EXPLORATIONS OF EL-NINO EVENTS AND ASSOCIATED BIOLOGICAL POPULATION-DYNAMICS OFF CENTRAL CALIFORNIA

During El Nino events off central California, temperatures were elevat ed, salinities were depressed, and there was evidence of poleward and onshore advection. El Nino conditions seemed to delay the annual phyto plankton bloom, affect the distribution and abundance of invertebrates , improve recruitment of southern fish species, cause recruitment fail ures of rockfish (Sebastes spp.), and cause poor growth and condition of adult rockfish. The 1992-93 El Nino off central California was less extreme than the 1982-83 event, but much stronger than the 1986-87 ev ent. Water temperatures in 1992-93 were similar to the 1982-83 event, but poleward advection appeared to be weaker. Recruitment of southern species was higher in 1983 than in 1992; the condition of rockfish was better in the more recent event. Computer simulation indicated that f ishery management practices can influence the intensity of El Nino eff ects on a fishery for rockfish. Possible causes of rockfish recruitmen t failures during El Nino events are discussed.