Canary rockfish (Sebastes pinniger) COSEWIC assessment and status report: chapter 2

Species information

Canary rockfish (French: sébaste canari) (Sebastes pinniger) is one of 102 species of the genus Sebastes, of which at least 36 species are present in B.C. waters. Canary rockfish have been managed in B.C. waters as two principal stocks: a southern or west coast of Vancouver Island stock and a central, or Queen Charlotte Sound stock north of Vancouver Island. Although there is evidence for a biogeographical boundary at the north end of Vancouver Island, which could be considered a boundary between northern and southern populations of canary rockfish, this report treats canary rockfish as a single designatable unit in B.C. waters. Fishers report that canary rockfish are abundant in more northern areas, particularly off the west coast of the Queen Charlotte Islands; but landings from these areas have been limited owing to the lack of trawlable ground. The B.C. population probably overlaps to some extent with U.S. populations.

Distribution

Canary rockfish are found from the western Gulf of Alaska (Shelikof Strait) to northern Baja California. Populations are most abundant between B.C. and northern California. They are broadly distributed in continental shelf and coastal waters of B.C.

Habitat

Larvae and pelagic juvenile canary rockfish occupy the top 100 m for up to 3-4 months after live-birth (parturition) and then settle to a benthic habitat. Adults typically inhabit rocky bottom in 70-270 m depth on the continental shelf. Canary rockfish are a marine and sub-tidal species; thus, all Canadian habitat is within Federal waters. Most of these waters are currently exploited by commercial, recreational, and First Nations’ fishers.

Biology

Maximum observed length, weight, and age for canary rockfish from B.C. waters are 68 cm, 5.7 kg, and 84 y, respectively. Average weight in commercial samples is 2.03 kg. They first appear at age five in the fishery and are fully recruited by 13-14 y. The instantaneous rate of natural mortality (M) for males and young females is about 0.06. The M for females appears to increase as they mature with an overall age-averaged M of about 0.09. Age of 50% maturity is 13 and 7-8 for females and males, respectively. Generation time is 20-30 y.

Pelagic juveniles feed on an array of planktonic items. Adults and subadults primarily eat krill and small fishes. Significant predators probably include lingcod (Ophiodon elongatus). Like all rockfish, they have closed swim bladders and will usually die if released after routine capture. Tagging work in Oregon indicated that at least some individuals can move over 100 km. Trawl catches indicate a seasonal depth migration from 160-210 m in late winter to 100-170 m in late summer. The role and importance of canary rockfish in the ecosystem have not been examined.

Population sizes and trends

Surveys and commercial harvests suggest a current adult abundance of at least several million fish. In the southern part of the species’ range in Canada, the U.S. triennial bottom trawl survey (1980-2001) indicates a decline of 96%. The catch rates in a long-term (1975-2006) shrimp trawl survey off the west coast of Vancouver Island show high variability but a statistically significant decline over this period of 78%. Commercial bottom trawl catch rates in the same region appear stable since 1996. Age data from this region show little long-term trend in mean age of females but a decline in mean age of males from 1980-1990, followed by no trend. Inferred estimates of F (the instantaneous rate of fishing mortality) from catch curve analysis do not indicate overexploitation. The contiguous population in the USA is at a very low level (5-10% of unexploited) and was declared “overfished” in 1999; directed fishing was closed as part of a rebuilding plan.

For the northern part of the species’ range in Canada (Queen Charlotte Sound), there is no long-term index available, and available indices are considered of low reliability for this species. Two recently initiated surveys indicate increasing abundance since 1998 and 2003, respectively. Trawl catch rates appear stable since 1996; size and age composition provide no evidence of overexploitation. Fishers have long reported significant unexploited populations of canary rockfish further north, particularly off the west coast of the Queen Charlotte Islands, but no abundance trend is available for that population. Status of populations to the north (Alaska) is unknown.

A combined analysis of the two most reliable index series (US triennial, west coast of Vancouver Island shrimp survey) shows a decline of 86% in 30 years or 1 – 1.5 generations in the southern part of the Canadian distribution. Reported catches are consistent with this level of decline and plausible biomass estimates, indicating that fishing can explain the decline. Reduced recruitment may have contributed to the decline but there is no clear evidence that this occurred.

Limiting factors and threats

Fishing is the major known anthropogenic threat. Commercial fisheries are managed by harvest quotas, which are essentially unchanged in the most important fishing areas since the mid-1990s, and are well monitored. Recreational and First Nations’ catches are less well monitored but will probably remain negligible over the short term. A number of surveys have been implemented in B.C. since 2000 to improve tracking of relative abundance. U.S. fisheries may have had an impact on abundance in Canadian waters, but since the declaration in 1999 of an “overfished” status for canary rockfish for Washington-California waters, fishing effort and catches have been drastically reduced.

Mobile fishing gear may impact canary rockfish habitat, but the canary rockfish trawl grounds have been fished for 3-6 decades and, since the introduction of Individual Vessel Quotas in 1997, trawl activity has been limited to core areas. Oil and gas exploration could impact habitat but this is currently under moratorium on the B.C. coast. No other threats to habitat are known.

Special significance of the species

Canary rockfish are a significant economic component of the commercial fisheries (>800 t/y since 1995), but play a minor role in the recreational fishery, where they are a non-directed species. Catches are small in First Nations’ fisheries but their cultural importance may be larger than is reflected by the catches.

Existing protection or other status designations

Landings are currently constrained in the commercial fisheries through a variety of harvest controls, and are well monitored. Catches in the recreational fishery are controlled through bag limits for “rockfish” and by Rockfish Conservation Areas.