SFS Annual Meeting

6/04/2024  |   13:30 - 13:45   |  Freedom Ballroom F

GROW WITH THE FLOW: INFLUENCE OF HYDROLOGIC MOSAICS ON JUVENILE SALMON GROWTH IN PROGLACIAL WATERSHEDS Riverscapes can support diverse foraging and growth opportunities for mobile consumers. In proglacial watersheds, neighboring glacier-, snow-, and rain-fed streams provide starkly contrasting habitats on small spatial scales due to differences in light penetration, temperature, discharge, biogeochemistry, and flow event timing. Streams fed by glacial melt are cold, turbid, and frequently considered unproductive; however, these harsh environments provide habitat for many fishes, including robust salmon populations in Alaskan watersheds. Glacial streams may benefit fish by providing foraging opportunities when food sources in snow- and rain-fed streams are low, generating spatiotemporal asynchronies in growth potential across hydrologically heterogeneous watersheds. Our study investigates how juvenile salmonid growth rates differ between a glacial mainstem and three adjacent rain- or snow-dominated tributaries in Southeast Alaska. We collected individual growth histories of juvenile coho salmon using mark-recapture at three paired sampling sites representing a glacial mainstem and adjacent tributary, as well as a diverse set of physicochemical hydrologic parameters. We found that tributary and mainstem habitats displayed seasonally asynchronous trends in temperature, flow, and dissolved oxygen with higher daily volatility and seasonal extremes in tributaries and relatively steady records in the glacial mainstem. Despite these contrasting physicochemical regimes, seasonal patterns of fish growth did not differ drastically between habitat types. Further research is necessary to determine whether similar growth patterns are due to undetected fish movement or varying food web phenologies. Describing fish growth within hydrologic mosaics and identifying driving factors will aid future research in navigating climate change in proglacial drainages.

Lindsey McCulloch (Primary Presenter/Author), University of Alaska Fairbanks, lcmcculloch@alaska.edu;

Ryan Bellmore (Co-Presenter/Co-Author), USDA Forest Service, james.r.bellmore@usda.gov;

Jason Fellman (Co-Presenter/Co-Author), University of Alaska Southeast, jbfellman@alaska.edu;

Naomi Boyles-Muehleck (Co-Presenter/Co-Author), University of Alaska Southeast, naomiwbm@gmail.com;

Elizabeth Bruch (Co-Presenter/Co-Author), University of Alaska Southeast, erbruch@alaska.edu;

Marie Gutgesell (Co-Presenter/Co-Author), USDA Forest Service, Marie.Gutgesell@usda.gov;

Megan McPhee (Co-Presenter/Co-Author), University of Alaska Fairbanks, mvmcphee@alaska.edu;

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6/04/2024  |   13:45 - 14:00   |  Freedom Ballroom F

WHO DOESN’T LOVE A WARM NOOK? UNDERSTANDING THE IMPACT OF LAKE SHAPE ON THE NORTHERN DISTRIBUTION OF SMALLMOUTH BASS Lake water temperature is a critical limiting factor for many species, including smallmouth bass. With climate change, smallmouth bass distribution is showing a shift northward in Ontario, Canada. Although there is much research on abiotic factors on water temperature, lake morphology has not been as extensively researched, particularly the role of lake shape and associated embayments. Due to the smaller surface areas, embayments are likely to experience warmer peak water temperatures compared to the main body and may also experience warming and cooling earlier in the spring and autumn, respectively. We investigated how embayments may provide an opportunity for warm-water species, such as smallmouth bass, along their northern distribution to enhance growth and recruitment. We simulated different size and shaped lakes, and estimated water temperature regimes using climate and water quality data from current lakes along the northern limit of smallmouth bass distribution in Ontario. The temperature regimes were then used to estimate young-of-year bass growth and survivability in each of the different lakes. We found that in lakes with embayments, young-of-year body mass increased as embayment size decreased, with up to twice the body mass in the lowest embayment size by season end, compared to the lakes with no embayments. Lakes with small embayments showed an increased chance of winter survivability of young-of-year bass, relative to lakes with less shoreline complexity. Our results suggest that considering lake morphology is crucial for estimating aquatic species growth and distribution.

