NOTE 



LONGEVITY AND GROWTH OF 



TAGGED KING CRABS IN THE 



EASTERN BERING SEA 



During the period 1957 through 1959, the Bureau 

 of Commercial Fisheries (now the National Ma- 

 rine Fisheries Service) released 32,328 tagged 

 king crabs, Paralithodes camtschatica, in the 

 eastern Bering Sea. Since then several thou- 

 sands have been recovered, 23 of which exceed 

 previously reported maximum ages for this spe- 

 cies (Table 1) . These crabs were originally cap- 

 tured by Bureau research vessels, marked with 

 serially numbered plastic spaghetti tags inserted 

 through the isthmal muscle (method described in 

 Alaska Fisheries Board and Alaska Department 

 of Fisheries, 1955: 34-43) , and released immedi- 

 ately. Crabs were recaptured by the crab tangle 

 net fisheries of Japan and the Soviet Union, and 

 recapture data were provided by the two nations 

 as part of annual exchanges of scientific infor- 

 mation called for by bilateral fishing agreements 

 with the United States. 



We estimated the ages of the crabs at release 

 from size and age data for young king crabs 

 published by Weber (1967). Weber found that 

 both male and female king crabs in the eastern 

 Bering Sea mature at about 95 mm carapace 

 length; that males reach this size in 5 years 

 and females in 514 years (assuming a hatching 

 date of late April to early May) ; and that im- 

 mature crabs longer than 60 mm increased about 

 16 mm per molt. Growth curves for both sexes 

 were similar up to the fourth year of life (length 

 of 80 mm) , but after the females become ma- 

 ture they grow slower. The males, however, 

 continue to grow about 16 mm per molt through- 

 out the rest of their lives (Weber and Miyahara, 

 1962; Hoopes and Greenough, 1970). 



Total age was estimated for all four males, 

 and length data are available for three of the 

 four (Table 1). One male released in 1957 was 

 recaptured in 1968, having been at liberty for 

 11 years. This crab was estimated to have been 



6 years old at time of release, and if this esti- 

 mate is correct, it was 17 years old at time of 

 recapture. If the average growth per molt was 

 16 mm, this crab molted three or four times dur- 

 ing the 11 years between release and recovery, 

 and the other two crabs for which growth data 

 are available molted only once or twice in 9 years. 

 This molting frequency is much lower than that 

 reported by Weber and Miyahara (1962), but 

 we have no explanation for the reduced rate of 

 molting in the two crabs. Before this study, 

 the oldest known-age king crab reported in the 

 literature was a male that was tagged near Ko- 

 diak Island and recaptured 20 miles from the 

 release location 6 years and 4 months later 

 (Powell, 1965) . Powell estimated that this male 

 was 7 years old when tagged and 13 years old 

 when recaptured. 



Table 1. — Carapace lengths and estimated ages of 4 

 male and 19 female king crabs tagged in the eastern 

 Bering Sea by the National Marine Fisheries Service 

 in 1957, 1958, and 1959 and recovered 1966, 1968 and 

 1969. 



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