Experts have confirmed the first dead killer whale to be found on the shores of England and Wales in 20 years. The juvenile male was discovered in the salt marshes of The Wash on the UK’s east coast.
Analysis by the Zoological Society of London (ZSL) suggests it died weeks ago. It was likely deposited inland onto the nature reserve by tides.
Orcas are not unknown to British shores, although only Scotland’s west coast has a resident population. They are not often found this far south in UK waters, so the Cetacean Strandings Investigation Programme (CSIP), which ZSL is a part of, is investigating.
Samples of blubber, liver, muscle, and kidneys have been taken, which were mostly intact, despite the external decomposition indicating the cetacean died a few weeks ago.
Teeth have been taken to determine its age, though it's understood to be a young male, around 4.5 meters long (15 feet). Further testing and genetic analysis will determine which population it comes from, its diet, history, and whether it was contaminated by anything.
Orcas are a priority species for ZSL researchers because as apex predators, meaning they are top of the food chain, they absorb significant amounts of chemical pollutants like PCBs, through eating other marine creatures like seals that absorb them. Measuring toxicity levels in killer whales gives a good indication of toxicity levels in the seas.
Polychlorinated biphenyls, or PCBs, are manmade chemicals that do not break down quickly and so are still found in the environment, despite being widely banned in 1979. A 2018 study showed that current concentrations of PCBs in the oceans could lead to the disappearance of half the world’s populations of killer whales in heavily contaminated areas in just 30-50 years.
Cause of death is currently unknown, though ZSL said in an emailed statement there was no evidence of recent feeding as its stomach compartments were empty. Orcas swallow their meals whole, so their meals enter the first stomach compartment, which is an extension of the esophagus, then move to the main stomach where it gets digested and broken down, and then finally the third part, where it is prepared to be absorbed by the intestines.
The team did find a large fragment of plastic in the orca’s first stomach compartment, but that wasn’t what killed it.
“It is important to note that the plastic didn’t kill the animal – as no gastric impaction was caused – but evidently it’s not good to find it there,” ZSL said in the statement.
It's always sad to see the demise of a majestic creature like a killer whale (which are not actually whales, but members of the dolphin family), but as this is such an unusual discovery, the opportunity to study it will provide invaluable information for UK marine mammal research for years to come, ZSL said.
