Interest in health of Motu River

FIELD DAY FUN: Freshwater scientist Richard Montgomerie uses electrofishing to sample a small part of the Motu River. The younger members of the group were excited when he brought up an eel estimated to be about 25-years-old at Kotare Station, Matawai. Picture by Kim Parkinson

AN ecological field day funded by the Ministry for Primary Industries (MPI) Erosion Control Program for the Motu Catchment Project attracted a good turnout at Kotare Station in Matawai recently.

There were hands-on demonstrations by ecologist Richard Montgomerie from Freshwater Solutions.

Mr Montgomerie took water samples and assessed the living biodiversity, providing training in habitat monitoring to gauge the health of the Motu River for those farming families in the catchment project.

Project managers of the Motu Catchment Project and environmental consultants Lilian Sherman and Kerry Worsnop said it was an opportunity for the community to learn about the indicators of good water quality.

Mr Montgomerie has expertise in the impact of different land uses on fresh water rivers and streams.

He collected a sample of invertebrates and had the group identify the different species while explaining the purpose of a macroinvertebrate community index (MCI) as an indicator of water quality and overall stream health.

By using electric fishing equipment he caught and released several eels including one he estimated was about 25 -years-old.

“The electric shock only stuns them temporarily and allows me to identify species,” he said.

Electrofishing is a common technique used by fisheries biologists to sample fish populations in bodies of freshwater.

The group concluded the river at Kotare Station had a significant number of invertebrate species in the high value index, as well as eels and trout, meaning the water was of good quality.

“Motu is a big area catchment and it is a long term project — the benefits of what you do now will be seen by future generations.”

He said fencing the river and planting the surrounding areas were the first steps towards improving water quality.

Mrs Worsnop said the project was “in action mode now in terms of fencing and planting with funding available from the Ministry for Primary Industries for those 13 farms involved, located within the Motu catchment in the Gisborne district.”

Streams have a food chain and the key drivers of the food chain are sun, water and nutrients.

Mr Montgomerie explained how too much algae affects the pH balance of the water and can reduce dissolved oxygen in rivers.

“Sediment is another contaminant which has adverse effects on a river as does changing the flow and manipulating it.”

“You are near the top of the Motu catchment here so you have a big responsibility — what goes into the river stays in the river,” he told the group.

“But you’ve got lots of tributaries and that’s when the fencing and planting can have a positive effect more quickly, making the river healthier.”

He also talked about the different ways of assessing water quality, from sending samples to a laboratory to self-testing using a stream health assessment monitoring kit.

The project managers were happy with the large community turnout and said it was great these farmers had taken the initiative to apply for funding and improve the environmental outcomes for their catchment.