Largemouth catchability linked to parenting skill

Champaign, Ill. — Having trouble hooking one of the many trophy largemouth bass in your favorite lake?

Maybe you should target one that happens to be a bad father.

Scientists at the University of Illinois say the notion wouldn’t make you all that crazy. They contend new research shows that the same qualities that make a male bass a good father also make the fish gullible to an angler’s fishing lure.

The take-away: fishing is able to quickly alter behavioral traits and that characteristics associated with lower vulnerability to angling may also decrease reproductive fitness of fish.

“To our knowledge this study is the first showing that angling-induced selection can reduce reproductive success,” said David Sutter, a fisheries ecologist at the U of I and a member of the research team.

Sutter said the research is based on an earlier study that showed that vulnerability to angling is a heritable trait that can be selected against in the wild – resulting in fish becoming harder to catch.

“The outcome of this previous experiment was the creation of two lines of largemouth bass, one with high and one with low vulnerability to fishing,” said Sutter. “A couple of follow-up studies have then shown that this decrease in vulnerability to angling is also associated to behavioral and metabolic differences between the two lines.”

The present study analyzed how these differences in the two lines of largemouth bass might affect parental care behavior and reproduction.

It was concluded that males do not only become harder to catch but also become less willing to defend their nests.

“This results in the production of fewer offspring and, thus, lower overall recruitment of fish characterized by a low vulnerability to angling,” said Sutter.

But these findings do not mean that bass populations are in danger of becoming too hard to catch and at the same time totally inefficient at reproducing, said study co-author David Philipp, a conservation geneticist and director of the Illinois Fisheries Genetics Lab for the Illinois Natural History Survey.

“Does it mean that we are impacting populations of bass in ways that we never envisioned and don’t understand well at all?” Philipp offered. “Most certainly.”

In their paper published in the Proceedings of the National Academy of Sciences, Sutter and Philipp write that their research shows that male bass that tend to their young are more likely to be caught by hooks hidden in fish lures.

Among largemouth bass, while the female lays the eggs, it’s the male fish that does the child care. They go weeks without food to guard their nests from predators.

The U of I research contends that the same aggressive behavior that some bass exhibit when protecting their young can cause them to be more vulnerable to being caught by fishermen.

Fisheries biologists and others that manage fish populations have learned that some bass are more likely to strike at a lure and thus be caught then others.

Luckily for anglers, not all male bass are good fathers. Having a population that is less-suseptible to being caught also helps keep the population strong and abundant.

The research team set up underwater cameras to watch the males as they cared for the eggs of their young in hatcheries. In so doing, they discovered that those fish that took their job very seriously, appeared to consider a lure a threat, and thus were more likely to attack it.

Sutter said the experiment has only be conducted with largemouth bass.

“It is likely that the outcome might be similar for other species showing parental care [sunfish] but this remains to be tested,” he said. 

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