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Long‐term effects of evolving fisheries management, changing angler practices, and stream habitat development on stream trout fisheries in southeastern Minnesota, USA, were examined by analyzing data on >1,000 weekly winners from a single‐watershed, catch‐and‐harvest Brown Trout Salmo truttafishing contest spanning 54 years. The weights of winning fish declined significantly across the period examined. No‐entry weeks increased within the past two decades, corresponding to expanding catch‐and‐release fishing. The streams that produced winning fish shifted as stream access increased, degraded stream habitat was improved, and various angling restrictions were instituted. Most winning fish were caught with live or preserved bait, although the proportion of winners caught with artificial lures doubled from the 1960s to the 2010s. The interpretation of contest results must consider various angling regulations (e.g., protected slot lengths, artificial lures only, catch and release only) that were placed on some reaches during and after the 1980s, increasing voluntary catch‐and‐release practices of contemporary anglers, and expanding stream access and habitat improvements within the watershed.

AbstractMundahl ND, Hoisington J. 2020. Game fish response to dredging of a eutrophic urban lake in Minnesota. Lake Reserv Manage. 37:170–185. We compared relative abundances, average weights, and growth rates of 6 game fish species before and after the 1999–2001 partial dredging of Lake Winona, a eutrophic, urban lake in Minnesota, to determine whether lake dredging sustainably changed fish population structure to the benefit of anglers. Relative catch rates (trap nets, gill nets, electrofishing) and growth rates were obtained from various fish population assessments and lake surveys conducted by the Minnesota Department of Natural Resources (MN DNR) from 1980 to 2016 for both Lake Winona and Lake Oscar, an ecologically similar lake that has not been dredged. Before-after control-impact (BACI) analyses revealed that compared to Lake Oscar, relative catch rates in Lake Winona after dredging declined significantly for bluegill (Lepomis macrochirus), black crappie (Pomoxis nigromaculatus), and northern pike (Esox lucius), and increased significantly for walleye (Sander vitreus) and largemouth bass (Micropterus salmoides). Average weights of yellow perch (Perca flavescens) and pike increased significantly after dredging. Only black crappie displayed improved growth after dredging. Largemouth bass catch rates for quality- and preferred-size fish increased in postdredging surveys. Although predredging data are lacking, population size structures and relative weights of bluegill, crappie, and bass post dredging were within ranges that meet MN DNR management objectives. Overall, dredging of Lake Winona was followed by improved quality and structure of game fish populations in this system, something that decades of previous biomanipulation and macrophyte management had not accomplished.

Background: Watersheds dominated by agriculture often have significant, negative impacts on local stream habitats and fauna. Our study examined stream biota and habitats within an entire stream in a karst agricultural landscape to determine if several decades of watershed conservation and management had reversed the severe degradation caused by poor land use and catastrophic soil erosion during the 1920s and 1930s. Results: Fish communities and stream habitats were degraded at over half of the 22 stream sites examined, and benthic macroinvertebrate communities were mostly poor throughout the entire stream. Poor fish communities were associated with missing or narrow riparian buffers, high percent fine sediments, high embeddedness of coarse substrates, and homogeneous run habitat. Invertebrate communities were dominated by filter-feeding taxa and those adapted to life on or within fine sediments. Stream sites with wide buffers and influenced by groundwater springs had higher fish community integrity and good to excellent instream habitat. Conclusions: Our results suggest that wide riparian buffers and karstic springs may have allowed recovery of some stream reaches, but more extensive buffers and additional soil conservation practices in upland areas likely are necessary to protect most stream segments and their biota from on-going agricultural activities. New state stream buffer laws instituted after this study resulted in establishment of vegetated buffers at all study sites, which may lead to improved stream habitat and biotic communities in future years. Benthic invertebrate community improvement also may require translocation of sensitive taxa from nearby watersheds due to limited dispersal abilities of many species currently absent from the study stream. Increased frequency and intensity of storm events and flooding may hinder future recovery of stream habitats and biota.

