Longspine thornyhead (Sebastolobus altivelis) COSEWIC assessment and status report: chapter 11
Technical Summary
Sebastolobus altivelis
Longspine thornyhead - sébastolobe à longues épines
Extent and Area Information
lat-surface area between isobaths 500 and 1,600 m
Grid of fish density (CPUE) using commercial trawl data
Population Information
Total population trend:
- WCVI (8y) -47%
- Tidemarks (4y) -31%
- Rennell (4y) -59%
Threats (actual or imminent threats to populations or habitats)
- Overfishing in low-productivity environments.
- Roughly 49 million fish removed coastwide from 1996-2004.
Rescue Effect (immigration from an outside source)
Quantitative Analysis
See Haigh et al. (2005)
Current Status
COSEWIC: Special Concern (April 2007)
Status and Reasons for Designation
Status: Special Concern
Alpha-numeric code: not applicable
Reasons for Designation: This slow growing rockfish has adapted to survive in deep waters where oxygen concentrations are minimal and productivity is low. Since the beginning of the fishery in the mid-1990s there has been an estimated decline in commercial catch per unit effort of over 50% in 8 years. Fishing is the primary and probably sole cause of this decline. While the fishery is managed by catch limits, and there is good monitoring of fishing activities, there is no management strategy in place that assures catches will be adjusted in response to abundance changes. The substantial decline in abundance indices over a short period taken together with the very conservative life history characteristics are cause for concern, but commercial catch per unit effort may not reflect abundance changes accurately and there is potential for rescue from adjoining populations in the USA.
Applicability of Criteria (A-E)
Criterion A: May meet criterion A2b for Endangered but there is lack of confidence in the indicators used to measure decline.
Criterion B: Not met - although the extent of occurrence (17,775 km²) is less than 20,000 km²("threatened" threshold), it is neither severely fragmented nor characterized by extreme fluctuations.
Criterion C: Not applicable.
Criterion D: Not applicable.
Criterion E: Not applicable.
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