SINGAPORE - The Society for the Prevention of Cruelty to Animals (SPCA) has called for the remaining 23 dolphins at Resorts World Sentosa (RWS) to be released back into the wild.

Noting that the death of Sharmila the dolphin on May 11 was the fourth RWS dolphin death, it said: "Subjecting these wild dolphins to a forced lifestyle in captivity, tamed against their will and introducing paid interaction programmes with the public... is, in essence, unabashed animal exploitation."

It said RWS should take a cue from the Baltimore National Aquarium in the United States, as well as the Italian Delfinario Rimini dolphinarium, which have been in the news over the impending end of their dolphin shows.

Many nations such as Britain and Brazil also do not hold ceteceans, including dolphins, in captivity, the SPCA said.

"In a country like Singapore, with the Wild Animals and Birds Act in place... it is extremely disappointing that we are accepting these wild-caught dolphins for the purpose of forcing them to adapt to an unnatural lifestyle in RWS' Marine Life Park attraction," it said.

"The act of catching and confining these animals in limited spaces and training them to be something they are not, cannot possibly contribute towards the constructive education of the public on marine life and environmental issues."

In 2010, RWS lost two of its dolphins in Langkawi to a water-borne bacterial infection, Melioidosis. A third dolphin died from acute infection on the flight to Singapore in November 2012.