There is concern about pollution, overfishing and even climate change when it comes to reduced wild fish populations.

Farmed fish is the obvious solution but critics have a response for that also - they contend that hatchery-raised fish won't be as well adapted to their new environments or that the wild population will be "tainted" by breeding with domesticated counterparts.

No, nature loves us all equally, finds a study in Evolutionary Applications. She doesn't know the difference between a hybrid or any other genetically modified creature and after a few generations of breeding and natural selection, these hybrid fish are genetically as robust as their purely wild forefathers. 

To get some answers, researchers headed to Algonquin Provincial Park, a fisherman's paradise of lakes stocked generations ago with hatchery salmon and trout. The team transplanted combinations of wild, domesticated and hybridized populations of Algonquin Park vbrook trout to new environments. The researchers then compared survival rates and physical characteristics to determine whether hybridization affects a fish's potential to adapt after multiple generations of natural selection in the wild. 

Brook trout, Algonquin Park. Can you tell the difference? Neither can nature. Credit: Dylan Fraser

It turns out that within five to 11 generations of fish (about 25 to 50 years), the foreign genes introduced into wild populations through hybridization are removed by natural selection. That means fish populations previously bolstered by hatchery stock are, genetically speaking, indistinguishable from purely wild populations.

The implications for conservation

The results provide hope for wild populations that were initially thought to be negatively affected by human-induced hybridization.

"If we can stop the incoming flow of foreign genes while maintaining an environment similar to what was there pre-hybridization, wild populations are likely to recover — possibly in less time than previously thought," says Concordia University biology professor Dylan Fraser. 

And it looks like that's true for more than just fish. Similar conclusions have recently been made about wolf species previously exposed to hybridization.