Helping out a threatened predator by culling their prey seems like a really stupid idea. But Scandinavian scientists have found that it might be the best strategy for helping some of our ailing fish stocks.
Lennart Persson and colleagues from Umeå University came up with this counterintuitive concept by running a 26-year natural experiment with the fish of Lake Takvatn, Norway. At the turn of the 20th century, the top predator in Lake Takvatn was the brown trout. Over-fishing sent its numbers crashing, and it was virtually gone by 1980.
In its place, a smaller fish - the Arctic char - was introduced in 1930. Char should make a good meal for trout, so it was surprising that when the trout were reintroduced they failed to flourish despite an abundance of food.
It was only in the 1980s, when the researchers removed over 666,000 char from the lake that the ...
