The New Zealand sea lion - one of the rarest sea lion species in the world - has been listed as "endangered" by an international conservation body.

The number of animals and plants at risk of extinction worldwide rose this year to 22,784 species, from 22,413 a year ago, according to the International Union for the Conservation of Nature's Red List.

The sea lion moved from "vulnerable" to the more serious "endangered" category on the list - backed by governments, scientists and conservationists - due mainly to disease, changes to its habitat caused by fishing and accidental death as a result of bycatch.

The animal primarily inhabits the subantarctic islands south of New Zealand and surrounding waters, though small numbers of them are found by Stewart Island and along the southeast coast of the South Island.

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Dr Bruce Robertson, senior lecturer at the University of Otago's Department of Zoology, said he wasn't surprised about the animal's new status.

He reviewed potential causes of the sea lion decline, published in the international science journal Mammal Review in 2011.

The main cause was fishing impacts - direct (bycatch) and indirect (resources competition). Disease had been suggested as an impact, but current research at the university showed it played only a minor role.

Dr Robertson said an immediate solution would be to revert to a "precautionary approach" to fishing in the squid fishery around the main breeding colonies on the subantarctic Auckland Islands.

"In this year's squid fishing season, fishermen did the smallest number of trawls ever recorded (616 tows; compared to the allowed number of tows in a season of 4700 tows).
Reducing the fishing effort in the squid fishery around the main breeding colonies would be a major step forward in protecting the NZ Sea Lion. Perhaps it is time to weigh up whether the impacts on the NZ Sea Lion is worth such a small amount of squid fishing effort."

The species covered by the Red List ranged from lions in West Africa to orchids in Asia, the Daily Mail reported.

Loss of habitats, such as clearance of forests for farmland, cities or roads, was the main cause of the rise.

Lions in Africa retained an overall listing as "vulnerable", one of the least endangered categories, thanks to conservation in southern Africa.

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But lions in West Africa were listed in a more severe category as "critically endangered" due to losses of habitat and a decline in prey caused by human hunting, the list said.

And it said there were also "rapid declines in East Africa, historically a stronghold for lions - mainly due to human-lion conflict and prey decline."

Trade in bones and other body parts for traditional medicines were an emerging threat.

In 2011, almost 200 governments set a goal of preventing by 2020 the extinction of known species and reducing threats to those most in decline. No known species went
extinct in 2015 but many came closer to the brink.

"We are not on track," said Craig Hilton-Taylor, head of the IUCN Red List Unit, told Reuters of the 2020 goals.

There were some conservation successes, such as the Iberian lynx, which rose to 156 adults in 2012 from 52 a decade earlier.

The list said that practically all of the 84 species of tropical Asian slipper orchid, which are prized ornamental flowers, were threatened, mainly because of over-collection and habitat loss.

Nine of 17 species from the tea plant family assessed were also endangered because they are used for making tea and medicines or as ornamental plants and firewood.