Number of porpoises in the North Sea seven-fold | Inland

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The results have been published in the Compendium for the Living Environment, a collaboration between Statistics Netherlands and Wageningen University. Since 3 November this year, the harbor porpoise is no longer on the Red List of endangered mammals in the Netherlands, and its survival is therefore no longer threatened.

For centuries the harbor porpoise was a common species in the Dutch part of the North Sea. From 1940 the number decreased sharply. The population development of porpoises shows a strong upward trend in 1991-2019. In 2019 the population counted more than seven times as many animals as in 1991.

The increase in the number of porpoises in the Dutch part of the North Sea is related to a shift of animals from the northern North Sea to the south. The numbers of porpoises vary within a year from 26,000 (in October-November 2010) to 86,000 (March 2011). From 2014, the numbers of porpoises close to the coast, at most a few hundred meters from land, will decrease.

With the increase in the number of porpoises in the coastal zone, the number of strandings of dead porpoises increased sharply after 1991. This number went from at most a few decades in the early 1990s to a few hundred per year from 2004. The largest number of strandings since the start of the registration were 962 in 2011 and 980 in 2012. After this peak, this number decreased again. This is consistent with the lower numbers observed close to the coast.

Established causes of death for stranded porpoises include drowning in fishing gear, infectious diseases, starvation, collisions with propellers and attacks by gray seals

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