Black rockfish are a major component of nearshore commercial and recreational fisheries, with increasing importance from the San Francisco area northward.
Distribution, Stock Structure and Migration
Black rockfish range from Amchitka Island, Alaska to Huntington Beach in southern California, but are uncommon south of Point Sur. They frequently occur in loose schools ten to twenty feet above shallow (to 120ft) rocky reefs, but individuals may also be observed resting on rocky bottoms, or schooling midwater over deeper (to 240ft) reefs to 1200ft.
Records for black rockfish show or describe a range of movement/migratory patterns from residential (no movement) to transient (movement to 345 mi.).
Age and Growth
This species may attain a maximum length of 27.6 in. in California, although individuals over 25 in. are rarely observed today. Average size observed in commercial and recreational fisheries now is 14 to 15 in. in northern California and 11 to 13 in. in central California. .
Black rockfish have a relatively fast growth rate. First-year growth is usually 3.5 to 4.0 inches. Most individuals become available to the fishery by the time they have reached 3 to 4 years of age and are approximately 10 to 11.5 inches.
Reproduction, Fecundity and Seasonality
In California, age at first maturity for males is 3 yr, or 9.8 in. TL. For females, age at first maturity is 5 yr or, 11.8 inches. At 6 yr, or about 14 in., half of all males are sexually mature. At 6 to 7 yr, or about 16 in., half of all females are sexually mature.
As with all members of the genus Sebastes, fertilization and development of embryos is internal. Black rockfish mating generally occurs between July and August.
Females store the sperm internally until their eggs mature in December or January, at which time the eggs are fertilized. The larvae develop within thirty days, at which time the black eyespots become visible to the naked eye. The eyed larvae are spawned from late January to May, peaking in February off California.
Larvae are planktonic for three to six months where they are dispersed by currents, advection, and upwelling. They begin to reappear as young-of-the-year fish in shallow, nearshore waters by May, but the major recruitment event usually occurs from July to August.
Mortality estimates have been calculated for black rockfish along the Pacific coast. The instantaneous rate of natural mortality has been found to vary between 0.2 and 0.4 for unsexed fish along the Pacific coast.
As larvae, black rockfish feed on nauplii, invertebrate eggs and copepods. As adults, they remain primarily planktivorous, feeding on small fishes (including juvenile blue and other rockfishes) as well as crustaceans, polycheates, cephalopods, chaetognaths and jellyfish.
Black rockfish co-occur with blue and olive rockfishes in the water column and with black-and-yellow rockfish near and on the bottom.
Black rockfish are commonly associated with other nearshore fish species, particularly other rockfishes. No other schooling rockfish was closely associated statistically with black rockfish, but three benthic species, gopher, China, and brown rockfishes, showed an affinity to the same habitat and depth range as black rockfish.
Larval black rockfish are pelagic. Young-of-the-year (approximately 1.5 in.) settle nearshore, generally in the shallower portions of the kelp beds (15 to 40 ft) where they frequent the sand-rock interface, seagrass beds, kelp canopy, midwater column and high-relief rock. They have also been found on artificial reefs, and in bays, estuaries and tide pools.
Adults inhabit the midwater and pelagic areas over high-relief rocky reefs. They are found in and around kelp beds, boulder fields and artificial reefs.
Status of Stocks
An assessment of the black rockfish fishery in 2007 indicates the stock is at 70% of the virgin biomass. California Recreational Fishery Survey showed that, in Humboldt and Del Norte Counties (northern California), black rockfish comprised approximately 85 percent of the annually nearshore rockfish complex. South of the northern California, black rockfish gradually decreases in the recreational catch and are infrequently observed south of Point Sur (central California).
Information on this page was originally presented in the Nearshore Fishery Management Plan (these profiles updated July, 2010).