Monday, 30 July 2012

Shetland seal populations are in decline, between 2007 - 2010 harbour seals numbered just over 3,000, a decline from the previous survey 2000- 2005 when 6883 present.

Seals are protected by law under the new Marine (Scotland) Act 2010 so it was disappointing to hear last week, that two men stand accused of unlawfully killing seals at a salmon farm in Vaila Sound Shetland.

Marine Scotland received 7 applications to shoot seals under licence. Of these, an application of 341 Grey seals, was reduced to 109 to be shot under licence, where as an application of 32 common seals was reduced to 6. This was a 10% reduction from the previous year.

Both Grey and Common seals can live for over 30 years. Approx 38% of the Grey seal population can be found in UK waters (around 111,300) with nearly 90% of these in Scottish waters, 30% of all common (harbour) seals can again be found in UK waters (36500), a decline -  40% in 2006.
                                                            Grey Seals around Noss

The distemper virus of 1988 and 2002 is thought to have had little effect on the Scottish population . Recently, mutilated carcasses of a large number of seals have been washed up on UK beaches. Unexplained 'cork screw' lacerations have been found on the dead seals. In Norfolk, 50 seals have been found, but in parts of Scotland, up to 10% of the breeding population have been found dead. No one is sure why these deaths have occurred. So far no seals with these lacerations have been found in Shetland, although seals with these injuries have been found as close as Orkney.

Orcas (Killer whales) may be to blame for a large number of seal deaths, especially common seals. Researchers have estimated that between 1997- 2006 around 1600 Common(harbour) seals may have been taken, but this is thought to be a massive underestimate. More Killer whales are being reported in Shetland waters each year !.
                                           Common seals on Mousa
                                            Easter Quarff
The decline in Sandeels may also be to blame in the falling numbers of seals as these play an important part in their diet.

It is always great to see seals , which tend to be very inquisitive and to see them hunting underwater is quite a sight.

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