Threat danger reduced for New Zealand sea lions

The latest Department of Conservation marine mammal threat status has removed the New Zealand sea lions from its nationally critical list.

Whilst still seen as threatened, sea lions have been rated a two-step improvement to a new status of nationally vulnerable.

The DOC threat status classification has three stages under the “threatened” category – nationally critical at the most extreme, with nationally endangered and then nationally vulnerable as the lesser marks.

The more favourable “at risk” category is rated under two stages – recovering and then naturally uncommon.

A final category is “not threatened”.

The department assesses the threat status of the country’s plant and animal life every five years, including the risk of extinction based on abundance and population trends.

The other major positive moves concerned right whales, once hunted to near extinction, and Hector’s dolphins.

Right whales, like sea lions, have been accorded a two-step improvement to nationally vulnerable status.

Hector’s dolphins have improved from nationally endangered to nationally vulnerable.

Their population has been estimated at close to 15,000 although the review panel was faced with conflicting evidence on the level of decline in the 40-year period to 2015.

Maui dolphins remain on the nationally critical list with a population of less than 100.

Significant decline is still a risk over the next three generations due to uncertainty in remaining threat from overlap with fisheries and diseases such as toxoplasmosis.

However, recent DNA-based abundance estimates, and demographic modelling indicate the population may have stabilised and may be growing.

A revised threat management plan is due next month.

The main breeding ground for sea lions is the wild and inhospitable Auckland Islands, 460km south of Bluff, where there are three colonies.

There is also a substantial colony on Campbell Island and for the first time in 150 years a colony has established on mainland New Zealand – at Stewart Island.

On the Auckland Islands, 1758 pups were born last summer, with another 704 on Campbell.

The Deepwater Group has been supporting researchers on Campbell in combatting the high mortality caused by pups falling into naturally occurring coastal mud holes and pools and becoming trapped.

Fisheries risks are actively managed and closely monitored.

Fisheries New Zealand have an Operational Plan to manage sea lion risks in the southern squid trawl fishery.

This includes requirements to have a minimum of 70 percent government observer coverage of the fishery (with around 90 percent coverage typically achieved) and for vessels to deploy sea lion exclusion devices (escape holes in the top of the trawl).

This strictly enforced management regime has greatly reduced captures in the fishery, now averaging only two per year with near complete observer coverage.

DOC’s Sea Lion Threat Management Plan recognises a range of threats facing sea lions, both natural and from man, and the concerted and ongoing efforts from all to manage these provides optimism for their future.