Research focusing on wrong species
IrrigationNZ says new research from the Cawthron Institute looking at the effects of river flows on fish focuses too
much on “imported species” rather than native fish.
“Trout are not indigenous species; they have been introduced to New Zealand. There is solid evidence demonstrating how
native fisheries have been devastated by these foreign invaders. We should be setting minimum flows and allocation
limits based on native species, not introduced ones,” says IrrigationNZ CEO Andrew Curtis.
A minimum flow is the point at which an irrigator can no longer take water from a river. In Europe it is described as a
hands-off flow, as it does not guarantee river flows will be maintained above this level.
“If there is no rainfall in the foothills post the minimum flow being triggered, river flows will continue to fall. Many
of our east coast foothill rivers and streams naturally go dry from time to time. For example there are reports from
anglers going back to the mid 1800s for the Selwyn and Ashley Rivers confirming long dry spells, this is well before
irrigation became commonplace. Indigenous species have adapted to these conditions – unlike trout and salmon,” says Mr
Curtis.
“If we decide we want river flows to be guaranteed for trout and salmon the only way we can achieve this is through
water storage. As an example, the Opuha Dam has guaranteed river flows on the Opihi River through releasing stored
water. During the recent drought neighbouring catchments rivers have run dry due to lack of rainfall and fish have been
rescued from these catchments and released into the Opihi River.
The focus needs to be on building more water storage and integrating community aspirations into these projects, rather
than knocking irrigators over and over again for taking consented water that is already meeting minimum flow
requirements,” says Mr Curtis.
ENDS