Alan Bui (Primary Presenter/Author), University of Toronto, minh.bui@mail.utoronto.ca;

Donald Jackson (Co-Presenter/Co-Author), University of Toronto, don.jackson@utoronto.ca;

Brian Shuter (Co-Presenter/Co-Author), University of Toronto, brian.shuter@utoronto.ca;

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6/04/2024  |   14:00 - 14:15   |  Freedom Ballroom F

Temporal dynamics of spawning and assemblage composition of young-of-year fishes in a large Great Plains river The natural flow regime has acted to shape life history strategies of many riverine fishes. Species-specific mechanisms evoke variable responses to flow events. While some native species have persisted in systems with altered flow regimes, others have faced negative population outcomes. Despite documented success in managing water releases to enhance recruitment for species of conservation concern, knowledge of population responses to environmental flows in the Great Plains region remains limited. This study aims to develop testable predictions for flow-ecology relationships for fishes in the Kansas River, addressing three main questions: (1) How do young-of-year (YOY) species abundances change over the growing season? (2) Do shifts in YOY assemblage structure coincide with changes in discharge? and (3) How do spawning and hatch dates align with discharge? YOY fishes in the Kansas River were sampled in summer 2022 and 2023. Extended drought in 2023 resulted in prolonged low flows throughout summer and fall coinciding with a 275% increase in YOY abundance. We used generalized linear models to predict abundance as a function of year, month, and discharge. Abundance significantly increased across years and discharge (p=0.03, p=0.022, respectively) . Early life stage abundance of sand shiner Notropis stramineus, in particular, was negatively associated with discharge (p=0.008) suggesting that flow events are not essential to achieve recruitment for some small-bodied cyprinids. Our findings illustrate important contrasts in YOY fish assemblages in the Kansas River between an average and a drought year. Continued sampling will help identify specific responses under different hydrologic scenarios.

Elle Krellwitz (Primary Presenter/Author), Kansas State University, ekrellwitz@ksu.edu;

Trevor Jones (Co-Presenter/Co-Author), Emporia State University, trevorcjo@gmail.com ;

Heidi Mehl (Co-Presenter/Co-Author), The Nature Conservancy, heidi.mehl@tnc.org;

Laura Totten (Co-Presenter/Co-Author), US Army Corps of Engineers, laura.a.totten@usace.army.mil;

Keith Gido (Co-Presenter/Co-Author), Kansas State University, kgido@ksu.edu;

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6/04/2024  |   14:15 - 14:30   |  Freedom Ballroom F

Habitat Use and Resource Overlap of Blue Catfish and Channel Catfish Populations in Two Midwestern Reservoirs Changes in anthropogenic disturbances and environmental processes associated with aging reservoirs create socio-ecological systems that are inherently challenging to understand and manage. In particular, modifying reservoir management strategies, expanding species distribution, and stochastic environmental inputs can alter fish community structures and the interspecific interactions among reservoir fishes. A notable trend over the last decade in the midwestern and eastern regions of the United States is the increasing abundance of Blue Catfish Ictalurus furcatus a commercially and recreationally valuable species. The implications of increasing Blue Catfish populations are not clearly understood but could be influencing the competition for resources with other species. Previous studies have suggested prey resource competition and habitat partitioning between coexisting Blue Catfish and Channel Catfish Ictalurus punctatus populations. We used acoustic telemetry and non-lethal gastric lavage to quantify the habitat and diet of these species in Milford and Tuttle Creek reservoirs in eastern Kansas. A permutational multivariate analysis of variance (PERMANOVA) on a Euclidean distance matrix reflecting habitat use revealed no significant difference between species (p=0.524) and no significant interaction of species and reservoir (p=0.784) suggesting that Blue Catfish and Channel Catfish have overlapping habitat and potentially other resources. Stomach content analysis revealed that aquatic macroinvertebrates and fish were the shared dominant prey items for both Blue Catfish and Channel Catfish across reservoirs; however, Channel Catfish fed more opportunistically on uniquely divergent prey resources, including gar Lepisosteus spp. eggs and zebra mussels Dreissena polymorpha.

