Anglers catching chinook salmon in Lake Wanaka are being asked to give the heads of the fish to Otago Fish and Game for DNA sampling.
Chinook (also known as quinnat) salmon are thriving in Lakes Hawea and Wakatipu but the population in Lake Wanaka has plummeted.
Otago Fish and Game is investigating the genetic differences in populations of chinook salmon in the three alpine lakes to determine why there are so few salmon in the lake and whether they have migrated to other lakes.
Fish and Game field officer Paul van Klink said salmon can get from Lake Wanaka to Lake Wakatipu by using the Clutha River.
However, one theory was that the fish had headed up to the Makarora end of the lake.
"Fishing guides on Lake Wanaka used to almost guarantee you could catch a salmon towards the [Wanaka] outlet but that has changed."
"One fishing guide I talked to yesterday reckons they have all gone to Wakatipu," he said.
Mr van Klink said anyone wishing to give Lake Wanaka chinook fishheads can email Fish and Game to arrange collection.
He said they would also appreciate information on the length, weight, date and location of where the salmon was caught in Lake Wanaka.
