RESUTLS FROM THE INDICES WORKING GROUP ON THE DEVELOPMENT AND USE OF ENVIRONMENTAL INDICES IN THE PREDICTION OF POLLOCK RECRUITMENT IN THE EASTERN BERNING SEA

The goal of the Southeast Bering Sea Carrying Capacity (SEBSCC) program is to document the role of juvenile pollock in the eastern Bering Sea ecosystem. This includes examination of factors that affect their survival and development and testing of annual indices of pre-recruit (age-1) abundance (from the SEBSCC Concept Paper, July 1995). Within this framework, the purpose of the Indices Working Group (IWG, which was developed at the SEBSCC Principal Investigators meeting held in January 2001) is as follows. Based on the best understanding of ecosystem dynamics, identify potential single-or multi-parameter constructs or indices (e.g., wind mixing, time of spring bloom, etc.) that lead to development of survival indices for pollock in the egg, larval and young of the year life history stages. This information will provide input to the National Marine Fisheries Service (NMFS) stock assessment model and/or models of juvenile pollock for use by fisheries scientists at the Alaska Fisheries Science Center (AFSC)/NMFS. As noted by Napp et al (2000) pollock is the most abundant species harvested in the Bering Sea, accounting for > 65% of the total groundfish biomass and during the 1980s when their total biomass exceeded 20 million tones. The biomass trends of three major trophic guilds in the eastern Bering Sea (1979 to 1998: Schumacher et al., in press) show that while the total biomass of pollock in the 1990s is less than in the 1980s, they still dominate biomass in any of the guilds which include marine birds, mammals, other fishes and crabs. Walleye pollock is a nodal species in the food web (NRC Report, 1996) with juveniles being the It is natural that that pollock have been the focus of the Coastal Ocean Program's SEBSECC. The choice of developing a survival index for the early life history stages (eggs through young of the year) allows an early forecast of potential recruitment to the fishery and a metric that can be compared to existing time series of age-1 abundance (Figure 1). A switch model was developed for the eastern Bering Sea (Megrey et al., 1996), which identifies candidates for causing mortality by life history stage and the mortality variability of each stage indicating the stage contributing the most variability in recruitment to the fishery is set (Figure 2). In this model, transport and turbulence have their greatest impact on mortality of yoke-sack through feeding larval stages. It is the vertical structure of temperature, …

[1]  R. Reynolds,et al.  The NCEP/NCAR 40-Year Reanalysis Project , 1996, Renewable Energy.

[2]  K. Sherman,et al.  Large marine ecosystems of the world : trends in exploitation, protection, and research , 2003 .

[3]  J. Ianelli,et al.  Eastern Bering Sea Walleye Pollock Stock Assessment , 2002 .

[4]  P. Stabeno,et al.  Bering Sea shifts toward an earlier spring transition , 2001 .

[5]  G. Kruse,et al.  Effects of water temperature and wind on year‐class success of Tanner crabs in Bristol Bay, Alaska , 2001 .

[6]  D. Irons,et al.  BREEDING STATUS, POPULATION TRENDS AND DIETS OF SEABIRDS IN ALASKA, 2000 , 2001 .

[7]  Steven R. Hare,et al.  Empirical evidence for North Pacific regime shifts in 1977 and 1989 , 2000 .

[8]  Napp,et al.  A synthesis of biological and physical processes affecting the feeding environment of larval walleye pollock (Theragra chalcogramma) in the eastern Bering Sea , 2000 .

[9]  B. Megrey,et al.  On relationships between cannibalism, climate variability, physical transport, and recruitment success of Bering Sea walleye pollock (Theragra chalcogramma) , 2000 .

[10]  D. Schell.  Declining carrying capacity in the Bering Sea: Isotopic evidence from whale baleen , 2000 .

[11]  John F. Piatt,et al.  Community reorganization in the Gulf of Alaska following ocean climate regime shift , 1999 .

[12]  Shoshiro Minobe,et al.  Resonance in bidecadal and pentadecadal climate oscillations over the North Pacific: Role in climatic regime shifts , 1999 .

[13]  R. Reed.  A time series of temperature, salinity, and geopotential across the southeastern Bering Sea shelf, 1995-1999 , 1999 .

[14]  James D. Schumacher,et al.  The Physical Oceanography of the Bering Sea , 1999 .

[15]  Steven R. Hare,et al.  Inverse Production Regimes: Alaska and West Coast Pacific Salmon , 1999 .

[16]  H. J. Niebauer.  Variability in Bering Sea ice cover as affected by a regime shift in the North Pacific in the period 1947–1996 , 1998 .

[17]  D. Mackas,et al.  Interdecadal variation in developmental timing of Neocalanus plumchrus populations at Ocean Station P in the subarctic North Pacific , 1998 .

[18]  W. Wooster,et al.  Year‐to‐year variations in Bering Sea ice cover and some consequences for fish distributions , 1998 .

[19]  Steven R. Hare,et al.  Effects of interdecadal climate variability on the oceanic ecosystems of the NE Pacific , 1998 .

[20]  P. Livingston,et al.  Incorporation of Predation into a Population Assessment Model of Eastern Bering Sea Walleye Pollock , 1998 .

[21]  J. Wallace,et al.  A Pacific Interdecadal Climate Oscillation with Impacts on Salmon Production , 1997 .

[22]  P. Stabeno,et al.  On the climatological mean circulation over the eastern Bering Sea shelf , 1996 .

[23]  J. Piatt,et al.  Sea birds as proxies of marine habitats and food webs in the western Aleutian Arc , 1996 .

[24]  R. Beamish,et al.  Climate change and northern fish populations , 1995 .

[25]  James D. Schumacher,et al.  Ubiquitous eddies of the eastern Bering Sea and their coincidence with concentrations of larval pollock , 1994 .

[26]  Jon T. Schnute,et al.  A General Framework for Developing Sequential Fisheries Models , 1994 .

[27]  C. Mcroy,et al.  The paradox of pelagic food webs in the northern Bering Sea—III. Patterns of primary production , 1993 .

[28]  P. Livingston.  Importance of predation by groundfish, marine mammals and birds on walleye pollock Theragra chaicogramma and Pacific herring Clupea pallasi in the eastern Bering Sea , 1993 .

[29]  David H. Peterson,et al.  1976 step in the Pacific climate: forty environmental changes between 1968-1975 and 1977-1984 , 1991 .

[30]  J. Mcgowan,et al.  Climate and change in oceanic ecosystems: The value of time-series data. , 1990, Trends in ecology & evolution.

[31]  C. Mcroy,et al.  The paradox of pelagic food webs in the northern Bering Sea—II. Zooplankton communities , 1989 .

[32]  Robert Pinkel,et al.  Diurnal cycling: observations and models of the upper-ocean response to diurnal heating, cooling, and wind mixing. Technical report , 1986 .

[33]  R. B. Tripp,et al.  Bering Strait the Regional Physical Oceanography , 1975 .

[34]  H. Sverdrup,et al.  On Conditions for the Vernal Blooming of Phytoplankton , 1953 .