Status of the Pacific mackerel resource and fishery 1994 and 1995

The California fishery for Pacific mackerel, Scomber japonicus, has declined precipitously since 1990, and statewide landings during 1994 totaled only 11,070 short tons. The principal cause of the low catches has been low biomass and poor availability on the traditional fishinggrounds in southern California waters.Several sources of information are available on the status of the Pacific mackerel stock. Landing statistics were available since 1978 for both the U.S. and Mexican fisheries, and both fisheries show similar declines during recent years. Other fishery-independent data from aerialobservations and plankton surveys (mackerel larvae samples) also show declines in abundance compared to the early 1980's.We used a tuned virtual population analysis (VPA) model called ADEPT to estimate Pacific mackerel abundance. The model finds the best statistical fit between fishery-based age-structured biomass estimates and other data from the aerial observations and the plankton surveys. A model-derived biomass estimate for July 1, 1994 was 71,000 tons. Based on the estimated number of fish in each year class at the end of 1994, and using certain assumptionsconcerning expected fishing mortality during the first half of 1995, we project that the Pacific mackerel biomass will be 56,000 tons at the beginning of the 1995/96 fishing season, on July 1, 1995.The Fish and Game Code specifies that when the biomass is between 20,000 and 150,000 tons, the season's quota shall be 30 percent of the biomass in excess of 20,000 tons. Using that formula and our projection for July 1, 1995, the commercial fishery quota for the 1995/96 fishing season is 10,800 tons.(21pp.)