Declining Rockfish Lengths in the Monterey Bay, California, Recreational Fishery, 1959-94

California’s Monterey Bay area is an important center of recreational fishing for rockfish of various Sebastes species. The species composition of commercial passenger fishing vessel catches from 1959 to 1994 varied with changes in fishing location and depth. The shift from shallow nearshore locations to deeper offshore locations in the late 1970’s and 1980’s changed the emphasis from the blue rockfish, S. mystinus, of shallow waters to the deeper, commercially fished chilipepper, S. goodei, and bocaccio, S. paucispinis. The mean size of rockfish in the catch increased as the latter species were targeted at greater depths but then declined as stocks of older fish disappeared by the mid 1980’s. During 1960–94 the mean size of all ten leading species in the recreational catch declined. The declines ranged from 1% for canary rockfish, S. pinniger, to 27% for chilipepper. The sizes of the deeper living species declined more than those of shallower species. The low frequency of strong recruitment events and increase in fishing mortality and natural mortality appear to have contributed to the declining mean size. The scarcity of older fish, observed as a drop in mean size to below the size of maturity for 50% of females, leads to concern for future recruitment of the larger species, especially bocaccio, chilipepper, yellowtail rockfish, S. flavidus, and canary rockfish. nia since the late 1920’s (Clark and Croker, 1933). Passengers pay a fee to be taken to one or more offshore fishing sites, where they fish while the boat drifts over bottoms from 9 to 274 m deep (Sullivan, 1995). The skipper locates concentrations of fish on the bottom or in midwater, and anglers catch an average of 11–12 fish per day (Karpov et al., 1995). For the purpose of this paper, the Monterey Bay area, approximately 100 km south of San Francisco, includes all sites normally fished by CPFV’s from the ports of Santa Cruz, Moss Landing, and Monterey (Fig. 1) and extends from Ano Nuevo, about 35 km north of Santa Cruz, to Point Sur, about 35 km south of Monterey. This area received 24% of CPFV effort and produced 43% of CPFV landings in northern California from 1981 to 1986 (Karpov et al., 1995). Most of the fish caught (85%) are of the genus Sebastes, commonly called rockfish (Miller and Geibel, 1973; Karpov et al., 1995). Rockfish have dominated the catch from CPFV’s in the Monterey Bay area from the 1950’s to the present (Miller and Geibel, 1973; Karpov et al., 1995; Reilly et al.1; Wilson-Vandenberg et al.2). At least 29 species of rockfish appear in the CPFV catch (Miller and Geibel, 1973), but the fishery heavily targets the few aggregating species found in limited areas. Over 72% of the catch in 1960–86 (Mason, 1995) and 76% in 1987–91(Reilly et al.1) came from six aggregating species: bocaccio, S. paucispinis; chilipepper, S. goodei; blue rockfish, S. mystinus; yellowtail rockfish, S. flavidus; widow rockfish, S. entomelas; and olive rockfish, S. serranoides. Over the years the proportions of these species in the catch have changed from predominantly blue rockfish in the 1950’s, to both blue and yellowtail rockfish in the 1960’s (Miller and Geibel, 1973), to more chilipepper and bocaccio in the 1980’s (Mason, 1995), and back to more blue rockfish in the 1990’s (Wilson-Vandenberg et al.2,3; Wilson et al.4). The continuous harvest of rockfish by the CPFV fishery has raised questions about the sustainability and health of this fishery. Some anglers and boat operators believe that rockfish are smaller 1 Reilly, P. N. , D. Wilson-Vandenberg, D. L. Watters, J. E. Hardwick, and D. Short. 1993. On board sampling of the rockfish and lingcod commercial passenger fishing vessel industry in northern and central California, May 1987 to December 1991. Calif. Dep. Fish Game, Mar. Res. Div. Admin. Rep. 93-4, 242 p. 2 Wilson-Vandenberg, D. , P. N. Reilly, and L. Halko. 1995. Onboard sampling of the rockfish and lingcod commercial passenger fishing vessel industry in northern and central California, January through December 1993. Calif. Dep. Fish Game, Mar. Res. Div. Admin. Rep. 95-2, 122 p. 3 Wilson-Vandenberg, D. , P. N. Reilly, and C. E. Wilson. 1996. Onboard sampling of the rockfish and lingcod commercial passenger fishing vessel industry in northern and central California, January through December 1994. Calif. Dep. Fish Game, Mar. Res. Div. Admin. Rep. 96-6, 96 p. 4 Wilson, C. E. , L. A. Halko, D. WilsonVandenberg, and P. N. Reilly. 1996. Onboard sampling of the rockfish and lingcod commercial passenger fishing vessel industry in northern and central California, 1992. Calif. Dep. Fish Game, Mar. Res. Div. Admin. Rep. 96-2, 103 p.