Science Response 2010/004

A Review of Ice Conditions and the Harp Seal Total Allowable Catch (TAC) for 2010

Context

Harp seals, Pagophilus groenlandicus, are the most abundant pinniped in the northwest Atlantic with an estimated total population size in 2009 of 6,851,600 (95% CI=5,978,500 to 7,697,200) (Hammill and Stenson 2009).

Ice conditions, measured primarily as ice cover have been declining over the last decade. Conditions in 2010 in the Gulf of St. Lawrence and off the southeastern coast of Labrador are about 80% below expected levels, which is the lowest level ever seen since 1969, the start of the ice cover database (1969 in the Gulf, 1971 at the Front) maintained by Environment Canada. The very poor conditions are expected to result in higher mortality of young harp seals before they become independent, which in combination with harvesting could have longer term negative impacts on the population. The objective of this response is to examine the impact of this potential high young of the year mortality on the population when it occurs in combination with a Canadian commercial harvest of 330,000. In this analysis we have adopted an extremely conservative and pessimistic approach in assuming that mortality would be high (70% of animals born), there would be an immediate drop in productivity of the herd as seen over the past decade (decline in reproductive rates of 3%). It has also been assumed that ice related mortality would persist in subsequent years (Mice=12%), and finally, in spite of current poor market conditions it was assumed that the entire harvest of 330,000 would be taken each year of the projection period.

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