Research Document 2020/014
Updated Estimates of Harp Seal Bycatch and Total Removals in the Northwest Atlantic
By Stenson, G.B. and Upward, P.
Abstract
Accurate estimates of mortality are critical in order to determine the abundance of any population. Mortality of Northwest Atlantic Harp Seals (Pagophilus groenlandicus) can be divided into ‘unidentified’ (or unreported) mortality which is estimated by a population model: ice-related mortality and human-induced mortality. The latter mortality consists of subsistence hunts in Greenland and the Canadian Arctic, a commercial hunt in Atlantic Canadian waters, as well as seals that are killed but not landed or reported during hunting (‘struck and lost’) and bycatch in commercial fishing gear. Commercial and subsistence hunts account for the majority of the removals.
The level of Canadian commercial catches have varied considerably with catches averaging approximately 288,000 Harp Seals annually prior to the introduction of quotas in 1972. Between 1972 and the demise of the large vessel hunt in 1982, an average of 166,000 seals were taken annually. Catches decreased after 1982 and remained low, averaging approximately 52,000 per year until 1995, at which time interest in the hunt increased significantly. Annual catches consisting primarily of young of the year (YOY) increased to an average of 272,600 between 1996 and 2006. Since then catches have declined, averaging 63,000 per year between 2009 and 2019. Since 1980 Greenland catches increased relatively steadily to a peak of approximately 100,000 in 2000. Between 2011 and 2017, catches have declined with an average of 60,000 seals reported annually.
Catches in the Canadian Arctic are not well documented but appear to be low with likely fewer than 1,000 Harp Seals taken annually in recent years. Estimates of Harp Seal bycatch in the Newfoundland Lumpfish (Cyclopterus lumpus) fishery increased from less than 1,000 per year in the early 1970s to a peak of 46,400 in 1994, declining to approximately 5,000 by 2003. Based on published bycatch rates in the Newfoundland Lumpfish fishery and data on Lumpfish landings, bycatch appeared to have increased again in the mid 2000s to approximately 35,000. Since then, Lumpfish landings have declined significantly and the bycatch of Harp Seals was estimated to be 555 in 2018.
Low numbers of Harp Seals are also caught in United States (U.S.) fisheries. Combining these various sources of human induced mortality results in estimates of total removals. Between 1952 and 1982, approximately 395,000 Harp Seals were killed annually. This declined to 177,000 per year between 1983 and 1995. With the renewed interested in hunting in Canada and increased catches in Greenland, the average annual removal from 1996-2006 was 476,000. Since 2008, reduced catches, particularly in Canada has lowered the annual total removals to approximately 200,000 Harp Seals per year. The greatest uncertainty in these estimates are associated with the bycatch in Newfoundland fisheries, the Greenland catch as well as struck and lost rates, although changes in the latter are unlikely to affect the abundance estimates significantly.
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