A wetland area built by Christchurch City Council last year is already teeming with fish life including a rare 50-year-old longfin eel.
The new Buller’s Stream Stormwater Wetland on QEII Drive in eastern Christchurch was completed in March last year.
There are signs the four-hectare wetland, which is open to the public, has become a popular habitat for fish, including a number of eels who have made themselves at home over the past year.
A fish salvage exercise was carried out recently during minor repair work and 15 fish, including 11 shortfin eels and four longfin eels, were caught in the open part of the wetland.
One of the longfin eels was measured at over a metre (1042mm).
Ecologist Greg Burrell, who led the exercise, says the large longfin eel was an exciting find.
“It was likely in the order of 50 years old and longfin eels are a declining species. The large number of big eels caught in the open area was a surprise and indicates that they’ve rapidly colonised this new wetland.”
The New Zealand longfin eel is the largest freshwater eel in the country, an endemic species with a threat status of 'At risk - declining'.
“It’s really nice that we're seeing a species at risk of extinction populating this brand new habitat so quickly. Bigger eels don’t tend to move around much day to day, tending to stick within a small home range, so it’s neat that they’re moving in there.”
Council Land Drainage Manager Keith Davison says it’s encouraging to have evidence the wetland, which was needed to manage stormwater in the area, has become an attractive home for wildlife.
“It suggests that water quality in the area is good and our efforts to make an appealing habitat have been effective.”
Extensive landscaping has been carried out at the site with native riparian (water edge and banks) plants, large boulders and inverted tree stumps designed to appeal to fish, eels and other species, including native insects and birds.
A fish-friendly flap gate has been installed at the outlet pipe from the wetland to Buller’s Stream allowing them to move freely between Buller’s Stream and the new wetland.