An investigation is under way into the deaths of three sharks which were moved to an aquarium in Norfolk.
The black tipped reef shark were moved from Great Yarmouth
The black tipped reef sharks were three of five moved 70 miles (112km) from Great Yarmouth to their refurbished tank at the Hunstanton Sea Life Centre.
The centre said the deaths were "almost unprecedented in the Sea Life network" after "over 100 shark transportations over the past 20 years".
Manager Nigel Croasdale said he was "deeply concerned" at the loss.
"Something has clearly gone wrong on this occasion and we are determined to identify this problem," he said.
He said a full investigation would be carried out after the incident on Friday.
In February, Mr Croasdale said the movement of the sharks was a potentially dangerous job.
He said: "I wouldn't advise anyone not experienced in handling fish or sharks to do it because it would probably be dangerous.
"But for our people experienced in moving sharks it should be quite a straightforward operation.
"As long as they treat the creatures with a great deal of respect and care it should go smoothly."