63°N 



62°N 



61 °N 



60°N 



59°N 



58°N - 



57°N 



56°N 



55°N 



54°N 



180° 



178°W 



176°W 



174°W 



60°W 



158°W 



Figure 2.— Statistical subdivisions of Ibe study area used for the 1975 eastern Bering Sea baseline survey. 



1976 Survey Area 



For the demersal trawl survey of 1976, the same subdivisions of 

 the study area, boundary lines, and station densities were used as 

 in the 1975 survey, with the following changes (Fig. 3): 



1) A reduction of the northern survey coverage in subdivisions 

 3N, 4N, and 4S, in anticipation that spring ice cover would 

 probably block ship operations above lat. 59°-60°N; 



2) Smoothing of the outer boundary lines of subareas 1 , 2, and 

 3N and S; and 



3) The extension of sampling to a fifth major subarea 

 ("Slope") along the upper continental slope between the 

 183-457 m (100-250 fathoms) isobaths. 



A summary of the geographical areas surveyed is given in Table 

 1. The purpose of extending systematic sampling to the upper 

 continental slope was to better define the importance of this 

 area — in terms of changes in species composition and abun- 

 dance, size, and age distributions — relative to survey areas on the 

 continental shelf (depths 10-183 m). The slope subarea was sub- 

 divided into northern (3 Slope) and southern (2 Slope) regions 

 (Fig. 3). Samples were to be taken along 29 transects of five sta- 



tions each. Transects were located crossing the slope subarea at 

 approximately 14 km intervals, usually oriented as continuations 

 of the diagonal rows of grid stations located on the continental 

 shelf. Along transects, stations were to be distributed at positions 

 with bottom depths of ca. 183, 250, 320, 390, and 457 m. 



Other divisions of the survey area, "otolith areas," were used 

 for the collection and analysis of individual specimen information 

 (Fig. 4). Data that were geographically identified by otolith area 

 were: Age determinations derived from field-collected otoliths 

 and scales, length-weight measurements, and length-maturity ob- 

 servations. As explained in Pereyra et al. (see footnote 2), the 

 original purpose for these separate divisions of the survey area for 

 specimen data was to group statistical areas in a manner that 

 would enable testing of differences in age composition, individual 

 growth rates, body form, and reproductive condition between 

 north and south regions. For the 1976 survey, the same distribu- 

 tion of statistical subareas to otolith areas, and boundaries within 

 the reduced survey area, were used as in the 1975 survey, with the 

 following changes: 



1) The extension of otolith area B to include subdivision 2 

 Slope, and otolith area D to include 3 Slope; and 



2) The inclusion of subdivision 3N within otolith area D, 

 rather than otolith area E. 



