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Photo: IMR.Photo: IMR

Hooded seals (Cystophora cristata)

19.03.2013 // Hooded seals are local to the North Atlantic. Hooded seals breed on pack ice and there are three main whelping areas – those being : off Newfoundland in Canada, in the Davies Strait between Canada and Greenland, and in the Jan Mayen area of the Greenland Sea. The degree of exchange among these whelping areas remains unclear.

Whelping occurs in mid–late March. The intensive lactation period lasts only 3 to 5 days, after which the adults mate, and the females desert their pups. 

Hooded seals of the Jan Mayen stock haul out to moult (June/July) on pack ice north of the usual breeding area, i.e. northwest of the island of Jan Mayen. 

Satellite tracking indicates that hooded seals from the Jan Mayen stock occupy ice-covered waters off the east coast of Greenland much of the year. But, both between breeding and moult, and after the moulting period, they may make long excursions to distant waters (temperate as well as Arctic), presumably to feed. During these excursions, which may last for more than three months, the seals apparently never haul out, even when they spend time in coastal areas. In the Greenland Sea, squid is the main food, followed by polar cod. In other areas they may also feed considerably on other fish species, e.g. redfish and Greenland halibut. 

Sealing

The West Ice stock of hooded seals has been subject to commercial exploitation for centuries by German, Dutch and British companies. Harp seals were the most important catch object in the early seal hunting years in the Greenland Sea, whereas hooded seals occurred more frequently in the catches from the 1890s on. After 1920, a substantial increase occurred in the Jan Mayen hooded seal hunt with average annual catches ranging between 40 and 50 thousand individuals. Quotas for the Jan Mayen stock were imposed in 1971. 

Stock status and regulations

The Jan Mayen population is managed jointly by Norway and Russia. The population is assessed every second year by a Joint Working Group of the International Council of the Exploration of the Seas (ICES) and the North-West Atlantic Fisheries Organisation (NAFO) and management advice is provided by ICES. Based on results from the most recent meeting in the Working Group, ICES made an assessment of current status in an historical perspective of this stock in 2007. Model explorations indicated a decrease in population abundance from the late 1940s and up to the early 1980s. In the most recent two decades, the stock appeared to have stabilized at a low level of approximately 71 thousand. This may be only 10-15% of the level observed 60 years ago. The modelling exercises included two pup production estimates as well as available information about catches, reproduction and estimates of natural mortality. 

ICES recommended an approach based on Potential Biological Removal level (PBR) in the assessment of this stock. The PBR approach identifies the maximum allowable removals that will ensure that the risk of the population falling below a certain lower limit is only 5% and that would allow a stock that dropped below this limit to recover. Using the PBR approach, the catch limit was calculated as 2.189 animals. 

However, results from a Norwegian aerial survey in 2007 suggested that current pup production (15 thousand) was lower than observed in a comparable 1997 survey (24 thousand). Scientists believe that the populations decline is due to mass mortality caused by PDV (occurring among seal in the Northeast Atlantic) or Brucella (occurring in Jan Mayen hooded seals). However, there are yet no observations of carcasses or diseased animals to support this hypothesis. Further, a hypothesis that the recent decline in available pack ice in the Jan Mayen area has caused a shift in breeding area or reduced whelping, cannot be excluded. Due to the recent uncertainty about population status, ICES advised no catch on this stock in 2007 until new information on abundance becomes available.  On this basis there has not been catch quotas for hooded seals since 2007.


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