Freshwater fish

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A 3D Printer is helping save New Zealand’s endangered native fish
About 76 per cent of indigenous freshwater fish species, that’s 39 out of 54, are threatened with extinction or at risk of becoming threatened.
Nearly half of New Zealand’s river network is partially or fully inaccessible to migratory fish, a new study shows.
What does science tell us about New Zealands' migratory galaxiids?

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2020_03_06_Alvin Setiawan_RAS

About RAS

Recirculating aquaculture systems (RAS) are a land-based production technology for aquatic organisms and high-value finfish. They utilise simple water treatment technologies (mechanical and biological filtrations) to minimise water use and maintain a tightly controlled environment. These can range from very open systems that use only basic treatment technologies to reuse some of their water resource, to fully closed systems which reuse 100% of the water and only add new water to account for splashing and evaporation. RAS vary in their design and functionality depending on the species being produced, the local conditions and the cost/access to a local water resource.

Advantages of using RAS

  • Reduced water requirements 
  • Water is treated and recirculated, significantly reducing water requirements. 
  • Production Control
  • Water can be heated/cooled, high oxygen can be maintained, pH adjusted, pathogens treated, and waste products removed to maximise health, growth rates, and the welfare of the stock. 
  • Increase in long-term production
  • Stock are unaffected by seasonality, periodic disease events and adverse weather, allowing continuous and reliable production.  
  • Reduced environmental footprint
  • Waste streams are treated and recycled to ensure they have the least impact on the environment as possible. Being land-based, there is also no risk of fish escaping and interbreeding with wild populations. 
  • Flexible design
  • The system can easily be customised for different species, locations and consumer preferences. 
The world's most mysterious fish

A video about The world's most mysterious fish. NIWA researchers are working with iwi to try to unlock the secrets of New Zealand tuna—freshwater eels. Every year tiny, glass eels wash in on the tide at river mouths along our coast. But where do they come from and how do they get there?


Freshwater fish swim their all for science

The tiny inanga have been plucked from Waikato streams and held in a darkened laboratory for the last month, undertaking highly advanced testing to find the strongest, fittest and fastest fish.

NIWA freshwater fish scientists are trying to understand how long they can swim at given speeds – between rests - and how much variation there is between fish of the same species.

The New Zealand Freshwater Fish Database (NZFFD) contains over 50,000 freshwater fish observations from across New Zealand from 1901 to the present.
As a young child growing up on an Irish farm, one of Eimear Egan’s chores was to regularly clean out the well from where her family drew its drinking water. In the well lived a large eel that, no matter how many times it was shifted, just kept coming back.
The Fish Passage Assessment Tool has been developed to provide an easy to use, practical tool for recording instream structures and assessing their likely impact on fish movements and river connectivity.
More information about our online freshwater databases.
Tuna are found in all sorts of habitats (places), including coastal estuaries, lakes, wetlands, rivers, mountain streams and even alpine tarns.

Learn how to use the New Zealand Freshwater Fish Database (NZFFD)

Inanga are the predominant species in the modern whitebait fishery.
All species of freshwater tuna spawn at sea, although the spawning grounds of only four species are known with certainty worldwide.
We have prepared a breakdown of the different guidelines that are available for sampling freshwater fisheries. The overview provides links to key documents that explain what should be considered when designing fish monitoring studies and how to implement the various sampling techniques.
NIWA is leading a new six-year research project that seeks to increase our understanding of piharau/kanakana/lamprey, using Mātauranga Māori, social science and biophysical science approaches.

If you suspect overfishing is reducing fish numbers, contact DOC or Fish & Game.

The largest member of the Galaxiidae family.
Smelt have a distinctly forked tail and a strong cucumber smell.
Grey mullet have a worldwide distribution and Aotearoa is at the southern limit of their range.
Kōaro are excellent climbers and like clear, swiftly flowing, forested streams.

Has a receding lower jaw and black spots behind the head.

Banded kōkopu juveniles are very good climbers and will try to escape from buckets by clinging to and wriggling up the sides.

Pest species of fish and plants will need to be controlled or eradicated if they are threatening the success of your restoration project.


All staff working on this subject

Fisheries Population Modeller
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