Orlando-based SeaWorld has faced sagging attendance along with criticism about its treatment of the captive marine mammals, and some activists had called for the end of public exhibition of killer whales, or orcas, altogether.
SeaWorld Entertainment Inc, which has parks in San Diego, Orlando and San Antonio, said in November it would replace its signature killer whale shows in San Diego with displays focused on conservation.
The company, whose shares rose as much as six per cent in morning trading, also said it would scrap plans for a $US100 million ($A132.5 million) project called Blue World that would have enlarged its 30-million-litre orca habitat at SeaWorld San Diego.
California regulators had approved the project, but only on the condition that the company cease captive breeding of orcas as well as the transfer of new killer whales to the park.
"These changes are something that advocates have been urging for years and I think SeaWorld will find that visitors will reward their actions with a renewed interest in the parks," California Congressman Adam Schiff, author of the ORCA Act, which seeks to phase out captivity of orcas, said in an email.
Some activists have called for SeaWorld to release its orcas into coastal sanctuaries, but the company says that whales raised or born in captivity would likely die in the wild.
SeaWorld also faced a backlash after the release of the 2013 documentary Blackfish, which depicted the captivity and public exhibition of killer whales as inherently cruel.
Dr Naomi Rose, a marine biologist with the Animal Welfare Institute who was an adviser to the film, said SeaWorld's move was a "monumental and important first step forward in achieving a more humane business model for the company".
Animal rights group People for Ethical Treatment of Animals said SeaWorld had taken a step forward, but renewed its call for the company to link its tanks to ocean sanctuaries.
SeaWorld, which has not collected orcas at sea for almost 40 years, has 29 killer whales under its care.
