Killer whale strands in Waterford: UPDATED with preliminary PM results

31st Jan 2015

3 February 2015

A post mortem examination of the killer whale was carried out on Sunday in a local council yard. A team from the IWDG and the Galway-Mayo Institute of Technology were joined by a team from UCC and all eight “butchers” were needed to examine this whale. The cutting up of the whale had to be carried out carefully as the local community in Dunmore East wanted to retain the skeleton for preparation and display, so bones were removed without breaking or cutting.

The adult female measured 5.2 mt and was in good nutritive condition, with no signs of body mass loss. The teeth of the whale were completely flat which is characteristic of a type 1 killer whale. There are thought to be two ecotypes of killer whales in the North Atlantic: type 1 which are predominantly fish eating and are smaller than the type 2 mammal eating ecotypes. Both killer whales fully examined in Ireland to date (including this one) have been type 1.

 

The stomach and intestines were removed. This will contribute to studies on diet but also a study on the incidence of macro and micro-plastics in some of Ireland's top marine predators.  Sorting of the intestines in GMIT on Monday revealed a high infestation of tape worms but whether this contributed to its death is not known yet. Samples of skin were taken for genetic analysis and blubber, liver, kidney and muscle are taken for a range of studies including determining contaminant burden and stable isotope analysis (which explores where in the food chain these whales are feeding). The reproductive organs have been removed and preserved to see if the whale had ovulated (i.e. was sexually mature) and had produced any calves.

It is thought killer whales in the NE Atlantic may have high levels of persistent pollutants, which can lead to reproductive infertility. We are presently working with the Marine Institute analysing some whale tissues for contaminants and it is hoped we can include samples from this killer whale to get results of its contaminant burden over the next few weeks.

As biologists we can only explore the life of this whale and not determine the cause of death.  Obviously, if there was something obvious or a severe infection etc., we would recognise this but often an animal may have a number of “conditions” which are not fatal and determining cause of death is based on the most likely fatal condition. Unfortunately, Ireland does not have a formal post-mortem system in place for marine mammals, unlike most European countries, so the factors under-pinning the mortality of stranded animals are generally not known. The IWDG have been calling for, facilitating and encouraging such a programme for nearly 25 years, and there is potential to link in with the Regional Veterinary Labs, but without the political or departmental will to establish such a scheme, we will remain in the dark regarding the causes of amazing animals, such as this killer whale, dying in Irish waters.

We will post results of analysis as they come on on www.iwdg.ie

Dr Simon Berrow

IWDG Chief Science Officer

31 January 2015

A 5m female killer whale was found yesterday, 30 January, at Saleen, near Tramore, Co. Waterford. The animal was in very fresh condition and all her teeth were very worn - this may have resulted in her death perhaps from malnutrition or infection. This is the 15th stranding for this species on the IWDG cetacean strandings database and the first since 4 October 2010 in Co. Mayo. A post mortem on the animal will be carried out tomorrow by a team from IWDG and GMIT and it is hoped that the skeleton will be preserved to be put on display locally.

This stranding comes at the end of a month which has seen a disturbingly high number of stranded cetaceans around the Irish coast. With still some more records to come in, we have already recorded 32 strandings of 9 identifiable species since January began. This is double the average number of strandings recorded in the month of January over the previous five years. 

We do not know why there have been so many strandings recently and it is likely due to a number of factors. Strong westerly winds are likely to be pushing dead floating animals ashore whether those animals have died from natural causes or not. There has been an increase in the number of common dolphins washed ashore in the northwest, some of which show outward signs which suggest that they are the result of being bycaught in trawl nets. At the same time, a huge, 153m trawler was fishing north of Mayo - this is very similar to the spike in common dolphin strandings in Mayo in January/February 2013 when post mortem results on five animals were consistent with them being bycaught in trawl nets - at the same time that huge factory trawlers were operating offshore.

Recent stranding numbers have also been pushed up by the unprecedented strandings of 8 Cuvier's beaked whales on the Irish coast between mid December and mid January. There were 6 strandings of this deep diving species in Scotland during the same period. Most of the carcasses were in poor condition and appeared to have died at around the same time offshore and then been blown/washed ashore by wind and currents. IWDG is concerned that mass strandings of beaked whales have previously been associated with naval exercises and our attention was drawn to newspaper reports of a major naval search (presumably using low and/or mid frequency active sonar) west of Scotland for an unidentified submarine.

As is too often the case, we have no cause of death for any of these strandings and so cannot say for certain why they died. Until we can, it is difficult to see how agencies and stakeholders are going to be able to work together to safeguard our offshore wildlife.