‘Real special’ juvenile kanakana eel found during monitoring work at Mataura River

‘‘LOOK what I’ve caught,’’ young environmental cadet Josh Aitken shouts excitedly.

He is carrying out monitoring work on the Mataura River and has just caught a brilliant silver-blue juvenile kanakana (lamprey).

Freshwater ecologist Matt Dale beams as he inspects the tiny creature: ‘‘This is real special.’’

He has never seen one upstream from Te Au-Nui (Mataura Falls) and says it means the work that Hokonui Ru¯ nanga is doing to restore the river is working: ‘‘It means they’re getting past the fall.’’

The taonga species was once abundant throughout New Zealand and numbers were so great at the Mataura River, South Island¯ Ma¯ ori would travel from as far as Otautahi (Christchurch) come harvest time. These pouched lamprey were found as far north as Piano Flats – 85km away from the falls.

But as the nutrients in the streams and tributaries where they live have changed and habitats have been lost, kanakana have become threatened. Hokonui

Ru¯ nanga Kaia¯ rihi Taiao (environmental lead) Riki Parata could not say for sure that his team’s mahi was a direct contributor to the find: ‘‘It’s an indication that we’re doing more intensive studies,’’ he said.

It has only been during the past few decades that numbers have dwindled, Parata said. ‘‘I remember when I was a child, we used to catch sacks full.’’

The Mataitai Reserve at Te AuNui was the first of its kind when it was established in 2006 and the ru¯ nanga now has agreements with businesses either side of the falls to ensure the area is safe for kanakana. The Taiao team is working with Niwa and Alliance Group – which operates a plant on the river – to build a bridge for kanakana to help them move over the weir at the falls. The species breed in freshwater, head out to sea as juveniles, and then return when it’s time to spawn.

Te Au-Nui used to be wide, but industry has narrowed the river at the falls, making it difficult for the kankana to get up.

In the meantime, Parata and some kauma¯ tua have been going out physically plucking the lamprey off the falls and take them to the other side, he said. ‘‘But we can’t be there all the time.’’

For the past two years, juvenile eels have been trapped and transferred with the hope of having a permanent solution in place by next season. In the next migration season, they will be tracking migrating tuna (eels) with microchips to see if they are going into the hydro turbines on the river – which will give the team an idea of the impact the weir is having.

‘‘They’re the ones that go out to sea to breed, and the babies come back up [the river] again.

‘‘We’re involved in the whole cycle, trying to just maximise the numbers.’’

The team have also been monitoring kanakana during the past two years.