Keith Gido (Co-Presenter/Co-Author), Kansas State University, kgido@ksu.edu;

Kade Jackson (Primary Presenter/Author), Kansas State University , kadejackson123@ksu.edu;

Ben Neely (Co-Presenter/Co-Author), Kansas Department of Wildlife and Parks, ben.neely@ks.gov;

Jeff Koch (Co-Presenter/Co-Author), Kansas Department of Wildlife and Parks, jeff.koch@ks.gov;

Brett Miller (Co-Presenter/Co-Author), Kansas Department of Parks and Wildlife, brett.miller@ks.gov;

Ely Sprenkle (Co-Presenter/Co-Author), Kansas Department of Parks and Wildlife, ely.sprenkle@ks.gov;

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6/04/2024  |   14:30 - 14:45   |  Freedom Ballroom F

Cross continental analyses reveal that NEON’s fish data achieve statistical power The National Ecological Observatory Network (NEON) is designed to assess the continental patterns of ecological systems. NEON has monitored fish abundance in 23 wadeable streams from Alaska to Puerto Rico since 2016 to assess how climate and land-use affect fish assemblages. We leveraged empirical estimates of fish abundance via 3-pass depletion between 2016 and 2023 across all wadeable streams and evaluated the time to which statistical power was achieved for abundance trends of 2.5%, 5%, 7.5%, and 10% under two scenarios: 3-pass depletion across three fixed reaches and 3-pass depletion in one fixed reach. Here, we defined statistical power as the ability to reliably detect a significant trend, where trends represent the percent declines year over year of the fish abundance. First, the power to detect abundance trends of 7.5% and 10% was achieved by 20 years for all wadeable streams under NEON’s current monitoring program. Second, monitoring three versus one fixed reach decreased the time to achieve power by ~2 years among all sites. This suggests that current fish monitoring at NEON’s streams will achieve statistical power within NEON’s proposed 30-year sampling window, and that reducing the number of fixed reaches from three to one will only slightly increase the number of years to which statistical power is achieved. NEON’s stream fish data have substantial potential to assess how fish assemblages are responding to changes in climate and land-use. This example is one of many ongoing projects to explore the statistical validity of NEON’s fish data product.

Ryan McClure (Primary Presenter/Author), National Ecological Observatory Network, mcclurer@battelleecology.org;

Jeff Wesner (Co-Presenter/Co-Author), University of South Dakota, Jeff.Wesner@usd.edu;

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6/04/2024  |   14:45 - 15:00   |  Freedom Ballroom F

Length Based Estimation of Yield for Nile Tilapia Stock (Oreochromis niloticus) on Lake Hayq, Wollo, Ethiopia Abstract The study was conducted at Lake Hayq, in Wollo, Ethiopia. Data were collected daily for 365 days (6-8-2022 to 6-7-2023) in the fish landing area. Baseline information collected at the site included the length percentage of O.niloticus caught during the fishing activities, the total O.niloticus harvest, and the increase in fishing activity. The purpose of the study was to estimate the size of the O.niloticus population and the fishing mortality rate in individual length groups as well as to estimate the fish yield in the lake. The Jones length-based cohort analysis model and the Thompson and Bell length-based yield prediction model were used to estimate yield. The estimated yearly yield was 159.138 tons of tilapia per year at Lake Hayq. Keywords: current yield, fishing effort, stock assessment, tilapia

Alemken Mengist (Primary Presenter/Author), Bahir Dar University , alemkenberihun@gmail.com;

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