DISTRIBUTION AND REPRODUCTIVE BIOLOGY OF 



THE GOLDEN KING CRAB, LITHODES AEQUISPINA, IN 



THE EASTERN BERING SEA 



David A. Somerton 1 and Robert S. Otto 2 



ABSTRACT 



The golden king crab is a large anomuran that supports a new, rapidly expanding fishery in the eastern 

 Bering Sea and Aleutian Islands. Based on size, sex, and abundance data collected by U.S. observers 

 aboard foreign trawlers and by National Marine Fisheries Service personnel aboard research vessels, 

 we examined latitudinal and depth variation in mean size (carapace length), size at maturity, weight at 

 size, and relative abundance. Mean size decreases by 6.2 mm for males and 4.6 mm for females with 

 each 1 degree increase in latitude. Size at maturity decreases with increasing latitude from 130 mm for 

 males and 111 mm for females in the southern area to 92 mm and 98 mm in the northern area. These 

 decreases may be due to a temperature induced decrease in growth rate. Weight at size increases by 

 10% from the southern to the northern area owing to a latitudinal change in body shape. Mean size and 

 relative abundance of both sexes increase with a decrease in depth, suggesting that an onshore ontogenetic 

 migration occurs and that adult males migrate into somewhat shallower water than adult females. Fecun- 

 dity (number of uneyed embryos) of northern females increases with size according to -24815 + 323 

 CL, where CL is carapace length. This relationship changes with latitude and southern females carry 

 about 1,330 fewer eggs than equal-sized northern females. Mean length of uneyed eggs is 2.2 mm. Based 

 on the lack of a clear seasonal change in the occurrence of eyed and uneyed clutches, golden king crab 

 appear to have protracted, or perhaps year-round, breeding. 



The golden king crab, Lithodes aequispina, is a large 

 anomuran that inhabits the upper continental slope 

 from southern British Columbia, Canada, northward 

 to the Bering Sea and westward to Suruga Bay, 

 Japan (Butler and Hart 1962; Suzuki and Sawada 

 1978). Although similar in size to red king crab, 

 Paralithodes camtschatica, and blue king crab, P. 

 platypus, the traditional species harvested by 

 Alaskan crab fisheries, golden king crab have not 

 been intensively harvested because they live in 

 deeper water than red and blue king crabs and are 

 therefore more difficult and expensive to capture 

 (McNair 1983). Since 1980, however, precipitous 

 declines in abundance of red and blue king crabs 

 have stimulated growth of directed fisheries for 

 golden king crab. These fisheries expanded rapidly 

 in the eastern Bering Sea and Aleutian Islands, and 

 between 1981 and 1983 the catch of golden king crab 

 increased from 50 t to 4900 t or 44% of the total 

 king crab catch from these areas. 



Northwest and Alaska Fisheries Center Seattle Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, 7600 Sand Point Way 

 N.E., Seattle, WA; present address: Southwest Fisheries Center 

 Hawaii Laboratory, National Marine Fisheries Service, NOAA, 

 2570 Dole Street, Honolulu, HI 96822-2396. 



2 Northwest and Alaska Fisheries Center Kodiak Laboratory, Na- 

 tional Marine Fisheries Service, NOAA, P.O. Box 1638, Kodiak, 

 AK 99615. 



snt -sr* 



Manuscript accepted September 1985. 

 FISHERY BULLETIN: VOL. 84, NO. 3, 1986. 



The fisheries for golden king crab have been 

 managed according to regulations designed for red 

 and blue king crabs (Alaska Department of Fish and 

 Game 1983; Miller 1976) because little biological in- 

 formation was available to establish more specific 

 regulations. Although golden king crab have been 

 studied before, published reports either concern 

 Asian stocks (Hiramoto and Sato 1970; Suzuki and 

 Sawada 1978; Rodin 1970) or are restricted to tax- 

 onomy (Benedict 1895; Makarov 1938), distribution 

 (Butler and Hart 1962; Slizkin 1974), or early life 

 history (Haynes 1981). 



In 1981, the National Marine Fisheries Service 

 (NMFS) began collecting biological data on golden 

 king crab necessary for establishing minimum size 

 limits and fishing seasons. We summarize these data 

 here, focusing our attention on latitudinal and depth 

 gradients in mean size, size at maturity, weight at 

 size, and sex ratio as well as various aspects of the 

 reproductive biology. We then examine the manage- 

 ment implications of our findings. 



MATERIALS AND METHODS 



Data Sources 



Golden king crab were sampled by NMFS re- 



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