Not Catching As Many Bass These Days?

If so, you're not the Lone Ranger. As a matter of fact, you have lots of company, starting with avid angler and veteran fisheries biologist Hal Schramm. Saw a paper the other day he had published last year on this subject and found it interesting, so decided to share his thoughts about the science involved.

Schramm noted that fishermen all the way from Sam Rayburn Reservoir in Texas to Mille Lacs Lake in Minnesota are complaining about it being harder to catch a bass these days. "While some just want to blame fishing pressure for the problem," said Schramm, "there is good science to support claims that bass actually may be getting tougher to catch."

He first offered a quick history lesson, explaining that 60 years ago, bass fishing was primarily a Southern thing. Many new reservoirs had growing largemouth populations, plus good habitat that was easy for anglers to identify. Bass fishing was excellent--for a while--but then, over time, catch rates began to decline.

"Angler harvest was partly to blame," said Schramm. "So agencies implemented minimum-length and reduced-bag harvest limits to protect bass numbers. The real game-changer, though was an evolving catch-and-release ethos. Using bass tournaments as a stage, and with strong media support, the bass-fishing community promoted the idea of catch-and-release fishing during the 1970s. Today, live-release rates are at 85 to 95 percent among bass anglers, and fish are as abundant as ever in most waters.

"So, why aren't you catching more of them? Well, for starters, bass learn, and that reduces catchability (the research term for the probability of a fish being caught with a fixed amount of effort)."

The veteran biologist then discussed a 2017 study out of Mississippi State University, in which researchers, working in small unfished ponds, saw rapid declines in largemouth bass-catch rates under continued fishing pressure of one angler per acre per week. Then they stopped fishing for two months, and when they started again, the catch rates shot back up. The bass forgot what they had learned--to avoid lures--after a couple of months without fishing pressure.

"Another interesting aspect of the Mississippi State study," according to Schramm, "was that testers systematically used 11 different types of lures during each weekly outing, and few bass were caught multiple times. If the bass learned to avoid only one lure, they should be caught on the other lures, right? But it was possibly the other intrusions from fishing--maybe the vibrations of the motor, the boat, or the sounds of anglers--that prevented the bass from biting.

"But there's more to it than individual bass learning to avoid lures," he continued. "Some bass are innately harder to catch."

Another study spanning nearly two decades was done by Illinois Natural History Survey fishery scientists into whether catchability is an inherited trait. In this study, adult largemouth bass in a 17-acre impoundment were fished for a summer and marked each time they were caught. Then the lake was drained, and the bass were sorted. Fish that were caught multiple times--the highly catchable fish--were stocked in one pond to spawn, and the fish that were caught infrequently or not at all were stocked in another pond to spawn. The progeny from both groups was reared to adulthood, fished, and again sorted into separate ponds.

After three generations of selective breeding, the catch rate of the highly catchable fish remained the same, but the catch rate of low-catchable fish declined with each successive generation. Catchability was a heritable trait. In other words, the researchers were able to breed bass that were harder to catch.

Both studies were done on small waters, but what about bass populations in big lakes?

Said Schramm, "I analyzed catch rates from 311 bass tournaments on major bass fisheries throughout the country. And from 1972 to 2015, the average catch rate in these tournaments increased at a rate of only .06 bass each year. Pros were catching slightly more fish each tournament season, but consider that there were tremendous advancements in technology, knowledge, and the development of bass pros who fished for a living (not just a hobby) over this time.

"The upshot of these studies is that even though catch-and-release is common these days, not all bass are released and not all released bass survive. As easily caught bass get removed from the gene pool, those hard-to-catch bass continue to reproduce elusive offspring. So even top anglers will have a tougher time putting bass in the boat. The solution? Fish harder and fish smarter."