“WHITEBAIT”

Weeds strangle whitebait sites

By STAFF REPORTERS - The Greymouth Star | Friday, 26 October 2007

SPAWNING SITE SURVEY: Department of Conservation officer, Henk Stengs with
local whitebaiters while visiting an inanga spawning site during his survey.

A Department of Conservation survey of 136 West Coast whitebait spawning sites has found 67 are infested with invasive weeds and 50 trampled by sheep and cattle.

DOC conservation officer Henk Stengs, of Greymouth, visited the inanga spawning sites from Karamea to Haast between March and June. Inanga are the main adult species of whitebait. He found a central Westport creek suffocated with crack willow, and at another stream a farmer had unknowingly sprayed the long grass needed for the spawning eggs. If the grass is too short the sun will dry them and they will die. However, Mr Stengs also watched for 15 minutes as one “huge shoal” swam past him in the Okarito Lagoon, and — with two herons — watched some inanga spawn near Haast. Of the 136 sites he visited, only 26 were on DOC-managed land.

“At some sites, it can take as little as five minutes to get rid of weeds. In others, it would be several weeks.” Mr Stengs made five recommendations:

Exclude stock from riverside margins.
Carry out weed control.
Involve other agencies such as local councils.
Look at the wider tidal areas.
More public education.

He also admitted there were challenges, particularly the cost. “It would be a long term project, and we would have to maintain landowner support.” Inanga lay their eggs in riverside grasses during the big spring tides that occur during autumn. They hatch and head out to sea, returning in spring as whitebait. Mr Stengs said there were other factors that affected inanga spawning — for example, mice ate the eggs and perch and trout were known predators of inanga.

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