Two dolphins who died a slow and agonising death at a Swiss zoo after it hosted a weekend-long rave were probably killed by a heroin substitute according to a leaked toxicology report.
The dolphins died within five days of each other in November of last year after “Connyland” park bosses had rented land near their training pool to organisers of a weekend rave party for thousands of clubbers.
Prosecutors said at the time that they believed that antibiotics given by zoo vets were to blame for the deaths of the two dolphins at the zoo in Lipperswil, Switzerland, and they were considering negligence charges.
But now another toxicology report has been leaked to Swiss media that was carried out at the time by the forensics institute in St Gallen – which found the heroin substitute Buprenorphin was present in the animals urine.
Dutch marine biologist and dolphin expert Cornelis van Elk said: “Opiates are extremely dangerous for underwater mammals and would never be used in any legitimate treatment.
The reason is that dolphins are conscious breathers which means they actively decide when to come to the surface to breathe, for which they need to be awake.
Even when sleeping – there is part of the brain that automatically controls the breathing instinct in the same way as it does for people when asleep.
Drugging them with opiates could well cause this part of the brain to switch off with fatal consequences.”
It was originally suggested by keepers that rave-goers could have caused the death by feeding the dolphins illegal recreational drugs but prosecutors had rejected this, blaming the zoo’s vets.
Now Connyland spokesman Erich Brandenberger has said they would be asking questions about why the prosecutors had not followed up the investigation that the dolphins were poisoned instead of blaming the zoo’s vets.
The two dolphins Shadow and Chelmers had died after what staff described as a “drawn out and painful” death. Connyland keeper Nadja Gasser told local media: “The death was very drawn out and painful. The death went on for over an hour. It was horrendous. I have not been able to sleep since.
“When we went to start the dolphin training we noticed the same thing that had happened to Shadow was happening with Chelmers.
“He was drifting under the water and was clearly in trouble and so we jumped into the water. We tried to hold him. He was shaking all over and was foaming at the mouth.
“Eventually we got him out of the water. His tongue was hanging out. He could hardly breath. He was given adrenalin, but it didn’t help. After an hour the dolphin died,” she added.
Furious animal activists say they warned both the marine park and local planners – who gave permission for the rave – of the dangers before the event.
They had been concerned that the high levels of noise could damage the marine mammals sensitive sonar and hearing and harm their delicate immune system. Connyland has consistently denied any wrong-doing.