Otago Fish Floundering
Otago’s native fish are in crisis. The latest Department of Conservation-appointed review has found the region has the highest number of threatened native freshwater fish in the country. Of the 12 freshwater fish species under threat in the region, four are in the highest possible threat category.
Another six have been classified as nationally endangered and two are nationally vulnerable. Worse yet, three of these species are only found in Otago.
The news is not surprising given the barrage of threats: habitat loss, land use changes, water abstraction, degraded water quality and migration barriers. But according to DOC Otago freshwater ranger Pete Ravenscroft, it is the increased movement of trout into new sites that is having the most devastating impact.
“Trout habitat is still naturally expanding into new waterways, without human assistance … to the detriment of our native fish,” he says.
Unlike their whitebait counterparts, these galaxiids don’t migrate, which makes safeguarding their few habitats even more critical. Pete says it is even more imperative for the longer-living species, which can live up to 20 years. “They have big eggs and low fecundity. It doesn’t take much to impact on the species,” he says.
Otago has lost 20 per cent of its rare fish in the past 13 years. The Clutha flathead galaxias has been hit especially hard. Threats have reduced the population of this unique species by 60 per cent, and the survivors are limited to waterways across just 12 hectares of land.
Pete says if the current rate of loss continues, the Clutha flathead and the Central Otago roundhead galaxias could become extinct within the next 20 years. “Something has to be done now to prevent future losses,” he says.
One immediate solution for Otago’s endangered fish is to remove trout from galaxiids’ habitat and set up fish barriers to keep them out. Pete stresses this does not interfere with recreational angling. “We’re not talking about the wholesale removal of trout. Galaxiids are confined to the odd population in discrete locations. Most of these rivers are a metre wide … and have no value to recreational fishing.”
Fish and Game is working with DOC to create these trout free habitats. In fact, Fish and Game Otago region chief executive Niall Watson says the organisation has gone a step further and put forward its own proposals to DOC to reduce the possibility of reinvasion.
In addition, most of these streams pass through private land, which means rescue efforts cannot come from DOC alone.
Thankfully, word is getting around about Otago’s unique native freshwater fish and the increasing need to protect them. Community groups such as Otago Regional Council, water user groups, landowners and iwi are heeding the call to act.
Pete says without community support even more of our native freshwater fish would have disappeared, but insists a lot more needs to be done to counter the “biodiversity crisis going on in our rivers”.
DOC has proposed other measures such as protecting habitat, enhancing water quality and improving fish passage. The department has also undertaken a review of its three freshwater fish recovery plans and groups to pinpoint what is working, what is not and what can be done in the future.
Lan Pham, director of education and conservation charity Working Waters Trust, is keen to get more people talking about galaxiids. “These fish have their own unique stories and are found nowhere else in the world. The tragedy is we are losing these incredible species before we even get to know them,” she says.