The Waitaki longjaw galaxias is very small — about 50mm long. A new population of the threatened fish was discovered in a small section of the Maryburn Stream. PHOTOS: DEAN NELSON & SJAAN BOWIE A new population of a tiny fish — nicknamed ‘‘jaws’’ — has been discovered in the Waitaki catchment, in a boost to the species clinging to survival. The Department of Conservation said yesterday the discovery had allowed rangers to create an ‘‘insurance’’ population of the nationally critical fish in a nearby ‘‘safe stream’’. Waitaki longjaws, also known as lowland longjaw galaxias, have a pencil-thin body and a preference for cool streams and springs associated with braided rivers. They are only found in the Waitaki River catchment. The department said in the past 20 years at least three known populations of the fish had disappeared. The Waitaki longjaw galaxias. But a previously unknown sub-population of 22 fish was recently found by DOC in a small section of the Maryburn Stream, near Twizel. DOC principal ranger Dean Nelson said rangers were able to take 10 longjaws from the site, along with 20 from the nearby Fraser Stream to create the ‘‘insurance’’ population. Waitaki longjaws were affectionately referred to as ‘‘jaws’’, due to their distinctive underbite, he said. Mr Nelson said it was ‘‘amazing’’ the species had survived at all. The insurance population was ‘‘crucial’’ to their survival. ‘‘They really need our help in the face of multiple pressures, otherwise we’re likely to see more extinctions of their populations.’’ Threats included predation and competition from trout, invasive aquatic weeds that ruined their habitat, habitat loss and climate change. Trout exclusion barriers had been put in place to protect most of the populations, but trout could get past the barriers when streams flooded. Department of Conservation principal ranger Dean Nelson translocates Waitaki longjaw fish into Waterwheel Wetland. PHOTO: SJAAN BOWIE DOC created the new longjaw site by constructing a trout exclusion barrier at trout and weed-free Waterwheel Wetland. The site also protected a similar species called bignose galaxias, with the two species known to co-exist peacefully, Mr Nelson said. ‘‘Effectively, we now have two new populations, giving us a total of nine longjaw sites. ‘‘This helps spread the risk of losing the species to a catastrophic event and improves Waitaki longjaws’ overall security. There were actions people could take, he said. ‘‘For those that live or work in the catchment, protecting springs and side channels, managing invasive aquatic weeds and limiting stock access can help improve Waitaki longjaws’ prospects.’’ charley-kai.john@odt.co.nz
