http://www.sciencedaily.com/releases/2014/11/141104111536.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Ftop_news%2Ftop_environment+%28ScienceDaily%3A+Top+Environment+News%29

Fish integration: Nature adores a hybrid


Date:

November 4, 2014


Source:

Concordia University


Summary:


After a few generations of breeding and natural selection, hybrid fish are genetically as robust as their purely wild forefathers, new research shows. 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.

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Overfishing, climate change and pollution have reduced fish populations in Canadian lakes and rivers. While hatchery-raised fish could return numbers to normal, they aren't as well adapted to their new environments, and there's been concern that the wild population is "tainted" once it breeds with its domesticated counterparts.



But new research from Concordia, published in the journal Evolutionary Applications, shows that after a few generations of breeding and natural selection, these hybrid fish are genetically as robust as their purely wild forefathers.

Fishing for results

Under the leadership of biology professor Dylan Fraser, the research team -- which included Concordia graduate student Andrew Harbicht and research scientist Chris Wilson from the Ontario Ministry of Natural Resources and Forestry -- 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.

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

Fraser, himself an avid fisherman, says these results provide hope for wild populations that were initially 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," he says.

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.


Story Source:

The above story is based on materials provided by Concordia University. Note: Materials may be edited for content and length.

Journal Reference:
1.Andrew Harbicht, Chris C. Wilson, Dylan J. Fraser. Does human-induced hybridization have long-term genetic effects? Empirical testing with domesticated, wild and hybridized fish populations. Evolutionary Applications, 2014; DOI: 10.1111/eva.12199


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Concordia University. "Fish integration: Nature adores a hybrid." ScienceDaily. ScienceDaily, 4 November 2014. <www.sciencedaily.com/releases/2014/11/141104111536.htm>.

". . . after a few generations of breeding and natural selection, these hybrid fish are genetically as robust as their purely wild forefathers."

That seems to be the key. Wild fish become hatchery fish after a few generations of hatchery fish culture. Why wouldn't selection, natural or otherwise, work in the reverse direction, whereby hatchery fish become wild fish after a few generations of breeding in the wild and experiencing the effects of natural selection?

Sg

This makes perfect sense and is exactly what genetic theory tells us. We've only had one problem. In many cases, we can't seem to get to the point of limiting or eliminating hatchery influence to allow it to happen.

Isn't that the underlying theory to re-establishing certain species by using broodstock from nearby river(s) and labeling those non-clipped fish as "wild" precluding recreational harvest?

Larry,

Yes. For example, with hydro projects on the Cowlitz and Lewis Rivers, hatchery stocks were created from the native wild stocks. Now with modern fish passage on the drawing boards and in the water, some of those same hatchery fish are being used to re-create the original wild stocks. And some anglers are pissed that they have to release unmarked salmon and steelhead in those rivers because they have been factories for hatchery fish for decades. They are unwilling to believe that the unmarked fish are really wild fish because they are descended from hatchery fish. Of course, the only way to restore those wild populations is if people don't bonk the unmarked fish and let them migrate to the fish facilities and be transported upstream.

Sg

Sg - As a frequent recreational angler on the Lewis Rv, I'm glad you used the phrase "some anglers" before your mild rant. I have no problems releasing wild fish, and every angler I know who fishes on the Lewis feels the same. Ideally those wild fish are going to places in the Lewis Rv watershed where they can spawn in the wild, i.e., not the hatcheries.