A survey of whitebait catches along the Clutha River is being carried out by the Department of Conservation (Doc).
The department hopes the survey will determine whether the enhancement work it and Contact Energy have been doing along the river has increased whitebait numbers.
As part of its resource consent conditions for the Clutha hydro dams, Contact was required to work with Doc on a native fish implementation plan in the lower Clutha.
Doc freshwater ranger Pete Ravenscroft said the work included finding inanga (whitebait) spawning sites and fencing parts of the river to ensure stock did not graze on vegetation where whitebait spawned.
About 10km of the river had been fenced so now most spawning sites on the true-left of the Matau (northern) branch were protected. Work would begin on the Koau branch next year.
''There are still large sections of the river that are not fenced and are grazed by stock. We hope to work with landowners in these areas in the future.''
The invasive weed glyceria had been sprayed and planting had been carried out along the banks of the river.
While it was too early to release the final results of the survey, anecdotally it appeared catches were improving - a large whitebait spawning site was discovered last year, Mr Ravenscroft said.
Contact Energy environmental adviser Daniel Druce said the results from the programme so far were heartening.
