The California Coastal Commission – an independent, quasi-judicial government agency – has recommended SeaWorld’s expansion plans for its San Diego attraction should be permitted.

A meeting on 8 October will decide whether multi-million dollar improvements to the facility’s orca tanks will go ahead. However, animal rights supporters fear granting permission to increase the size of the killer whales’ habitat would only serve to endorse keeping the animals in captivity and encourage the attraction to breed orcas at the facility.

SeaWorld San Diego, California, announced in August 2014 its “bold vision” for a new orca environment, Blue World Project, that would almost double the volume of its existing tank to 10 million gallons. The company sweetened its proposal further, promising US$10m (€9m, £6.6m) in funds for orca research.

The Commission included a number of conditions with its recommendation. Among them, the body advised San Diego SeaWorld should not be able to house newly captured orcas; the attraction’s orca population should not significantly increase; the attraction should not house orcas captured after February 2014, unless they are rescued animals approved for rehabilitation in San Diego, and nor should it breed using orcas captured after this time.

SeaWorld has said it agrees to those conditions, which would only affect the San Diego facility, where the California Coastal Commission has authority. According to SeaWorld, 80 per cent of its killer whales were born in its parks or other zoos.

At the time the plans for Blue World Project were announced, then-CEO Jim Atchison said: “Our new killer whale homes and research initiatives have a bold vision: to advance global understanding of these animals, to educate and to inspire conservation efforts to protect killer whales in the wild.”

“Through up-close and personal encounters, the new environment will transform how visitors experience killer whales. Our guests will be able to walk alongside the whales as if they were at the shore, watch them interact at the depths found in the ocean, or a birds-eye view from above.”

Atchison stepped down in January this year as profits and visitor numbers continued to plummet in the wake of the 2013 documentary Blackfish and public sentiment increasingly turns against keeping animals such as orcas in captivity.

New SeaWorld CEO Joel Manby addressed concerns in a recent statement, saying: “We realise we have much work ahead of us to recover more of our attendance base. Fully resolving our brand challenges, specifically in California, will require sustained focus and commitment to correct misinformation.”

If the Blue World expansion proposal gains approval, it would be completed by 2018.