Browsing by Subject "Walleye"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    Development of Thermally-Enhanced Walleye Aquaculture
    (University of Minnesota Duluth, 1988-07-01) McDonald, Michael E
    The culture of walleye in Minnesota can be enhanced by the use of heated waters. Wild-caught walleye fingerlings were maintained in the Aquaculture Research Facility at Minnesota Power's Clay-Boswell Plant. These fingerlings were subsequently induced to feed on a pelleted dry feed and to grow, increasing their size 8.8 times. Fingerling mortality within the facility after conversion to dry diet was minimal. Feed conversion (food fed to body weight increase) ranged from 2.2 to 3.2 over the project's duration. Growth predictions from walleye bioenergetics models, developed for each of the strains in the Aquaculture Research Facility, were extremely close to actual growth in the facility (within 2%). Because of the short duration of the project, it is too early to assess the walleye model's ability to predict mortality and food conversion efficiency. However, initial inspection suggests that it may predict walleye mortality (after fish have switched to dry diet) quite well, but does not predict food conversion well at this point. The walleye bioenergetics model appears to provide a means of detecting growth differences in different strains of walleye, which could be extremely valuable in choosing faster growing strains for future culture.
  • Thumbnail Image
    Item
    Evaluation of stock assessment methods for commercial walleye (Sander vitreum) Fishery of Red Lakes, MN.
    (2010-05) Takade, Helen Mariko
    In 1997, the Red Lakes walleye (Sander vitreus) fishery was closed due to extremely low population numbers and a massive rehabilitation program was started for the walleye in 1998, by tribal, state and federal authorities, because of the ecological, economic, and cultural importance of the walleye fisheries. Management authorities recognized that a stock assessment of some manner would be necessary to monitor the reopened fishery if it were to be maintained on a sustainable basis. However, it would be necessary to choose from a variety of methods, ranging in complexity from an index of abundance to an age-structured method such as a statistical catch-at-age model. The primary goal of this research is to examine different types of models that may be appropriate for use in the fishery and determine how they may perform when used for the Red Lakes fishery. A secondary goal was to determine if a simulation of potential unaccounted for catch or if previous research into annual growth factors might improve the predictive capability of the delay-difference model. This research found that generally, the age-structured models performed better than the delay-difference model, the inclusion of the walleye environmental coefficients improved the fit of the delay-difference model, the assumed black market catch resulted in only limited improved fit of the delay-difference model with general increases in fishing effort, and the environmental coefficients had limited explanatory power in changes in population abundance.
  • Thumbnail Image
    Item
    Fish growth and degree-days: Advice for selecting base temperatures in both within- and among-lake studies
    (2013-08) Chezik, Kyle August
    Ectotherm growth and development are largely a function of temperature. Within the range of thermal tolerance, growth and development increases linearly over a mid-range of temperatures. Degree-days (DD; °C;days) are a method of quantifying the thermal experience of an organism over the linear range and are an increasingly popular method for describing growth and development in fish. To limit degree-day calculations to temperatures within the linear range, a lower temperature threshold (To) is incorporated that defines the onset of growth. However, there is currently no convention for choosing To and the implications of choosing an inappropriate To are largely unknown. This uncertainty has resulted in a wide range of To values currently in use both among- and within-species. In this thesis I explore i) how To affects the ability of DD to explain within-population variation in fish growth, and ii) the effect of To on apparent growth among populations in thermally dissimilar environments. To address these objectives, I first use simulated data to determine the theoretical relationship between To and growth. I then demonstrate these theoretical relationships using immature length-at-age data from 8 species and 85 waterbodies in Minnesota USA and Ontario Canada. My results show that DD at low To are highly correlated and that these highly correlated low To values explain variation in growth equally well within a single population. Furthermore, growth rates among populations of thermally dissimilar habitat become increasingly dissimilar as To deviates from the To that minimizes the variation in growth rate among populations. This effect is especially apparent when the among-population range in thermal habitats is large. These findings suggest that, although To matters little when accounting for variation in growth within a single population, an inappropriate To can lead to the appearance of among-population differences in growth. When choosing To, I recommend estimating To using the Charnov and Gillooly (2003) “10°C rule” and then rounding to the nearest To standard (0, 5, 10 and 15°C). Choosing a To standard in this way will minimize the effect of To error on growth bias in among-population studies. In general, standardization i) simplifies To identification, ii) facilitates comparative studies, and ii) promotes the use of DD in future studies.
  • Thumbnail Image
    Item
    Mimicking Nature: How water level management on a large reservoir affects walleye (Sander vitreus) spawning habitat
    (2015-08) Papenfuss, Jason
    The Namakan Reservoir, located on the Minnesota-Ontario border, has been successively managed under two water-level management policies (‘rule curves’) in recent decades. To compare the effects of the rule curves on walleye spawning, I modeled wave energy, ice scour, and habitat availability at 44 spawning locations. Wave energy increased (18% for observed water levels, 6% for modeled water levels) and ice scour decreased 11% (both P < 0.01) over spawning habitat during the most recent rule curve. Observed water level data suggested available spawning habitat on Lake Kabetogama increased 95% (P < 0.01), but availability on Namakan and Sand Point Lakes was unaffected. However, when controlling for weather events, habitat availability increased significantly (Kabetogama = 179%, Namakan = 72%, Sand Point = 93%, P < 0.01) on all three lakes. These findings suggest that the most recent rule curve is likely to improve reproductive success for walleye in the reservoir.
  • Thumbnail Image
    Item
    Sport Fish Behavioral Responses to a Littoral Coarse Woody Habitat Addition in a North-temperate Lake
    (2021-05) Smith, Quinnlan
    The availability of suitable habitat throughout an ecosystem is important for the long-term sustainability of natural resources. Coarse woody habitat (CWH) littoral zone additions to north-temperate glacial lakes in the Midwestern United States have become popular to mitigate the effects of increased and intensified lakeshore residential development (LRD) and associated removals of natural CWH. Relatively few of these CWH additions have been treated as deliberate experiments regarding fish and aquatic ecosystem responses. Whole-lake CWH removal experiments have shown detrimental effects on fishes that use the habitat for foraging, refuge, and spawning. Whole-lake CWH additions that have been treated as deliberate experiments have shown increased availability and diversity of prey available to fishes as well as pronounced behavioral changes; however, many of these studies have only focused on singular behavioral responses in singular species and in simple fish communities. To address questions of multiple fish behavioral responses in a complex fish community to CWH addition, a long-term study was initiated on Sanford Lake, Vilas County, Wisconsin, where 160 trees were added to the littoral zone of the lake in summer 2018. I tested for behavioral responses in muskellunge (Esox masquinongy), smallmouth bass (Micropterus dolomieu), and walleye (Sander vitreus) to this CWH addition. To test for behavioral responses to CWH addition, I used radio telemetry data to estimate home range changes, and passive integrated transponder (PIT) data along with radio telemetry data to estimate movement rates between habitats in muskellunge, smallmouth bass, and walleye during pre-manipulation (2017) and post-manipulation (2018 and 2019) time periods. Across species, home ranges and movement rates between habitats increased following the large-scale CWH addition. In the following chapters, I show that complex, species-specific behavioral responses to CWH addition can be expected, and should be taken into consideration before implementing littoral habitat enhancements in diverse fish communities.