Coldwater Fish and Fisheries Working Group Report
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Coldwater Fish and Fisheries Working Group Report This report provided content for the Wisconsin Initiative on Climate Change Impacts first report, Wisconsin’s Changing Climate: Impacts and Adaptation, released in February 2011. Wisconsin Initiative on Climate Change Impacts Coldwater Fish and Fisheries Working Group Report December 2010 Coldwater Fish and Fisheries Working Group Primary Authors Matthew Mitro – WDNR, Science Services John Lyons – WDNR, Science Services Sapna Sharma – UW-Madison, Center for Limnology Working Group Participants Matthew Mitro – WDNR, Science Services – chair Mike Bozek – UW-Stevens Point/Wisconsin Cooperative Fisheries Research Unit Marty Engel – WDNR, West Central Region Andy Fayram – WDNR, Central Office Steve Greb – WDNR, Science Services Laura Hewitt – Trout Unlimited John Lyons – WDNR, Science Services John Magnuson – UW-Madison, Center for Limnology Frank Pratt Jr. – WDNR, Northern Region Dave Seibel – WDNR, Northern Region Sapna Sharma – UW-Madison, Center for Limnology Brian Sloss – UW-Stevens Point/ Wisconsin Cooperative Fisheries Research Unit Jana Stewart – USGS-Middleton Jack Sullivan – WDNR, Science Services – sponsor Gene Van Dyck WDNR, South Central Region Jake Vander Zanden – UW-Madison, Center for Limnology Dave Vetrano – WDNR, West Central Region Jordan Weeks – WDNR, West Central Region Kurt Welke – WDNR, South Central Region Steve Westenbroek – USGS-Middleton 2 WICCI Science Council Reviewers Barry Johnson George Kraft Phil Moy Jack Sullivan Additional Reviewers Laura Hewitt – Trout Unlimited Jana Stewart – USGS-Middleton Brian Wiegel – WDNR, Science Services Cover Photo Credits (Clockwise from top left) Mount Vernon Creek, Dane County – Matthew Mitro Male spawning brook trout – Matthew Mitro Cisco – John Lyons WDNR electrofishing Elk Creek, Vernon County – Matthew Mitro Brown trout in Timber Coulee Creek, Vernon County – Matthew Mitro 3 Table of Contents 5....... Executive Summary 6....... Introduction 7....... Future Climate Impacts 7…………... Streams 9…………... Lakes 10…... Vulnerability Assessment 10…... Sensitivity Analysis and Uncertainties 11…………... Climate Change Modeling—Streams 12…………... Climate Change Modeling—Lakes 13…... Adaptation Strategies 13…………... Streams 13…………………... Land Management 15…………………... Riparian Management 15…………………... Water Management 16…………………... Stream Restoration 16……………........... Triage 17…………... Lakes 18…... References 20…... Tables 24…... Figures 4 Executive Summary the state agencies entrusted to manage these resources. Anglers also make a significant Wisconsin is recognized for its contribution to our local and state economies in abundance of coldwater streams, which includes their pursuit of trout and other coldwater fishes. over 10,000 miles of classified trout streams that In the face of changing climate conditions it is provide fisheries for brook trout and brown important to assess the potential impacts to trout. Expected climatic changes in air coldwater fish and fisheries and to implement temperature and precipitation patterns across the adaptive management strategies to ameliorate state may threaten the viability of Wisconsin’s climate change impacts on Wisconsin’s inland trout resources. In this analysis, we use coldwater streams and inland lakes and their computer models to show how the distribution fisheries. of some coldwater fishes may change in We used watershed-scale models to response to climate warming and we discuss predict the changes in coldwater habitat and adaptation strategies that can be employed to distributions of coldwater fishes that might lessen the impacts of climate change on occur under three different climate change coldwater fishes in Wisconsin. scenarios. For streams, we considered three Wisconsin has rich and varied coldwater coldwater species: brown trout, brook trout, and resources including streams, spring ponds, and mottled sculpin. For stratified lakes, we thermally-stratified lakes. In addition to over considered one species: cisco. We did not have 10,000 miles of managed trout streams, another enough information to model spring ponds. 22,000 of Wisconsin’s 54,000 stream miles may For the coldwater streams and stratified be suitable for coldwater species such as mottled lakes, we ran models for each stream reach or sculpin. Wisconsin also has about 1,000 spring stratified lake in the state under current climate ponds that support coldwater fishes such as conditions and three climate warming scenarios brook trout and nearly 3,000 stratified lakes of projected for Wisconsin by the Climate Working which about 170 contain self-sustaining Group: (1) a “best case” scenario, in which populations of coldwater fishes such as cisco. summer air temperature increased by slightly Lake trout are indigenous to Wisconsin and are more than 1.8°F and water temperature by also present in some inland lakes. 