05-02-2008, 08:21 PM
PORTAGE -- Well-kept angler diaries may provide insights into lake and river fisheries that are not provided by traditional netting and shocking surveys, a Department of Natural Resources fisheries biologist said.
"I think the results from hook-and-line anglers is more representative of the fish population," said Tim Larson, fisheries supervisor for the south central region of the Lower Wisconsin River.
"The data we get from DNR shocking is totally different from what we get from hook-and-line results. Shocking turns up a lot of smaller fish, whereas angler diaries show a higher proportion of larger fish."
Larson, who recently presented his findings at the annual meeting of the Wisconsin Chapter of the American Fisheries Society, based his comments on an assessment of the Wisconsin River that included 9,000-acre Lake Wisconsin and 35 river miles upstream to the Wisconsin Dells Dam.
The lake is heavily fished and annually hosts a number of fishing tournaments, whereas the river is less accessible and thus has reduced fishing pressure.
Smallmouth bass are the primary tournament target, though largemouth are also present, along with walleye, northern pike, musky, sturgeon and a variety of panfish.
Larson's goal -- spurred by angler interest and concerns -- was to determine the status of largemouth and smallmouth bass in the lake and river, utilizing angler diaries and fishing tournament data.
He provided waterproof notebooks to about 10 bass fishing guides and avid anglers over the past five years, asking them to record the size of every bass they caught.
"The value of this technique is that it's very inexpensive," Larson said. "The hard part is getting to know good, reliable fishermen and developing a trust with them. You don't need a lot of participants, just a few good ones."
When comparing all bass 10 inches or larger, DNR shocking surveys found 65 percent of river smallmouth and 78 percent of lake largemouth were between 10-13 inches long.
By contrast, angler diaries showed just 32 percent of smallmouth and 48 percent of largemouth they caught fell into that size range.
Similarly, DNR shocking efforts found 14 percent of smallmouth and 8 percent of largemouth 10 inches and larger were at least 16 inches long.
Diary anglers reported 44 percent of smallmouth and 13 percent of largemouth exceeded 16 inches.
Larson said anglers fish the entire river while DNR crews can only sample limited segments due to the inability to navigate the shallow river. "Shocking only works in shallow water, and is typically used close to shore, whereas fishermen also sample off-shore and deeper water," he said.
"Both methods have their biases. Angling may be more biased toward larger fish but whatever method is used, as long as the same method is used from year to year, the results can be compared."
Larson, who is nearing retirement, said he has used angler diaries throughout his career on several different fisheries.
"You have to use discretion on where you use it," he said. "It's comparable to a DNR creel census. While you are not able to establish fishing pressure, it allows data on all sizes of fish caught. Lengths from creel census are limited to only harvested fish."
The impact of fishing tournaments on the fishery has come under statewide scrutiny.
Using tournament data to estimate the bass population, Larson found tournament anglers are annually handling 25 percent of the population of legal size bass (14 inches and larger) on the Lake Wisconsin-Wisconsin River system.
While the scheduling of tournaments during cooler months will increase survival of released fish, Lake Wisconsin tournament anglers often venture far upstream, leading to worries that fish released near lake-based tournament headquarters might remain in the lake and thus adversely impact the upriver fishery, Larson said.
"However, returns from tagged bass indicate two-thirds of released smallmouth moved into the upper river," Larson said. "Largemouth bass did not move as far as smallmouth."
According to Larson, the lake-river system with its 14-inch minimum size on bass currently houses a fishery equal to catch and release bass fisheries in other states.
"I think the river bass fishery is excellent," he said. "It's as good as anywhere.
"To anglers who complain that the size of the fish has gone down, I say 'Show me the data.' I don't know if we need to change anything. I don't know if bass fishing can get any better than it is."
But if the situation changes, anglers and the DNR have diaries to compare.
"I think the results from hook-and-line anglers is more representative of the fish population," said Tim Larson, fisheries supervisor for the south central region of the Lower Wisconsin River.
"The data we get from DNR shocking is totally different from what we get from hook-and-line results. Shocking turns up a lot of smaller fish, whereas angler diaries show a higher proportion of larger fish."
Larson, who recently presented his findings at the annual meeting of the Wisconsin Chapter of the American Fisheries Society, based his comments on an assessment of the Wisconsin River that included 9,000-acre Lake Wisconsin and 35 river miles upstream to the Wisconsin Dells Dam.
The lake is heavily fished and annually hosts a number of fishing tournaments, whereas the river is less accessible and thus has reduced fishing pressure.
Smallmouth bass are the primary tournament target, though largemouth are also present, along with walleye, northern pike, musky, sturgeon and a variety of panfish.
Larson's goal -- spurred by angler interest and concerns -- was to determine the status of largemouth and smallmouth bass in the lake and river, utilizing angler diaries and fishing tournament data.
He provided waterproof notebooks to about 10 bass fishing guides and avid anglers over the past five years, asking them to record the size of every bass they caught.
"The value of this technique is that it's very inexpensive," Larson said. "The hard part is getting to know good, reliable fishermen and developing a trust with them. You don't need a lot of participants, just a few good ones."
When comparing all bass 10 inches or larger, DNR shocking surveys found 65 percent of river smallmouth and 78 percent of lake largemouth were between 10-13 inches long.
By contrast, angler diaries showed just 32 percent of smallmouth and 48 percent of largemouth they caught fell into that size range.
Similarly, DNR shocking efforts found 14 percent of smallmouth and 8 percent of largemouth 10 inches and larger were at least 16 inches long.
Diary anglers reported 44 percent of smallmouth and 13 percent of largemouth exceeded 16 inches.
Larson said anglers fish the entire river while DNR crews can only sample limited segments due to the inability to navigate the shallow river. "Shocking only works in shallow water, and is typically used close to shore, whereas fishermen also sample off-shore and deeper water," he said.
"Both methods have their biases. Angling may be more biased toward larger fish but whatever method is used, as long as the same method is used from year to year, the results can be compared."
Larson, who is nearing retirement, said he has used angler diaries throughout his career on several different fisheries.
"You have to use discretion on where you use it," he said. "It's comparable to a DNR creel census. While you are not able to establish fishing pressure, it allows data on all sizes of fish caught. Lengths from creel census are limited to only harvested fish."
The impact of fishing tournaments on the fishery has come under statewide scrutiny.
Using tournament data to estimate the bass population, Larson found tournament anglers are annually handling 25 percent of the population of legal size bass (14 inches and larger) on the Lake Wisconsin-Wisconsin River system.
While the scheduling of tournaments during cooler months will increase survival of released fish, Lake Wisconsin tournament anglers often venture far upstream, leading to worries that fish released near lake-based tournament headquarters might remain in the lake and thus adversely impact the upriver fishery, Larson said.
"However, returns from tagged bass indicate two-thirds of released smallmouth moved into the upper river," Larson said. "Largemouth bass did not move as far as smallmouth."
According to Larson, the lake-river system with its 14-inch minimum size on bass currently houses a fishery equal to catch and release bass fisheries in other states.
"I think the river bass fishery is excellent," he said. "It's as good as anywhere.
"To anglers who complain that the size of the fish has gone down, I say 'Show me the data.' I don't know if we need to change anything. I don't know if bass fishing can get any better than it is."
But if the situation changes, anglers and the DNR have diaries to compare.