Three sharks which died while being transferred between different branches of the Sea Life Centre chain died because their water was too cold.
The three Black-tipped reef sharks died last month while being moved 70 miles/112 km from Great Yarmouth Sea Life Centre to a newly refurbished tank at the Hunstanton Sea Life Centre.
According to a report from the BBC, the Centre confirmed that the water was two degrees centigrade below the minimum required for sharks due to a mistake made by a staff member.
While not conclusive, this is believed to have been the cause of the sharks' demise.
A spokesman told the BBC that the deaths were "almost unprecedented in the Sea Life network", after 100 shark movements over the past 20 years: "Action has been taken to ensure this cannot happen again, including a retraining and assessment programme for the relevant personnel.
"Everyone connected with Sea Life was shocked by the tragedy of the three Hunstanton sharks."