Tope (Galeorhinus galeus) COSEWIC assessment and status report: chapter 2

Executive Summary

Tope
Galeorhinus Galeus

Species information

Tope (Galeorhinus galeus), commonly referred to as soupfin shark, is one of 39 species belonging to the family Triakidae or houndsharks. Tope is the only representative from the family Triakidae on Canada’s Pacific coast. In French this species is referred to as milandre. 

The population structure of tope in Canadian waters and throughout the eastern Pacific is unknown. Tope are considered highly migratory, moving north during the summer and south into deeper waters during the winter. Assuming that tope found in Canada are part of a larger highly migratory population, genetic structure, if it exists would be restricted to behavioural mechanisms as there are no known geographical or ecological barriers to gene flow. For the purposes of this document, tope in Canada’s Pacific waters are considered as a single designatable unit.

Distribution

Tope occur in temperate and subtropical seas between 68°N - 55°S latitude. Tope are found in the eastern Pacific from northern British Columbia (no records from Alaska) to the Gulf of California as well as waters off Peru and Chile. In Canada’s Pacific waters records for tope occur primarily from continental shelf waters along Vancouver Island, Queen Charlotte Sound, and into Hecate Strait. There is no known research or commercial fishing record of tope being taken from the Strait of Georgia.

Habitat

Tope prefer temperate continental shelf waters from close inshore, including shallow bays, to offshore waters up to 471 m deep. They are generally thought to occur near the bottom but have been captured by pelagic floating longlines in deep waters. Pups and juveniles utilize shallow nearshore habitats for one to two years before moving offshore. There is no direct protection of tope habitat.

Biology

Little is known about the breeding behaviour of tope. The reproductive cycle for tope is reported as one to three years with a gestation period of one year. Tope are ovoviviparous, with females carrying between 6 and 52 pups released between March and July with pups being an average 35-37 cm long. Tope exhibit rapid growth during the first three years followed by steady growth until about 10 years of age and then slow continued growth through maturity. In the northeast Pacific maximum length of females is 195 cm and 175 cm for males. Aging and determination of longevity is constrained due to the difficulty in reading vertebral sections. Tope are slow growing and reach a maximum age of at least 45 years. Age of maturity in females is about 13-15 years and males at about 12-17 years. In eastern Pacific waters, females are mature at 150 cm total length and males are mature at 135 cm. Generation time is estimated at 23 years.

Movement patterns of tope in the northeast Pacific are poorly understood. Overall there appear to be both bathymetric and latitudinal movements that vary by both sex and season. Tagging studies suggest that at least some component of the population undergoes extended migrations and that they are capable of travelling long distances over a short period of time.

Commercial fisheries

Tope were the target of a brief but extensive commercial fishery throughout their northeast Pacific range beginning in 1937 in California and then in British Columbia, Oregon, and Washington in the early 1940s. The focus of the west coast tope fishery was for their liver which contains the highest concentrations of vitamin A of any fish on the Pacific coast. A total of approximately 840,000 tope may have been taken from the northeast Pacific population of which about 50,000 were landed in Canadian ports and an unknown amount actually caught in Canadian waters.

There are no present-day directed tope fisheries in Canada’s Pacific waters. Tope are caught in low numbers as bycatch in trawl and longline fisheries while in pursuit for other commercial species. An estimated 143 tope per year are caught by the trawl and longline fleets.

Population sizes and trends

There are no indices of tope abundance anywhere in their northeastern Pacific range. Overall abundance and population trends inCanada’s Pacific waters are unknown.

Limiting factors and threats

The intensive fishery for tope between 1937 and 1949 throughout their migratory range in the northeast Pacific would have caused a rapid depletion in the adult biomass. Since that time tope have not received any commercial or research attention aside from reported landings by state fisheries departments and incidental catch in Canadian fisheries. A clear limitation to understanding the status of this species is the lack of information.

Special significance of the species

The liver of tope has the highest known concentration of vitamin A of any fish species on Canada’s Pacific coast.

Existing protection

The IUCN lists tope as vulnerable (VU A1bd) globally based on its history of stock collapse in the northeast Pacific as well as from a reduction in the global population over the last 60 -75 years.

COSEWIC History

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) was created in 1977 as a result of a recommendation at the Federal-Provincial Wildlife Conference held in 1976. It arose from the need for a single, official, scientifically sound, national listing of wildlife species at risk. In 1978, COSEWIC designated its first species and produced its first list of Canadian species at risk. Species designated at meetings of the full committee are added to the list.  On June 5, 2003, the Species at Risk Act (SARA) was proclaimed. SARA establishes COSEWIC as an advisory body ensuring that species will continue to be assessed under a rigorous and independent scientific process.

COSEWIC Mandate

The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assesses the national status of wild species, subspecies, varieties, or other designatable units that are considered to be at risk in Canada. Designations are made on native species for the following taxonomic groups: mammals, birds, reptiles, amphibians, fishes, arthropods, molluscs, vascular plants, mosses, and lichens.

COSEWIC Membership

COSEWIC comprises members from each provincial and territorial government wildlife agency, four federal entities (Canadian Wildlife Service, Parks Canada Agency, Department of Fisheries and Oceans, and the Federal Biodiversity Information Partnership, chaired by the Canadian Museum of Nature), three non-government science members and the co-chairs of the species specialist subcommittees and the Aboriginal Traditional Knowledge subcommittee. The Committee meets to consider status reports on candidate species.

Definitions

Wildlife Species

A species, subspecies, variety, or geographically or genetically distinct population of animal, plant or other organism, other than a bacterium or virus, that is wild by nature and is either native to Canada or has extended its range into Canada without human intervention and has been present in Canada for at least 50 years.

Extinct (X)

A wildlife species that no longer exists.

Extirpated (XT)

A wildlife species no longer existing in the wild in Canada, but occurring elsewhere.

Endangered (E)

A wildlife species facing imminent extirpation or extinction.

Threatened (T)

A wildlife species likely to become endangered if limiting factors are not reversed.

Special Concern (SC) Footnotea

A wildlife species that may become a threatened or an endangered species because of a combination of biological characteristics and identified threats.

Not at Risk (NAR) Footnoteb

A wildlife species that has been evaluated and found to be not at risk of extinction given the current circumstances.

Data Deficient (DD) Footnotec

A category that applies when the available information is insufficient (a) to resolve a species' eligibility for assessment or (b) to permit an assessment of the species' risk of extinction.

 

Canadian Wildlife Service

The Canadian Wildlife Service, Environment Canada, provides full administrative and financial support to the COSEWIC Secretariat.

 

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