Are Anglers Changing Genetics?
Research Proves Vulnerability Is Hereditary Trait

Photo: ESPN Outdoors University of Illinois ecology and conservation researcher David Philipp contends that spawn-time fishing – and in particular, tournament fishing during the spawn like that shown above at the Clear Lake Bassmaster Elite Series – affects the genetics of a bass population.

Turns out, recent research proves that some bass are simply more apt to bite a lure than others, and in fact, those fish can pass that trait on to their offspring.

But what it also means is some fish are less apt to be caught, if ever – a trait that can be passed on as well.

And most importantly, the same research presents evidence that catch-and-release angling during the spawn impacts a fishery because it creates a population of bass that are much less likely to ever bite a lure.

20-Year Look

A study by a University of Illinois research team headed by David Philipp recently published a paper titled Selection for Vulnerability to Angling in Largemouth Bass in the peer-reviewed Transactions of the American Fisheries Society (138:189-199, 2009).

Others on the research team included Steven Cooke, Julie Claussen, Jeffrey Koppelman, Cory Suski and Dale Burkett.

What's so remarkable about the study is not only the results, but also the length and breadth of the research.

Research Methods

Carefully controlled experiments were conducted over a period of 20 years on a single Illinois waterbody.

The study began in 1975 with the resident population of bass in Ridge Lake, an experimental study lake in Fox Ridge State Park in Charleston. The fishing was controlled. For example, anglers reserved 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. All fish were then released.

"We kept track over 4 years of all of the angling that went on, and we have a total record – there were thousands of captures," said Philipp, ecology and conservation researcher at the University of Illinois. "Many fish were caught more than once. One fish was caught three times in the first 2 days, and another was caught 16 times in one year."

After 4 years, the pond was drained and more than 1,700 fish were collected.

"Interestingly, about 200 of those fish had never been caught, even though they had been in the lake the entire 4 years," Philipp noted.

Controlled Breeding

Among the collected fish, 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 university research ponds.

Similarly, males and females that had been caught four or more times in the study were designated High Vulnerability parents and were spawned in different ponds to produce a line of High-Vulnerability offspring.

The two lines were then marked and raised in common ponds until they were big enough to be fished.

"Controlled fishing experiments clearly showed that the High-Vulnerability offspring were more vulnerable to angling than the Low-Vulnerability offspring," Philipp said.

The same selection process was repeated for several generations over the course of the 20-year experiment.

With each generation, the difference in angling vulnerability grew even larger. "As we'd predicted, vulnerability was a heritable trait," Philipp said.

Photo: TPWD Was this Texas ShareLunker caught by Chris McEntyre genetically more vulnerable to being caught? Perhaps.

In summarizing the research findings, Philipp made several points.

First, he said the study proved that vulnerability was a heritable trait. Also, the difference in vulnerability between the two groups grew over generations. However, most of the change occurred in the Low-Vulnerability group. There was only a small increase in vulnerability in the High-Vulnerability group.

Philipp noted that the experiment sped up what actually occurs in nature – that is, anglers are harvesting more High-Vulnerability fish, because they're the fish that are caught most often.

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

"We've known for 50 years that commercial fishing exerts selection on wild populations," Philipp added. "We take the biggest fish, and that's changed life histories and growth patterns in many populations of commercially harvested species. Because there's no commercial fishing for bass, we were assessing the evolutionary impacts of recreational fishing."

Bed-Fishing Problem?

While some of the conclusions will certainly fascinate many anglers, another conclusion might cause some consternation.

As stated above, one of the purposes of the study was to assess "evolutionary impacts of recreational fishing." And the conclusion was that on a whole, bass are evolving toward being less vulnerable to angling (i.e. they're becoming tougher to catch).

Philipp then applied those findings to the practice of bed-fishing and reasoned that, as a vulnerable fish is taken from a bed, that bed will contribute less to the population, and the bass that survive on other beds will be from less-catchable parents.

In other words, it's his contention that bed-fishing creates a population of harder-to-catch bass.

Philipp noted that the perception among anglers is that catch-and-release has no negative impact on the population. During the spawning season, however, he contends that if bass are angled and held off their nests for more than a few minutes, when they're returned to the lake, it's too late – other fish have found the nest and are quickly eating the babies.

"One of the big issues for concern is the explosion of tournaments," Philipp added. "Lots of bass tournaments are held during the springtime because there are lots of big fish available. In tournaments, you put fish into livewells, and yes, they're released, but they could be held for up to 8 hours first. They're brought back to the dock, miles from their nest. So basically, if a fish is caught in a tournament and brought into the boat and put into a livewell, his nest is destroyed."

Philipp said that if fishing tournaments are held during the spawning season, then regulations should require that there be immediate catch-and-release. He also urged management agencies to set aside a portion of each lake as a bass-spawning sanctuary, where all fishing would be prohibited until after bass reproduction is complete. In the rest of the lake, mandatory catch-and-release regulations should be put into place during that same reproductive period.

"The potential for angling to have long-term evolutionary impacts on bass populations is real," Philipp concluded. "If we truly want to protect this valuable resource into the future, then we need to understand that and adjust our management strategies."

Notable

> There's more and more talk lately about tougher fishing due to "pressured fisheries." Could it instead be what Philipp's research contends? That bed-fishing has created whole populations of bass less vulnerable to angling? What do you think? Click here to tell us about it.

> In light of the above research, there's a new BassFan poll that asks your opinion on fishing during the spawn. To participate in the poll and view the results, click here to visit the homepage, then scroll down the right-hand margin.