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Fishery Bulletin 104(2) 



Fish assemblages differed noticeably among the inner, 

 middle, and outer domains in the EBS; many species 

 (sculpins, poachers, and eelpouts) primarily inhabited 

 a single domain and many flatfishes and skates inhab- 

 ited all three domains (Kaimmer'; Kinder and Schum- 

 acher, 1981; Smith and Bakkala, 1982: Tables 1 and 

 2). Because of the distinct domain environments and 

 assemblages, the flatfish and roundfish species groups 

 were analyzed by inner, middle, and outer domains 

 separately and all domains were combined to detect the 

 influence of climate change on each assemblage. 



Species groups 



The taxonomic level of species identification for the 

 entire survey period (1975-2002) has varied because 

 of an incomplete knowledge of species characters and 

 because of survey time constraints at-sea. Historically, 

 survey goals were to obtain fisheries data on commer- 

 cially or potentially commercially important species, 

 and limited effort was put forth for identification of 

 other species. However, given more efficient technolo- 

 gies, better identification field guides, and increased 

 focus on noncommercial species, species identification 

 has improved and is approaching the current extent of 

 taxonomic knowledge. 



Efforts in recent years (1998-2002) have increased 

 our knowledge of current species distributions in the 



Kaimmer, S. M., J. E. Reeves, D. R., Gunderson, D. R.. Smith, 

 G. B., and R. A. Macintosh. 1976. Baseline information 

 from the 1975 OCSEAP survey of the demersal fauna of 

 the eastern Bering Sea. In Demersal fish and shellfish 

 resources of the eastern Bering Sea in the baseline year 

 1975 (W. T Pereyra, J. R. Reeves, and R. G. Bakkala, eds.), 

 p. 157-367. NWAFC Processed Report. Alaska Fisheries 

 Science Center, National Marine Fisheries Service, NOAA, 

 7600 Sand Point Way N.E. Seattle WA 98115. 



EBS shelf region. To assess species-identification con- 

 fidence over the study period, current species distribu- 

 tions from the AFSC survey and primary literature not 

 associated with AFSC survey data, as well as historical 

 fish collections of selected taxonomic groups (University 

 of Washington Fish Collection, Oregon State University 

 Fish Collection, and Auke Bay Fish Collections) were 

 examined. After this assessment, it was subjectively 

 determined whether species in this study were identified 

 correctly throughout the study period. Species that were 

 determined to be distinguishable and correctly identified 

 were examined as individual species, and species that 

 were possibly misidentified were grouped at a higher 

 taxonomic level for this study. The resulting list of spe- 

 cies or species groups includes the greatest number of 

 fish taxa (Tables 1 and 2). 



At least 15 flatfish species (within the order Pleu- 

 ronectiformes) and more than 75 species of fish and 

 elasmobranchs not of the order Pleuronectiformes were 

 recorded during the AFSC summer surveys (1975-2002) 

 on the EBS shelf (20-200 m). Although flatfish make 

 up about 16% of the total number of fish species, they 

 contribute approximately 50% of the biomass of all fish 

 combined (2001 and 2002 AFSC EBS survey estimates). 

 Walleye pollock (Theragra chalcogramma) and Pacific 

 cod (Gadus macrocephalus) represent approximately 

 42% of the survey biomass, and 8% of the biomass that 

 included all other roundfish. Because of the extremely 

 large biomass of walleye pollock and Pacific cod, the 

 biodiversity indexes used are uninformative when wall- 

 eye pollock and Pacific cod are included owing to the 

 "swamping" effect by their relatively large biomasses 

 when compared to those of other species. To account 

 for this, two species guilds were defined: flatfish and 

 roundfish. The flatfish guild included all Pleuronecti- 

 formes recorded from the EBS survey and comprised 

 11 species or species groups (Table 1). The roundfish 



