River guardians back in the water

Fish & Game has launched a diving programme to monitor New Zealand’s trout populations and assess the health of the nation’s waterways.

Fish & Game staff equipped with diving gear will drift and glide down hundreds of kilometres of rivers across the country, recording water clarity and temperature, assess instream fish habitat, the number of native fish, algal growth and the various instream insects present.

Divers will explore well over 250km of waterways, covering around 100 different rivers throughout the country.

The information from the trout population surveys will be used to help set catch limits for anglers.

North Canterbury and Central South Island Fish & Game officers drift dive the Hurunui River in Canterbury. Photo: Richie Cosgrove

Corina Jordan, Fish & Game New Zealand chief executive, says the programme highlights the important environmental monitoring role of the organisation.  

“Drift diving enables us to give rivers a close-up health check. Combined with our assessment of the trout population -- the species that has the highest water quality requirement of any of New Zealand’s fish-- these observations will give us a good gauge on how healthy our rivers are.

“It is going to be interesting to see how the North Island rivers in particular have fared after Cyclone Gabrielle.”

Many regions have information dating back over 30 years, the longest running dataset of its kind, which can give valuable insight into the long-term trends of river health.

“No other organisation or government agency does more of this important type of monitoring of our waterways than Fish & Game,” says Ms Jordan.

“It will give us unique insights into the interactions between trout and some of our native fish, such as eels, which co-exist quite happily.

“In fact, it’s not uncommon for divers to see trout being eaten by eels, or trout with bite marks on them, which shows trout have become an important component of the food chain in many New Zealand rivers.”

The drift dive programme is expected to run until early April.  

Fish & Game is a non-profit organisation that receives no government or taxpayer money, it is funded solely from the purchase of licences to fish for trout and salmon and hunt game birds.