General description: Rockfishes (Sebastes spp.) are a diverse group of marine fishes. More than thirty species occur in Alaska's coastal waters, with at least twelve species ranging as far north as the Bering Sea. Adult rockfishes range in size from 5 to 41 inches with most species attaining sizes between 20 and 24 inches. These fish are characterized by having bony plates or spines on the head and body, a large mouth, and pelvic fins attached forward near the pectoral fins. The spines are venomous, and although not extremely toxic, can still cause pain and infection. Some species are brightly colored, and many are difficult to distinguish from one another. Rockfishes appear somewhat perch-like or bass-like, and are often called sea bass.

Ecology: Rockfishes inhabiting Southeast Alaska can be separated into three ecological groups: (1) demersal shelf rockfishes (DSR), rockfish species that occur on the continental shelf, reside on bottom, and are generally associated with rugged, rocky habitat; (2) pelagic shelf, species that live on the continental shelf, but spend much of their time up in the water column and off the bottom; and (3) slope, species that live in deeper waters, on the edge of the continental shelf and continental slope. The DSR assemblage is comprised of seven species of nearshore bottom-dwelling rockfishes: yelloweye (Sebastes ruberrimus), quillback (S. maliger), china (S. nebulosus), rosethorn (S. helvomaculatus), tiger (S. nigrocinctus), canary (S. pinniger), and copper (S. caurinus).  Management emphasis is placed on yelloweye rockfish, as it is the dominant species in the DSR fishery. Quillback and copper rockfishes are also commonly taken in the DSR fishery.

Reproduction: Rockfishes are different from many other fish species in that they do not spawn—the release of unfertilized eggs and sperm into the water. Instead they parturate or release developed larvae. Rockfishes court, copulate, and then eggs are internally fertilized. Females store sperm, so fertilization may be delayed, up to several months in some species (Love et al. 2002). Yelloweye rockfish extrude larvae over an extended time period, with the peak period of parturition occurring in April and May (O’Connell 1987).

Life History: Rockfishes are slow-growing, late maturing, and extremely long-lived (Adams 1980, Gunderson 1980, Archibald et al. 1981). Yelloweye rockfish become sexually mature from 20 to 25 years of age and may live to 100 years of age (O’Connell and Fujioka 1991). One Southeast Alaska yelloweye rockfish was aged to 121 years (O’Connell and Funk 1986). Many yelloweye rockfish living today were also alive during the Civil War and when the United States bought Alaska from Russia in 1867. Most rockfish species are fairly resident, staying in the same general area over their lifespan.

Food habits: Juvenile rockfishes consume primarily zooplankton, as well as fish eggs. Adult rockfishes eat a variety of food items. Yelloweye are a predatory fish that consume shrimp and fish, such as herring, sandlance, and small rockfishes (Rosenthal et al. 1988).

Management: DSR rockfishes are susceptible to mortality when brought to the surface from depth due to the structure of their swim bladder, a balloon-like organ used to regulate buoyancy. They have a closed swim bladder that is connected to their circulatory system for gas exchange through the blood; consequently, they cannot withstand quick changes in pressure. Therefore most DSR, including discarded bycatch, are usually fatally injured when landed on fishing gear. As a result, a regulation is in effect for full retention of DSR species in both state and federal waters in all fisheries.
Due to their life history characteristics, rockfishes are very susceptible to over-exploitation and are slow to recover once driven to a low population level (Leaman 1991); as a result, the harvest rate is set low. ADF&G manages the commercial DSR fishery to limit total annual removal to no more than 2% of the exploitable biomass of yelloweye. The directed fishery quotas are set after accounting for bycatch mortality in other fisheries. The biomass of yelloweye rockfish is estimated by a habitat based method, which incorporates an area estimate of rocky habitat.
 

References
Adams, P. B. 1980. Life history patterns in marine fishes and their consequences for fisheries
            management. Fish Bull. 78(1):1-12.
Archibald, C. P., W. Shaw, and B. M. Leaman. 1981. Growth and mortality estimates of rockfish
            (Scorpaenidae) from B. C. coastal waters. 1977-1979. Can. Tech. Rep. Fish. Aquat. Sc. No. 1048. 57p.
Gunderson, D. R. 1980. Using r-K selection theory to predict natural mortality. Can J. Fish. Aquat. Sci.
            37:1522-1530.
Leaman, B. M. 1991. Reproductive styles and life history variables relative to exploitation and
            management of Sebastes stocks. Env. Biol. Fishes. 30:253-271.
Love, M. S., M. Yoklavich, and L. Thorsteinson. 2002. The Rockfishes of the Northeast Pacific.
            University of California Press, Berkeley.
O'Connell, V. M. 1987. Reproductive seasons for some Sebastes species in Southeastern Alaska. Alaska
            Department of Fish and Game Information Leaflet 263: 21 p.
O'Connell, V. M. and J. T. Fujioka. 1991. Demersal shelf rockfishes (Gulf of Alaska) IN Loh-Lee Low
            (ed.). Status of living marine resources off Alaska as assessed in 1991. NOAA Tech. Memo. NMFS F/NWC-211, 95 p.
O'Connell, V. M. and F. C. Funk. 1987. Age and growth of yelloweye rockfish (Sebastes ruberrimus)
            landed in Southeastern Alaska. In B. R. Melteff (editor). Proceedings of the International Rockfish    Symposium. p 171-185. Alaska Sea Grant Report No. 87-2.
Rosenthal, R. J., V. Moran-O’Connell, and M. C. Murphy. 1988. Feeding ecology of ten species of
            rockfishes (Scorpaenidae) from the Gulf of Alaska. Calif Fish and Game 71(1): 16-37.

Some text adapted from ADF&G Wildlife Notebook Series, Rockfishes by Mark W. Schwan 1994 http://www.adfg.state.ak.us/pubs/notebook/fish/rockfish.php