Shares in the company slumped by 9% following the results announcement while it also admitted that it spied on animal rights activists.

The group, which owns and runs 11 attractions across the US, saw pre-tax profits for 2015 drop from $78.8 million to $72.8 million.

Overall attendance levels climbed slightly from 22.4 million to 22.5 million but revenue fell from $1.38 billion to $1.37 billion.

On a conference call chief executive Joel Manby said the board had "directed management to end the practice in which certain employees posed as animal rights activists."

“This activity was undertaken in connection with efforts to maintain the safety and security of employees, customers and animals in the face of credible threats."

Two of the company’s parks saw visitor number drops: Texas and California.

While the problem in the former was down to the specific product offering, the issues around its San Diego park are more wide-ranging.

The problem stems largely from the Blackfish documentary, released in 2013, which was highly critical of the company.

Although SeaWorld disputed many of the findings in the film, there was a widespread backlash.

A bill to ban orca shows was introduced in the California state legislature and the company is currently embroiled with the California Coastal Commission over restrictions put in place on SeaWorld’s proposed Blue World project.

The plans for a new a new killer whale environment have been put on hold by SeaWorld after it was prohibited from breeding or transporting the whales at the facility.

Last week SeaWorld announced a management shake-up with both the chief parks operations officer Dan Brown and chief zoological officer Brad Andrews stepping down from their positions.