Paul Kanehl’s research while affiliated with Wisconsin Department of Natural Resources and other places

The goal of this study was to compare the possible locations, timing, and characteristics of potentially spawning shovelnose sturgeon (Scaphirhynchus platorynchus), blue sucker (Cycleptus elongatus), and associated species during the spring of 2007–2015 in the 149-km-long lower Wisconsin River, Wisconsin, USA, a large, shallow, sand-dominated Mississippi River tributary. A 5-km index station of two pairs of rocky shoals surrounded by sandy areas was electrofished for shovelnose sturgeon and blue sucker in a standardized fashion a total of 40 times from late March through mid-June, the presumed spawning period. On one date in 2008 and two dates in 2012, all rocky shoals and adjacent sandy areas in the lowermost 149 km of the river were also elec-trofished for both species. Shovelnose sturgeon and blue sucker appeared to spawn in the limited rocky areas of the river along with at least four other species: mooneye (Hiodon tergisus), quillback (Carpiodes cyprinus), smallmouth buffalo (Ictiobus bubalus), and shorthead redhorse (Moxostoma macrolepidotum), usually at depths of 0.8–2.0 m and surface velocities of 0.4–1.0 m/s. However, apparently spawning shovelnose sturgeon were found only on mid-channel cobble and coarse gravel shoals within a single 7-km segment that included the 5-km index station, whereas apparently spawning blue suckers were encountered on these same shoals but also more widely throughout the river on eroding bluff shorelines of bedrock and boulder and on artificial boulder wing dams and shoreline rip-rap. Both species showed evidence of hom-ing to the same mid-channel shoal complexes across years. Blue sucker tended to concentrate on the shoals earlier in the spring than shovelnose sturgeon, usually from late April through mid-May at water temperatures of 8.0–15.5°C along with quillback and shorthead redhorse. In comparison, shovelnose sturgeon usually concentrated on the shoals from mid-May through early June at 13.5–21.8°C along with mooneye and smallmouth buffalo. Based on recaptures of tagged fish, at least some shovelnose sturgeon and blue sucker returned to the shoals at one-year intervals, although there was evidence that female blue sucker may have been more likely to return at two-year intervals. Most shovelnose sturgeon could not be reliably sexed based on external characteristics. Spawning shovelnose sturgeon ranged from 487 to 788 mm fork length,

Recruitment plays a fundamental role in structuring fish populations and is influenced by many abiotic and biotic variables. Identifying the variables that influence recruitment patterns in fish populations is crucial to understanding, assessing, and managing those populations. Populations of Smallmouth Bass from seven streams in Southwest Wisconsin have been sampled intensively since 1989. Scale samples were collected and catch per effort (CPE) data was calculated during each year of the study. Beginning in 2010, crews collected water temperature and streamflow data annually. Stream temperatures and flow characteristics were assessed to determine how changes in these variables influence Smallmouth Bass populations. Regression tree analyses, using the randomForest package in the R statistical program, were used to determine the importance of stream temperature and flow variables on recruitment of age-0 Smallmouth Bass from 2010-2015. July mean temperatures explain the majority of variation in CPE of Smallmouth Bass populations from 2010-2015. Temperature may be more influential than previously thought; however, six years of data may not be sufficient to fully explain what and how environmental variables affect riverine Smallmouth Bass populations in Southwestern Wisconsin.

Recruitment plays a fundamental role in structuring fish populations and is influenced by many abiotic and biotic variables. Identifying the abiotic variables that influence recruitment patterns in fish populations is crucial to understanding, assessing, and managing those populations. Populations of Smallmouth Bass from seven streams in Southwest Wisconsin have been sampled intensively since 1989. Scale samples were collected and catch per effort (CPE) data was calculated during each year of the study. Beginning in 2010, crews collected water temperature and streamflow data annually. Stream temperatures and flow characteristics were assessed to determine how changes in these variables influence Smallmouth Bass populations. Regression tree analyses, using the randomForest package in the R statistical program, were used to determine the importance of stream temperature and flow variables on recruitment of age-0 Smallmouth Bass from 2010-2015. July mean temperatures explain the majority of variation in CPE of Smallmouth Bass populations from 2010-2015. Temperature may be more influential than previously thought; however, six years of data may not be sufficient to fully explain what and how environmental variables affect riverine Smallmouth Bass populations in Southwestern Wisconsin.

