Unprecedented numbers of strandings on Irish coast

13th Mar 2012 The number of cetaceans stranded on the Irish coast during 2012 remain unprecedented compared to previous years.

In 2011, 162 strandings were recorded by the IWDG Cetacean Stranding Scheme which included 11 live strandings and 151 dead animals in various stages of decomposition. Numbers vary each year but this is around 25 - 30 strandings more than we would have expected and a significant increase was noted for both common dolphins and harbour porpoises.

As we are now well into 2012, it is clear that the numbers are still much higher than expected.

In January 2012, 21 cetaceans were reported stranded to IWDG, this is the highest figure yet recorded for the month of January, the previous highest being January 2005 with 19 strandings recorded. The average for the same month in the previous five years (2007 to 2011) was 13. This trend has continued through February 2012 with 30 cetacean strandings recorded compared to an average of 11.4 based on the previous five year period (2007 to 2011) which included a low of two in 2010 and a high of 23 in 2011. In February very high numbers of harbour porpoise were recorded stranded and over the last three weeks, high numbers of long-finned pilot whales.

The two main questions now are what are the causes of these increases and are the high numbers going to continue?

The truth is that in the majority of strandings we can't say why the animal has died and whether the cause was natural or man-made and, of course, there is no single cause for all these strandings. There may be some influence from the point of education and subsequent recorder effort but this is unlikely to account for an increase over the course of just one year.

There is some evidence of fisheries bycatch of common dolphins and in a handful of cases, there is evidence of harbour porpoise injuries consistent with attack from bottlenose dolphins. What has been noticeable over the last year is the number of carcasses which had washed ashore with tail fluke/fins apparently cut away.

The IWDG have informed the National Parks and Wildlife Service, who are the statutory body with responsibility for the conservation of cetaceans and their habitats and keeping them updated on current stranding trends.

Mick O'Connell

IWDG Strandings Co-ordinator

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