The California Department of Fish and Game started routinely acoustically surveying the smaller schooling pelagic fish resources in the California Current System in 1966. This report covers the first 6.5 years of these surveys (1966–1973).

The purpose of these surveys was to determine the abundance, distribution, availability, and other pertinent biological information of the commercially important northern anchovy, jack mackerel, Pacific sardine, and Pacific mackerel. Latent resource species including Pacific saury, Pacific hake, squid, and pelagic red crab also were surveyed. The principal technique consisted of running acoustic transects with a horizontal ranging sonar and vertical echo sounder during daylight hours and fishing a midwater trawl at night.

Results show the northern anchovy grossly dominates all other species in terms of biomass and abundance with the southern California-northern Baja California region containing most of the total population. Although it was not possible to determine absolute population size, results indicate the estimates of 2 to 6 million tons made from egg and larvae surveys are reasonable. Behavior and availability studies indicate that although the anchovy population is large, its vulnerability to harvest by the present commercial fishery varies considerably from year to year as well as seasonally. Most of the common schooling behaviors are unfavorable for effective harvest by roundhaul net. Only a small portion of the population is harvestable during any particular time period.

Acoustic surveys were much less effective for estimating abundance of Pacific sardines, Pacific mackerel, and jack mackerel. The distribution of jack mackerel was patchy with nearly all significant concentrations located at a limited number of rocky banks and island coasts. Pacific sardine and Pacific mackerel population levels in California were apparently too low to assess. There were indications of larger populations of both species in Baja California.

of the latent resource species under survey, pelagic red crabs and market squid appear to be the most favorable for future exploitation. However, the crabs are located almost entirely within Mexican territorial waters and the vulnerability of squid for large scale harvest is uncertain.