Rockfish

Biology

Rockfish, of the family Scorpaenidae, are among the more interesting and colorful groups of fishes found in the Pacific Ocean. There are 34 species in the genus Sebastes in the Gulf of Alaska, and about a dozen are taken in the sport fishery. They range in length from 8-40 inches and are characterized by large scales and spines on the head, gill covers, and fins. The spines are mildly toxic and can cause pain and infection. Many species are harvested for their tasty white fillets. Some rockfish are bass-like in appearance, and are often erroneously called "sea bass," or "black bass". The yelloweye rockfish is often called "red snapper". Actually, the true basses (family Serranidae) and snappers (family Lutjanidae) are found only in tropical or sub-tropical waters. Other species such as lingcod, kelp and rock greenling, or sculpins ("Irish lords") are also mistakenly called rockfish.

The rockfishes are typically divided into three groups, or assemblages, based on habitat preferences and biological characteristics:

Pelagic Shelf: these species are usually found in large schools up in the water column, above or near rocky areas on the continental shelf. There are five species in this group, but only three, the black, dusky, and yellowtail rockfish, are common in the northern Gulf of Alaska. They are generally not as long-lived as other assemblages. Most pelagic rockfish taken in the sport fishery are 5-30 years old.
Demersal Shelf: these species are generally found in close association with the bottom in rocky areas of the continental shelf, where they often set up defined territories. This group includes yelloweye, quillback, copper, tiger, and China rockfish, among others. Many demersal species can live in excess of 50 or more years. Yelloweye rockfish in excess of 100 years of age have been harvested in the sport fishery.
Slope: these species are also found closely associated with the bottom, but generally in deeper waters of the continental shelf or on the continental slope. Silvergray, rougheye, and shortraker are the most commonly caught species in this assemblage, but generally make up a small proportion of the sport harvest. These species are all long-lived, with some exceeding 150 years of age.

Rockfishes are slow to mature and extremely long-lived, compared to most other fishes. They may not start reproducing until they are 7 to 20 years old or more. Unlike egg-laying fishes, all rockfishes give birth to thousands or millions of tiny, free-swimming larvae, many of which die before settling onto the ocean floor. Most species show a strong preference for specific habitats and some display strong site fidelity. Tagging studies in other areas have shown that although pelagic species tended to move more than non-pelagic species, most did not venture more than a few miles from the site of tagging.

Table 1. Management assemblages and common and scientific names of rockfishes (genus Sebastes) commonly taken in the Southcentral Alaska sport fishery.

Recreational Use

Substantial numbers of rockfish are taken in recreational fisheries in nearshore waters of the Gulf of Alaska from Kodiak to Prince William Sound. Although rockfish are targeted occasionally, most of the harvest is by anglers targeting halibut or rockfish in combination with other species such as lingcod. Anglers will often target rockfish if they are unsuccessful for halibut, salmon, or other more desirable species. Anglers trolling or mooching for chinook salmon or coho salmon also catch rockfish, especially black and dusky.

Figure 2. Recreational harvest of rockfish (all species) in Southcentral Alaska, 1977-2003. Estimates are from the ADF&G Statewide Harvest Survey.

The estimated sport harvest of all rockfish species combined has been highly variable, rising from 22,000 fish in 1977 to a peak of 71,000 fish in 1988, then varying between 40,000 and 63,000 fish since 1990. The North Gulf Coast fishery based in Seward has accounted for 42-57% of the estimated harvest in Southcentral Alaska since 1990. Estimates of harvest may be biased slightly high due to misidentification of other species as rockfish by survey respondents.

An estimated 20,000 to 92,000 additional rockfish have been caught and subsequently released annually in Southcentral Alaska since 1990. Rockfish suffer decompression injuries when brought to the surface from depths greater than 10 fathoms. The species composition and depths of capture for these released fish are unknown, but it is safe to say that the total removals by the recreational fishery exceed the harvest estimates

The recreational harvest is a significant source of removals, especially in nearshore waters. For example, documented commercial rockfish harvest in state waters of the Cook Inlet and Prince William Sound (Cape Douglas to Cape Suckling) ranged from about 158,000 to 281,000 pounds during the period 1999-2003. The corresponding sport harvest biomass for the same area and period ranged from about 211,000 to 336,000 pounds, or 52-64% of the total removals.

Management and Stock Status

The State of Alaska has management authority for recreational rockfish fisheries in state waters (0-3 miles) and federal waters of the Exclusive Economic Zone (3-200 miles). Section 306 of the Magnuson-Stevens Act allows the state to regulate sport fishing in federal waters when there is no fishery management plan or applicable federal regulations. The Alaska Board of Fisheries sets bag limits, seasons, and other regulations.

There is ample reason for concern for the long-term sustainability of rockfish fisheries throughout the northern Gulf of Alaska. Rockfish are fairly easy to locate and catch, and most species take a long time to reach maturity. Reproductive success is spotty and believed to be highly dependent on ocean conditions. Most rockfish caught as bycatch in other fisheries probably don't survive. Almost no information exists on the relative or absolute abundance of nearshore rockfishes in this region. Available life history data as well as case histories from southeast Alaska, British Columbia, and Washington point to the ease of overharvest and the difficulty of managing for sustained yield. Commercial and recreational fisheries typically develop on the standing stock rather than the annual production, resulting in localized depletion. Limited data from commercial test fishing and the recreational harvest near Resurrection Bay suggest that the relative abundance of older black rockfish may have declined since the early 1980s. Observations made along the coast from Granite Island to Point Elrington in 1997 suggested decreased abundance of black rockfish in the proximity of Resurrection Bay (unpublished ADF&G data). Other sections of the coast are unsurveyed.

Because of the lack of information regarding rockfish stocks, there are no specific fishery objectives and the fishery is managed under conservative regulations. The department has adopted an informal policy of recommending bag limits that discourage directed sport harvest of non-pelagic (demersal and slope species), but are liberal enough to allow retention of incidental harvest. The daily bag limits in the Alaska Peninsula and Kodiak areas, where the harvest is relatively small and dominated by pelagic species, is set at ten fish. In the more heavily fished waters of the Cook Inlet-Resurrection Bay area, the bag limit is five rockfish daily, no more than one of which may be a non-pelagic (demersal or slope) species. In Prince William Sound, where demersal species make up the majority of the harvest, the bag limit during the summer season is five rockfish, no more than two of which may be non-pelagic species. Anglers must retain the first two non-pelagic species they catch. There are no size limits because rockfish taken from waters in excess of 10 fathoms suffer decompression injury and are believed to have low survival when released.

More Rockfish Information

Southcentral Region Groundfish Staff