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North Pacific Marine Science Organization

The Bering Sea: Current status and recent trends
by Lisa Eisner2014 (Fig. 2). The latter event occurred at a time when thesea ice extended to near the Pribilof Islands. The maximum
extent of the sea ice was considerably less, and the retreatof the ice edge to the north was earlier than during theheavy ice years of the recent past. This meant an early
onset of warming in the spring of 2014; by mid-May, sea
surface temperatures on the central and southern portion of
the shelf were 1–1.5°C above normal.

Climate and oceanography
Overall, the eastern Bering Sea shelf experienced muchdifferent weather during the past cold season of 2013–14.
Specifically, it was 1–2°C warmer than normal for theperiod of October 2013 through March 2014 comparedwith the relatively cold temperatures that have prevailed
since 2007. The past cold season included anomalously
high sea level pressure (SLP) from eastern Siberia acrossthe Gulf of Alaska (Fig. 1). The consequence for the meanwinds was weak anomalies from the north along the shelfbreak between the Bering Sea shelf and the deep basin, andweak anomalies from the south near the west coast ofmainland Alaska.
The warm weather can be attributed mostly to relatively
warm and moist air over the Bering Sea shelf. This warm
air was due to a ridge of anomalously high geopotential
heights aloft, centered over the Gulf of Alaska and extending
into mainland Alaska. These conditions produced greater
downward longwave radiation fluxes than normal over theBering Sea shelf and Alaska. The result was a reduced rateof cooling of the ocean over the shelf, and less tendency forthe development of extremely cold air masses over Alaska,
the usual source of the lower-atmospheric flow for theBering Sea shelf.

Fig. 1The only prominent and multi-day cold snaps at St. Paul,for example, were during mid-February and mid-March

Fig. 2NOAA sea level pressure (mb) composite anomaly (deviationsfrom 1981–2010 climatology) for October 2013–March 2014.
Figure courtesy of N. Bond.

Daily air temperature (°F) at St. Paul Island October 2013–March 2014. The reddish and aqua lines at the top and bottom, respectively, refer tothe all time high and low temperatures for each date; the tan lines in the center refer to the average daily high and low temperatures for eachdate. The period of record is 1892 to present. Figure courtesy of N. Bond.

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Fig. 3 Eastern Bering Sea ecosystem assessment indicators. * indicates time series updated in 2013.

mean is driven primarily by the increase in Pacific codfrom low levels in the early 2000s. Arrowtooth flounder,
while still above its long-term mean, has declined nearly
50% from the early 2000s, although this may be due to a
distributional shift in response to colder water over the last
few years rather than a population decline. Thick-billedmurre reproductive success on St. George Island was above
average in 2013, suggesting that foraging conditions werefavorable for piscivorous seabirds.

Eastern Bering Sea ecosystem considerations
Highlights from the 2013 eastern Bering Sea ecosystem
considerations chapter (Fig. 3) compiled by the Alaska
Fisheries Science Center (AFSC) indicate that survey
biomass of motile epifauna has been above its long-termmean since 2010 and fairly stable since the early 1990s.
However, the trend of the last 30 years shows a decrease incrustaceans (especially commercial crabs) and a long-term
increase in echinoderms, including brittle stars, sea stars,
and sea urchins. It is not known if this reflects changes insurvey methodology rather than actual trends. Survey
biomass of benthic foragers has remained stable since
1982, with interannual variability driven by short-term
fluctuations in yellow fin and rock sole abundance. In
contrast, survey biomass of pelagic foragers has increased
steadily since 2009 and is currently above its 30-year mean.
While this is primarily driven by the increase in walleye
pollock from its historical low in 2009, it also reflects
increases in capelin from 2009–2013, perhaps due to cold
conditions prevalent in recent years. The springtime larval
drift patterns for 2013, based on Ocean Surface Current
Simulations (OSCURS) model time series runs, do notappear to be consistent with years of good recruitment for
winter-spawning flatfish such as northern rock sole,arrowtooth flounder and flathead sole.

