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First Special Issue of the Bering Sea Project Published

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Apr-May-June 2012
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Hot off the press this summer are 23 research articles from the Bering Sea Project (aka BEST-BSIERP). Published in Deep Sea Research II, the special issue represents findings of a partnership of the National Science Foundation, North Pacific Research Board, NOAA, and several other academic and federal partners.

About 100 researchers studied Bering Sea ice and ecosystem conditions over 6-years to understand the processes that influence the eastern Bering Sea marine ecosystem. The special journal issue features multiple papers describing the changes in sea-ice, the distribution of important nutrients, and how fish, seabirds, fur seals, and whales are responding.

NOAA, through the AFSC and Pacific Marine Environmental Lab (PMEL), played a key role in the study of this important large marine ecosystem and how it responds to climate variability.  NOAA and its partners contributed a combined amount of $52 million during the 4 years of field research (2007-10).  NOAA scientists comprised about one-third of the approximately one hundred experts from universities and other institutions working on this special project.  Critical to the results of this study and the special issue were measurements made by NOAA scientists in the decades before the recent study began.  For5 example, the AFSC is the only institution with long time series of observations of zooplankton, larval fish, adult and juvenile fish, fur seals, and whales   These observations allowed Bering Sea project participants to put the most recent measurements in context.

To give you a flavor of their findings, short summaries of articles are provided in the table below with NOAA senior authors (either AFSC or PMEL).

Authors and Title


Overland J.E., Wang M., Wood K.R., Percival D.B., Bond N.A. Recent Bering Sea warm and cold events in a 95-year context.

In the past decade, Bering Sea shelf waters experienced a multi-year, very warm spell followed by a very cold spell. These events were compared to a 95-year long weather record. Such extreme events were rare but not unique. We found that while modest long-term warming due to climate change is expected in the North Pacific Ocean and southeastern Bering Sea, the historical records suggest that the most important climate feature over the next few decades will be large random variability.

Stabeno P.J., Farley E.V. Jr, Kachel N.B., Moore S., Mordy C.W., Napp J.M., Overland J.E., Pinchuk A.I., Sigler M.F. A comparison of the physics of the northern and southern shelves of the eastern Bering Sea and some implications for the ecosystem.

Measurements made during the 6-year study show a potential impact of climate change on species from zooplankton to whales living on the Bering Sea shelf, a relatively shallow portion of the sea directly off the Alaskan coast. The study projects warming of southern shelf waters will limit the distribution of Arctic species such as snow crab, while the distribution and abundance of whales will change as their food source moves.

Stabeno P.J., Kachel N.B., Moore S., Napp J.M., Sigler M.F., Yamaguchi A., Zerbini A.N. Comparison of warm and cold years on the southeastern Bering Sea shelf and some implications for the ecosystem.

From 1972 to 2000, there was high interannual variability of areal extent of sea ice during spring (March–April). In 2000, this shifted to a 5-year period (2001–05) of low ice extent during spring, which transitioned to a 4-year period (2007–10) of extensive sea ice. During the warm period, there was a lack of large copepods and euphausiids over the shelf; however, their populations rebounded during cold period. Small crustacean zooplankton taxa did not appear to vary between warm and cold years.

Ladd C., Stabeno P.J. Stratification on the eastern Bering Sea shelf, revisited.

NOAA historical data demonstrated that stratification of the water was not simply a matter of whether or not the water column was warm or cold.  Strong stratification during the summer prevents the refertilization of the surface waters and decreases the amount of production.

Mordy C.W., Cokelet E.D., Ladd C., Menzia F.A., Proctor P., Stabeno P.J., Wisegarver E. Net community production on the middle shelf of the eastern Bering Sea·      

The presence or absence of sea-ice was previously thought to have a large impact on the production of microscopic plant life (phytoplankton). We found that the wind accounts for a larger piece of the phytoplankton production puzzle, and this finding can be implemented for future models of the Bering Sea ecosystem.

Ressler P.H., De Robertis A., Warren J.D., Smith J.N., Kotwicki S. Developing an acoustic index of euphausiid abundance to understand trophic interactions in the Bering Sea ecosystem.

We developed a new time series of euphausiid zooplankton (or krill) biomass and distribution, and documented 1) a recent increase coinciding with the end of a warm period and the beginnings of a cold period in the eastern Bering Sea and 2) an inverse relationship with adult walleye pollock biomass.

Smart T.I., Duffy-Anderson J.T., Horne J.K., Farley E.V., Wilson C.D., Napp J.M. Influence of environment on walleye pollock eggs, larvae, and juveniles in the southeastern Bering Sea.

Using historical data collected on larval fish surveys conducted by the AFSC, we documented a shift in the location of larval fish between warm and cold years.  In cold years they were much closer to the edge of the shelf, while in warm years they were closer to the middle of the shelf.  This has important implications for their transport and survival.

De Robertis A., Cokelet E.D. Distribution of fish and macrozooplankton in ice-covered and open-water areas of the eastern Bering Sea

Using sonar installed on an icebreaker, we made the first comprehensive observations of fish in the ice-covered Bering Sea. During winter periods of ice cover, the cold and icy arctic-like conditions force fish southeastward, out of their summer habitat. 

Hollowed A.B., Barbeaux S.J., Cokelet E.D., Farley E., Kotwicki S., Ressler P.H., Spital C., Wilson C.D. Effects of climate variations on pelagic ocean habitats and their role in structuring forage fish distributions in the Bering Sea.

The distributions of forage fish (fish used as food by other fish, seabirds, and marine mammals) are affected by the warm and cold cycles in the eastern Bering Sea.  We examined historical survey data collected by the AFSC in warm and cold years and described how they differ and the consequences of these shifts in spatial distribution.

Stevenson D.E., Lauth R.R. Latitudinal trends and temporal shifts in the catch composition of bottom trawls conducted on the eastern Bering Sea shelf.

Overall biomass of the epibenthic community declines with increasing latitude in the eastern Bering Sea, which is primarily driven by declining fish catches in the northern Bering Sea.The fish fauna in northern latitudes is increasingly dominated by gadids, with smaller species becoming more common in the north. The biomass of the invertebrate megafauna remains relatively consistent throughout the eastern Bering Sea, but invertebrates make up a larger proportion of the catch in bottom trawls conducted at higher latitudes.

Friday N.A., Waite J.M., Zerbini A.N., Moore S.E. Cetacean distribution and abundance in relation to oceanographic domains on the eastern Bering Sea shelf: 1999 to 2004.

Visual line transect surveys for cetaceans were conducted on the eastern Bering Sea shelf in association with pollock stock assessment surveys aboard the NOAA ship Miller Freeman in June and July of 1999, 2000, 2002, and 2004. Fin whales were the most common large whale in all years except 2004 when humpback whales were more abundant. Dall’s porpoise were the most common small cetacean in all years.

Sigler M.F., Kuletz K.J., Ressler P.H., Friday N.A., Wilson C.D., Zerbini A.N. Marine predators and persistent prey in the southeast Bering Sea.

A predator’s foraging mode and their restrictions during breeding affect their response to prey persistence. We examined whether this association with ecologically important prey (euphausiids, age-1 pollock) is influenced by differences among predator species (baleen whales, seabirds) in foraging modes (travel cost, surface feeder or diver) or whether the predator species is a central place forager or not.

A second special issue received 29 submissions with reviews now underway. To date, 58 peer-reviewed journal articles have been published by the Bering Sea project.

By Jeff Napp and Mike Sigler

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