ASPECTS OF THE BIOLOGY OF TWO SCYLIORHINID SHARKS, 

 APRISTURUS BRUNNEUS AND PARMATURUS XANIURUS, FROM 

 THE UPPER CONTINENTAL SLOPE OFF SOUTHERN CALIFORNIA 



Jeffrey N. Cross' 



ABSTRACT 



The distribution, abundance, reproductive cycle, and food habits of two scyliorhinid sharks are discussed. 

 Catsharks occurred on 87% of 71 longline sets and in 6% of 48 trawls. Longline catches were stratified 

 by habitat into banks (hard substrate) and mud (soft substrate). Apristurus brunneus occurred more 

 frequently on mud sets than on bank sets, but its abundance was similar in both habitats. Parmaturus 

 xaniuTus occurred equally frequently on mud and bank sets, but it was more abundant on bank sets. 

 Catches of both species consisted of adults and adolescents; juveniles were rare or absent. Historical 

 collections suggest that juveniles are mesopelagic. 



Male P. xaniurus matured at a smaller size than msXeA. brunneus. Females of both species matured 

 at about the same size and fecundity increased with female size. The proportion of body weight devoted 

 to gonads and maximum oocyte size were greater among P. xaniurus, but fecundity and the proportion 

 of females carrying egg cases were greater among A. brunneus. Seasonal changes in gonadal develop- 

 ment were not well defined for either species. Members of both populations may have been reproduc- 

 tively active throughout the year. 



The diets of both species comprised, in order of importance, crustaceans, teleosts, and squids. Most 

 prey consumed were pelagic; however, it is not known where in the water column the catsharks obtained 

 their prey. 



The Scyliorhinidae is the largest family of living 

 sharks with about 94 valid species (Nelson 1984). 

 Commonly known as catsharks, they occur world- 

 wide from tropical to cold-temperate and arctic 

 waters from the intertidal to depths greater than 

 2,000 m. Little is known about the biology of most 

 scyliorhinid sharks despite their abundance and 

 widespread distribution (Springer 1979; Compagno 

 1984). 



Apristurtis hrunneus Gilbert, the brown catshark, 

 occurs in the eastern Pacific Ocean from northern 

 British Columbia, Canada, to northern Baja Califor- 

 nia, Mexico, and perhaps south to Central America 

 and Peru. It is common on the outer continental 

 shelf and upper slope off British Columbia, Wash- 

 ington, and northern California (Springer 1979) but 

 is considered uncommon off central and southern 

 California (Miller and Lea 1972). DeLacy and Chap- 

 man (1935) and Cox (1963) described its egg case. 

 Jones and Geen (1977) made observations on its 

 distribution, reproduction, and food habits in British 

 Columbia waters. 



^Southern California Coastal Water Research Project, 646 W. 

 Pacific Coast Highway, Long Beach, CA 90806. 



Parmaturus xaniurus Gilbert, the filetail cat- 

 shark, occurs in the eastern Pacific Ocean from cen- 

 tral California to the Gulf of California, Mexico. It 

 is fairly common on the outer continental shelf and 

 upper slope (Compagno 1984). Cox (1963) described 

 its egg case. Lee (1969) reported that juveniles were 

 captured by midwater nets in the Santa Barbara 

 basin off southern California. Springer (1979) re- 

 ported that P. xaniurus were observed eating mori- 

 bund lanternfishes (Myctophidae) at the bottom of 

 the oxygen-poor Santa Barbara Basin. 



The objective of this study was to increase the 

 knowledge of the life histories of A. brunneus and 

 P. xaniurus by analyzing data on the distribution, 

 abundance, reproduction, and food habits of these 

 species collected during a survey of the fishes of the 

 upper continental slope off southern California 

 (Cross 1987). 



MATERIALS AND METHODS 



Fishes occurring on or near the bottom between 

 290 and 625 m were collected by otter trawl and 

 longline. Forty-eight trawls were made between 

 November 1981 and August 1983 (Fig. 1). A single 

 warp semiballoon trawl with 7.6 m headrope, 8.8 m 



Manuscript accepted June 1988. 



FISHERY BULLETIN: VOL. 86, NO. 4, 1988. 



691 



