High mortality figures of animals at Scarborough Sea Life Centre is due to a formatting error, says owner.
A BBC investigation, looking into deaths of animals at Sea Life centres around the UK, found that there were 965 deaths at Scarborough centre in 2016.
This is believed to be almost a third of its entire animal stock.
But Merlin Entertainments, owner of Sea Life, said that the "unusually high" mortality figure was due to a formatting error and the true total for the year was 590 animals.
The proportion of shark and ray deaths at Scarborough is the second highest out of the UK centres, according to figures gained by the BBC.
It is believed 16% of sharks and rays died during 2016.
A Sea Life spokesperson said: “Sea Life places the very highest priority on the welfare of the animals at its sites, which are supported by experienced animal care teams, marine biologists and world-renowned veterinary consultants.
"Sea Life has a strong track record in animal husbandry and complies with all the laws and regulations under the Zoo Licencing Act.
"Furthermore we take an active role in promoting conservation, playing a leading part in rescue and rehabilitation, breeding select species at our facilities and educating the many millions of visitors to our attractions.”
Jonathan Bramley, Scarborough Borough Council Environment and Regulation Manager said: “There is a requirement for Scarborough Sea Life Centre to submit annual stock levels to us as part of their licence conditions and these include mortality rates.
"The purpose of the information is to ensure compliance with Defra guidelines on stock reporting for modern zoo practice. Figures submitted to us in January 2016 related to the previous calendar year and tally with the figures currently being investigated by the BBC.
“Following the receipt of the figures, a joint inspection with a vet from Defra, the centre’s own appointed vet and our licensing officers, was carried out in March 2016. Vets address several aspects at an inspection, including animal welfare, safety, security, stocklist data and mortality rates, because different species have widely differing lifespans.
"The outcome of that inspection was a good report and the vets had no concerns about animal welfare.
“We have this week been informed by Scarborough Sea Life Centre that there were discrepancies in the figures supplied to us.
"This does raise concerns, because incorrect stock figures, in effect, invalidate compliance with Defra guidelines.
"The centre is already reviewing its stock reporting process and we will be asking staff to make changes to how they report annual stock figures to us to help prevent problems occurring in the future.”