Traditionally, monitoring of pest fish species has required intensive trapping or electric fishing to detect incursions or identify the spread of species.
The detection of species using environmental DNA (eDNA) has been developing over the past 30 years. All organisms leave traces of DNA in their environment, through shedding cells such as hair, scales, skin and faeces. Thus, a sample of water, soil or sediment can be used to detect species present. Genetic material is extracted from the sample using PCR (polymerase chain reaction. It is a technique used to amplify a segment of DNA of interest or produce lots and lots of copies), and DNA sequences are matched against a database of known sequences for species.
Living Water has used eDNA testing to identify whether koi carp (Cyprinus carpio) are present at Lake Ruatuna alongside conventional pest fish surveys run in 2015, 2018 and 2019. Two of six initial samples collected in 2018 indicated presence of koi carp, however, further intensive eDNA sampling in early and late 2019 and repeat pest fish netting suggest no koi are present.
The initial positive indication could mean several things:
- No koi present in Lake Ruatuna
- Koi present at low abundance, or at locations not targeted in further sampling
- Contamination, false positives or false negatives
Living Water’s eDNA investigations at Lake Ruatuna are contributing to further DOC work into the use of eDNA to detect species.
Here are 3 samples we have the full species lists for:
For more information or if you're interested in doing eDNA testing head to the Wilderlab website