Abstract.- Fecundity of the yel- 

 low rock crab Cancer anthonyi was 

 examined seasonally over two years. 

 Ovigerous crabs varied in size from 

 89 to 153 mm carapace width. Crabs 

 held in the laboratory brooded more 

 than three clutches per year without 

 molting or mating. Crab fecundity 

 varied seasonally, with peaks in late 

 spring-early summer and late fall- 

 early winter. Ovigerous crabs carried 

 an estimated 0.73-3.30 million eggs, 

 depending on crab size, stage of egg 

 development, and season. The log 

 body size-log fecundity relationship 

 changed significantly with crab em- 

 bryogenesis. Estimates of reproduc- 

 tive potential, defined in terms of 

 the total number of eggs produced 

 throughout the entire adult life span, 

 were based on the mean number of 

 eggs produced at the mean adult 

 size, the minimum and maximum 

 number of mature instars, the min- 

 imum and maximum number of 

 broods per instar, and the number of 

 broods oviposited per year. For a 

 female C. anthonyi, it was 14.7-29.4 

 million eggs, which was relatively 

 higher than other members of the 

 genus. 



Fecundity and the Reproductive 

 Potential of the Yellow Rock 

 Crab Cancer anthonyi 



Jeffrey D. Shields 



Department of Biological Sciences and the Marine Science Institute 

 University of California. Santa Barbara. California 93 1 06 

 Present address: Department of Biological Sciences. Lilly Hall of Life Sciences 

 Purdue University, West Lafayette, Indiana 47907 



Robert K. Okazaki 



Department of Biological Sciences and the Marine Science Institute 

 University of California, Santa Barbara, California 93106 

 Present address: Department of Biological Sciences, 

 Southeastern Louisiana University, Hammond, Louisiana 70402 



Armand M. Kuris 



Department of Biological Sciences and the Marine Science Institute 

 University of California. Santa Barbara. California 93106 



Manuscript accepted 22 October 1990. 

 Fishery Bulletin, U.S. 89:299-305 (1991). 



The yellow rock crab Cancer antho- 

 nyi Rathbun, 1897, supports a grow- 

 ing fishery in southern California. 

 The rock crab fishery exceeds 600 

 tons annually ($2 million ex-vessel 

 value), with the Santa Barbara dis- 

 trict representing 40-60% of the 

 total catch (Resource Agency of Cali- 

 fornia 1981-87, Carroll and Winn 

 1988). Three species of rock crabs 

 comprise the fishery (C. antennarius, 

 C. anthonyi, and C. productus), with 

 Cancer anthonyi being most preva- 

 lent in catches in southern California 

 (Winn 1985, Carroll and Winn 1988). 

 At present, rock crabs are exploited 

 with no restrictions on sex or repro- 

 ductive condition; ovigerous and non- 

 ovigerous females are both removed 

 by the fishery. 



Little is known about the reproduc- 

 tive biology of most Cancer species 

 (for review, see Shields 1991). We in- 

 vestigated fecundity and aspects of 

 the reproductive biology of Cancer 

 anthonyi as part of a larger study 

 that examined brood mortality re- 

 sulting from nemertean predation 

 (Shields et al. 1990). We report obser- 

 vations on multiple broods per crab 

 and interbrood periods, and present 



an analysis of crab fecundity in re- 

 lation to size, embryogenesis, and 

 seasonality. Lastly, we define repro- 

 ductive potential in terms of the 

 maximum lifetime fecundity of an in- 

 dividual crab, and compare reproduc- 

 tive potential within the genus. 



Methods 



Ovigerous female crabs were trapped 

 by a commercial fisherman at depths 

 of 10-100m from the Santa Barbara 

 Channel, between Summerland and 

 Gaviota, California (approximately 

 34°23'-34°25'N, 119°34'-120°12'W). 

 Twenty to twenty-five female crabs 

 were obtained at monthly or bimonth- 

 ly intervals for two years (November 

 1981-November 1983). We sampled 

 345 ovigerous Cancer anthonyi of 

 which 311 were completely processed 

 (see Shields et al. 1990). Carapace 

 width (CW) was measured, and the 

 entire second left pleopod was ex- 

 cised and stored in 5% formalin in 

 seawater for further analyses. Crabs 

 were then released or maintained in 

 flowing seawater aquaria for addi- 

 tional observations. 



299 



