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Rare find in Te Arai River

26 Feb 2015

Rare find in Te Arai River

A rare shortjaw Kokopu (Galaxias postvectus) was found by staff from Council, Department of Conservation and the Environment Centre during a spotlighting expedition in the Te Arai River last night.

The agencies have joined forces to survey the effects of fish passage barriers on the Te Arai River.

“Numerous fish have been identified during this survey in the Te Arai, including crans bullies, torrentfish, koaro, inanga, koura, longfin and shortfin eels, as well as this lone rare shortjaw kokopu,” says environmental data officer Peter Hancock.

“The shortjaw has a distinctly undercut lower jaw, black spot behind its gill opening, a mottled olive colouration and orangey coloured fins.

“The fish is regionally rare and hasn’t ever been found in the Poverty Bay catchment, with the next closest finding having been in the Mata River.
“Its conservation status nationally is defined as being ‘At Risk: Declining’, thought primarily due to loss of forest cover on the edges of streams.”

The surveying assesses the extent to which barriers restrict fish passage, primarily to determine how much these barriers prevent fish from completing their life cycle and in turn how this affects the native fish populations.

“Ensuring in-stream structures do not become barriers is important as many of our native fish species need to get from the ocean as youngsters back into freshwater where the live as adults to complete their life cycle,” says Mr Hancock. “The term ‘barrier’ is loosely used, I like to think of them more as bottlenecks rather than barriers.

On the Te Arai River, there are 2 weirs and 14 concrete vehicle crossings.

Each of these act as a bottleneck, making it harder and harder for many species to reach the pristine upper catchment waters to live in as adults.

Council has progressed plans to modify Pykes monitoring weir to better allow for fish passage with support from Hort NZ.

Our native fish have a range of climbing abilities, from the good, to the not so good. Tuna (eels) for example are found all throughout the river and you’d be amazed at what small eels can wriggle up, including wet vertical concrete walls.

"But adult eels are too big, and some other fish species can’t climb those walls altogether.
Think of each barrier like a landslip on the road when you’re trying to drive from here to Napier. You may be able to get a 4WD vehicle through, but a majority of other vehicles simply can’t.
The more barriers or bottlenecks there are, the harder it is to get through to complete your journey.”

Shortjaw Kokopu