Sunday, April 19, 2009

Angling drives evolution in bass

Cool article over at Scientific American on fishing.
A new, 20-year study, led by University of Illinois at Urbana–Champaign ecologist David Philipp, "provides the first direct experimental evidence that vulnerability to angling is a heritable trait," the authors wrote.
So how'd they figure this out?
With the help of anglers, Philipp and his colleagues tagged and released largemouth bass in a state park pond in central Illinois beginning in the mid-1970s. Many fish were caught time and again, they found—up to 16 times in a single year. The researchers drained the pond in the 1980s and discovered that 200 of about 1,700 fish had never been hooked.
From there they did ...
From this stock, they have since bred the separate groups of "low-vulnerability" and "high-vulnerability" bass, and through three generations the offspring have stayed true to their parents' susceptibility—or aversion—to getting caught.
Pretty cool. So what does this mean?
"This type of selection experiment, which we propose has been going on in all bass lakes since the inception of angling, has the potential to alter, perhaps quite significantly, the behavior and even the life history of individual fish in those populations," the study said.
What form does the impact take?
Female largemouths swim away from their eggs after laying them; it is the male that guards them for their first month of life. The aggressive males are best at protecting their fry from predators—but they also may strike more readily at lures in their territories, making them more vulnerable to being caught.

Most times of the year male and female fish are caught in equal numbers. But during spawning season, males are caught the most. And hanging on to a caught male for longer than a few moments during nesting season could spell death by predation for the fry.

"Anglers may be negatively impacting the populations without knowing it," Philipp says.

1 comment:

laurel said...

interesting study, but I would think that if this had been going on since the inception of angling, then the fish more likey to be caught and loose offspring, would be present in lower numbers after all these years.

My husband is works with herps, and I have a background in wildlife, sometimes I really miss being able to actually see and count and identify what you are working with. I am always amazed by wildlife seminars at how "easy" it all seemed... not that netting a herd of bighorn sheep was actually easy, but it sure is different game than playing with microbes!