'Safe nets' queried as sea lions die

Conservation groups including the New Zealand Sea Lion Trust and Forest and Bird have questioned the efficacy of Sleds. Photo / Greg Bowker

The deaths of two New Zealand sea lions inside fishing nets designed to help them escape has prompted calls for better protection of the critically endangered species.

The Ministry for Primary Industries has confirmed the "incidental capture" of two sea lions by vessels operating in the southern blue whiting fishery, at Campbell Island, during this year's season.

With a declining population of around 10,000, the New Zealand sea lion is the rarest sea lion species in the world and a recently-discovered drop in pup numbers at the Auckland Islands, its main breeding ground, spurred the fast-tracking of a threat management plan.

The Green Party said the deaths called into question the effectiveness of sea lion exclusion devices (Sleds), which are designed to let sea lions swim free.

They have been required by all operators in the fishery after 16 sea lions were killed within three weeks last year.

"The Government doesn't allow hunters to accidentally kill kakapo, and we shouldn't be allowing fishing methods that kill sea lions," spokeswoman Eugenie Sage said.

Conservation groups including the New Zealand Sea Lion Trust and Forest and Bird have also questioned the efficacy of Sleds, something Otago University zoologist Dr Bruce Robertson said had not been academically resolved despite official estimates of 85 per cent of captured sea lions escaping.

Dr Robertson claimed Sleds might even be allowing captured dead sea lions to drop out of the nets, suggesting official mortality rates could be under-estimates.

But George Clement, chief executive of industry body Deepwater Group, said millions of dollars had been spent on fitting cameras which showed there weren't any unaccounted deaths.

"We have worked on this thoroughly and it's now very clear by all impartial observers that the cause of the decline is not fishing."

The use of Sleds had led to a significant drop in sea lion bycatch deaths, he said.
Mr Clement said while two deaths was two too many, he suspected a bacterial disease, Klebsiella pneumoniae, could be to blame for the population decline.

While some scientists had expressed doubt over disease as a major cause, it would be considered as a potential factor in a comprehensive assessment at key breeding sites this summer.