Climate change may be the ultimate cause of Brook Trout (and Brown Trout) population decline or extirpation, but proximate causes may involve factors other than intolerance to high temperatures. We hypothesize that species interactions between Brook Trout, Brown Trout, and gill lice in the context of changing environmental conditions can lead to Brook Trout declines and possibly extirpation. Gill lice Salmincola edwardsii were first documented in Ash Creek, Wisconsin, USA in 2010 and became epizootic in 2012 coincident with changes in environmental conditions consistent with climate change. Gill lice infection prevalence was 95% and intensity averaged 5 and 23 (maximum 16 and 97) parasites per age 0 and age 1 or older trout; Brown Trout were not infected. Stock-recruitment data indicated a 77% decline in Brook Trout (but not Brown Trout) recruitment in 2012 compared to 2007-2011. Community dominance shifted to Brown Trout, and Brook Trout are at risk of extirpation. We present additional data from other sympatric trout populations in Wisconsin streams in which Brook Trout have declined, approaching extirpation, following recent epizootics of gill lice, which support the hypothesis that biotic interactions under stressful environmental and ultimately climatic conditions can be a proximate cause of Brook Trout loss.

We evaluated the ability of a wild brook trout population to serve as a long-term source of eggs for Wisconsin’s wild trout stocking program. We surveyed Ash Creek in spring and autumn 2004-2012 to obtain demographic data for brook trout comprising two strata: in-stream spawners and those removed for 6-8 weeks for in-hatchery spawning. The annual apparent survival rate was 0.15 and we detected no significant difference in survival between in-stream and in-hatchery spawners. Annual variability in abundance, size structure, and average fecundity resulted in variable potential egg production, which varied from 73,000 to 519,000 eggs per year and affected our ability to meet propagation objectives. The percentage of brook trout removed for egg collection ranged from 32% to 84% of female spawners. Recruitment, however, did not vary as a function of egg production. Recruitment was likely limited by flooding events and an increasing population of brown trout. Brown trout had been annually suppressed by removal until fish transfer protocols changed in 2007 following the discovery of viral hemorrhagic septicemia in Wisconsin lakes. We discuss current risks to the wild trout stocking program and management options for ensuring program viability.

The Wisconsin Department of Natural Resources (WDNR), with support from the U.S. EPA, conducted an assessment of wadeable streams in the Driftless Area ecoregion in western Wisconsin using a probabilistic sampling design. This ecoregion encompasses 20% of Wisconsin's land area and contains 8,800 miles of perennial streams. Randomly-selected stream sites (n = 60) equally distributed among stream orders 1-4 were sampled. Watershed land use, riparian and in-stream habitat, water chemistry, macroinvertebrate, and fish assemblage data were collected at each true random site and an associated "modified-random" site on each stream that was accessed via a road crossing nearest to the true random site. Targeted least-disturbed reference sites (n = 22) were also sampled to develop reference conditions for various physical, chemical, and biological measures. Cumulative distribution function plots of various measures collected at the true random sites evaluated with reference condition thresholds, indicate that high proportions of the random sites (and by inference the entire Driftless Area wadeable stream population) show some level of degradation. Study results show no statistically significant differences between the true random and modified-random sample sites for any of the nine physical habitat, 11 water chemistry, seven macroinvertebrate, or eight fish metrics analyzed. In Wisconsin's Driftless Area, 79% of wadeable stream lengths were accessible via road crossings. While further evaluation of the statistical rigor of using a modified-random sampling design is warranted, sampling randomly-selected stream sites accessed via the nearest road crossing may provide a more economical way to apply probabilistic sampling in stream monitoring programs.

Thirteen years of annual habitat and fish sampling were used to evaluate the response of a small warm water stream in eastern Wisconsin to agricultural best management practices (BMPs). Stream physical habitat and fish communities were sampled in multiple reference and treatment stations before, during, and after upland and riparian BMP implementation in the Otter Creek subwatershed of the Sheboygan River watershed. Habitat and fish community measures varied substantially among years, and varied more at stations that had low habitat diversity, reinforcing the notion that the detection of stream responses to BMP implementation requires long term sampling. Best management practices increased substrate size; reduced sediment depth, embeddedness, and bank erosion; and improved overall habitat quality at stations where a natural vegetative buffer existed or streambank fencing was installed as a riparian BMP. There were lesser improvements at locations where only upland BMPs were implemented. Despite the habitat changes, we could not detect significant improvements in fish communities. It is speculated that the species needed to improve the fish community, mainly pollution intolerant species, suckers (Castomidae), and darters (Percidae), had been largely eliminated from the Sheboygan River watershed by broadscale agricultural nonpoint source pollution and could not colonize Otter Creek, even though habitat conditions may have been suitable.