Harbour Seal National Census

Regular monitoring of seal populations is required to assess seal population trends and their conservation status, as well to understand factors driving population trends. Population censuses are also part of international monitoring of pinniped species in the north Atlantic, which is a responsibility of the Icelandic government as a participant in North Atlantic Marine Mammal Commission (NAMMCO).

The population estimate is carried out from Cessna airplanes and the possibility of using drones is also being explored. The survey is conducted during the moulting period from the end of July through August and the whole coast of Iceland is covered three times to maximise the significance of the results. Seals are counted directly by two observers and photographs are taken when groups of seals are encountered, to provide an opportunity to double check the number of animals in the group. Correction factors are then applied to the counted number of seals to yield an estimate of the total population size.

Aerial censuses of harbour seals in Iceland have been carried out at regular intervals since 1980. The population has declined from an estimated 33.000 animals in 1980 to 7.652 in 2016, the most recent census. Between 2011 and 2016, the population declined by approximately one third. The management objective presented by the Icelandic government in 2006 states that the harbour seal population should be at least 12.000 animals and if the population decreases significantly below that number, measures should be taken. According to the latest population estimate, the harbour seal population is now well below the recommended number.

Due to the recent rapid decline in the Icelandic harbour seal population, NAMMCO has recommended that Iceland conduct more regular monitoring of the population. NAMMCO also recommend increased research on other ecological parameters regarding the Icelandic pinniped populations (see the project Harbour seal population dynamics). The current aim is to conduct aerial surveys to produce estimates for the size of the Icelandic harbour seal population every other year. Increased monitoring of the population will create an important foundation for an improved management plan for the Icelandic population. Presently, specialists at the Marine and Freshwater Research Institute are working to build population models to test whether the current level of bycatch and hunting can account for the observed population decline. Data from different databanks will be used with the aim to construct a model to explain possible explanations for the large decline in the harbour seal population.

The next harbour seal census was conducted in 2018 and the results will be released before the end of the year.