New ways of understanding our streams

Freshwater scientist Caleb Royal says he has never been bitten by a tuna (native eel), but has been nibbled hundreds of times.

This was certainly proved to be the case at the stream behind Papawai Marae in Greytown where Caleb was speaking last week (17 February) about the cultural health monitoring techniques he has developed in Otaki.

More than 70 people from around Wairarapa and Wellington came to hear about his technique which blends western science and traditional Maori values.

In a nutshell, Caleb’s cultural health monitoring technique measures the health of a stream and everything that lives in it and around it – plants, animals and people.

He developed this technique after talking to his kaumatua about how bad the water quality was in the stream that runs through hapu land in Otaki.

“I was telling them about how much phosphorous there was in the stream, up to 10 milligrams per litre, which is a very high and toxic level. One of the kaumatua said ‘that’s interesting boy, is that good?’ So I decided I had to come up with something that was more relevant.”

One of the main uses for the stream had historically been catching tuna for food and storing them the in stream, live in wash-through boxes. So tuna became one of the main focuses of his study.

Caleb has found that while tuna can live in polluted waterways where most fish and insects have long since given up, they show many signs of stress. In polluted water the tuna get fin-rot, suffer lesions and other skin problems and grow much more slowly than in clean water.

Caleb says in polluted water there is a lot less food around and the tuna are getting just enough to survive, which explains the stunted growth. He has aged eels from polluted streams and found them to be growing two or three times slower than eels in healthy streams.

The day was organised by Greater Wellington, Department of Conservation and Papawai Marae. Caleb is also an advisory member of Greater Wellington’s Catchment Committee.

Greater Wellington Maori Liaison Officer Mike Grace says there was a lot of interest in Caleb’s techniques which could easily transfer to Wairarapa.

“Tuna are very significant to Wairarapa. The tuna fishery was the heart of the Maori economy and the most extensive tuna fishery in the North Island. Draining wetlands, declining water quality and fishing pressure have made a huge dent in tuna numbers.”

Department of Conservation Wairarapa Area Manager Chris Lester says there is growing concern throughout Wairarapa about the decline of the tuna population.

“Caleb’s approach helps illustrate the change in tuna numbers and condition and uses values that most in our community can understand and relate to. We know need to follow his example and look to make a difference in our local area” says Chris.