Eels to be rehomed as Avon River repaired
Some elderly river residents are on the move as repairs to their homes are carried out.
As part of the development of the Avon River precinct, longfin eels will be captured and moved to another stretch of water while work is under way between the Montreal St bridge and Colombo St.
Some of the eels are estimated to be 80 years old.
EOS Ecology aquatic scientist Shelley McMurtie said a method known as electric fishing would be used to catch the eels, which would be returned to their usual patch once work was complete.
''Electric fishing does not harm the fish but temporarily stuns them to enable trained ecologists to capture and relocate them,'' McMurtie said.
The electric fishing equipment uses a backpack battery, wand and earth wire. The current is pulsed through the wand into the water and riverbed, temporarily stunning the fish.
Staff wear rubber gloves and waders to insulate them from the current while they catch the fish.
While some fish would naturally move out of the way while work in the river was carried out, others burrowed into the sediment or tried to hide along the banks or in aquatic plants, she said.
''This is why we either electric-fish parts of the channel, or fish the sediment after it's been collected.''
McMurtie said more than 150 fish, including eels, flounder and lamprey, had been rescued from the sediment and returned to the river so far this year.
In addition to the relocation of the eels, it is expected that bluegill bullies will be temporarily shifted from the area below Mill Island and around Victoria Square when work is done in those parts of the river.
''We are enhancing the river for these animals so it's important to make sure they are still around to benefit from it,'' she said.
This phase of the in-river works between the bridge and Colombo St will take place this month and the next, and the work would continue through to Fitzgerald Ave after the trout-spawning season.
The works will result in ecological improvements by removing excess silt layers, including liquefaction sand, and forming low level plains to improve water flow and species habitats.
Christchurch Central Development Unit director Warwick Isaacs said the work was part of the goal to make the river a ''world-class feature for the city''.