Demersa! Fish Resources of the Eastern 

 Bering Sea: Spring 1976 



GARY B. SMITH and RICHARD G. BAKKALA' 



ABSTRACT 



INTRODUCTION 



Purpose 



In the summer of 1975 and spring of 1976, the Northwest and 

 Alaska Fisheries Center (NWAFC), National Marine Fisheries 

 Service (NMFS), conducted multivessel surveys of demersal fish 

 and macroinvertebrates of the continental shelf and upper con- 

 tinental slope regions of the eastern Bering Sea. These resource 

 assessment surveys — a part of the NMFS Marine Monitoring, As- 

 sessment and Prediction program — were also in response to needs 

 of the Bureau of Land Management to assess the demersal fish 

 stocks of the Bering Sea and their vulnerability to oil de- 

 velopment. 



Results of the first phase trawl survey, conducted August- 

 October 1975. were summarized in Pereyra et al. (1976 2 ). These 

 included a review of the history of commercial fisheries in the 

 eastern Bering Sea, results from previous research surveys in the 

 region, the 1975 survey results for demersal fish and invertebrates, 

 and summaries of the status of knowledge of commercially im- 

 portant species and their stock conditions. 



The present study summarizes results of the second phase of 

 the field studies — the spring 1976 demersal trawl survey. The pur- 

 pose of this second survey was to describe the distributions of 

 demersal fish and invertebrates at a time when they were expected 



•Northwest and Alaska Fisheries Center, National Marine Fisheries Service, 

 NOAA, 2725 Montlake Boulevard East, Seattle, WA 98112. 



! Pereyra, W. T., J. E. Reeves, and R. G. Bakkala. 1976. Demersal fish and 

 shellfish resources of the eastern Bering Sea in the baseline year 1975. Unpubl. 

 manuscr., 619 p. Northwest and Alaska Fisheries Center, National Marine 

 Fisheries Service, NOAA, 2725 Montlake Boulevard East, Seattle, WA 98112. 

 Bound copies are available on request. 



to be near the winter extreme of their seasonal, geographical 

 movements. Maximum ice. cover in the southeastern Bering Sea 

 generally occurs during March and April, with maximum cooling 

 of the water column (Potocsky 1975; McLain and Favorite 1976). 

 The objectives of this report are 



1) To describe the species composition, geographical distri- 

 butions, and apparent abundance of demersal fish resources 

 of the eastern Bering Sea during the survey period, April- 

 June 1976; 



2) To describe characteristics of the important demersal fish 

 populations that could be changed by environmental stress 

 (e.g., abundance, size and age composition, growth rates, 

 and body form); and 



3) To compare and explain results of the 1975 and 1976 

 surveys. 



Environmental Setting 



The regional setting for the investigations was the eastern Be- 

 ring Sea between lat. 54°-63°N and from long. 180° eastward to 

 the Alaska coast. The area is a unique subarctic ocean environ- 

 ment because of its recent geological origin (i.e., submergence), 

 partial separation from the Pacific Ocean by the Aleutian Ridge, 

 unusually broad and flat continental shelf, and variable seasonal 

 ice cover (Fig. 1). The area is also distinguished biologically by 

 large marine mammal and seabird populations. 



The topography of the eastern Bering Sea continental shelf 

 shows an extremely flat, featureless plain. The width of the con- 

 tinental shelf varies from about 500 km in the southeast to over 

 300 km in the north, with an average gradient of 0.24 m/Tcm. 

 Along the outer edge the continental slope is a steep, rugged, and 

 deeply canyon-scarred 3,200-3,400 m declivity (Sharma 1979). 



