CONSERVATION ISSUES - MARCH 2005

Researchers have discovered that chemicals may cause whale hearing loss, and deafness could lead to whales beaching themselves. A toxic chemical used to prevent barnacles clinging to ships hulls may cause deafness in marine mammals. The hearing loss would be the latest environmental hazard linked to TBT, a chemical already known to be harmful to some aquatic life and is already banned by many Countries, but is still widely used. Since many marine mammals use sonar to get around, it’s possible that deafness is contributing to whale and dolphin beaching and hitting ships.  The Yale researchers based their theory on a study of guinea pigs, because mammals have similar ear structures.   

The lack of fish and competition for food may be the cause of recent increase in Bottlenose Dolphin attacks on Harbour Porpoises, which are two thirds the size of the dolphins. Evidence comes from counts of porpoises washed up, and post mortem examination of the animals. Annual reports show a steady rise in the number of porpoise strandings, with 40 in 1995 and more than 120 in 2004. Most of the strandings in the study occurred on the Welsh coast. Post mortem examinations reveal that of those 120, nearly three quarters were killed by Bottlenose Dolphins, which ram the porpoises with their beaks, causing multiple injuries that include internal bleeding, rib fractures, ruptured lungs and dislocated spines. Analysis of the animals stomachs suggested that they had all eaten recently, but had taken some unusual fish species, perhaps indicating that they were having difficulty in finding their normal prey. One theory suggested the violence may be re-directed aggression when access to females is limited, but female dolphins had also been observed taking part in the attacks on the porpoises. Another idea is that the behaviour might help to develop hunting skills, even though the victims are never eaten. A spokesman for the study group said that more research was needed to access fish declines in coastal waters, for the attacks were undoing conservation work to save porpoises from dying as by-catch in fishing nets.  

A 1½ ft. long Kemps Ridley turtle was found alive, but in a poor condition, at the waters edge at Carbis Bay on February 2nd. Emergency care was given and The Blue Reef Aquarium, Newquay agreed to take the malnourished and exhausted turtle in for rehabilitation. Turtles in similar condition have been successfully rehabilitated there in recent years and have been flown abroad to where they are normally found for their release. Unfortunately this female turtle died the following day. The shell had been covered in a greenish/brown/black algae, and a small organism , possibly a parasite, was visible near the centre of the shell. It also had an infection, denoted by a pinkish colour of the costal scales. It was collected for post mortem at a University of Exeter faculty in Cornwall. 

A breeding programme at the Blue Reef Aquarium has been successful for a number of species of Seahorses. There are currently 13 babies in their nursery. Visitors will be able to see them feeding and learn more about the threats they face in the wild. These threats include pollution, loss of habitat, the souvenir trade and traditional Far East medicine. These are believed to account for the death of 20 million seahorses each year.

Unidentified dolphins were reported 9 times during February, and Bottlenose were seen 6 times all between Fal Bay and Sennen. A pod of 8 Common Dolphins was seen 5 miles south of Nare Head, and 2 adults and a juvenile off Porthgwarra. 6 reports of  Harbour Porpoises were all off West Penwith. A small cetacean was watched swimming between the boats in Mylor Harbour and then it became stranded on the 20th Feb. It swam off after  members of the public put it back in the water. Grey seals were reported 5 times, and there was a Leatherback Turtle as well as the Kemps Ridley Turtle mentioned above.

Three cetacean carcasses were found on Cornish Beaches during February, 2 unidentified Dolphins and a Harbour Porpoise. There were also 7 Grey Seals and the Kemps Ridley Turtle mentioned above. Other items stranded were, Goose Barnacles at Chapel Porth and birds. 3 Guillemots, 2 Herring Gulls, 1 Black Headed Gull, a Gannet, a Fulmar and a Jackdaw.

Conservation Officer Raymond Dennis

Back to top                                                             Back to Conservation Index