Research Document - 2008/077

Abundance of Northwest Atlantic harp seals
(1960 – 2008)

By M.O. Hammill and G. Stenson

Abstract

The impacts of different catch options on the Northwest Atlantic harp seal population were examined to provide science advice for the 2009 harp seal hunt, using the same model formulation reviewed by the National Marine Mammal Peer Review committee at the 2005 assessment. Catch data from the Canadian and Greenland harvests were updated, along with information on ice conditions encountered over the last 3 years. Reproductive rates were assumed not to have changed since the 2005 assessment.  Pup production has increased from an estimated 609,900 (se=22,200) in 1960 to 982,300 (se=118,300) in 2005 then declined slightly to 955,900 (se=153,400) animals in 2009. The total population has increased from 2.74 million (se=100,000) in 1960 to a maximum of 5.71 million (se=796,200) in 2005 and then declined slightly to 5.61 million (se=1.06 million) in 2009. Catch options harvesting more than 270,000 animals in 2009 had a more than 20% probability that the population would fall below the Management objective level of N70 or 4.1 million animals. Catch options taking 270,000 or 250,000 animals would have a greater than 20% probability of the population declining below N70 after the 2010 hunt, while a catch option of 200,000 animals would fall below N70 after the 2011 hunt. Although there is considerable uncertainty associated with the predicted impacts of different TAC levels on the population, five years after the last assessment, the cumulative impact of high harvests over the past decade is the main factor driving the current population trends.

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