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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

Anglers have accepted different regulations on several trout waters in return for having a greater chance of catching more fish and/or larger fish. © John E. Nelson
Anglers have accepted different regulations on several trout waters in return for having a greater chance of catching more fish and/or larger fish.

© John E. Nelson

October 2007

Tailoring the take to the fishery

In some streams, special size and bag limits can encourage trout populations that better match angler expectations.

Larry Claggett


As with all natural resource programs, providing quality fishing on trout streams is as much about working with anglers and improving habitat as it is about providing fish. Wisconsin's trout fishing regulations are designed to provide different experiences and opportunities that the trout-fishing public is seeking. Collectively and individually, they have wide-ranging interests.

In a broad survey done in the late 1980s, most trout anglers rated being outside in nature and the physical beauty of trout as important factors that kept them satisfied when fishing, but there were differences some fishers as well. Some anglers want to catch lots of trout. Others are seeking fewer, but larger fish. Some want to eat some of their catch while others are perfectly content to practice catch-and-release as long as their rods keep bending. To provide a range of opportunities on streams that can meet those desires, fisheries biologists proposed a category system of trout fishing regulations back in 1990. Three of those categories (1-3) were designed to increase trout harvest for those who want to keep and eat their catch, and two (4-5) were meant to improve the catch rate and size of fish caught. Category 5 regulations were deemed "special" because they combined various regulations tailored to each water and were designed to maximize catch rate and size of trout that would be subsequently released.

A brief history of trout fishing regulations might help here to understand how we got to where we are today. Prior to 1990, most streams had general statewide regulations that allowed each angler to keep 10 trout over six inches in length per day (5 browns and rainbows during May). A southern zone of counties established in 1986 had a three trout per day bag limit with a nine-inch minimum size limit. Special regulations that required the release of all or nearly all trout caught applied to portions of 11 streams totaling 33.5 miles. These waters comprised less than one-half of one percent of the total of 9,560 miles of trout stream in the state. Bob Hunt, one of our trout researchers at the time, found that the waters where these special regulations were put in place were used by more anglers than other streams, they attracted greater use by nonlocal and nonresident anglers, more anglers came back for return visits, the catch rates were substantially better, and ratios of trout released per trout kept in the creel helped bulk both the size and number of trout in these waters. Therefore, the group of biologists working on 1990 regulations recommended expanding the group of special regulation waters. That number was increased to 91 streams and 280 miles, or about three percent of the state total.

Half of these special regulations used slot-sizes to regulate the harvest (where fish above and below a certain size have to be released). About one-fourth of the waters relied on larger minimum size limits before fish could be kept, and catch-and-release requirements were put in place on the remaining fourth of special waters.

The effects of those regulations were reviewed and revamped in 2003. Category 1 was dropped to simplify the number of streams that had to be listed in the trout regulations pamphlet, and special regulations were adjusted to better fit the streams where they were used.

Reductions in the bag limit and special size limits increased the catch of larger brook trout in Lincoln County. © Don Blegen
Reductions in the bag limit and special size limits increased the catch of larger brook trout in Lincoln County.

© Don Blegen

The benefits of fishing regulations on fish populations are not always easy to detect because so many natural factors also influence how well fish populations survive and thrive. Drought, floods, stocking, habitat changes, water quality and predators can all have an effect. We really need to look at long-term trends before judging if a regulation change helps in a particular stream, lake or river. We sample trout populations by using an electrofishing tow barge – a small skiff that we typically drag behind us as we don waders and slog our way upstream. Electric probes in the water temporarily stun the trout. They float up, we net them, measure and examine them, and sometimes fin-clip the fish for recapture studies.

We used those techniques to study the consequences of changing trout regulations on the Tomorrow River in Portage County and the Prairie River in Lincoln County. On the Tomorrow River, regulation had changed from a bag limit of 10 fish (five browns) over six inches, to a bag of one brook trout at least 10 inches long and a minimum size of 18 inches for brown trout. Artificial lures were required to reduce hooking mortality. Surveys were done nearly every year starting in 1988. Population estimates were averaged from 1988-91 before the regulations were put in place and compared to post-regulation years (1995-97) after waiting a few years for the populations to stabilize.

Brown trout showed an increase from 469 fish per mile to 709 fish per mile. Brook trout populations stayed about the same at 400 fish per mile, but the average size of both species improved. Brook trout over eight inches improved from 13 percent of the adult population to 21 percent. Brown trout over 12 inches increased from 5 percent to 20 percent, and brown trout over 18 inches increased tenfold from 0.3 fish per mile to three fish per mile. The special regulations were successful in producing a good catch-and-release fishery that could sustain harvesting some fish.

On the Prairie River in Lincoln County, the regulation changed in 1993 from a 10-fish bag limit (five browns) over six inches, to a two-fish bag limit with only one brown trout over 20 inches and one brook trout over 14 inches. Trout population estimates were compared from two years (1985 and 1988) before the changes, to four different years (1995, 2004-06) after the regulation. Brook trout over 10 inches improved 840 percent, and brown trout of quality size (over 12, 14 and 16 inches) all increased over 100 percent. Some of these changes may be attributable to habitat improvements made in this stretch in 1985. Regardless, the habitat work and the regulations working together have greatly improved the size and numbers of trout in this stretch of stream.

More recent changes were made on the Onion River in Sheboygan County in 2004. The upper part of the watershed was changed from a bag limit of three and a nine-inch size limit to a bag limit of one fish of at least 15 inches in length. The lower part of the river continues to have the three-fish bag, nine-inch minimum size limit. The river was surveyed before the change in 1997 and after the change in 2006. In addition, a lower section of the same river where these regulations are not in place can be considered a control stretch to compare to the upper section. In the special regulation section, the catch rate of brown trout increased by 1,327 from 1997 to 2006. This compares to an increase of 379 percent in the control section. The percentage of fish over 12 inches was 14.3 percent in the special regulation section and 9.4 percent in the control section. Although all indices increased due to improving conditions in the watershed, they clearly increased more in the special regulations section.

Though we've had some success, fisheries biologists have also learned from mistakes that special regulations don't work in all situations and we can't always judge ahead of time which streams will respond well when we lower angling pressure aiming to grow larger, healthier fish. For instance, on Rowan Creek in Columbia County, putting a 12-inch minimum size limit resulted in less fishing, less harvest, and no appreciable increase in numbers or size of brown trout. The regulation was subsequently changed back to the standard in the rest of the county streams of a three-fish bag limit with a nine-inch size limit.

Yet a different experimental regulation shows promise in thinning crowded trout populations while increasing the numbers of larger fish. On Sand Creek in Polk and Barron counties, surveys from 1999 and 2007 show the number of brown trout caught increased from 39 fish per stream mile to 129 fish per mile. And the number of big browns (better than 14 inches in length) increased from seven to 36 fish per mile after special regulations were put in place. In a nearby control stream, South Fork Clam River, the numbers of brown trout of similar sizes decreased over a similar time period.

In summary, special regulations, applied in the right situation, can measurably increase both the numbers and size of large trout, providing different kinds of fishing challenges for anglers willing to work with biologists to limit their takes and adjust fishing techniques to provide a wider variety of fishing experiences.

Larry Claggett is DNR's coldwater fisheries ecologist. Data and photos for this story were provided by John Nelson, Heath Benike, Tom Meronek, Dave Seibel and Tim Larson of DNR's fisheries management program.