Posted 7:02am 5th May 2012.
More than 50 dolphins are found dead off the Cornish coast in just four months.
Experts say half show signs of being caught in fishing nets.
One creature had a chunk of flesh missing from its back.
Cornwall Wildlife Trust fears it could have been cut for eating: "This is a known practice on French boats and French pair trawlers were working close to the south coast at the time. The dolphin's tail had been cut off in the course of cutting the animal free from a winch strop, which was used to lift it over the side of the boat. Local people were very upset to see what had been done to this beautiful animal and to hear that this was just one of many".
Local cetacean researcher Nick Tregenza says, "UK mid-water trawlers have been pushed outside the twelve mile limit by national fishery regulations but French vessels are allowed to come in closer. Some research is underway by the Sea Mammal Research Unit at St Andrew's University in Scotland. They're hopeful of finding an acoustic deterrent to keep animals out of the nets but there's no EU requirement on fisheries to use such a device. In the present situation we believe that EU mid-water trawlers should be subject to video monitoring to assess the size of the bycatch offshore of these animals that are so highly valued by people here and across the world".
Cornwall Wildlife Trust also recorded dolphins that died in gill nets and four stranded porpoises it believes were caught by local boats.
It says it is, "encouraged that some inshore fishermen are showing an interest in using the acoustic pingers that are known to greatly reduce the accidental capture of these animals".
Nick adds, "They are really right up there with the great apes and ourselves. They have an idea of self and what other animals have in their minds which is very, very sophisticated. That's what makes them interesting to watch.
"Porpoises used to be quite common in our estuaries, the Fal, the Fowey, the Tamar and so on. We'd really like to see them back in those estuaries and it is quite a possible thing that could be achieved over the next twenty or so years".
Cornwall Wildlife Trust is urging people to report stranded marine animals as quickly as possible to the Marine Strandings Network on its hotline; 0845 201 2626.
A list of recent strandings and their locations can be found on the website for the Marine Strandings Network