NIWA makes a date with freshwater fish

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NIWA researchers have produced a series of calendars to inform people when New Zealand's native freshwater and sport fish are migrating and spawning.

It is the first time the information has been available in one place and, although it was designed to assist the forestry industry minimise the effects of their business on key freshwater fish species, NIWA hopes it will be used by anyone wanting to carry out work near freshwater.

The calendars cover 41 key freshwater fish species in New Zealand – 34 are native and the other seven are sport fish, including trout and salmon. The two New Zealand species of koura have also been included.

In addition to the calendars, there are also fact sheets listing important details about each species, including conservation status and preferred habitat, and a ranking given to each species based on their ability to adapt to changes brought about by forestry activities.

NIWA fish researcher Josh Smith said the calendars were produced after reviewing scientific papers and books, and combining those findings with the knowledge and experience of NIWA's freshwater fish biologists.

"Native freshwater fish populations have been declining in number and distribution. If we are going to maintain them, we need to take care to protect their spawning habitat and migratory paths," he said.

Most of New Zealand's native fish species are less than 150 mm long, and many move between fresh water and the sea as part of their life cycle. Being able to get from one to the other is crucial for the distribution and survival of a species.

The calendars, produced with the assistance of funding from the Ministry for Primary Industries, outline the spawning range for each species, the migration of adults to spawning habitats, and the upstream migrations of juveniles to adult habitats.

The researchers assigned rankings to each species based on their susceptibility to turbidity, sedimentation and afforestation which can affect such things as migration, feeding, foraging and stream morphology. The rankings in each category were then added together and an overall score applied. There were 20 species which scored 40 or above, and considered highly sensitive. A further nine scored between 30 and 39.

The fish Mr Smith found to be most at risk are seven species of non-migratory galaxias found in the South Island.

Mr Smith said if work was to be carried out near a waterway, the potential impacts need to be considered.

"Just knowing what fish species are present is not enough as each fish species has a spawning period with possible migrations that may be adversely affected.

"Once someone knows what fish species occur in their catchment, their work timetable can be assisted by using the calendars to assess if their work will adversely affect the life cycles of the species present."

Download the calendars

Download Freshwater Fish Spawning and Migration Periods [1.5MB PDF]

View the calendars' webpage 

Further information 

People can find out what fish species occur in their catchments by looking up NIWA's New Zealand Freshwater Fish Database. 

Access the Freshwater Fish Database 

Te riu waipoua tuna. [Credit: Rohan Wells]
Research subject: Fish