Sharks and whales at risk - is plastic pollution the cause?
On Shark Awareness Day we look at the reasons sharks in the Mediterranean are threatened and the cause for increasing beach strandings of whales on UK shores. Plastic pollution may contribute to both trends.
Today is Shark Awareness Day, launched by the World Wide Fund for Nature (WWF) to raise awareness of threatened sharks in the Mediterranean. This may also be a good time to reflect on other forms of marine life at risk, such as rays, porpoises and whales.
In a report, WWF highlighted overfishing, as only some sharks are caught for food, many sharks are often caught in fishing nets by accident. Plastic pollution is also addressed, thought to be threatening shark populations that ingest or become trapped in plastic waste.
As a result, over half of shark and ray species in Mediterranean are considered under threat - with almost a third fished to near-extinction. According to the IUCN Red List of endangered species, there are 79 endangered shark and 120 endangered ray species.
A quarter of whales, dolphins and porpoises are threatened with extinction, stressed by pollution and climate change. The number of stranded whales on UK shores has increased over the years. From 2011 to 2017, 4896 whales, dolphins and porpoises died on beaches - a 15% rise since 2004.
The animals typically become stranded on beaches to die, as a result of dehydration, infectious diseases or other health issues. Plastic pollution has been recently identified by scientists to be an additional influence. Even so, the underlying causes of these animals becoming stranded is largely unknown. Scientists study these events so they can find out to what extent human activity is an influence.
Discussing strandings, Rob Deaville of the Zoological Society of London said: "There's a misconception that we're trying to stop strandings - we're not, we're trying to learn more about those that are due to human activities and then try and mitigate those where we can."
Long fin whale stranded in Orkney
On 9 July this year, a 16-18 metre long fin whale was seen struggling off the coast of Burray in Orkney. British Divers Marine Life Rescue volunteers investigated, and found that the animal was not entangled or caught on anything. It appeared to be freely swimming, though was in ill-health. The reason for the animal’s poor condition was not readily known.
Sadly, as the tide slowly dropped, the animal became stranded in shallow waters. Medical professionals monitored the scene, to measure its breathing rate and protect the animal from disturbance. Unfortunately, they reported that the animal was in such poor health and so malnourished that it would be very unlikely to survive out at sea. Refloating a whale of this size, weighing over 40 tonnes, would not be possible. Fin whales at adult stage can reach 26 metres in length and weigh up to 80 tonnes.
By 10 July, the stranded whale was confirmed as dead. Due to COVID-19 a full post-mortem could not be carried out to discover the cause of death.
British Divers Marine Life Rescue volunteer medics announced: “Whilst expected, this is never the outcome we want as medics, but it was the best outcome for this particular animal that was already heavily compromised.
“Medics are currently working closely with the Scottish Marine Animal Strandings Scheme to gather as much data as possible for their records, however due to the current COVID-19 restrictions in place a full post-mortem will not take place.
“Whilst members of the public are always interested in seeing these ocean giants up close, the landowner has requested that people do not visit the site and we would once again ask for his wishes to be respected. Thank you.”