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COSEWIC assessment and status report on the Bocaccio in Canada

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COSEWIC
Executive Summary

Bocaccio
Sebastes Paucispinis

Species Information

Bocaccio is one of over 35 species of rockfish found in marine waters off British Columbia (B.C.). It is distinguished from other rockfish (Sebastes spp.) by its large jaw. It ranges in colour from olive orange to burnt orange or brown on the back, becoming pink to red on the underside. Other common names for bocaccio include rock salmon, salmon rockfish, Pacific red snapper, Pacific snapper, and Oregon snapper. This report treats all the bocaccio of the BC coast as a single population; there has been no research to address evolutionarily significant units within BC.

Distribution

Bocaccio are found in coastal waters of the eastern Pacific Ocean from the Gulf of Alaska to Baja California, Mexico. The population of bocaccio in B.C. probably overlaps to some extent with U.S. populations to the north and south. Most B.C. catches come from the outer Pacific coast near the edge of the continental shelf, with the largest catches coming from the northwest coast of Vancouver Island and from Queen Charlotte Sound. They have been reported from some inlets and the Strait of Georgia.

Habitat

In California, larval bocaccio have been caught up to 480 km from the coast. Young of the year reside near the surface for a few months, then settle in nearshore areas where they form schools and are found over bottom depths of 30-120 m. Adult bocaccio can be semi-pelagic and are found over a variety of bottom types, most commonly over depths of 60-340m. In B.C., they are caught with several other groundfish species including Pacific ocean perch, yellowtail rockfish, and canary rockfish.

Biology

There has been limited research on bocaccio in B.C. waters. Most of the biological information comes from studies done in California. Bocaccio are livebearers. Fecundity, during the egg stage, ranges from 20 000-2 300 000 eggs and increases with the size of the female. Copulation occurs in early fall but fertilization is delayed. Fertilized eggs are retained in the body of the female through hatching and much of larval development. Embryonic development takes about one month and, in B.C. waters, young are released in the winter. Settlement to the littoral and demersal habitat extends from late spring through the summer. Larvae are approximately 4-5 mm long at release and then metamorphose into pelagic juveniles over the next several months. Bocaccio are thought to mature at 4 to 5 years of age and can reach a weight of almost 7 kg and a length of over 90 cm. Females tend to be larger than males. Radiometric dating of the otoliths suggests a maximum age of 40 or more years.

Juvenile bocaccio feed on fish and invertebrate larvae, pelagic shrimp, young rockfish, surfperch, mackerel and various small inshore fishes. Adult bocaccio prey on other rockfish, sablefish, anchovies, lanternfish and squids. The main predators of juvenile bocaccio in California are sea birds and the main predators of adults are marine mammals. Bocaccio are host to a number of parasites including a nematode that occurs in the muscle tissue and has given bocaccio a market reputation for “worminess”. Bocaccio may also be the only host for one species of tapeworm.

Population Sizes and Trends

The abundance of bocaccio is poorly known in B.C. waters. Its low commercial importance has inhibited directed research; and the low catches of bocaccio in the fisheries limit the utility of fishery-dependent data for tracking abundance. Catches indicate that the population is present in coastal waters at the edge of the continental shelf from the Washington to Alaska state borders. The distribution in inshore waters is less well known, although adults continue to be caught in several inlets and the Strait of Georgia. The trend in abundance is unknown for the outer north and central coasts.

Off the west coast of Vancouver Island, numbers appear to have declined by more than 95% in the last two decades, and by more than 90% over the last 10 years. No trend is apparent over the last five years. Numbers may be declining in the Strait of Georgia, however quantitative data are lacking. In neighbouring U.S. waters to the south, abundance is thought to have declined by over 90% over the last two decades.

Limiting Factors and Threats

Commercial trawl fisheries landings (1996-2000) have ranged from 200-300 t/y. Trawl discarding was 9 t in 2000. Landings from hook and line fisheries are approximately 2 t/y. Discards have been reported in the hook-and line fisheries, but the extent is unknown. If significant, it would affect productivity as bycatch usually results in death due to expansion of the swimbladder. Aboriginal and recreational catches are probably negligible at present, but recreational catches could increase as the recreational fishery grows and shifts to targeting on non-salmonid species.

The decline in abundance of bocaccio in Washington State probably means that fewer U.S. recruits are entering B.C. waters, however, the extent to which the Canadian population relies on this immigration is unknown. U.S. harvests are now significantly restricted through reduced trip limits, but discarding is not monitored.

There are no means for estimating the impact of the two parasites on bocaccio populations. There is also no information regarding other biotic or abiotic environmental impacts on bocaccio populations, however, it is generally perceived that the 1990’s produced poor recruitment for most species of groundfish in B.C. and neighbouring U.S. waters. Whether recruitment will improve in the 2000s is yet unknown.

Special Significance of the Species

Bocaccio were part of aboriginal fisheries, have played a minor economic role in B.C. fisheries, and may become of interest to some anglers as rockfishes attract greater attention. They may be the unique host for one species of tapeworm; however, the presence of this tapeworm in B.C. waters has not been confirmed.

Existing Protection or Other Status Designations

There is no specific protection or status for this species in Canadian waters. In U.S. waters, it has been petitioned for listing under the Endangered Species Act. It is considered to be critically endangered by the IUCN, and endangered by WWF.

Summary of Status Report

The biology of bocaccio in B.C. waters is poorly known. It is a marine fish found along the Pacific coast but captured primarily along the edge of the continental shelf. It is difficult to infer population abundance trends. Where some of the best data exist, the west coast of Vancouver Island, there is evidence of a decline of over 90% in the last 10 years and 95% over the last 20 years (data to 2001). A strong decline in the overlapping population in neighbouring U.S. waters raises further concern about the status of bocaccio in B.C. Threats primarily include the harvest and bycatch of fisheries, and poor recruitment.