Longspine thornyhead (Sebastolobus altivelis) COSEWIC assessment and status report: chapter 11

Technical Summary

Sebastolobus altivelis

Longspine thornyhead - sébastolobe à longues épines

Range of Occurrence in Canada:
Pacific Ocean

Extent and Area Information

Extent of occurrence (EO) (km²)
lat-surface area between isobaths 500 and 1,600 m
17,775 km²
Specify trend in EO
No change
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km²)
Grid of fish density (CPUE) using commercial trawl data
11,700 km²
Specify trend in AO
No change
Are there extreme fluctuations in AO?
No
Number of known or inferred current locations
Continuous distribution
Specify trend in #
N/A
Are there extreme fluctuations in number of locations?
N/A
Specify trend in area, extent or quality of habitat
No known change

Population Information

Generation time (average age of parents in the population):
30 years
Number of mature individuals:
Unknown

Total population trend:

  1. WCVI (8y) -47%
  2. Tidemarks (4y) -31%
  3. Rennell (4y) -59%
% decline over the last/next 10 years or 3 generations.
Unknown
Are there extreme fluctuations in number of mature individuals?
Unlikely
Is the total population severely fragmented?
No
Specify trend in number of populations:
No change
Are there extreme fluctuations in number of populations?
No
List populations with number of mature individuals in each:
N/A

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)

Status of outside population(s)?
Continental USA: Lightly exploited
Is immigration known or possible?
Possible
Would immigrants be adapted to survive in Canada?
Possibly
Is there sufficient habitat for immigrants in Canada?
Probably
Is rescue from outside populations likely?
Possibly

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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