1.4°F; (2) a “moderate case” scenario, in which Climatic changes in air temperature and air temperature increased by 5.4° F and water precipitation will affect water temperature and temperature by 4.3° F; and (3) a “worst case” flow in streams. Climate change will also affect scenario, in which air temperature increased by water temperature and groundwater input to 9° F and water temperature by 7.2° F. For these spring ponds. Many lakes in Wisconsin models we assumed water temperature responds thermally stratify during summer, with the the same to air temperature in all streams, there coldest layer occurring at the bottom. The was no change in precipitation across the climate suitability of this cold layer of water for change scenarios, and there was no change in coldwater fishes will be affected by climate land use over time from current conditions. change impacts on the duration of stratification These assumptions will be relaxed in future and the consequent depletion of dissolved model development. Improvements to the stream oxygen in this layer. An increase in the duration models are in progress and include capabilities of lake stratification during the open water to incorporate variation in precipitation and period will worsen the depletion of dissolved groundwater inputs across the state for use in oxygen in the coldwater layer to levels stressful predicting stream water temperatures. For the or lethal for coldwater fishes, resulting in the stratified lakes model, the model did not appear decline of populations of coldwater fishes. to be strongly sensitive to lake productivity even Coldwater fishes native to Wisconsin though lake productivity is expected to affect are an integral part of our state’s natural legacy, dissolved oxygen in the bottom cold layer of and coldwater fisheries are a core part of our water and hence lake suitability for cisco. culture and identity. The restoration of native Climate change will likely cause fisheries to Wisconsin waters is a stated goal of reductions in all coldwater habitats and fish 5 species in Wisconsin. Increases in air to those coldwater habitats most likely to realize temperature will negatively affect thermal success. Some streams, for example, may face conditions required for the persistence of inevitable losses of coldwater fishes, some may coldwater fishes. Changes in the amount and be resilient to climate impacts, and some may distribution of precipitation across the state may allow for persistence of coldwater fishes ameliorate or exacerbate the reductions in contingent on management approaches used to coldwater habitat and fishes. The magnitude of counteract climate impacts. Appropriate the reductions in coldwater fishes will therefore management actions may include environmental depend on the type and location of the habitat, adaptation strategies as well as changes to the particular fish species that live there, and the angling regulations and fish stocking strategies. nature and severity of the climate change that We expect that a proactive application of these occurs. adaptation strategies will help protect Under current conditions, our models Wisconsin’s coldwater fishes and fisheries from show mottled sculpin to be the most widespread the impacts of our changing climate. coldwater fish species in Wisconsin streams, with brook trout the least widespread and brown Introduction trout intermediate. All three species declined in distribution under all three climate change The purpose of the Coldwater Fish and scenarios. Brown trout declined least and brook Fisheries Working Group is to identify the trout the most. Under the worst-case climate potential impacts of climate change on change scenario, brook trout were predicted to coldwater fish and fisheries in Wisconsin be extirpated from Wisconsin streams, with streams and inland lakes and to develop mottled sculpin reduced in distribution by 95% management adaptation strategies in response to and brown trout by 88%. Losses of habitat were climate change impacts. The focus of the Group expected to occur evenly across the state and is to make use of existing information and to were not noticeably concentrated in any propose and implement new research where particular geographic region. The models for necessary to assess the vulnerabilities and stratified lakes indicated that climate change sensitivity of coldwater resources to climate could also cause major declines in cisco change, characterize uncertainties thereof, and populations. advance science-based management of Climate-induced changes in stream coldwater fish and fisheries by developing temperature and flow will not be uniform. adaptation strategies