These are the last of the UK’s resident orca population

Orcinus orca, the killer whale, the highly intelligent and adaptable apex predator of the oceans, second only to human beings in global distribution. If you were to ask the average person where the best place to see an orca would be, their response might be the Antarctic, Vancouver Island, Iceland or a number of other hot spots around the world, but the United Kingdom? Unlikely, but it was not always that way. If you visit UK shores today, you would have to be very lucky to see one and this article explores why.

The UK currently has only one resident pod of orca left roaming its waters, consisting of eight known individuals. The most regularly seen is the enigmatic John Coe, a male first identified—from his distinctively notched dorsal fin—back in the 1980s. He and the other remaining members make up the ‘West Coast Community’ of orca, most commonly seen around the north west coast of Scotland.

This group of orcas are genetically and morphologically distinct from other known North Atlantic orca, and are known as a type ‘two’ orca. They are thought to feed exclusively on marine mammals and are more closely related to their fellow Antarctic mammal hunting orcas than their type ‘one’ fish eating cousins found offshore in Atlantic waters.

The group has not been seen with a calf in over twenty years and appears doomed to extinction. Here we dip into anecdotal tales and scientific study to explore what may have happened to this pod, are they a quirk of evolution or a relic of what was once a healthy population?

Figure 1. Orca types and forms currently recognised globally. Credit: NOAA Southwest Fisheries Science Center
Figure 1. Orca types and forms currently recognised globally. Credit: NOAA Southwest Fisheries Science Center

What can history tells us?

There are many tales of orca roaming UK shores. From Gavin Maxwell’s famous Ring of Bright Water book to various fishermen’s stories, it’s clear that the UK used to be a hot spot for orca sightings and was once home to a population substantially greater than the eight that remain. Orcas were regularly seen in the coastal North and Irish seas up until the 1960s and were reported to feed on harbour porpoise, indicating they belonged to the same population as the type two group.

However, sightings have become very rare in those areas over the past 50 years and in many areas are now considered unheard of. It would appear the remaining eight are a relic of a once substantial population which perhaps roamed all throughout Britain’s waters—so what changed in the last five decades?

A toxic relationship
As top level predators, toxins lingering lower down in the food chain bio accumulate substantially by the time orcas ingest their prey. One of these chemicals, PCB’s (Polychlorinated biphenyl—formerly used for electrical transformers) is particularly damaging. Although banned in the UK since 1981, these are extremely persistent chemicals and do not disappear swiftly, particularly in coastal waters.

Unfortunately, studies have shown they remain in high quantities in Western European waters, locked away in the sea bottom until trawlers or bad weather shake things up and they are released back into the ecosystem again. They are fat-soluble contaminants and bind to small particles, making their way up the food chain from plankton to fish to marine mammals. By the time these mammal eating orcas ingest their prey, they accumulate a level of PCB akin to what we would class as toxic waste.

The toxic PCB’s are stored in fat and a female orca will transfer her accumulated PCB’s into her fat rich-milk to nourish her offspring during nursing. This is good news for the mother’s PCB levels but very bad news for the calf’s. High levels of PCB’s have been shown to suppress the immune system, which leads to a high susceptibility to diseases and other functionality problems which have been found as a potential cause of fatally stranded orca throughout the region.

High PCB rates also result in high mortality rates for young calves in this population, possibly explaining why the pod have not been seen with a calf for the twenty years they have been studied. Although banned, a large quantity of PCB’s still remain in storage and there is evidence that inadequate controls and monitoring is resulting in a continued leakage of these chemicals into the ocean today. Coastal waters are often the most vulnerable to pollution and so it’s no surprise that coastal orcas are faring worse than their offshore cousins.

Family of orca. Photo by Evan Landy
Family of orca. Photo by Evan Landy

Not all black and white

There are, however, reasons to temper this line of thought. It is impossible to prove categorically that PCB’s are the sole reason for the probable extinction of this pod. As marine mammals form a large part of their diet, it could be that this population became fragmented long ago as North Atlantic whale populations, a major prey source, were decimated by whaling over the past few centuries.

It is conceivable too that this pod may be a victim of the orcas habit of forming distinct and somewhat isolated populations. It may be natural for some of these populations to thrive and for some to ultimately die out. In addition, whilst this pod have never been seen with other orca, it is still possible there are other type ‘two’ orca out there forming part of this population and ready to take advantage of a niche in the habitat that may be left behind once the last eight British orcas cease to exploit UK waters. Long term viability of any coastal populations, however, will no doubt be linked to ensuring threats such as PCB’s are significantly reduced.

Turning to the future

Turning the attention to perhaps the world’s most famous orcas can reveal more. The waters around Vancouver Island and Washington are home to several distinct and coastal populations of orca. Perhaps between these and the relic UK pod we have a glimpse of the past, the present and the future. Could John Coe and family have once been part of a wider population similar to the communities of several hundred orcas found in the North East Pacific? It is highly likely. Could the fate awaiting the last UK pod also befall coastal Pacific orca populations? It would be unwise not to realise this possibility.

Perhaps John Coe’s family legacy, should they indeed succumb to extinction, could be that their demise boosts the long term survival prospects of other orca around the world. The more we learn about orca, the more evident it has become that isolated and distinct subpopulations like these exist throughout the ocean—therefore conservation of orca cannot be done at species level as the coastal populations are always likely to be the most vulnerable.

For the UK, the adaptability and intelligence of orcas may mean there are still reasons for optimism. It may ultimately be too late to save John Coe and the last relic members of this group from extinction but if PCB levels can be reduced, it is possible that other orca pods which occasionally pass through UK waters will eventually find improved habitat opportunities and may stay. As the UK increases the number of its marine conservation zones, there is hope that one day a healthy population of orca may well be able to call UK waters home once more.

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