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Common or European carp (Cyprinus carpio) were eliminated from Lake Winona during a 1973 lake reclamation project. Multiple efforts to prevent their return and eliminate spawning opportunities have failed. Carp have remained in the lake for the past 50 years, but more recent observations of spawning activity in the lake suggest that their numbers have increased. We used shoreline electrofishing data from Lake Winona (2005–2021), along with carp abundance and effects models, to estimate the abundance of carp in Lake Winona, and to evaluate the need for future carp management within the lake. Carp size (mean TL = 614 mm, mean weight = 3.42 kg) did not differ between eastern and western basins, but densities were three times higher in the western basin (105 compared to 34 fish/hectare), and carp had significantly higher relative weights in the western (117%) versus the eastern (107%) basin. Carp biomass estimates for the eastern (116 kg/hectare) and western (360 kg/hectare) basins suggest that the lake may soon experience significant declines in macrophyte cover and other ecological damage associated with that loss. With an estimated adult carp population of >6900 fish and a carp biomass (23,750 kg) 1.5 times greater than the biomass of all carp killed during the 1973 reclamation, carp management activities (e.g., fish removal and spawning migration barriers) should be initiated soon to protect the Lake Winona game fish community. [ABSTRACT FROM AUTHOR]

The objective of this study was to assess the growth rates and general body condition of two common game fishes (largemouth bass Micropterus nigricans and bluegill Lepomis macrochirus) in a productive midwestern USA lake, Lake Winona, 20+ years after one of its two separate basins was partially dredged. We also used historical lake survey data spanning 19 years before and 15 years after dredging to assess the pre- and post-dredging growth of these species. Dredging was expected to improve the growth rates and conditions (relative weights) of both species due to post-dredging changes to lake habitats (more open water and reduced macrophyte beds) and the fish community structure in the dredged basin. Both species displayed significantly faster growth in the dredged basin, with the bluegill by age 3 and the bass by age 6. The mean relative weights of both species were significantly higher in the non-dredged basin (bass were in good condition: 106% versus 100%; bluegill were in fair condition: 84% versus 80%), although both bluegill and largemouth bass exhibited significant declines in relative weight with increasing lengths in the non-dredged basin. The growth rates for largemouth bass have declined from historical levels, especially in the non-dredged basin, whereas bluegill growth rates have remained stable or improved, especially in the dredged basin. Overall, largemouth bass and bluegill growth rates and relative weights are responding to differences in habitat and fish communities between dredged and non-dredged basins, indicating that the two lake basins are isolated enough from one another to allow for separate biological responses to occur in each. [ABSTRACT FROM AUTHOR]

The thermal conditions of transitional (ranging from warm to cold) coldwater streams impact the ranges and resource availabilities for biota inhabiting these lotic systems. With ongoing climate change and increasing land modifications, thermal boundaries may shift, altering thermal transition zones and their biotic communities. The objective of this study was to investigate the condition of trout across three forks of the Whitewater River catchment, located in southeastern Minnesota, and to investigate factors influencing fish community composition and distribution. Each fork was characterized into three separate sections: headwater (coolwater), middle (warmwater), and lower (coldwater). Springs were identified throughout each fork, with greatest concentrations in the lower sections of each fork. Using single-pass electrofishing, we sampled 61 sites across the three forks in the Whitewater River system (North = 21 sites, Middle = 19, South = 21), and catch statistics were used to calculate diversity, trout abundance, and trout condition. In general, diversity increased, and trout were healthier but less abundant in middle and headwater sections, whereas diversity decreased slightly, trout condition decreased, and trout abundance increased in lower reaches, with changes differing somewhat among forks. Canonical correlation analysis highlighted strong significant correlations showing that Simpson diversity and trout condition increase going upstream, with high non-trout abundance, while trout catch rates decrease and width narrows. The Whitewater River is a catchment exhibiting transitional temperature-pattern characteristics with generally low fish community diversity and trout conditions that range from thin, normal, and robust. Dominated by a changing landscape (agriculture) and intensifying climate change, we may begin to see stream temperatures increase along with species diversity. Understanding how spring temperature influences species composition and distribution can bring potential stressors to light, increasing our understanding of thermal conditions and helping to mitigate the negative impacts from land use and climate change. [ABSTRACT FROM AUTHOR]

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 trutta fishing 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. [ABSTRACT FROM AUTHOR]

Mundahl 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. [ABSTRACT FROM AUTHOR]

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 cepedianum in 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]