environment

Bleak outlook for these seven NZ species

Despite concerted efforts to save New Zealand’s most threatened species, some are losing the survival battle.

An article published in the Journal of the Royal Society of New Zealand looks at seven species to understand why even with help, their prospects are bleak.

The article points out that the scale of New Zealand’s conservation challenge is enormous and describes the Department of Conservation’s budget as too small.

Threats faced include changing ecosystems, pollution and invasive species. 

For some, such as the Māui dolphin, the article includes lack of direction as a threat, saying it results in indecision.

Photo: Department of Conservation CC BY-SA 3.0 nz

Maui dolphin

The rarest dolphin in the world is found off the west coast of the North Island. About the size of a 10-year old child, they are also the smallest dolphin in the world. The number of adults is estimated to be between 55 and 63. Described as the hobbit of the ocean, Māui dolphins are a sub-species of Hector’s dolphin, which are threatened by commercial fishing and toxoplasma gondii - a parasite spread by cat faeces.

An ocean sanctuary banning gill nets and limiting trawl fisheries in their core habitat exists.

The article lists the main conservation issues as economic conflict from fisheries, conflict between stakeholders, low genetic diversity and disease.

“ … stakeholders still struggle to coordinate conservation actions. Māui dolphins have an uncertain future.”

The article's prediction for the next 30 years: “Likely extinction.”

Photo: Duncan CCBY-SA 2.0

Toanui/flesh-footed shearwater

This sea bird feeds mainly on squid and fish and has colonies in several countries. The colonies in New Zealand represent 16 percent of the global population. Since the 1930s, at least four New Zealand colonies have vanished.

It was thought rats may be to blame, however, even on rat-free islands the population is decreasing.

Fishing poses a bycatch risk to the birds. Plastic pollution is also an issue, having been found in the digestive tracts of birds and chicks.

In New Zealand the birds have been a low priority for conservation funding, however, predictions are the local population will be halved by 2050.

The article's prediction for the next 30 years: “Continued serious decline.”

Photo: Tomas Sobek CC BY 2.0
 

Pīngao/golden sand sedge

Once common on New Zealand’s coastlines, the golden sand sedge has declined in recent years. Factors for the decline are habitat loss and degradation and invading weeds.

Dunes where the sedge once thrived have often been stabilised by invasive species such as marram grass, tree lupin and pines.

The slow growing sedge also struggles with disturbance from human and vehicle traffic. Sea level rise also poses a risk.

The plants have been grown by seed and planted in Department of Conservation dune restoration projects. Community groups also make a considerable effort to restore dune environments by planting the sedge, however, without ongoing protection the species future is uncertain.

The article's prediction for the next 30 years: “Continued serious decline.”

Echyridella aucklandica (top two mussels) and Echyridella menziesii (bottom two mussels). Photo: Supplied

Kākahi/freshwater mussels

There are three species of freshwater mussels found in New Zealand. There is very little known about echyridellas onekaka species, thought to be only found in the north-west of the South Island. The other two species echyridellas menziesii and aucklandica are declining.

The long-living mussels can live for up to, and possibly more than 50 years, and only now are scientists beginning to understand their lifecycle.

Water quality and the ability of host fish to carry the mussels' young to travel upstream are potential issues for the their survival.

Attempts are being made to breed the mussels and translocations have been made. These may not be enough according to the article:

“To date, conservation actions have not enhanced recruitment of E. aucklandica populations in northern NZ, and more targeted measures are needed to reinstate regional recruitment processes and prevent local extinction."

The article's prediction for the next 30 years is different for each species. The widespread menziesii could have a stable future, while the aucklandica has low conservation prospects. So little is known about the onekaka, no prediction can be made.

Photo: Auckland Museum CC BY 4.0

Forest ringlet butterfly

The forest ringlet butterfly used to be found as far south as Greymouth and Lewis Pass, but is now classed as at risk.

It’s not known what’s causing the decline in numbers, but habitat loss, collection, parasites and being eaten by introduced wasps, birds, rodents and feral pigs are thought to be contributing factors.

So far, there are only surveys to monitor the reduction in numbers and there is no work being done to reverse the decline.

For this reason, “lack of direction” is listed as a threat to the future of the species.

The article's prediction for the next 30 years: “Localised extinctions likely without conservation action.”

Photo: Duncan Wright CC BY-SA 4.0

Hihi/stitchbird

The tiny nectar-feeding stitchbird nests in tree cavities. Since the arrival of humans, who cleared forests, and ship rats, the number of birds plummeted until the only remaining population was based on Little Barrier Island.

Without conservation efforts such as providing the birds with a pest-free home it’s likely they would become extinct.

A recovery programme has been under way since the 1980s and birds have been translocated to other pest-free locations. To survive in all but one location they require supplementary feeding.

The article notes: “ ... the species has little prospect of increasing in numbers until large tracts of mature forest are cleared of introduced predators on the mainland and suitable regenerating forests mature on offshore islands.”

The article's prediction for the next 30 years: “Additional populations may increase numbers.”

Otago skink. Photo: Pseudopanax Public Domain

Grand and Otago skinks

The grand and Otago skinks used to live in tussock grasslands of Central Otago. Now they inhabit less than 10 percent of the area they once did. Two pockets remain, one in the east and one in the west of central Otago, and are dependent on conservation efforts for their continued survival.

They are at risk of habitat destruction, wildlife trafficking, predators and competition from introduced species.

Conservation efforts began in the 1980s and include predator-free fencing and monitoring. A government cross-agency group, the Wildlife Enforcement Agency, used to exist to target wildlife smugglers but the group has now been disbanded.

The article's  prediction for the next 30 years: “Managed eastern populations remain stable; others go extinct. Western populations extinct in wild, unknown outcome for managed areas.”

The future

While the current prospects look dim, even for species which are getting a helping hand, there are some positives the article lists. New Zealand leads the world in its ability to clear islands of predators. There are now 100 mammal-free islands and the goal of predator-free 2050 may help some species. 

Real hope will take more than just removing predators, though. Habitat protection or changes to fishing practices will also be needed.

Also underway is a plan for managing biodiversity from 2020 to 2040. At the same time, a National Policy Statement on Indigenous Biodiversity is expected to be finalised which is hoped to give biodiversity on private land more protection. 

The Ministry for the Environment is due to release a report on New Zealand's biodiversity on Thursday.

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