New research out today confirms New Zealand’s native freshwater fish are in dire straits, says Forest & Bird.
“Our native freshwater fish are in serious trouble, and they are doing worse in farmed areas,” says Forest & Bird freshwater advocate Annabeth Cohen.
The journal article Decline in New Zealand's freshwater fish fauna: effect of land use, is authored by freshwater ecologist Mike Joy and others.
The study examined 25 fish species using 47 years of data, of which 20 were native species. In total 19 species or 76% had negative trends associated with land use. Native fish species were observed to be faring worst in farmed catchments.
The report concludes that without bold initiatives to reduce farming intensity and to restore habitats, New Zealand's freshwater fish will continue to decline.
Ms Cohen says the research shows that agricultural practices need to change quickly.
“First, we need to reduce the agricultural pollution getting into our rivers and streams. We need to halt the intensification of farming, and in some places this will mean fewer dairy cows.”
“We also need to ensure fish have enough water to swim and breed. This means we need to stop draining wetlands, and stop taking so much water from our rivers for irrigation.”
“We also need to be restoring wetlands in places where they used to exist, and ensure stream banks are planted with natives.”
Among the most at risk fish are the Canterbury mudfish, and the many galaxiids found in Otago, such as the lowland longjaw found in Kakanui River, the Teviot flathead and the Clutha flathead.
Ms Cohen says other threats facing our native fish include climate change, dams, invasive fish and for some species, commercial whitebaiting.