BASS BIOLOGY: Largemouth bass seem to pass on a susceptibility to being caught from generation to generation.
Image: COURTESY OF DAVID PHILIPP
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That trophy largemouth you caught might come from a long line of bass that take the bait.
And in the same pond, there are hundreds of fish you'll never see. You may never see their offspring, either.
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.
But Philipp says the discovery amounts to more than just gee-whiz genetics. Previous research has documented that commercial fishing can change gender ratios and drive down fish size by selecting for the largest. But the new study is the first to suggest recreational fishing can cause evolutionary changes, too.
"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.
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 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.
The researchers aren't sure which inherited behavior is causing the differences, but they speculate that a wariness of anglers' hooks may be passed on to offspring. And largemouth bass reproductive strategies, combined with angling pressures, might amplify the evolutionary selection.
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.
He says the findings, published recently in the journal Transactions of the American Fisheries Society, carry lessons for the timing of recreational angling seasons, particularly tournaments, during which bass are kept on boats for up to eight hours before being released.
To maintain healthy bass populations across North America, he says that management agencies need to protect the nesting males during the spawning season (early April through mid-June in Illinois).
Meanwhile, the research team is studying other aspects of the evolutionary implications of largemouth bass behavior.
Because the readily caught fish are more aggressive, "they likely have higher mating success in terms of the number of eggs," Philipp says. But the researchers suspect that those fish often have lower reproductive success, because when they're snared they lose babies. They're curious whether the hook-avoiding fish prove to be worse dads, because they're less aggressive against predators and provide less protection for their young.
Philipp, an angler himself, says "the vast majority of anglers are conservationists" and are likely unaware of their impacts on fish populations.
"Showing anglers that removing nesting males may be creating populations of bass less adept at raising their young," he says, "should help them change how they fish in the future."
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6 Comments
Add CommentHmm, very interesting. So what if you are fishing, and practice catch and release. Is it affecting the male large mouth bass in the same manner if you have them back in the water within 10-15 minutes?
Reply | Report Abuse | Link to thisYes, it can still affect them. Even if the bass are off of the nest for a short time, nest predators can consume a large number of eggs. One study by Steinhart et al. (2004) showed that as many as 1,100 eggs can be eaten in only 1.4 minutes of a bass being off the nest. Another study by Philipp from 1997 (interviewed in the article) showed that keeping a bass for 10 minutes meant that the bass took on average 9 minutes to return to his nest. That same study found that when a bass takes 5 or more minutes to return to his nest, there is a 50/50 chance that he will abandon. The 9 minute return time associated with a 10 minute handling time by the angler would likely result in greater than a 50% chance of the bass abandoning his nest (which would result in him losing all of his offspring).
Reply | Report Abuse | Link to thisBass energy stores can be severely depleted by angling and nest predators can eat the eggs even if there is catch and release. It is probably better for bass populations to let them nest without interruption.
As the bass is a top aquatic predator the next or second predator small mouth bass will fill in. The bass fingerlings love to eat each other, if they didn't do this the ponds and lakes would become over run with top predators.
Reply | Report Abuse | Link to thisFirst, there are many lakes with only largemouth or smallmouth bass, not both. It is not always true that the other bass species would "fill in". Besides, I wouldn't want to exchange one for the other. If both were present, both should remain.
Reply | Report Abuse | Link to thisSecond, cannibalism is not the only thing that controls bass populations. Food abundance, the number of spawners, weather, the amount of habitat, and many other things can affect population size. There are many lakes in which bass are not as abundant as people would like.
The juvenile largemouth bass consumes mostly small bait fish, scuds, small shrimp, and insects. Adults consume smaller fish (bluegill), snails, crawfish (crayfish), frogs, snakes, salamanders, bats and even small water birds, mammals, and baby alligators. In larger lakes and reservoirs, adult bass occupy deeper water than younger fish, and shift to a diet consisting almost entirely of smaller fish like shad, trout, ciscoes, shiners, and sunfish. Prey items can be as large as 25 to 35% of the bass's body length. Studies of prey utilization by largemouths show that in weedy waters, bass grow more slowly due to difficulty in acquiring prey. Less weed cover allows bass to...
Reply | Report Abuse | Link to thishttp://wiki-fish.22web.net/Largemouth_bass.html
The largemouth bass also known as a black bass is more and more everyday becoming the best sports fish in the United States. It is definitely a sought after game fish that we have made into a sport. Fishing departments have control over the size you may keep depending on your state, which helps control the bass population, and will continually better the sport for all anglers. On a ranking of 1 to 10 bass for eating quality opinions vary, but for the most part, people enjoy the taste.
Reply | Report Abuse | Link to thisTo identify the largemouth bass, look for a black band on each side of the bass that run from head to toe. If you look at different bass ...
http://usafisherman1.0fees.net/ljm.html