Food Web Comparisons in the Eastern and Western Bering Sea

Summary

The proportion of energy flow into each compartment above Trophic Level 1 ultimately deriving from pelagic sources (phytoplankton and pelagic detritus; red) or benthic sources (benthic detritus; blue) for the eastern Bering Sea shelf.

The Alaska Fisheries Science Center (AFSC) and the Russian Pacific Institute of Fisheries and Ocean Research (TINRO) each have conducted substantial ecosystem studies on their respective sides of the Bering Sea over the past 50 years.  In a management context, the waters of the Bering Sea lie in both Russian and U.S. Exclusive Economic Zones (EEZs), with international waters in a section of the central basin commonly known as “the donut hole.”

The Bering Sea covers more than 2.3 million km2 and supports high biological production and multiple fisheries.  On one hand, the differences in physical and biological conditions between the eastern and western areas may result in fundamentally different responses to ecosystem change.  On the other hand, the presence of the same commercially important fish species such as walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus) in both areas may result in profound similarities.

In order to develop meaningful measures of large marine ecosystem (LME) function and health, a comparative study of ecosystems is required.  One basis for comparison is the food web—the system of predator/prey relationships by which energy originating in sunlight is passed through plankton, fish, birds, marine mammals, and humans.  The study of changes in the structure and function of food webs over time may reveal critical relationships between marine ecosystems, climate, and fishing.

Such comparisons require synthesizing large bodies of literature that exist in different locations and contain results in different contextual formats not readily adaptable for comparison.  Our study aimed to synthesize data on ecosystem production and energy pathways in the eastern and western Bering Sea shelf and slope regions by developing and comparing quantitative food web models of these areas by combining data from fisheries agencies on both sides of the Bering Sea.

The resulting models both highlight the dominant predator/prey processes as they can be gleaned from the data and help focus on major data gaps relative to their importance in the ecosystem as a whole. An 11-page summary of the study is available as the feature article in the April-June 2003 issue of the AFSC Quarterly Report. (pdf; 1.87MB) The full models resulting from this study were published in Aydin, K. Y., V. V. Lapko, V. I. Radchenko, and P. A. Livingston. 2002. A comparison of the eastern and western Bering Sea shelf and slope ecosystems through the use of mass-balance food web models. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-AFSC-130, 78 p, available online in the Publications section of the AFSC websiteat  www.afsc.noaa.gov/Publications/AFSC-
TM/NOAA-TM-AFSC-130.pdf.

AFSC Quarterly
Research Reports
April - June 2003