Striped dolphin strands alive

25 January 2008

A male striped dolphin (Stenella coeruleoalba), a relatively uncommon sight in inshore Cornish waters, has stranded alive on the south coast. A member of the public reported the dolphin to British Divers Marine Life Rescue (BDMLR).

Trained volunteers arrived on the scene at Church Cove, Gunwalloe, near Helston, to find the dolphin lying on the beach not far from the surf. It was almost certainly stranded on the outgoing tide. At first sight, it looked relatively unscathed and the volunteers followed their usual procedure of trying to keep the animal as comfortable as possible, covering him with a light sheet and keeping him wet to prevent his skin from drying out in the wind. The dolphin remained calm throughout and the volunteers had hoped that the animal was in good enough condition to be refloated, once a vet had examined it.

James Barnett, the veterinary coordinator for BDMLR, carefully examined the dolphin and assessed its state of health. "Initially, the animal looked in reasonably good condition, although he appeared to be only moderately nourished. He had various abrasions on the edges of his pectoral fins and tail from contact with the rocks, but most of this damage was superficial. However, when I examined his beak, I noticed a large wound on his lower jaw, where a flap of skin and underlying tissue had come away exposing the underlying bone. If this animal had been released back to the sea with this injury, it is highly likely it would have developed osteomyelitis - infection of the bone - and suffered a great deal. So the only option was to put the animal to sleep."

All those assisting agreed that this was the best course of action to avoid the dolphin from suffering any further. "It was a beautiful animal and it's a really difficult decision to make. Naturally we were all sad about it", said Cheryl Mills, one of BDMLR's volunteers, "but the long term welfare of the animal must come first and I'd hate to think that we'd put an unhealthy animal back in the sea to suffer a slow, painful death."

Some of the volunteers involved are also members of the Cornwall Wildlife Trust's Marine Strandings Network (MSN) and they recorded the animal and took photos of it for the Natural History Museum and Institute of Zoology. Volunteers then transported the dolphin to Truro so that a post-mortem examination could be carried out to try to determine why the animal stranded.

"We couldn’t see any obvious marks on the dolphin to indicate that it had been caught in fishing gear," said Jeff Loveridge of the MSN, "and possibly it was diseased. But hopefully the post-mortem will tell us something as we rarely get striped dolphins washing ashore: this is only the 14th striped dolphin we've had in the last five years and it's even rarer for them to strand alive – this is only the second one that we know of in Cornwall."

"We're really lucky in Cornwall to have two organisations that work so closely together and share a deep concern for dolphins and seals in the county," Jeff continued, "and it's amazing how many people will turn out on a week day to do what they can to help or to learn more about these amazing creatures."

Striped dolphins are very acrobatic, often performing somersaults, tail spins and bow-riding: they have even been known to leap up to 7 metres out of the water. They are not often seen in coastal waters, preferring deeper, offshore habitat where they feed on pelagic fish, squid and shrimps. They may form very large groups up to 3,000 strong, although 10 - 500 is more normal. These are usually broken up into age groups with mothers and nursing youngsters, immature animals and adults forming separate sections. Groups are seldom seen around Cornwall, however a pod of 40 or more was sighted in June of last year off Lands' End.

BDMLR is always pleased to receive reports of live stranded dolphins or seals in difficulty and the public can reach them at any time on 01825 765546. Their web site can be found at www.bdmlr.org.uk.

Dead marine animals can be reported to the CWT Marine Strandings Network on 0845 201 2626.

Sightings of live dolphins or other marine animals can also be reported to the Cornwall Wildlife Trust’s Seaquest Southwest project via the online recording form at www.cornwallwildlifetrust.org.uk.

For more information on this species, see our Identification & Ecology page or visit the Convention of Migratory Species web site.