Jellyfish, primarily Chrysaora melanaster, remained abundantin the summer 2013 surveys, although catch per unit effort(CPUE) was down slightly from 2012. The years 2009–2013 continue a trend of higher abundance, relative to theyears 2001–2008 when catch rates of jellyfish were low.
For additional information on ecosystem indicators, see
http://access.afsc.noaa.gov/reem/ecoweb/index.php.
Eastern Bering Sea spring mooring survey
The spring mooring survey conducted by the Pacific
Marine Environmental Laboratory (PMEL) and AFSC
Fisheries Oceanography Coordinated Investigations (FOCI)
occurred May 6–17, 2014, onboard the R/V Oscar Dyson.
Oceanographic variables and zooplankton were sampledaround Unimak Pass, along the 70 m isobath, off the shelfand over Bering Canyon. Six moorings were deployed in
the southeastern Bering Sea. Since 2014 may be a warm
year, additional analyses (primary productivity experiments

Fish apex predator survey biomass is currently near its
30-year mean. The increase since 2009 back towards the47

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North Pacific Marine Science Organizationand microzooplankton identification) were done to better
understand the effects of a warming climate on lower trophic
levels. Preliminary observations suggest that zooplankton,
jellyfish and icthyoplankton were patchily distributed along
the 70 m isobath.

2014 will be the first year without a western Bering Sea
salmon survey by TINRO, Russia.
Upcoming meetings
Meetings in the second half of 2014 and early 2015 ofinterest to scientists working in the Bering Sea include: PICES-2014, October 17–26, 2014, Yeosu, Korea;
 9th International Flatfish Symposium, November 9–14,2014, Cle Elum, WA, USA;
 Alaska Marine Science Symposium, January 2015,Anchorage, AK, USA; 3rd PICES/ICES/IOC Symposium on “Effects of Climate
Change on the World’s Oceans”, March 23–27, 2015,Santos City, Brazil.
Acknowledgements Many thanks to the following scientists whohelped create this report: Dr. Nicholas Bond (NOAA, PMEL),
Colleen Harpold (NOAA, AFSC), Dr. Carol Ladd (NOAA,PMEL), Dr. Kim Martini (NOAA, PMEL), Dr. Olga Temnykh(TINRO, Russia), and Dr. Stephani Zador (NOAA, AFSC).
_____________________________________________________

Photo from spring mooring cruise, courtesy of K. Martini.

Recent and future 2014 Bering Sea fisheries oceanography
surveysSurveys in 2014 include: Eastern Bering Sea Spring Ichthyoplankton, AFSC, R/VOscar Dyson, May 20–June 8;
 Eastern Bering Sea Bottom Trawl, AFSC, F/Vs
Vesteraalen and Alaska Knight, June 1–August 11; Aleutian Islands Bottom Trawl, AFSC, F/Vs Sea Stormand Alaska Provider, June 5–August 15;
 Eastern Bering Sea Pollock Echo Integration Trawl(EIT), AFSC, R/V Oscar Dyson, June 12–August 13;
 Western Bering Sea Pollock Trawl-Acoustic, TINRO,Russia, R/V TINRO, August 10–September 4;
 Bering Arctic Subarctic Integrated Survey (BASIS),
southeastern Bering Sea fisheries oceanography, AFSC
and PMEL, R/V Dyson, August 17–October 14;
 North Bering Sea Pelagic Trawl, Alaska Department ofFish and Game and AFSC, F/V Alaskan Endeavor,
August 31–September 24.

Summer 2014

Dr. Lisa Eisner (lisa.eisner@noaa.gov) is a Biological/Fisheries
Oceanographer at the Alaska Fisheries Science Center of NOAAFisheries in Juneau, Alaska and Seattle, Washington. Her
research focuses on oceanographic processes that influence
phytoplankton and zooplankton dynamics and fisheries in theeastern Bering Sea. She has been the lead oceanographer for theU.S. component of the BASIS program (Bering Aleutian Salmon
International Surveys). She is a scientific steering committee
member of NOAA’s Fisheries and the Environment program(FATE) and a co-PI on current (and past) eastern Bering Sea andChukchi Sea research programs.

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