The article discusses a study on the incubation of a Wood Duck hen on an open stick nest in a residential yard on the shoreline of Weaver Bottoms backwater marsh of the Upper Mississippi River of Wabasha County in southeastern Minnesota in May/June 2009. It provides a description of the nest in the said area and discusses the nesting behavior of the Wood Duck hen. It discourages the use of open nesting strategy by wood ducks as it presents risk from inclement weather and nest predators.

The thermal tolerance (critical thermal maximum, CTM) of field-acclimatized Orconectes rusticus was examined on both a seasonal and diel basis. Seasonal changes in stream water temperature from 2.5 to 33.0°C caused a 10.8°C elevation (27.4 to 38.2°C) in mean CTM of adult O. rusticus. Juvenile O. rusticus exposed to a 6.9°C diel temperature change during summer altered their mean CTM by 1.2°C. Excessively high water temperatures (>39°C) in an isolated stream pool in southwestern Ohio during mid-July forced most O. rusticus to abandon the pool and dig burrows in sand and gravel beneath rocks near the shoreline. Mean water temperature in these burrows was >6°C cooler than that of the open pool. Orconectes rusticus physiologically adjusts its thermal tolerance to compensate for both seasonal and diel changes in its natural environment, but when temperatures change rapidly and become too high the species may search for or create cooler thermal refugia.

Abundance and growth of Ephemerella subvaria, E. invaria, and Isoperla signata nymphs were examined at five riffle sites near a surface-release hydroelectric power plant on the Sturgeon River in northern Michigan. Abundance (51/m2) and growth of E. invaria nymphs were similar at sites above and below the plant. Growth of I. signata nymphs was similar at all sites, but nymphs were 6× more abundant (46/m2vs.7/m2) below the power plant. Ephemerella subvaria nymphs grew more slowly, but were 4× more abundant (136/m2vs.33/m2), below the power plant. Growth rates of E. subvaria increased as distance below the plant increased, but at 10 km below the power plant growth rates were still lower than those above the plant. The presence of macrophytes and the release of seston from the reservoir resulted in high densities of invertebrates immediately below the power plant. Releases of warm reservoir surface waters by the power plant in autumn suppressed the growth rates of E. subvaria nymphs near the plant, but apparently had no observable effect on growth rates of the other species examined.

A population of central stonerollers, Campostoma anomalum, in Harker's Run, Butler County, Ohio U.S.A., was examined during autumn, 1980, to determine the species' movements, density, and home range size. During the study period, 170 fish were marked by fin clips and released into the specific pool or riffle where they were captured within the 187 m study section. Eighty percent of the recaptured, marked fish (20) were recaptured in their initial capture area (specific pool or riffle). No fish moved more than 135 m from its original capture area. Density estimates of C. anomalumfor each pool and riffle within the study section ranged from 0.10–3.91 fish m−2(mean = 1.25 fish m−2). Home range size was estimated to be 35.2 ± 14.1 m (mean ± 95% CI) of stream length. Campostoma anomalumin Harker's Run occurred at densities similar to those reported for the species in other streams, and their home ranges in this system were of similar size to those of other small, stream-dwelling fishes.

Adult bowfins Amia calvawere reintroduced (initial density approximately 32 fish/ha) into Lake Winona, Minnesota, from 1984 to 1986 to evaluate their effectiveness in controlling overabundant, stunted bluegills Lepomis macrochirusand other sunfishes (centrarchids) in a system with extensive macrophyte beds. Bowfin catch rates (trap nets, gill nets and electrofishing) declined rapidly after reintroductions ended in 1986. Catch rates and growth rates of bluegill and black crappie Pomoxis nigromaculatushave not changed since bowfin reintroduction. In 1992, only adult bowfins (average age, 10 years; average weight, 2.4 kg) were captured in Lake Winona, and they were concentrated in or near dense macrophyte beds. The final population estimate for bowfin in the west basin was 114 fish (3.17 fish/ha). Captive bowfins exhibited no size selection when feeding on sunfish and consumed on average less than 5 sunfish/24 h. Bowfin consumption rates declined by 80% when the density of artificial vegetation exceeded 500 stems/m2. Bowfins preferred both fathead minnows Pimephales promelasand virile crayfish Oronectes virilisover sunfish in prey choice trials. Lack of natural reproduction by bowfins in Lake Winona, their rapid decline in numbers after stocking, and their low rate of sunfish consumption may explain why bowfins apparently have been ineffective in controlling the lake's bluegill population.

