Thousands of salmon are being salvaged from the Tekapo canal as the second stage of multimillion-dollar repair work begins.
Owner Genesis Energy says the canal has had problems with leaks since it opened in the 1970s and recent deterioration led to a $140 million repair programme being launched in 2012.
Mount Cook Alpine Salmon, which farms on the hydro-electricity canals, is having to move its fish to other sites.
A Genesis Energy spokesperson says Fish and Game staff will also help move wild trout and salmon to other parts of the canal.