Lolita, an orca whale, performs for visitors at a Miami poll seven days a week. Picture: Twitter/@Independent

New York - Animal rights activists are staging a protest to free an orca whale that has been held in a tiny Miami pool for 46 years.

Lolita, who is the property of a London investment firm, was captured in 1970 off the North West US coast, has lived in a tank measuring around 50 foot wide and 20 foot deep - around the same size as a hotel swimming pool. She is thought to be the longest held captive whale.

Her life started off with trauma. According to One Green Planet, the men who herded up the pod of orca whales in 1970 used nets, ropes and explosives to separate the adults from the babies. During the capture, five whales were killed.

Lolita now lives at the Miami Seaquarium in Florida, owned by Arle Capital, an investment company based near Pall Mall in central London.

Howard Garrett, of Orca Network, the US-based organisation that is leading a lawsuit to move Lolita to a marine refuge, told The Sunday Times: “We assert that the conditions of Lolita's captivity violates America's Endangered Species Act prohibiting harm or harassment of an endangered animal.”

Animal rights protesters have already gathered outside the offices of Arle Capital, which could prove embarrassing for its managing partner John Arney and his colleagues, who control around £2 billion ($2.9bn) worth of assets.

The company acquired Lolita when it bought Spanish entertainment company Parques Reunidos, which in turn owns Palace Entertainment, the firm behind Seaquarium. According to Seaquarium's website, “conservation and education go hand in hand”. The Florida attraction is estimated to make annual profits of around £750 000 ($1.09 million). Lolita performs seven days a week for visitors.

Julie Foster, of Arle Capital, said vets make sure Lolita is healthy and the pool fits legal requirements. “It would be a reckless and cruel experiment [to take her out of the tank] which would put her through a traumatic transport process and jeopardise her life”, she said.

“Each year more than 85 000 schoolchildren and 600 000 other guests visit Miami Seaquarium to see and learn about Lolita. “We believe that this remarkable, educational experience creates awareness and appreciation for orcas and marine life in general.”

The fight to free Lolita has been going on for years, involving groups such as People for the Ethical Treatment of Animals, which sued Seaquarium last year. The movement gained momentum after the release of documentary “Blackfish” which exposed the cruel treatment of the whales.

Orca whales are very sociable and swim in tight-knit pods. Her former companion whale, Hugo, died in the same tank 34 years ago, after continually bashing his head against the side of the tank. Opponents of the release plan point to other whales who were set free and died as a result. The whale Keiko was released near Iceland in 2002 but died after he was rejected by other orcas.