО. - 2009. - Т. 158. - С. 275-292.

6. Грицай Е.В., Степаненко М.А. Межгодовая изменчивость пространственной дифференциации и функционирование восточноберинговоморской популяции минтая // Изв. ТИНРО. - 2003. - Т. 133. - С. 80-93.

7. Дулепова Е.П. Динамика продукционных показателей зоопланктона как основы кормовой базы нектона в западной части Берингова моря // Изв. ТИНРО. - 2014. - Т. 179. - С. 236-249.

8. Степаненко М.А. Возрастная изменчивость пространственной дифференциации минтая Theragra chalcogramma в восточной и северо-западной частях Берингова моря // Изв. ТИНРО. - 2001. - Т. 128. - С. 125-135.

9. Степаненко М.А. Межгодовая изменчивость пространственной дифференциации минтая Theragra chalcogramma и трески Gadus macrocephalus Берингова моря // Вопр. ихтиол. - 1997. - Т. 37, № 1. - С. 19-26.

10. Степаненко М.А., Грицай Е.В. Состояние ресурсов, условия обитания и промысел минтая в восточной и северо-западной частях Берингова моря в начале 2010-х годов // Вопр. рыб-ва. - 2013. - Т. 14, № 2(54). - С. 219-241.

11. Шунтов В.П., Волков А.Ф., Темных О.С., Дулепова Е.П. Минтай в экосистемах дальневосточных морей : моногр. - Владивосток : ТИНРО, 1993. - 426 с.

12. Bailey K.M. Population ecology and structural dynamics of walleye pollock, Theragra chalcogramma // NOAA ERL Special Report. - 1998. - P. 3-54.

13. Bailey K.M., Brodeur R.D., Hollowed A.B. Cohort survival pattern in walleye pollock, Theragra chalcogramma, in Shelikof strait, Alaska: a critical factor analysis // Fish. Oceanogr. - 1996. - Vol. 5 (suppl. 1). - P. 179-188.

14. Brodeur R.D., Kruse G.H., Livingston P.A. et al. Living marine resources (Groundfish, salmon and crabs // Rept. FOCI Intern. Workshop - Recent Conditions in the Bering Sea, 1998. - Р. 37.

15. Eisner L. The Bering Sea: Current status and recent trends // PICES press. - 2016. - Vol. 24, № 1. - P. 42-45.

16. Hunt G.L., Jr., Coyle K.O., Eisner L. et al. Climate impacts on eastern Bering Sea foodwebs: а synthesis of new data and an assessment of the Oscillating Control Hypothesis // PICES press. XIX Ann. Conf. - 2010. - P. 15.

17. Hunt G.L., Jr., Coyle K.O., Eisner L. et al. Climate impacts on eastern Bering Sea foodwebs: a synthesis of new data and an assessment of the Oscillating Control Hypothesis // ICES Journ. of Marine Science. - 2011. - Vol. 68(6). - P. 1230-1243.

18. Ianelli J.N., Hollowed A.B., Haynie F.J. et al. Evaluating management strategies for Eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment // ICES Journ. of Marine Science. - 2011. - Vol. 68(6). - P. 1297-1304.

19. Ianelli J.N., Honkalehto T., Barbeaux S., Kotwicki S. Assessment of the walleye pollock stock in the Eastern Bering Sea // NPFMC Bering Sea and Aleutian Islands Stock assessment and fishery evaluation report for the groundfish resources for 2015. - 2014. - P. 102 (http://www.afsc.noaa.gov/REFM/Stocks/assessment.htm).

20. Ianelli J.N., Honkalehto T., Barbeaux S., Kotwicki S. Assessment of the walleye pollock stock in the Eastern Bering Sea // NPFMC Bering Sea and Aleutian Islands Stock assessment and fishery evaluation report for the groundfish resources for 2016. - 2015. - P. 100 (http://www.afsc.noaa.gov/REFM/Stocks/assessment.htm).

21. Mueter F.J., Bond N.A., Ianelli J.N., Hollowed A.B. Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change // ICES Journ. of Marine Science. - 2011. - Vol. 68(2). - P. 1284-1296.

22. Mueter F.J., Ladd C., Palmer M.C., Norcross B.L. Bottom-up and top-down controls of walleye pollock (Theragra chalcogramma) on the eastern Bering Sea shelf // Progress in Oceanography. - 2006. - Vol. 68. - P. 152-183.

23. Napp J.M., Kendall A.W., Schumacher J.D. A synthesis of biological and physical processes affecting the feeding environment of larvae walleye pollock (Theragra chalcogramma) in the eastern Bering Sea // Fish. Oceanogr. - 2000. - Vol. 9(2). - P. 147-162.

24. Schabetsberger R., Sztatecsny M., Drozdowski G. et al. Size-dependent, Spatial, and Temporal Variability of Juvenile Walleye Pollock (Theragra chalcogramma) Feeding at a Structural Front in the Southeast Bering Sea // Marine Ecology. - 2003. - Vol. 24, № 2. - P. 141-164.

25. Stepanenko M.A. Bering Sea pollock recruitment, abundance, distribution and approach to fishery management under changing environment // PICES press. XXI Ann. Conf. - 2012. - P. 74-75.

26. Stepanenko M.A. Interannual variability of juvenile and 1-year-old pollock abundance and recruitment in the Bering Sea // Abstr. 24th Lowell Wakefield Fish. Symp. «Resiliency of Gadid Stocks to Fishing and Climate Change». - Anchorage, Alaska, 2006. - Р. 151.

27. Stepanenko M.A., Gritsay E.V. Eastern Bering Sea Pollock recruitment, abundance, distribution and approach to fishery management // Fish. Sci. - 2014. - Vol. 80(1). - P. 151-160.

28. Stepanenko M.A., Gritsay E.V. Effect of biological and physical factors on recruitment variability of eastern Bering Sea pollock // PICES press. XIV Ann. Conf. - 2006. - P. 152.

29. Swartzman G.L., Winter A.G., Coyle K.O. et al. Relationship of age-0 pollock abundance and distribution around the Pribilof Islands with other shelf regions of the Eastern Bering Sea // Fish. Res. - 2005. - Vol. 74. - P. 273-287.

30. Wespestad V.G., Fritz L., Ingraham W.J., Megrey B.A. On relationships between cannibalism, climate variability, physical transport and recruitment success of Bering Sea walleye pollock, Theragra chalcogramma // ICES Intern. Symp. recruitm. dynamics expl. marine populations: physical-biological interactions. - Baltimore, 1997. - P. 12.

31. Wespestad V.G., Fritz L.W., Ingraham W.J., Megrey B.A. On relationships between cannibalism, climate variability, physical transport, and recruitment success of Bering Sea walleye pollock (Theragra chalcogramma) // ICES Journ. of Marine Science. - 2000. - Vol. 57. - P. 272-278.

32. Winter A.G., Swartzman G.L., Cianelli L. Early- to late-summer population growth and prey consumption by age-0 pollock (Theragra chalcogramma), in two years of contrasting pollock abundance near the Pribilof Islands, Bering Sea // Fish. Oceanography. - 2005. - Vol. 14, № 4. - Р. 307-320.

33. Zador S. Ecosystem considerations 2014 // 2014 Stock Assessment and Fishery Evaluation Report for the Groundfish Resources of the Bering Sea/Aleutian Islands Region // Techn. Rep. NPFMC. - 2014. - P. 263.

34. Zador S. Ecosystem considerations 2015 // 2015 Stock Assessment and Fishery Evaluation Report for the Groundfish Resources of the Bering Sea/Aleutian Islands Region // Techn. Rep. NPFMC. - 2015. - P. 297.