Is Bass Catchability Hereditary?

By Ralph Loos Staff Writer
Ohio Outdoor News

Which bass are more likely to strike and be caught by anglers? New research provides insight to that question.

That 5-pound bucketmouth you landed on only your second cast of the day? Turns out, it may not be your refined angling skills that put him in the boat. 

According to researchers at the University of Illinois, a largemouth's propensity to being caught may have more to do with its genes. Results of the 20-year study indicate that vulnerability to being hooked by anglers is a heritable trait in largemouth. Details of the findings recently were published by the journal Transactions of the American Fisheries Society. 

David Philipp, ecology and conservation researcher at U of I, indicated that a lot of fish were caught in order to complete the study. 

"We kept track over four years of all of the angling that went on, and we have a total record `there were thousands of captures," he said. "Many fish were caught more than once. One fish was caught three times in the first two days, and another was caught 16 times in one year." 

The U of I research team included Philipp, Steven Cooke, Julie Claussen, Jeffrey Koppelman, Cory Suski and Dale Burkett. Studies began in 1975 with the resident population of bass in Ridge Lake, an experimental study lake in Charleston, M. Because it was a controlled study, anglers had to reserve times, and every fish that was caught was put into a livewell on the boat. The fish were measured and tagged to keep track of how many times each fish had been caught. 

More than 1,700 fish were collected when the pond was drained four years later. 

"Interestingly, about 200 of those fish had never been caught, even though they had been in the lake the entire four years," Philipp said. 

Philipp explained that largemouth males and females that had never been caught were designated "low vulnerability" parents. To produce a line of low vulnerability offspring, these parents were allowed to spawn with each other in research ponds. 

Males and females that had been caught four or more times in the study were designated "high vulnerability" parents that were spawned in different ponds to produce a line of high vulnerability offspring. 

Fish in each group were then marked and raised in common ponds until they were sizeable enough to become targets for anglers. With each generation of bass, the difference in "catchability" grew. 

Most of the selection is occurring on the low vulnerability fish-that is, for the most part, the process is making that line of fish less vulnerable to angling, the study reveals. 

"We actually saw only a small increase in angling vulnerability in the high vulnerability line," Philipp said. 

Fisheries biologists have long known that females lay eggs and then leave the nest. Male bass become the primary parent, guarding the nest against brood predators for about three to four days before the eggs hatch. Even after the baby bass start to swim, the father bass stays with the young bass for roughly three weeks while they feed and grow. 

Philipp said the experiment sped up what actually happens in the natural world. 

"In the wild, the more vulnerable fish are being preferentially harvested, and as a result the bass population is being directionally selected to become less vulnerable," he said. "We selected over three generations, but in the wild, the selection is occurring in every generation." 

An offshoot of the research has led Philipp to question whether or not the growing practice of catch-and-release is helping conserve largemouth populations. 

"If bass are angled and held off their nests for more than a few minutes, when they are returned to the lake, it's too late; other fish have found the nest and are quickly eating the babies," he said. 

Philipp said he is recommending that to preserve bass populations across North America, management agencies need to protect males during the spawn. 

"There should be no harvesting bass during the reproductive period," he said. "That makes sense for all wildlife populations."