The National Aquarium of New Zealand has released its last two sharks from captivity back into the ocean this morning, following recurring injuries and the death of three other sharks.

The two sharks released, a 2.2 metre broadnose sevengill shark and a 1.2 metre school shark, were the only sharks left at the aquarium in Napier after three sharks died following “the impacts of Cyclone Gabrielle”, a school shark and two spiny dog fish.

A Napier City Council spokeswoman said that the necropsy, an animal autopsy, on the sharks was inconclusive so they could not determine a specific cause of death.

The spokeswoman said the aquarium went on and off generator power more than once during and after Cyclone Gabrielle.

In a statement released on Tuesday, council confirmed the released sharks were the aquarium’s last remaining sharks, and said the species are naturally occurring in Hawke Bay and are wide spread throughout New Zealand waters.

The council statement said there are no plans to introduce new sharks into the Oceanarium at the aquarium currently.

Rachel Haydon, general manager at the aquarium, said the decision to release the sharks was due to recurring abrasions the sharks experienced to their noses (rostrums).

“We have had success where the abrasions heal, but unfortunately it ultimately happens again. The team has implemented a lot of strategies to reduce chances of injuries, but have not been able to eliminate them completely. The best thing at this stage is to release these animals to the wild,” Haydon said.

“In the end, we need to do what’s right for these two individuals.”

Aquarium staff are confident that the damage to the sharks’ rostrums will heal with a change in environment.

“All other species housed in the Oceanarium are in good health and have not experienced similar issues,” the council statement said.

The statement said aquarium staff worked closely with local and international veterinarians on a plan for the release of the sharks before applying to the Ministry for Primary Industries and getting the release approved in April.

The staff were waiting for the right weather to safely carry out the release.

Napier City Council’s Maori Directorate Te Waka Rangapu and mana whenua, under the guidance of council Kaumatua, performed karakia and ensured tikanga was followed for the release of the two sharks.