Red King Crab Management and Research
Management
The U.S. federal government through the North Pacific Fishery Management Council (NPFMC) and the State of Alaska jointly manage the Bering Sea and Aleutian Islands crab stocks, whereas the State of Alaska solely manages the Gulf of Alaska crab stocks. Harvest strategies vary among areas and species, but all crab fisheries have minimum size limits, male-only restrictions, and specific fishing seasons (i.e., size, sex, and season, or “3-S” management). Minimum size limits have been enforced to provide at least one opportunity for males to mate with females. Single-sex harvest has been in effect to protect mature females for reproduction and specific fishing seasons are set to avoid harvesting crab during mating and molting (soft-shell) periods. A number of king and Tanner crab fisheries are managed with a guideline harvest level (GHL) determined either from available abundance estimates and appropriate target harvest rates or from historical average catches. The fishery performance within a season is monitored, and if the fishery is expected to exceed the GHL before the declared closure date, then the season is closed by an ADF&G Commissioner’s emergency order. Incidental mortality of crabs in other fisheries (trawl, pot, and dredge) is reduced by enforcing maximum allowable crab bycatch thresholds. Additional management measures include pot limits, permits, onboard observers, registration areas, reporting requirements, vessel tank inspections, legal gear specifications, and provisions for gear placement, removal, and storage.
Six Bering Sea crab stocks are managed by the NPFMC according to fishery management plans with thresholds for overfishing (an excessive annual rate of removal) and overfished (a minimum biomass level). These stocks are Bristol Bay red king crab, Bering Sea Tanner crab, Bering Sea snow crab, St. Matthew Island blue king crab, and Pribilof Islands red and blue king crabs. If the stock declines below the ‘overfished’ biomass level, then the stock is declared overfished, and management actions in the form of reducing fishing mortality or rebuilding plans must be implemented.
In addition to federal management regulations, the ADF&G has developed harvest strategies for king and Tanner crab stocks in selected fisheries of the Bering Sea and Gulf of Alaska. The harvest strategies aim to maintain sufficient spawning biomass for stock productivity by controlling the removal of mature males. Minimum stock size levels (mainly of mature portion) and minimum GHLs (for a few stocks) are estimated for assessing stock viability and for assuring manageability under continued fishing.
Research
The Commercial Fisheries Division of the Alaska Department of Fish and Game (ADF&G) conducts stock assessment surveys for red king crab in seven areas throughout the state. Trawl surveys are conducted on an annual basis in the Kodiak area, annual or biennial in Cook Inlet and Prince William Sound, and triennial in Norton Sound. An annual pot survey is conducted in Southeast Alaska, and occasional pot surveys in the Pribilof Islands, and the Petrel Bank grounds in the central Aleutian Islands.
NOAA Fisheries conducts annual multi-species trawl surveys in the Eastern Bering Sea, including Bristol Bay. In 2007 and 2008 the Bering Sea Fisheries Research Foundation conducted several trawl surveys in Bristol Bay targeting red king crabs with a small mesh size trawl and 5-minute tows.
Besides population estimation, stock assessment surveys are used to gather life history information on red king crab. Over the years, life history studies have provided information on movement, growth, natural mortality, and fecundity among others. This helps to improve population modeling techniques which support sustainable management of stocks.