November 12, 2025
By Dr. Rob Neumann, Steve Quinn, Dr. Hal Schramm & Ralph Manns
Field Research: Finding Bass Tournament bass anglers are thought to be highly specialized in their knowledge of bass seasonal movements and behavior and their ability to catch fish. But, how well do they find bass, and when they do locate them, how successful are they at catching them? We investigated how bass behaviors, angler behaviors, and environmental conditions affect tournament anglers’ ability to locate and capture largemouth bass.*
We tracked 49 largemouth bass using radio telemetry in Brushy Creek Lake, Iowa, from May to mid-August, and five tournament anglers per event were equipped with a GPS unit to track their location while fishing. We then determined bass home range, weekly movement rate, depth used, and spatial overlap with anglers, as well as depth of water where anglers fished, angler movement rate, and air and water temperatures. Using these factors, we estimated the probability of a bass being captured at tournaments and their effect on the number of bass caught per angler hour.
During the study, we attended 15 fishing tournaments covering 1,680 angler hours of fishing. Angler movement rates increased across the season ranging from 148 to 405 feet per hour. Average angler depth use increased from 12 feet in May to 20 feet in August, with an average depth of 16 feet. The average bass home range across the study period was 22 acres. Bass movement rates varied from 262 to 1,004 feet per week and fluctuated seasonally, increasing in the spring and decreasing later in the summer. Average weekly depth use of all bass ranged from 6 to 8 feet, while average depth use of individual bass ranged from 2.3 to 15 feet.
Largemouth bass in Brushy Creek Lake remained in relatively shallow water overall throughout the study, while anglers tended to fish deeper in summer. Anglers had higher catch rates when they fished shallower areas of the lake and overlapped more with bass in depth use. Angler overlap with bass was highest during early summer, when both fish and anglers tended to be in shallower arms of the lake. Alternatively, anglers fished deeper areas of the lake during warmer months when largemouth bass are thought to move to cooler, deeper waters, but bass in Brushy Creek Lake did not significantly change depth used over the study and remained in relatively shallow water, potentially due to the large amount of available wood cover and vegetation there.
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Anglers fishing in locations where bass were present increased the probability of an individual bass being captured and capture probability also increased with air temperature. Across the fishing season, more bass were brought into tournaments when bass movement rates were higher, anglers were fishing in shallower waters, and air temperatures were higher. Although bass tournament anglers were successful at identifying areas where bass were located, our results showed that bass capture probability at tournaments and the number of bass captured were only partially explained by their overlap with anglers. Thus, the alignment of many factors (i.e., anglers successfully locating bass, bass behaviors, and environmental patterns) affect the vulnerability of bass to tournament anglers.
–Dr. Andrea Sylvia, Brandon Maahs, and Dr. Michael Weber
*Sylvia, A., B. Maahs, and M. J. Weber. 2020. Influence of largemouth bass behavior and angler spatial overlap on capture probability at fishing tournaments. Trans. Am. Fish. Soc. 149:93-107.
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Health Notes: Parasite Protection Fish are hosts to many parasites , but typically only a few types can affect humans who eat raw or undercooked fish. While trematodes, such as black-spot and yellow grubs, look unappetizing, they’re harmless to humans. Two nematodes found in saltwater fish—cod worms and herring worms—can cause digestive problems in humans until the worms eventually die in the gut.
“In freshwater fish, the primary parasite of concern is the broadfish tapeworm,” reported Jeff Gunderson, former Director of Minnesota Sea Grant. “They’re not pleasant to get, potentially growing to 30 feet long and an inch wide in humans. Carriers of broadfish tapeworm include northern pike, walleye, yellow perch, and burbot, among others, and I wouldn’t rule out Great Lakes salmon and trout.” Anadromous salmon and trout also have been shown to pick up the tapeworm in fresh water.
A popular recipe for preparing pike, and sometimes walleye, is cold pickling, but pickling doesn’t guarantee parasites are killed, Gunderson said. Ceviche is another dish that relies on the acidity of citrus juice to lightly “cook” fresh fish, but the process doesn’t ensure parasites are killed.
“To kill parasites in fish, cook the flesh through to 145°F, when it turns opaque and flakes easily,” he said. “Another option is to freeze fish at -4°F for 7 days. Seven days sounds like a long time, but it takes quite a while for the middle of a package of fish to reach -4°F. Use a freezer thermometer to ensure sufficiently cold temperatures are reached. It helps to pack fish in thinner packages so the center of the package reaches the recommended temperature faster.”
Treating fish by freezing is a good option for those who dislike the texture of cooked pickled fish, and for cold-smoking and ceviche. While incidences of fish parasites infecting humans are relatively uncommon, Gunderson says it’s best to be on the safe side and treat the fish as if it has a parasite.
–Rob Neumann
From the Field: Record Paddlefish Has Been Around Cody James Watters and his son hoist the world-record 151-pound 14-ounce paddlefish from Keystone Lake. (Eric Brennan, OK Dept. Wildlife Conservation photo) Guide Jeremiah Mefford specializes in snagging big paddlefish from Keystone Lake in Oklahoma. He set the state record of 143 pounds in May 2020, only to have that mark broken by one of his clients in late June, with a fish weighing 146.7 pounds. Less than a month later, he guided Cody James Watters to the new rod-and-reel world-record paddlefish of 151 pounds 14 ounces, accompanied by his 9-year-old son at Keystone. It was verified by Oklahoma Department of Wildlife technician Eric Brennan and released in good condition.
The anglers noticed a metal band in its jaw, which Brennan examined and determined that the tagged fish was part of a research project conducted by Oklahoma State University. Further checking revealed it had been tagged by Craig Paukert while he was a graduate student there. He’s currently a fishery professor at the University of Missouri and recalled some details of its capture, back on January 4, 1997. “When we banded it, the fish was about two years old and two feet long,” Paukert says. “So this new record is 25 years old and going strong. The news made my day. It was great to know I caught a world-record fish but didn’t realize it until 23 years later!”
The corroded metal jaw tag removed from Watters’ paddlefish. (Eric Brennan, OK Dept. Wildlife Conservation photo) Paddlefish roam the rivers and reservoirs of the Mississippi and Missouri rivers, though they’re never abundant. Oklahoma’s paddlefish populations are considered among the healthiest in the U.S., and anglers visit the state to snag them, the only viable method of capture, since they’re plankton feeders. Careful selection of tackle and hook removal allows safe release, as the harvest limit is one fish per day and two per year.
–Steve Quinn
