Climate change has already dramatically altered many inland waters through a combination of warming water, changes in phenology, and alterations to aquatic food webs. All of these forces can alter the growth, reproduction, survival, and behavior of fishes. Because these changes can influence fishes’ complex interactions with their habitat, predators, prey, and competitors, climate change can cause shifts in fish community composition that are difficult to prevent or reverse. Yet fishes also have the capacity to adapt to a changing environment through, for example, use of thermal refugia or changes in diet and habitat use. These adaptations may buffer the direct effects of climate change on fish populations, but may also involve trade-offs - e.g., thermal refugia may have few prey resources. For fish species targeted by recreational, commercial, Tribal, or subsistence fisheries, changes in fishing behaviors may further challenge our ability to understand and predict climate change impacts. For example, as many coolwater fishes face climate-driven declines in productivity, will fishers switch to targeting warmwater species and thus provide coolwater species with a compensatory reduction in fishing mortality? And how might managers encourage and leverage such stabilizing social-ecological feedbacks in order to confer greater resilience on harvested fish populations under climate change?
This session will integrate research from a broad range of disciplinary perspectives seeking to understand the impacts of climate change on inland fish and fisheries. We welcome submissions focused on all mechanisms by which climate change is altering the biology, ecology, or fisheries of inland fishes. We also welcome talks that address management of inland fisheries under climate change and the social or economic consequences of climate change impacts.
Lead Organizer: Olaf Jensen, Center for Limnology, University of Wisconsin-Madison (olaf.p.jensen@gmail.com)
Co-organizers:
Ashley Trudeau, Center for Limnology, University of Wisconsin-Madison (ashley.trudeau@gmail.com)
Zachary Feiner, Center for Limnology, University of Wisconsin-Madison and Wisconsin Department of Natural Resources (Zachary.Feiner@wisconsin.gov)
Presentations
04:00 PM
TROUBLE IN THE “BLUE PEARL”: A 15 YEAR STUDY OF ANTHROPOGENIC THREATS AND FISH COMMUNITY CHANGE IN MONGOLIA’S LARGEST LAKE (8391)
Primary Presenter: Olaf Jensen, University of Wisconsin-Madison (olaf.p.jensen@gmail.com)
Lake Hovsgol is the largest lake in Mongolia and the 17th largest lake in the world by volume. Despite its remote location and low local population density, Mongolia’s “Blue Pearl” is subject to many of the same threats as other large lakes around the world. Joint Mongolian-American research expeditions since 2006 show that levels of microplastic pollution rival those in more developed watersheds. Extreme regional climate warming, changes in precipitation patterns, and increased demand for fish are all factors that may be responsible for declines in abundance and mean size of many of Lake Hovsgol’s fishes. Data-limited stock assessment methods suggest that depletion of some fish species is now approaching or surpassing sustainable limits, despite official prohibitions on fishing. Life history and spawning site diversity within the endangered endemic Hovsgol grayling may provide a measure of resilience for this species. However, fishes throughout the short food chain are heavily reliant on a single species of gammarid amphipod.
04:15 PM
AGENCY AND USER RAMIFICATIONS OF CLIMATE CHANGE EFFECTS ON WISCONSIN WALLEYE FISHERIES FROM PRESENT TO END OF CENTURY (7770)
Primary Presenter: Colin Dassow, Wisconsin Department of Natural Resources (colin.dassow@wisconsin.gov)
Recreational fisheries, like many social-ecological systems, will experience varied impacts from climate change. In freshwater systems, a warming climate is expected to lead to generally warmer water temperatures. Climate vulnerable species like Walleye (Sander vitreus) that rely on cool, well-oxygenated, waters are threatened by these changes, and so too are the cultures and economies supported by them. Here, random forest models were developed to predict the ability of individual lakes around Wisconsin to support self-sustaining and put-grow-take fisheries now and in the future. These models build upon existing models of recruitment success by integrating connectivity to fluvial populations and modeling adult presence/absence in addition to natural recruitment. The results of these models are used to classify lakes into those that lose self-sustaining walleye populations and those that lose adult populations altogether, resulting in lost opportunities for tribal harvesters and anglers. Using these classifications, the cost of maintaining walleye populations via stocking in lakes that lose natural recruitment can be estimated. The model predictions and stocking cost estimates developed here support proactive planning of management strategies for individual walleye populations around the state. Given resource limitations and the climate reality in many lakes, this work can assist decision makers in developing strategies for determining where and when to stock, as well as where and when to stop stocking.
