Tope (Galeorhinus galeus) COSEWIC assessment and status report: chapter 12

Technical Summary

Galeorhinus galeus

Tope – Milandre

Range of Occurrence in Canada:

Pacific Ocean

Extent and Area Information

Extent of occurrence (EO) (km²)
73 600 km². Based on spatial extent of the depth interval representing 95% of the captures in the trawl fishery.
Specify trend in EO
Unknown
Are there extreme fluctuations in EO?
Unknown
Area of occupancy (AO) (km²)
2000 km² (minimum). Based on occurrence in the commercial trawl fishery represented in 5X5 km grid squares. This value is a minimum.
Specify trend in AO
Unknown
Are there extreme fluctuations in AO?
Unknown
Number of known or inferred current locations
Unknown
Specify trend in #
Unknown
Are there extreme fluctuations in number of locations
Unknown
Specify trend in area, extent or quality of habitat
Unknown, likely stable

Population Information

Generation time (average age of parents in the population)
23 years
Number of mature individuals
Unknown
Total population trend:
Unknown
% decline over the last/next 10 years or 3 generations.
Unknown
Are there extreme fluctuations in number of mature individuals
Unknown, not likely
Is the total population severely fragmented?
Not likely
Specify trend in number of populations
Unknown
Are there extreme fluctuations in number of populations?
Unknown, not likely
List populations with number of mature individuals in each:
unknown

Threats (actual or imminent threats to populations or habitats)

On a global level fishing is the single largest threat to populations. Historical overfishing in the northeast Pacific during the late 1930s and early 1940s would have severely reduced the population. Fishing pressure on the NE Pacific population has been very low over the last 60 years and at present time likely poses a minimal threat; however, the population size is unknown.

Rescue Effect (immigration from an outside source)

Status of outside population(s)?
USA: Status of tope in US waters south of the Canadian border is unknown. Tope have not been recorded from Alaskan waters.
Is immigration known or possible?
likely only seasonal use of Canadian waters.
Would immigrants be adapted to survive in Canada?
Yes, seasonally
Is there sufficient habitat for immigrants in Canada?
Yes
Is rescue from outside populations likely?
Likely, but unknown.

Quantitative Analysis

A quantitative analysis was not undertaken.

Current Status

COSEWIC: Special Concern (2007)
IUCN: vulnerable (VU A1bd) globally

Status and Reasons for Designation

Status: Special Concern
Alpha-numeric code: n/a
Reasons for Designation: This Pacific coast shark is thought to be highly migratory across its range from Hecate Strait, BC to the Gulf of California. It shows no evidence of distinct populations and thus for the purposes of this assessment is considered a single population. It feeds primarily on fish, and in Canada occupies continental shelf waters between western Vancouver Island and Hecate Strait. Maximum length is less than two metres, maximum age is at least 45 years, maturity between 12 and 17 years, and generation time 23 years. The species is noted for its high concentration of liver vitamin A, exceeding that of any other north-east Pacific fish. Demand for vitamin A during World War II led to a large fishery that quickly collapsed due to over-exploitation. More than 800,000 individuals, primarily large adults, were killed for their livers between 1937 and 1949 throughout its migratory range. This shark is rarely seen today in Canadian waters. There is no targeted commercial fishery in Canada, but it continues to be caught as fishery bycatch in Canada and the U.S., and remains the target of small commercial and recreational fisheries in the U.S. Because there is no population estimate, the sustainability of current catches cannot be assessed. The ongoing fishery mortality, the lack of a management plan for Canadian bycatch, and the long generation time and low fecundity suggest cause for concern.

Applicability of Criteria

  • Criterion A: (Declining Total Population): No information exists on population trends.
  • Criterion B: (Small Distribution, and Decline or Fluctuation): Does not apply because the extent of occurrence is believed to exceed 20,000 km² and the area of occupancy is likely greater than 2,000 km².
  • Criterion C: (Small Total Population Size and Decline): No information exists on population size, or trends.
  • Criterion D: (Very Small Population or Restricted Distribution): No information exists on population size; restricted distribution does not apply as area of occupancy is much greater than 20 km².
  • Criterion E: (Quantitative Analysis): Not undertaken.

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