COSEWIC Assessments

COSEWIC Assessment & Status Report Summary: Basking Shark Cetorhinus maximus - Atlantic population

Assessment Summary – November 2009

Common name
Basking Shark – Atlantic population

Scientific name
Cetorhinus maximus

Special Concern

Reason for designation
This species, which attains a maximum length of over 15 m (the second largest living fish) is highly vulnerable to human–caused mortality because of its extremely low productivity. Females mature at 16 to 20 years old, gestate for 2.6 to 3.5 years (the longest known gestation period of any vertebrate), and produce litters of about 6 offspring. Based on recent tagging information, individuals in Canada are considered to be part of an Atlantic population shared with the USA, Europe, the Caribbean and northern South America. Population estimates in Canadian waters have large uncertainties and may number between 4918–10125 individuals. Population estimates outside Canadian waters are not available. Information from surveys along the Atlantic coast from Nova Scotia to Florida indicates no decline over the past two decades. However, available information suggests substantial population declines in the northeast Atlantic. The species is caught incidentally in trawl, longline, and gillnet fisheries in Atlantic Canada. Removals in fisheries with observer coverage have decreased since the 1980s consistent with a reduction in fishing effort, but information on bycatch from other fisheries is not available. There is no evidence of recovery following declines associated with fisheries in other parts of the range. Ship collisions are an additional threat.

Atlantic Ocean

Status history
Designated Special Concern in November 2009.


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Contact Person(s)

COSEWIC Secretariat
c/o Canadian Wildlife Service
Environment Canada
Ottawa, ON
K1A 0H3
Tel: 819-938-4125
Fax: 819-938-3984
Send e-mail

Related Species


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