This page contains information about minimising harm to eels during the rainy migration season.
16/02/2018 2:58 p.m.
Whangarei District Council Waste and Drainage Manager Andrew Carvell and his team have been over their safety measures to minimise harm to eels during the rainy migration season.
“Protecting migrating eels while reducing the risk of flooding on the Hikurangi plains is a major challenge for the Hikurangi flood management scheme,” he said.
“This is the riskiest time of year for the eels as they are getting ready to migrate and begin their breeding cycle so many more of them are on the move than usual. It is also when we often get heavy rain and we may have to use our pumps to protect farmland.
“We have introduced a number of safety measures over the years, with five Ngāpuhi hapū, Nga Kaitiaki O Wai Maori, Northpower, National Institute of Water and Atmosphere (NIWA), the Department of Conservation (DOC), Fonterra, farmers, Northland Regional Council working with us as the scheme operators.
“Some of the things we have done include trying to get a real count of the number of eels in the scheme, using electronic devices to repel them near the pump stations, using the pumps at different times during or after storms to minimise the harm, and installing smaller eel doors in the big flood doors.
“This year we will continue our aim to reduce the time the pumps run and by turn them on only if the main river channel rises and shuts the flood gate through the station. That way eels can move through the stations safely for longer and some may use the tuna doors.
“We appreciate the risk is still there if the pump runs but we will try and minimise operation,” Mr Carvell said.
“While the steps help, the best solution is likely to involve replacing the existing pumps with more fish friendly models.
“Only Archimedes screws will stop eels being harmed when the pumps are running, but, at an estimated cost of $2million each they are expensive and we plan to replace the existing pumps with more eel friendly versions between 2026 and 2037.”
“Other efforts to improve the situation for eels include spat ropes to help juvenile fish/eels get upstream. Further habitat has been environmentally restored on about 15ha of grazing or neglected areas over the last two and next few years to restore habitats for eels and other creatures,” he said.
“If you are driving along Jordan Valley Rd and look where all the privet has been chopped down as part of the environmental restoration project there with Living Water, you will notice that we have expanded the drain to create habitat for the endangered black mud-fish.
“We have also been creating nooks and crannies and oxbows in what were straight sections of river to, allow populations of creatures to build up again.”