Swiss Theme Park Reeling After Dolphin Drug Overdose

Toxicology reports that have just come in revealed that two dolphins who died last November at the Connyland Marine Park in Lipperswil, Switzerland, died from ingesting a heroin substitute that they likely encountered during a two-day rave that was held near the dolphins' training pool.

Shadow and Chelmers reportedly died within five days of each other just after Connyland owners rented out the Marine Park for the weekend rave party, which was attended by thousands, reports U.K.'s Daily Mail. At the time of Shadow and Chelmers' deaths, prosecutors assumed that the cause was negligent administration of antibiotics, but when the heroin substitute Buprenorphin was found in the animals' systems, this possibility seemed distinctly less likely.

"Opiates are extremely dangerous to underwater mammals and would never be used in any legitimate treatment," said Cornelis van Elk, a marine biologist. "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 .... Drugging them with opiates could well cause this part of the brain to switch off with fatal consequences."

Connyland keeper Nadja Gasser witnessed the heart-wrenching deaths of Shadow and Chelmers. "The death went on for over an hour," she said "It was horrendous. I have not been able to sleep since."

Animal activists are furious, saying they warned of the dangers of holding a rave so near the dolphins before it ever happened, on the grounds that loud noises can damage marine mammals' immune systems. Owners of Connyland deny any wrongdoing.