Jan16

Looking back at a tragic year for strandings

Categories // Whale & Dolphin General News

Looking back at a tragic year for strandings
A common dolphin stranded in Fareham in 2017

The recent death of a white-beaked dolphin found stranded on the Isle of Wight occured right on ORCA's doorstep, just across the Solent from our main offices in Portsmouth.

With 2017 seeing very high numbers of cetaceans stranding around the UK and beyond, ORCA wanted to look back at the challenges these animals face and the factors contributing to these sad deaths.

Common dolphins at serious threat of by-catch related stranding

In early Autumn, two members of the ORCA team attended a stranding right on our doorstep in Fareham Creek, where a common dolphin was found to be in significant difficulty. Both were trained Marine Mammal Medics and responded as BDMLR volunteers, but despite theirs and others best efforts, the animal was euthanised.

This was one example of a worrying trend of deaths of this species, with more than 75% of strandings being found to have been caused by by-catch from fishing activity. In the south-west particularly the last few years have shown an increase in strandings of common dolphins and is most closely associated with seabass and albacore tuna pelagic trawlers.

A recent study estimated that 3650-4700 individuals were straded by by-catch each year, making this a significant threats to the UK & European population of common dolphins.

Mass strandings worldwide amongst the worst ever

2017 saw the third-largest mass stranding event in New Zealand's history with 400 pilot whales beaching at the notorious Fairbank Spit on the South Island.

The animals stranded over a period of three days, with the gentle sloping incline of the coastal topography making it difficult for animals to identify the shallowing waters and thus increasing the risk of strandings.

Pilot whales in particular are at significant risk as their strong social bonds within groups means that individuals will continue to re-strand even after being floated.

In this instance, tragically there were more than 300 animals lost despite huge efforts made by local volunteers to assist in getting the animals back out to sea.

Work still to be done to establish the cause of many strandings

Despite geographical or industrial facts known to be impacting the number of animals stranding, there is still many causes that remain unknown and further research is being done to understand better what the key causes of cetacean stranding are.

Incidents have been associated with ship strike, noise exposure, toxic pollution and plastics and there are also clear trends that take place on a species by species basis.

Harbour porpoises are also at significant threat around the UK, and the proportion found suffering from starvation has increased from 4% in the 1990s to 16% in more recent years.

ORCA are working with industry, the public and the UK government to inform the development of interventions to prevent a wide variety of threats, and help to tackle some of the root causes of strandings around the UK and beyond. ORCA's citizen science research can also play a role in helping to understand what factors contribute to the deaths of these animals and help limit these tragic incidents for the future.