by Al Williams
A project to improve whitebait numbers in the Washdyke Lagoon is under way.
The establishment of a temporary spawning habitat at the north end of the lagoon is the brainchild of Environment Canterbury biodiversity officer Robert Carson-Iles.
Aiming to improve whitebait spawning at the lagoon, Mr Carson-Iles said he was working in partnership with Arowhenua Runanga, the Department of Conservation and Environment Canterbury.
The lagoon’s health has been the focus of authorities in recent years and the wider coastal area was declared a mataitai reserve by the Ministry for Primary Industries in August 2016.
About 70m of a vertical bank where the Seadown drain enters the north end of the lagoon has been battered back, and several straw bales put in place to act as a temporary habitat for spawning whitebait.
Mr Carson-Iles said the work would continue and the area would be monitored while vegetation, mainly cocksfoot and other grasses, became established.
The site was a known spawning ground for whitebait but had been limited because one bank was vertical and unvegetated, offering no spawning habitat.
“What they need is dense vegetation; otherwise they dry out,” Mr Carson-Iles said.
“They will now use this area as a habitat.”
Whitebait populations were dropping across New Zealand, primarily through habitat destruction and the degradation of waterways.
“The short-term [solution] at this site is straw bales to offer them cover.
“We are reseeding the whole area and it will be covered in cocksfoot.”
Department of Conservation operations manager Dave Winterburn Doc fully supported the project.
“Washdyke Lagoon and its tributaries are freshwater habitats of national and international significance for birdlife and native fish,” Mr Winterburn said.
“The whitebait fishery of New Zealand is a treasured resource with the most abundant whitebait species being inanga (Galaxias maculates), and Washdyke Lagoon is of regional importance for its spawning grounds and rearing habitat.”
Surface and stormwater studies were launched in February to improve the health of the lagoon.
ECan partnered with the Timaru District Council to gather more information about the lagoon and an update is due in April.
The project followed the establishment of a working group in 2015 and includes representatives from the district council, ECan, Doc, Fish and Game New Zealand and the Arowhenua Runanga.
District council archives show the lagoon was 250ha in size in 1881 and is now only 20ha. Coastal erosion and land development have both played a part in its reduction.