NATIVE NIPPER: If bitten, you won't die but you will feel like you're going to.

Killing New Zealand's most venomous spider could now earn culprits jail time or a $100,000 fine under changes to the law.

Giant weta, some weevils and beetles have also been given complete protection for the first time, but conservation advocates say the changes do not lessen the main threats to native species.

Conservation Minister Kate Wilkinson announced changes to the protection status of more than 50 species yesterday. "Whether they are weevils, wetas or beetles they deserve an appropriate level of protection." Under changes to the Wildlife Act, katipo spiders go from not being protected to having "absolute protection", as the kereru and kiwi have.

The maximum penalty for killing creatures with absolute protection is a year in prison or a $100,000 fine.

AgResearch scientist and spider expert Cor Vink welcomed the move to protect katipo, and said that, although it was almost impossible to determine how many there were in New Zealand, they were declining.

Katipo had disappeared from the Wellington region, but were still found frequently in parts of the South Island – with the main threats being habitat loss and predation by an introduced spider.

Katipo bites were "extremely" painful, and there had been two recorded deaths of children bitten by katipo, both before 1840. Some people were at risk of developing complications, but Dr Vink said it was unlikely a katipo bite would cause death. "You won't die, but you will feel like you're going to."

Forest & Bird advocate Quentin Duthie said the main threats to native plants and animals were from habitat destruction and pests.

"We agree with the changes, but fear the Government is rearranging deckchairs on the Titanic rather than putting the ship on a course that will avoid wildlife disaster."

Mr Duthie said kiwi were still declining despite being absolutely protected, and current proposals to open protected areas of the conservation estate to mining threatened to destroy more of its forest home.

"I'd like to see the Wildlife Act fixed so it protects the homes of our wildlife too, and DOC funding restored so we can control pests that kill daily despite the Wildlife Act."

Green Party conservation spokesman Kevin Hague also welcomed the increased protection for some species but said the moves took place against the backdrop of devastating biodiversity loss.

"The conservation of biodiversity in its richest sense, the ecosystems, the habitats – that's where the Government needs to focus."

Under the changes, manta rays and whale sharks – the largest fish in the world at 20m – also go from no protection to absolute protection.

Forest & Bird marine advocate Kirstie Knowles said threatened species, such as Hector's and Maui's dolphins, were still without absolute protection.

The spur-winged plover, deemed a "major hazard" to aviation and responsible for more than a third of bird strikes on aircraft, loses its absolutely protected status.