GROWTH, REPRODUCTION, AND FOOD HABITS OF OLIVE ROCKFISH, 

 SEBASTES SERRANOIDES, OFF CENTRAL CALIFORNIA 



Milton S. Love and William V. Westphal' 



ABSTRACT 



We collected data on age-length and length-weight relationships, age at first maturity, spawning 

 season, fecundity, and food habits of olive rockfish, Sebastes serranoides, off Diablo Cove, near Avila, 

 California. Fish were aged from otoliths. Von Bertalanffy age-length parameters for females were 

 L^= 5L9,^ = 0.18, and <o = -1.57; for males L-^ = 43.3, /j = 0.27, and /« = -1.03. Females grew at 

 a faster rate than males beginning at the age where most males were mature. Age at first maturity 

 ranged from 3 to 8 years, most fishes maturing by age 6. Olive rockfish spawned once per season, 

 between December and March, with peak spawning in January. Fecundity ranged between 30,000 and 

 490,000 eggs. Small individuals preyed primarily on plankton, and larger ones concentrated on fishes, 

 squids, and octopuses. 



The rockfishes (Scorpaenidae: Sebastes) are an 

 important constituent of many marine commu- 

 nities in the eastern North Pacific. Sixty-nine 

 species are known to inhabit these waters (Lea 

 and Fitch 1979) and members of the genus fre- 

 quent virtually every habitat from intertidal 

 regions to depths of well over 1,000 m. 



Though these fishes were of some importance in 

 commercial and sport fisheries in the past, popula- 

 tion declines of more popular fishes have led to a 

 steady increase in rockfish demand. Commercial 

 rockfish catches in the Northeast Pacific exceeded 

 30,000 t in 1978 (Pacific Marine Fisheries Com- 

 mission 1980) and in California, rockfishes are the 

 most important sport fishes, by number, in party 

 boat catches (Pinkas 1977). 



Major, deeper water, commercially important 

 species, such as Pacific ocean perch, S. alutus 

 (Westrheim 1973; Gunderson 1977; Wishard et al. 

 1980); chilipepper, S. goodei, and bocaccio, S. 

 paucispinis (Phillips 1964; Wilkins 1980; Wishard 

 et al. 1980); and yellowtail rockfish, S. flavidus 

 (Phillips 1964; Carlson and Haight 1972; Wishard 

 et al. 1980) have received most attention from 

 researchers. By contrast, with the exception of 

 blue rockfish, S. mystinus (summarized in Miller 

 and Geibel 1973), there are few papers on inshore 

 rockfishes. 



The olive rockfish, Sebastes serranoides, com- 

 poses a major portion of the sport fish catch, both 



from party boats and private vessels, along south- 

 ern and central California (Miller and Gotshall 

 1965; Wine and Hoban^; Maxwell and Schultze^). 

 It lives in areas of reef and kelp, from Del Norte 

 County, Calif., to San Benito Island, Baja Cali- 

 fornia, Mexico, and is most abundant in depths 

 of 5-100 m. 



Olive rockfish are active, fast-swimming, 

 streamlined predators, usually found in the 

 water column, but occasionally hovering over 

 or resting upon rocky substrates (Quast 1968a; 

 Hobson and Chess 1976; Love and Ebeling 1978). 

 Juvenile olive rockfish are primarily midwater 

 feeders, preying upon zooplankton and small 

 fishes, though some substrate feeding (on isopods, 

 caprellid amphipods, etc.) has been noted (Quast 

 1968b; Hobson and Chess 1976; Love and Ebeling 

 1978). No data were available on the food habits of 

 adults. Once they settle out of the plankton, 

 individuals apparently grow to adulthood in a 

 relatively small, circumscribed area (Love 1980) 

 and reefs can be readily depleted of large indi- 

 viduals by overfishing. Off Santa Barbara, Calif., 

 the diminishing sport catch of olive rockfish is now 

 mostly of juvenile and subadult fish, younger than 

 the age of first maturity (Love 1980). Yet, despite 



'Department of Biology, Occidental College, 1600 Campus 

 Road. Los Angeles, CA 90041. 



Manuscript accepted March 1981. 



FISHERY BULLETIN: VOL. 79, NO. 3, 1981. 



-Wine, v., and T. Hoban. 1976. Southern California inde- 

 pendent sportfishing survey annual report July 1, 1975-June 30, 

 1976. Calif. Dep. Fish Game, 109 p. 



^Maxwell, W D., and D. L. Schultze. 1976. Southern Cali- 

 fornia partyboat sampling study Calif. Dep. Fish Game, Mar. 

 Res. Adm. Rep. No. 76-3, 18 p.; 76-6, 18 p.; 76-9, 13 p. 



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