In the wake of CNN’s controversial documentary Blackfish, state legislation that could come into effect in California, US, could spell trouble for SeaWorld attractions, which would no longer be able to have orca shows in the state.

At present there are no laws preventing the captive display of killer whales, but there are federal laws governing the care, capture and research use of the creatures.

The proposed law would end performance-based entertainment for all killer whales in California, captive breeding programs and the export and import of genetic material, and the import and export of orcas within the state.

Also, the proposal would retire all captive killer whales to sea pens if available and would allow retired orcas to be on display, but not perform. The bill would also limit the amount of human interaction for trainer safety.

The documentary Blackfish recounts the 2010 death of trainer Dawn Brancheau by a 12,000-pound (5.4-ton) bull in Orlando, Florida, claiming that by being kept in captivity for entertainment the whale was driven to madness.

SeaWorld has strongly disputed the allegations of Blackfish and has called the film grossly one-sided and the product of animal activists, calling it “severely flawed on multiple levels.”

Spokesperson Becca Bides stated: "We trust that our leaders who are responsible for voting on this proposal will recognise the clear bias of those behind the bill.

"Included in the group are some of the same activists that partnered with PETA in bringing the meritless claim that animals in human care should be considered slaves under the 13th Amendment of the US Constitution – a clear publicity stunt. This legislation appears to reflect the same sort of out-of-the-mainstream thinking.”