The 2018 Eastern Bering Sea Continental Shelf and Northern Bering Sea Trawl Surveys: Results for Commercial Crab Species
March 21, 2019
The eastern Bering Sea bottom trawl survey has been conducted annually since 1975 by the Resource Assessment and Conservation Engineering Division of the Alaska Fisheries Science Center, National Marine Fisheries Service. The purpose of this survey is to collect data on the distribution and abundance of crab, groundfish, and other benthic resources in the eastern Bering Sea. These data are used to estimate population abundance and biomass for the management of commercially important species. This document includes the time series of results from 1975 to the present. In 2018, 375 total stations were sampled on the eastern Bering Sea shelf from 3 June to 31 July.
There was an overall increase in biomass and abundance of immature male red king crab (Paralithodes camtschaticus) and immature blue king crab (P. platypus), however, there was an overall decrease in biomass and abundance in mature red and blue king crab males. There was an overall decrease in mature and immature female red and blue king crab except for St. Matthew Island mature and immature female blue king crab which increased in abundance and biomass likely due to changes in distribution from previous years. Biomass and abundance of Pribilof Islands mature red king crab also increased in 2018. There were overall increases in immature, mature and legal male biomass and abundance in Tanner (Chionoecetes bairdi) and snow (C. opilio) crab, except for mature and legal male Tanner crab east of 166o W. There were overall increases in immature female biomass and abundance estimates in Tanner and snow crab. There was an increase in mature female snow crab biomass and abundance but a decrease in Tanner crabmature female biomass and abundance.
In addition to the standard eastern Bering Sea survey in 2018, following the conclusion of the standard survey, 49 stations were sampled in the northern Bering Sea region, encompassing the region south of Bering Strait, around St. Lawrence Island. These stations were centered in 30 × 30 nmi cells (55.56 × 55.56 km) and were sampled between 31 July and 14 August, as compared to the 145 stations centered in 20 × 20 nmi cells during the 2017 northern Bering Sea bottom trawl surveys. We report the results of this survey separately from the eastern Bering Sea survey, within the northern Bering Sea section of this report. Blue king crabs occurred largely in the region north of St. Lawrence Island, and had a lower average CPUE than was observed for the St. Matthew Island and Pribilof Islands stocks. Red king crab occurred on the edge of the Norton Sound Registration area, northeast of St. Lawrence Island as we did not survey Norton Sound in 2018. Snow crab dominated the northern Bering Sea region catch, with the highest densities observed at stations to the north and south of St. Lawrence Island. Immature male and female snow crab were predominate, although mature females were observed, primarily along the western edge of the survey grid, with highest densities just west of St. Lawrence Island. Morphometrically mature (“large-clawed”) male snow crab were scattered throughout the survey region, with highest densities occurring in the western-most survey stations.