04:30 PM
THE ROLE OF AQUATIC MACROPHYTES IN PROVIDING THERMAL REFUGIA FOR WALLEYE (7873)
Primary Presenter: Quinnlan Smith, University of Wisconsin - Madison (qcsmith2@wisc.edu)
Anthropogenic stressors such as habitat loss, species introductions, and overfishing have influenced fisheries for decades and climate change threatens to compound these factors. Within the Midwest United States, Walleye (Sander vitreus) are an ecologically, economically, and culturally important coolwater fish that are threatened by loss of critical coolwater habitat. Aquatic macrophytes have been proposed as thermal refugia in littoral areas of lakes due to shading and limiting mixing of surface waters by wind, but effects have not been quantified in a whole lake comparative approach. To evaluate macrophytes as potential thermal refugia for coolwater fishes we measured water temperature at 12 littoral sites (1 and 3m) using remote sensors in Sparkling Lake, WI from May-September in 2023. We modeled water temperature at different sites over the course of the summer and quantified macrophyte influence on water temperature. Water temperatures at macrophyte sites were on average 1.13°C cooler over the summer compared to sites without macrophytes. This cooling effect of macrophytes was more pronounced during peak summer and at deeper depths, with maximum differences of up to 3°C. As climate change and warming waters continue to threaten coolwater fishes such as walleye, there is a critical need to quantify habitat that may serve as thermal refugia. Our results suggest that macrophytes may contribute to fine-scale temperature differences in littoral areas and may play a key role in providing these fishes with critical thermal refugia in north-temperate lakes.
04:45 PM
Social-ecological systems modeling of a recreational fishery under climate change (8035)
Primary Presenter: Ashley Trudeau, University of Wisconsin Madison (aatrudeau@wisc.edu)
Wisconsin’s recreational fisheries are experiencing social and ecological changes. Interactions of warming waters, increasing shoreline development, and high levels of harvest are resulting in changes to fish communities that will be difficult or potentially impossible to reverse. Of particular significance is the loss of socially and economically important coolwater species such as walleye (Sander vitreus) in many lakes. Understanding and adapting to the ramifications of these changes requires integrating what we know about changing aquatic ecosystems with the dynamic behavior of recreational anglers. We are developing a simulation model that integrates projected changes in water temperature, fish population dynamics, and recreational angler behavior to investigate their emergent effects on the Wisconsin inland lake fishery under different climate scenarios. Within this model, population dynamics and growth of walleye and bluegill populations are parameterized by empirical data specific to particular lakes or watersheds. Across days and years, simulated recreational anglers with different preferences choose fishing sites based on empirically derived tradeoffs between travel time and fishing quality. In this step of model development, we are cross-validating simulation predictions against empirical observations of fishing effort and harvest. This development of a simple but effective baseline model will allow us to test key biological and social assumptions, evaluate management alternatives, and propose strategies for climate adaptive fisheries management.
05:00 PM
Hitting a moving target: Identifying critical periods for spawning and recruitment of walleye in north-temperate lakes (8067)
Primary Presenter: Zach Feiner, Wisconsin Department of Natural Resources (zachary.feiner@wisconsin.gov)
Fish recruitment is influenced by myriad abiotic and biotic factors that vary in space and time. “Critical periods” may exist when the presence or absence of optimal environmental conditions determines year class strength; however, critical periods are difficult to identify quantitatively and may be altered by broad-scale stressors like climate change. We used a sliding windows analytical approach to identify potential critical temperature and precipitation windows for recruitment from a 57-year time series of walleye (Sander vitreus) spawning, adult abundance, and recruitment data. Walleye spawn timing was strongly influenced by the interaction of water temperature and photoperiod, with photoperiod cues more important when water temperatures were suboptimal for spawning. Using the full time-series, we observed no significant temperature or precipitation critical periods for walleye recruitment. However, when dividing the data into early (1958-1984), middle (1984-2002), and recent (2003-2019) years, precipitation in the two weeks after spawning had a strong negative effect on recruitment only in recent years. Our results suggest a growing importance of precipitation for walleye recruitment, a concern given future climate projections for a wetter Wisconsin climate. More broadly, weak evidence for clearly defined critical periods may mean that biotic variables are more important than abiotic conditions, or that the relative importance of factors are context-dependent, complicating attempts to predict year class strength using predefined environmental variables.
SS36C - Climate Change Impacts on Inland Fish and Fisheries
Description
Time: 4:00 PM
Date: 5/6/2024
Room: Hall of Ideas I