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BROCHURE RACK

Britain's only resident orca pod – No breeding for 20 years

09/01/2013 22:43:25
whales/nov 2009/orca_uk

The Hebrides resident orca pod has not produced any calves for 20 years. Credit HWDT

Hebridean Orca pod study
January 2013. This week, BBC’s The One Show has been showcasing the endangered killer whale population that inhabits waters off the west coast of the UK and Ireland.  Mike Dilger experienced an amazing encounter with four of the nine killer whales left in this population. With group numbers so low, it is likely that this community will go extinct in our lifetime. 


No calves for 2 decades
In collaboration with Dr. Andy Foote, the Irish Whale and Dolphin Group and many others, the Hebridean Whale and Dolphin Trust (HWDT) have found that of the group, four members are male and five are female. All individuals within the community interact with each other, although certain individuals are more regularly sighted together. As Mike mentioned on Tuesday evening, no live calves have been recorded since research began almost two decades ago, it is likely that the females are post-reproductive and due to their social isolation they are unlikely to recruit any killer whales from other populations. This means that the conservation status of this group is critical.     

Sightings off Ireland & Wales
Photo-ID has also helped HWDT better understand the wide-ranging nature of these apex predators. Although dubbed the ‘west coast community', sightings off Ireland have been reported, and on one occasion all nine individuals were present off the Cork coast. The extremely distinctive male, ‘John Coe', was also sighted off the Pembrokeshire coast in 2008 and 2007.

The West Coast Community are about a metre
larger than other orca populations found off the
UK. Their eye patch orientation is also different
to other populations.

Related to Antarctic orca
As sad as this is, the loss of this group has severe consequences, resulting in the loss of an evolutionary significant group of individuals. Through our research, we have discovered that this group is physically different to other killer whale populations in the North East Atlantic, suggesting separate ancestry, - they are bigger in size (by about a metre) and have different tooth wear. Furthermore, genetic analysis indicates that this group is more closely related to a group of Antarctic killer whales than those found in Atlantic waters.

Feed on other cetaceans
Comparing the teeth in these killer whales to those in other populations suggests that this unique population is feeding exclusively on other cetaceans, such as harbour porpoises and Minke whales (orca were reported surfacing either side of a Minke whale in the Minch).  On the first programme the remains of a harbour porpoise was shown floating in the water.

The West Coast Community have virtually no tooth wear (pictured at the bottom) while in the other groups adults have worn their teeth down quite substantially (pictured at the top).

The West Coast Community have virtually no tooth wear (pictured at the bottom) while in the other groups adults have worn their teeth down quite substantially (pictured at the top).

Join a research trip or report a sighting
There is still much to learn about the Hebridean orca. Only with continued study can we better understand the only ‘resident' population found in British waters. HWDT Chairman Maxwell MacLeod said "I find it really alarming that no youngsters have been seen for such a long time. It is vital that we maintain this research as we know so little about the role these animals play in our eco-system". Every year HWDT welcomes volunteers onboard their research yacht Silurian to assist with data collection from onboard. These cetacean research surveys, alongside reports from the public and other organisations, have allowed for more information on Scotland's cetaceans to become apparent. If you would like to join HWDT onboard or would like to report a sighting please visit www.hwdt.org  

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