Ocean Park mystified by sudden death of six hammerhead sharks
Nearly half of the hammerhead population falls victim to unidentified disease within hours
Six hammerhead sharks at Ocean Park died one by one in just seven hours yesterday because of a disease the park has not identified.
The remaining eight sharks "were also at risk", the park said, and its staff would continue to closely monitor them, segregating them and administering treatment if the need arose.
The dead sharks were first found "swimming abnormally" in the Grand Aquarium in the morning yesterday. They had shown no signs of illness before then, a spokeswoman said. Staff then moved them to a different area for treatment and observation, but from about 11am the sharks - all females weighing 45kg to 60kg - died one by one, until the last one perished at about 6pm.
The park's chief veterinarian Paolo Martelli said the park was experiencing high morbidity - the rate of incidence of a disease - with rapid mortality in the hammerhead shark population.
"We are now performing necropsies to better understand the cause of death," Martelli said, in a statement from the park issued yesterday evening.
The six dead sharks - all about five years old - were among the 15 hammerheads introduced from Japan in late 2010.