Lowland longjaw galaxias (Galaxias cobitinis) thrive in cool springs and streams amongst the cobbles and gravels in the fast-flowing riffles of braided rivers.
The few remaining populations are in the Kauru and Kakanui rivers in North Otago, and in a handful of spring-fed streams in the Mackenzie Basin. The lowland longjaw galaxias found in the Kauru and Waitaki catchments are genetically distinct from each other.
The adults need clean, ‘roomy’, movable substrates so they can burrow into the cracks and crevices between rocks. In winter, their young can be spotted in schools swimming in slower moving water, such as pools and backwaters.
- Have a pencil-thin body and a long bottom jaw that protrudes over their top lip.
- Are pale lemon colour with handsome silver flecks lining their back over darkbrown splotchy patterns.
- Their outer eyes are sparkly gold in colour.
- One of the smaller species of galaxiid, typically growing up to 80 mm in length.
- They feed on small stream invertebrates such as mayflies and stoneflies.
- In the Kakanui they spawn from May to August, with juveniles recorded from June to January.
- In the Waitaki observations to date indicate spawning is later around August to December.
- They lay tiny 2 mm eggs in spring upwellings.
- Can live up to 3 years.
Their main threats are habitat loss from land development; the invasion of aquatic weeds (such as monkey musk), which clog waterways; and being eaten by introduced fish species such as trout. A combination of these threats recently caused the extinction of two lowland longjaw populations.
Changes in land use, such as stock access to streams, reduction of native vegetation, and forest harvesting are also contributing factors to its decline.
These land changes impact on the streams in which galaxiids live, increasing sedimentation, changing the natural flows through water abstraction, and reducing habitat available for spawning.
This map shows the known locations of lowland longjaw galaxias, as at 2013.
The Kauru River is one of the few places where these fish can still be found
Source: New Zealand freshwater fish database