environment

NZ’s at-risk fish: underwater and out of mind

Today's World Water Day’s theme is 'leaving no one behind' in access to clean water. Farah Hancock reports on whether New Zealand’s native freshwater fish are among those getting left behind.

Long after the filming of The Lord of The Rings and The Hobbit were complete, Gollum can still be found in New Zealand lurking in swamps and slow-moving margins of waterways.

Sightings are likely to be rare though.

With bulging eyes, a blunt and short face, and looking like “they’ve been dipped in gold metallic dust”, Gollum galaxias, a small native fish, is at risk of extinction due to threats such as land development and water extraction.

University of Canterbury professor Angus McIntosh said Gollum galaxias was first found in swamps in Stewart Island.

“The person who found that thought it was a sort of place that Gollum would hang out.”

The Gollum galaxias joined the three-quarters of New Zealand’s freshwater species facing the threat of extinction. This year, World Water Day is more focused on humans than biodiversity; however, other creatures have the same needs for clean water.

The Department of Conservation’s 2017 update of the conservation status of freshwater fish lists 39 species threatened or at risk of extinction. Only 12 indigenous species aren’t considered at risk.

Canterbury mudfish, torrentfish, longfin eels and giant kõkopu are among the many species facing danger.

The statistics are alarming. Over-fishing can play a role for some species, but for most the problem lies in access to the type of water they need during their life cycle.

"We’re taking lots of water out, and in many cases droughts, which are associated with climate warming, are increasing in intensity and causing large amounts of habitat loss.”

New Zealand freshwater fish are unique because many of them need to migrate. It’s something peculiar to New Zealand, according to McIntosh.

“It's understandable, when you think about the geological history of New Zealand. We're tiny oceanic islands being affected by lots of uplift during building processes where the land mass has been above and below the sea at various times.

“It's likely that those migratory strategies are an adaptation or a way for those fish dealing with being able to recolonise areas affected by those sorts of really large-scale disturbances.”

Many species need to travel to the ocean to breed, or travel to fresh water to breed, or need their young to feed in the ocean before returning to fresh water.

Barriers stop fish doing this and can limit their habitat. Structures such as damns and weirs are obvious, but there are other barriers which aren’t so apparent.

McIntosh gives an example of kōaro, a migratory whitebait species from the West Coast which is listed as at risk from extinction. In the wilds of the West Coast it should have access to 25,000 kilometres of habitat.

“A large proportion of that is lost. Probably 15,500 km of habitat are lost because of the inability of the fish to get to the habitat upstream. It's associated with intensive land use, which is probably mostly affecting the ability, in this case, of the fish to be able to see in the water due to turbidity and sediment.”

The murky water in low-lying areas is associated with agriculture means it's hard for them to find food on their way upstream. McIntosh said it's unlikely the numbers would have improved since the 2006 study which researched the issue.

“It’s a really incipient form of habitat loss. If there’s one point in a network and this has many kilometres upstream, then all of that habitat is lost.”

As well as putting sediment into water, taking water out of streams is an issue.

“It’s shrinking streams. We’re taking lots of water out, and in many cases droughts, which are associated with climate warming, are increasing in intensity and causing large amounts of habitat loss.”

At present, if it’s tasty, you can kill as many as you want, no matter how threatened they are.

One fish in grave danger is the Canterbury mudfish. The mudfish has the ability to live for several days burrowed into mud without water.

However, its ability to survive drought isn’t much use when its habitat is destroyed by agricultural intensification. The wetlands and streams of the Canterbury Plains, which were once their home, have been drained and turned into pasture.

With most of their habitat not part of conservation land, McIntosh said it’s not surprising it is the most endangered fish in New Zealand.

He describes them “as almost the coolest fish going around” due to their survival technique and their ability to survive poor quality water.

“They lower their metabolic rate and are hanging out - or waiting - for the water to come back. As soon as you pick them up and put them in a bucket of water, they swim. They’re incredible.”

Work is being done to help them, but whether it’s enough to save them from extinction remains to be seen.

McIntosh thinks more could be done across the board for freshwater fish, including his beloved Canterbury mudfish which he describes as playing an important role in the food web and "super good-looking and cuter than kākāpō". 

“In general the amount of action and effort that we've put in for things that live in the water, i.e. fish and insects and those sorts of things, pales in comparison to the amount we put into conservation of terrestrial systems.

"It's kind of like underwater, out of mind.”

Legislation to protect freshwater fish could be generously described as patchy. Victoria University of Wellington freshwater scientist Dr Mike Joy thinks they're better described as being similar to a Monty Python script.

None of New Zealand’s threatened native fish are legally protected, and five are harvested commercially.

Our one extinct fish, the grayling, has legal protection. With no grayling sightings since 1923, it’s hard to understand why a dead fish is protected while those teetering on extinction aren’t.

For other indigenous species, protections exist in the Freshwater Fisheries Act only if they’re not used for human consumption or scientific research. At present, if it’s tasty, you can kill as many as you want, no matter how threatened they are. Excluding the extinct grayling of course.

An analogy is having laws saying it's illegal to eat moa but okay to eat kiwi and kākāpō.

A Conservation (Indigenous Freshwater Fish) Amendment Bill is currently making its way through Parliament, which would enable closed fishing seasons to be imposed on indigenous fish. It’s received over 1500 submissions, many from people concerned white-baiting may be affected.

Rules around fish passage are also in place, but these only relate to structures.

Water quality issues such as sediment and pollutants are dealt with through the Resource Management Act.

A study completed by Joy in 2018 looked at the decline of biodiversity in fresh water, particularly in areas where there is pasture. 

The study notes the health of freshwater ecosystems has declined substantially in recent years. A 2004 study of 300 lowland waterways in pastural land showed 80 percent had level of nitrogen and phosphorus higher than guidelines allowed. Another 2010 study showed 44 percent of monitored lakes are now classed as polluted.

There’s a commitment by the Government to have rules in place by 2020 which will improve fresh water quality in five years.

Environment Minister David Parker announced the commitment in 2018 and said the Government would step in to solve issues such as nutrient discharge allocations which the Land and Water Forum couldn’t come to agreement on.

“In my view this shows the limits of collaborative processes. Sometimes the competing interests in the room cannot realistically be expected to reach agreement,” Parker said.

Regulations set to change include amendments to the Resource Management Act and the National Policy Statement on Fresh Water. A National Environmental Standard for Freshwater Management would also be created.

At the time, Joy, who is a member of the Science and Technical Advisory Group involved in the work programme, said he thought the timeframe should be tighter as the science was already done. 

For the Gollum galaxias there's still risk of extinction, but at least one population of them is safe. A plan to dam Central Otago's Nevis River and create an 8km lake was thwarted by the 70mm fish.

The fish was considered too precious - an "outstanding characteristic" - and was added to a water conservation order protecting the river. 

Since publishing Newsroom has learnt the galaxias in the Nevis river, thought to be the Gollum galaxias, has been found to be a distinct, although closely related species to the Gollum galaxias. It is now called the Nevis galaxiid.

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