Pacific Mackerel (Scomber japonicus) Stock Assessment for USA Management in the 2009-2010 Fishing Year, August 1, 2009.
U.S. West coast mackerels are now managed as part of a Coastal Pelegics Species Fishery Management Plan mandated by the Magnuson-Stevens Fishery Conservation and Management Act.
In the early part of the 20th Century, landings of the Pacific mackerel, Scomber japonicus, and the jack mackerel, Trachurus symmetricus, were not separated by species even though they are not closely related taxonomically. Both are schooling fish but Chub mackerel are a coastal representative of a generally high seas group of scombrids, the tunas, and the jack mackerel is an open ocean representative of group of fish, the Carangids which are largely coastal. Complete accounts of these species and their fishery are available in Leetet. al (1992) and Shimada et. al (1999).
Pacific mackerel are distributed from the tropics to the north temperate zoneoff British Columbia and also are found in the same latitudinal bands of all the continental boundaries. When the population is small, they appear to occupy only the warmer part of their habitats. They are a fast growing voracious predator on plankton and on the younger stages of all the pelagic species like anchovy and sardine, as well as their own young. The northern anchovy management plan incorporated an expression which would influence the harvest guidelines for anchovy based on the contemporary biomass of Pacific mackerel.
Jack mackerel are distributed from the temperate zone offshore of the Baja California coast as far north and west as the Aleutian Islands. They may live to 30 years and as such represent the lowest adult natural mortality of any of the pelagic schooling species in this region. Trial fishing for this species in the adult stages has been hampered by their scattered distributions. The local fishery is primarily on the younger fish schooling over the reefs and shoals in the Southern California Bight. The sardine, Pacific mackerel, jack mackerel and anchovy are found in mixed schools apparently assorted by size and swimming ability. The long term potential yield of jack mackerel is about 100,000 metric tons and the species is considered underutilized. Peak catches in 1953 and 1977 were 70,000 and 45,000 respectively.