Research Document 2020/056

Estimating Pup Production of Northwest Atlantic Harp Seals, Pagophilus groenlandicus, in 2017

By Stenson, G.B., Gosselin, J-F., Lawson, J.W., Buren, A., Goulet, P., Lang, S.L.C., Nilssen, K., and M.O. Hammill

Abstract

Photographic and visual aerial surveys were conducted off Newfoundland and in the Gulf of St. Lawrence during March 2017 to determine pup production of Northwest Atlantic Harp Seals. After extensive reconnaissance, four whelping areas were identified in the southern Gulf, northern Gulf and at the Front (‘Groais Island’ and ‘Strait’). Surveys were carried out between March 6 and18. Very few pups were born in the southern Gulf and no whelping concentrations were observed prior to March 5 which is approximately a week later than usual. Averaging the results of three surveys (two visual, one photographic) of the area, and correcting for pups that were born after the survey, provided an estimated pup production of 18,300 (SE=1,500, rounded to the nearest hundred). This is far lower than the 2012 survey estimate for the same area of 115,500 (SE=15,100). Pup production in the northern Gulf was also lower than in previous years at 13,600 (SE=3,000). A total of 714,600 (SE=89,700) pups were estimated to have been born at the Front; accounting for 96% of all pupping in 2017. Combining the number of pups found in all four areas resulted in an estimated total pup production of 746,500 (SE=89,900, CV=12%) which is the lowest since 1994. The timing of births in the southern Gulf of St. Lawrence was much later than normal in 2017 while unusually early pupping at the Front suggests that some females from the Gulf herd may have moved to the Front to whelp due to the lack of ice suitable for pupping in the Gulf. Although one large concentration formed as usual, approximately 15% of the pupping at the Front occurred in small, dispersed groups later than seen in previous years. Given the unusual ice conditions, distribution of whelping seals, and timing of pupping, assessing the results of the 2017 surveys relative to other estimates of pup production in the Northwest Atlantic is challenging.

Key words: Harp Seal, Pagophilus groenlandicus, pup production, survey, abundance, timing of births, Northwest Atlantic.

Research Document 2020/056 (PDF, 2,786 KB)

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