Tracking native freshwater fish
DNA analysis reveals hidden differences among bullies
Didymo escapes into new waterways
Port surveyed for invasive sea squirt
Partnerships key to better biosecurity
The discovery of the invasive alga Didymosphenia geminata in the Buller River by NIWA and Fish & Game attracted major media and public attention. Within days, further incursions were reported in four other rivers. This generated a major response by Biosecurity New Zealand, who commissioned NIWA to run a nationwide survey of ‘most likely’ didymo locations, based on a NIWA habitat suitability model and knowledge of public access points to rivers.
The survey was organised and begun within three days, and completed in three weeks.
DNA sequences in upland bullies show that fish from different catchments, while looking the same, have different DNA base composition.
Unlike some other bullies, upland bullies (Gobiomorphus breviceps, a native freshwater fish) don't disperse to sea. Being river-locked, there is less opportunity for genetic mixing between populations, so there are likely to be genetic differences between them.
To investigate this hypothesis, NIWA biologists compared mitochondrial DNA from 89 bullies collected from 19 catchments across their range.
Signals from electronic tags implanted in kokopu are picked up by aerials, allowing fish movements to be tracked automatically.
Knowledge of movements of native fish, and their habitat preferences, is essential for river management, especially protection and restoration of biodiversity.
The biosecurity challenges faced by NZ are huge, often difficult and expensive to resolve, and belong to us all. At the Third Biosecurity Summit held recently in Christchurch, MAF’s Director-General Murray Sherwin pointed out: ‘Everyone wants what they value protected, but everyone wants this at a reasonable cost.
NIWA has undertaken a survey for the invasive sea squirt Styela clava (clubbed tunicate) at 26 ports and marinas around New Zealand on behalf of Biosecurity New Zealand.
Fears that the clubbed tunicate – discovered at Auckland’s Viaduct Harbour in August – could cause problems on New Zealand marine farms and potentially compete with native organisms prompted a rapid response from Biosecurity New Zealand.
