Monitoring the health of freshwater ecosystems in Aotearoa New Zealand is becoming increasingly important, especially under the National Policy Statement for Freshwater Management 2020 (NPS-FM), which requires more comprehensive reporting on ecosystem health — including fish communities. Traditional fish monitoring relies on standardised electrofishing in wadeable streams, a method that is time-intensive and limited in spatial coverage.
This study compares multi-year electrofishing data from five wadeable streams with environmental DNA (eDNA) samples collected from the same locations to evaluate how well eDNA captures fish diversity. The researchers also assessed whether eDNA sequence read counts could provide a semi-quantitative indication of local (“near-field”) species abundance when compared with one-pass electrofishing results.
The findings show that although some methodological refinements are still needed, eDNA monitoring holds strong potential as a complementary tool for State of the Environment (SOE) reporting. It effectively detects fish diversity and offers a broader view of catchment-scale biodiversity — including birds and pest species — in both wadeable and non-wadeable streams. As a rapid and cost-effective approach, eDNA could significantly enhance freshwater monitoring across New Zealand.
Read the full article here.
