Science Advisory Report  2009/046

Recovery potential assessment for basking sharks in Canadian Pacific waters

Summary

• The Pacific population of basking sharks is designated by COSEWIC as endangered.
• Basking sharks are large planktivorous sharks that range across the north-east Pacific.
• They are very slow growing, slow to mature, and have low fecundity.
• The historic north-east Pacific population is estimated at 1,000-2,600 animals.
• Since 1996 there have been 12 sightings of basking sharks in Pacific Canadian waters.
• It is estimated that 200 years are needed before population numbers will return to their unexploited status but only if human induced mortality is zero. If human induced mortality exceeds 11-18 sharks per year the population could be extinct within approximately 30 years.
• A short-term goal for the basking shark is to promote the population’s recovery such that it can be downlisted from its current COSEWIC endangered status. An interim goal is to see positive population growth to the number of observations recorded for the 1945-1970 period. A long-term goal is to promote the sustained viability of a naturally-reproducing population.

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