Abbreviated Life History of Blue Rockfish
(Sebastes mystinus)

Blue Rockfish; Photo by Steve Lonhart of Simon/NOAA

Mystinus is derived from the Greek word for “priest” in reference to the species dark color. Blue rockfish were known as peche pretre (priest fish) to nineteenth-century Portuguese fishermen in Monterey (central California), while Puget Sound fishermen of the period called them black bass. The blue rockfish is a medium-sized, midwater rockfish important in both the recreational and commercial catches in California, and it is the most abundant rockfish in central California kelp beds.

Distribution, Stock Structure and Migration

Blue rockfish range from the Sitka Straight, Alaska to Punta Banda, Baja California, and from surface waters to a maximum depth of 1800 feet. They are less common south of the northern Channel Islands and north of Eureka, California.

It is believed that the last exceptionally strong year class of blue rockfish in central California occurred in 1993 and 1998. The late 1970s showed all time low recruitment, with 2006 among the three lowest recruitment years estimated.

No information is available regarding genetically discernable substocks of blue rockfish. However, genetic preliminary evidence has suggested two species of blue rockfish may exist in California.

Movement and migration studies of blue rockfish have determined them to be residential. Most authors report movement of less than 6 miles. In addition, tagging studies of adult blue rockfish indicate they rarely migrate laterally along the coast. While studies show adult blue rockfish populations are more or less discreet at each fishing port, it is not known how much larval drift occurs between fishing areas.

Age and Growth

Blue rockfish, sex unspecified, have been aged to a maximum of 44 yr using scales or otoliths. Rockfishes in general are considered to be slow-growing fishes. However, blue rockfish are among the faster growing rockfishes. First year growth may vary from 3.0 to 4.5 in., and after 2 yr blues may reach 6 inches. Anglers may catch an occasional 2- or 3-yr old blue rockfish, but most do not recruit to the sport and commercial fisheries until 4 to 7 yr of age when they range from 8 to 10 inches. Females grow at a slightly faster rate than males.

Reproduction, Fecundity and Seasonality

Age at first maturity for males has been found to vary between 3 yr (7.5 in. TL) and 4 yr (9.0 in. TL). For females, age at first maturity has been found to vary between 2 yr and 5 yr (10 in. TL). Age at 50% maturity for males has been found to vary between 3 yr and 7 yr (10.2 in. TL). For females, age at 50% maturity has varied from 4 yr to 6 yr (11.4 in. TL).

Studies in central California have shown that in males the gonads increase in size from May to July, but in females the eggs begin maturing from July to October. Mating takes place in October, but the embryos do not begin to develop until December when the eggs are fertilized by the stored sperm. Embryos develop within the female and hatch immediately upon being released into water; larval release usually peaks in mid-January.

Blue rockfish are thought to spawn once a year. Larvae are planktonic for four to five months, where they may be carried many miles by ocean currents. Young-of-the-year blue rockfish begin to appear in the kelp canopy and shallow rocky areas by late April or early May when they are about 1.2 to 1.4 in. in length.

Predator/Prey Relationships

Feeding habits vary considerably depending upon life history stage, depth, and locality. As larvae, blue rockfish are planktivorous and are known to feed on nauplii and invertebrate eggs as well as copepods. As adults they remain primarily planktivorous and are considered to be omnivorous/zooplanktivorous. They feed on jellyfish, tunicates, thaliaceans, algae, small crustaceans, and small fish.

Adults are subject to predation by other rockfish, lingcod, sharks, dolphins, seals, sea lions, and possibly river otters. Juveniles fall prey to other rockfishes, lingcod, cabezon, salmon, marine birds and porpoises.

Competition

Blue rockfish are commonly associated with other nearshore fish species, particularly other rockfishes. In a broad area along the entire Monterey Peninsula extending out to 240 feet deep, blue rockfish were the predominant species and were in close association with olive, yellowtail, and blacks.

Critical Habitat

Larval blue rockfish are pelagic. In the spring, YOY begin to appear in the kelp canopy, shallow rocky areas and nearshore sand-rock interface. Adults inhabit the midwater and pelagic areas around high-relief rocky reefs, within and around the kelp canopy and around artificial reefs. They are common in kelp beds, where food is plentiful and protection from predators is provided. In the kelp beds, they form both loose and compact aggregations.

Status of Stocks

In 2007, the California Department of Fish and Wildlife completed a stock assessment for blue rockfish in California waters, north of Point Conception. The assessment indicated the blue rockfish population is at 29.9% of the virgin biomass. They are one of the most important recreational species in California for anglers fishing from skiffs and Commercial Passenger Fishing Vessels, and is usually the most frequently caught rockfish north of Point Conception. This species truly has been the bread and butter of the nearshore recreational angler in central California.

Information on this page was originally presented in the Nearshore Fishery Management Plan (these profiles updated July, 2010).

Blue Rockfish