ABILITY OF MALE KING CRAB, PARALITHODES CAMTSCHATICA, 

 TO MATE REPEATEDLY, KODIAK, ALASKA, 1973 



Guy C. Powell.' Kenneth E. James.- and Charles L. Hurd'' 



ABSTRACT 



An experiment lo test abilities of male king crab to mate repeatedly in an environment 

 approximating natural conditions was conducted during the spring of 1970. Twenty-four males 

 of varying size and shell age were placed into separate undersea compartments for intervals 

 up to 56 days with 222 females. The ability of males to mate repeatedly was determined by 

 introducing females in mating condition to males at the rate of one every 5 days. 



No difference in mating capabilities of males of different types was evident until after expo- 

 sure to seven females. At this point egg fertility and relative fullness of brood chamber of the 

 females mated to the small old-shell males decreased significantly. Large new-shell males 

 showed a marked decline in mating ability after the ninth mating. One small new-shell male 

 mated with 13 females. 



Owing to declining stocks within the Kodiak 

 Island fishery, commercial harvest of king crab 

 has declined from 96 to 11 million pounds over 

 the past seven years. 1965-1971. To determine 

 the level of king crab brood stocks necessary for 

 perpetuation of a maximum sustained yield fish- 

 ery, the reproductive capabilities of the king 

 crab are being studied in detail. 



In 1964, biologists of the Alaska Department 

 of Fish & Game determined experimentally that 

 recently-molted sublegal (smaller than 146 mm 

 carapace length) male king crabs were capable 

 of mating. Eleven males ranging from 120 to 

 144 mm carapace length mated 51 females in 16 

 days (Powell and Nickerson. 1965). Observa- 

 tions on individual males were not obtained. In 

 1971. males as small as 85 mm carapace length 

 were found to be capable of mating (Powell. 

 Shafford. and Jones, 1972). Of 3.402 males ob- 

 served mating in nature from 1963 to 1971. how- 

 ever, only two were smaller than 100 mm 

 (Powell. Rothschild, and Buss^). 



' Alaska Dept. of Fish & Game, Commercial Fisheries 

 Div., Box 686, Kodiak, AK 99615. 



- Bio-Statistics Div., Dept. of Preventive Medicine, 

 Stanford University Medical Center, Stanford. CA 94305. 



■' Alaska Dept. of Fish & Game. Commercial Fisheries 

 Div.. Box 234. Homer, AK. 99603. 



* Powell, Guy C. Brian J. Rothschild, and James A. 

 Buss. 1972. A study of king, ParaUthodcs canushaiica 

 (Tilesius) brook stocks, Kodiak Island, Alaska, 1963-1971. 

 30 p. (Processed) 



Several authors have reported old-shell males 

 congregated with adult females during the mat- 

 ing season and indicated they may be capable 

 breeders because new-shell males were separate 

 from the females at the time (Gray and Powell, 

 1966; Miyahara and Shippen, 1965). 



Currently the reproductive success or failure 

 of any particular brood year is not readily appar- 

 ent until approximately 8 yr later when males 

 are entering the fishery. At this late date, it is 

 doubtful that we can, with any precision, eval- 

 uate the degree to which each of the limiting 

 factors contributes to the success or failure; con- 

 sequently we are unable to determine if resul- 

 tant abundance levels are attributable to initial 

 magnitude of egg production, environment, or 

 effects of commercial fishing. 



Prior to 1970, managers assumed that any 

 level of harvest of males was acceptable as long 

 as the 7-inch size limit (carapace width outside 

 spines) was observed. 



In recent years, we observed that the propor- 

 tion of adult females without eggs and with 

 partial broods had increased and that some of 

 the female population was not being serviced 

 (unpublished Alaska Department of Fish & 

 Game data). Large adult females have approxi- 

 mately nine times more eggs than small ones 

 (Haynes. 1968) and initial examination of un- 

 published Department of Fish & Game data 

 reveals that the incidence of adults without eggs 

 and with partial broods is greater among the 



Accepted tor publication June 1973. 

 FISHERY BULLETIN: VOL. 72. NO. 1. 1974 



171 