Orconectes rusticus currently is undergoing an explosive range expansion in the midwestern U.S.A., but information on the potentially important effects of water temperature on the species' biology is lacking. The thermal ecology of O. rusticus in southwestern Ohio, U.S.A., was examined by determining 1) the effects of four water temperatures (16, 20, 25, and 29°C) on survival and growth of juveniles, 2) the responses of juveniles and adults to a thermal gradient (7–27° C), and 3) the thermal tolerances (critical thermal maximum, CTMax, and critical thermal minimum, CTMin) of free-living, field-acclimatized juveniles and adults on a biweekly basis throughout the summer. Month-long growth experiments predicted maximum growth rates of juveniles at water temperatures between 26 and 28°C, but greatest survival between 20 and 22° C. Laboratory-acclimated (22° C) adults and field-acclimatized (2.5° C) juveniles both had an acute preferred temperature of 22° C. CTMaxs and CTMins of juveniles were 0.5–2.6° C higher than those of adults throughout the summer, suggesting that juveniles were exposed to water temperatures 1.5–6.8° C warmer than those of adults. Juvenile and adult O. rusticus prefer habitats where water temperatures favor maximum survival, but they usually are not found together in the same habitat; adults apparently displace the juveniles into warmer habitats. Warmer temperatures can decrease survival of juveniles but improve their growth rates, leading to enhanced fecundity and competitive ability. The past and future success of O. rusticus in expanding its range may depend, in part, on the species ability to adjust to new thermal environments occupied by other species of crayfish.

Selective feeding on and digestion of detritus in surface sediments (organic matter < 10%, nitrogen < 0.4%) by age-0 and adult (ages 3 and 4) gizzard shad Dorosoma cepedianumin Acton Lake, Ohio (water temperature = 15–18°C) were compared with those of age-0 fish fed two particulate diets (low-quality diet: organic matter = 10%, nitrogen = 0.3%; high-quality diet: organic matter = 89%, nitrogen = 6.7%) at 18°C in the laboratory. Fish feeding on natural detritus and the low-quality diet exhibited mean selection efficiencies, ratios of nutrient weight percentages in the gizzard to those in the sediment or food, of 1.8–2.9 for total organic matter, 2.4–4.4 for total carbon, and 3.2–13.2 for total nitrogen. Fish fed the high-quality diet exhibited no selective feeding. Mean digestive efficiencies, 100 [ 1 – (feces value ÷ gizzard value)], for total organic matter, total carbon, and total nitrogen in the diets had ranges of 50–66, 51–64, and 62–84%, respectively. Age-0 fish feeding on natural detritus and the two laboratory diets exhibited similar digestive efficiencies. In addition, age-0 and adult gizzard shad were equally efficient at digesting the components of natural detritus. Gizzard shad apparently can ingest selectively the more nutritious portions of low-quality particulate diets in the field and laboratory and digest a substantial proportion of the nutrients present.

A study was conducted to evaluate the influence of water temperature on food evacuation and feeding activity in age-0 gizzard shad Dorosoma cepedianum fed pulverized food. Fish kept at 5°C exhibited little feeding activity. At temperatures of 10, 15, and 20°C, food was evacuated through the digestive tract in 8.5, 4.9, and 4.4 h, respectively. Frequency of feeding acts also increased significantly with increased water temperature. These data, along with information on the dry weights of natural detritus in full digestive tracts of gizzard shad (ages 0–2) from Acton Lake, Ohio, were used to estimate the daily amounts of natural detritus consumed by age-0 fish. We concluded that a 6-g, age-0 fish can ingest and process natural detritus (dry weight) in amounts ranging from 3.2 to 7.7% of wet body weight per day.