Projected shifts in fish species dominance in Wisconsin lakes under climate change

Abstract

Temperate lakes may contain both coolwater fish species such as walleye (Sander vitreus) and warmwater fish species such as largemouth bass (Micropterus salmoides). Recent declining walleye and increasing largemouth bass populations have raised questions regarding the future trajectories and management actions for these species. We developed a thermodynamic model of water temperatures driven by downscaled climate data and lake-specific characteristics to estimate daily water temperature profiles for 2148 lakes in Wisconsin, US, under contemporary (1989US, under contemporary ( -2014 and future (2040-2064 and 2065-2089) conditions. We correlated contemporary walleye recruitment and largemouth bass relative abundance to modeled water temperature, lake morphometry, and lake productivity, and projected lake-specific changes in each species under future climate conditions. Walleye recruitment success was negatively related and largemouth bass abundance was positively related to water temperature degree days. Both species exhibited a threshold response at the same degree day value, albeit in opposite directions. Degree days were predicted to increase in the future, although the magnitude of increase varied among lakes, time periods, and global circulation models (GCMs). Under future conditions, we predicted a loss of walleye recruitment in 33-75% of lakes where recruitment is currently supported and a 27-60% increase in the number of lakes suitable for high largemouth bass abundance. The percentage of lakes capable of supporting abundant largemouth bass but failed walleye recruitment was predicted to increase from 58% in contemporary conditions to 86% by mid-century and to 91% of lakes by late century, based on median projections across GCMs. Conversely, the percentage of lakes with successful walleye recruitment and low largemouth bass abundance was predicted to decline from 9% of lakes in contemporary conditions to only 1% of lakes in both future periods. Importantly, we identify up to 85 resilient lakes predicted to continue to support natural walleye recruitment. Management resources could target preserving these resilient walleye populations.

Flexible Classification of Wisconsin Lakes for Improved Fisheries Conservation and Management

“…For example, Walleye were uniformly more abundant in cool lakes (and were most abundant in two-story lakes), a pattern consistent with other research on the species (Jobling 1981;Van Zuiden and Sharma 2016;Hansen et al 2017;Rypel et al 2018). These results also align with previous research characterizing the species as best suited for warm, clear-water habitats (Rypel 2009;Hansen et al 2017). In contrast, Largemouth Bass showed the highest abundances in warm lakes, especially warm-clear lakes.…”

“…For example, Walleye were uniformly more abundant in cool lakes (and were most abundant in two-story lakes), a pattern consistent with other research on the species (Jobling 1981;Van Zuiden and Sharma 2016;Hansen et al 2017;Rypel et al 2018). For example, Walleye were uniformly more abundant in cool lakes (and were most abundant in two-story lakes), a pattern consistent with other research on the species (Jobling 1981;Van Zuiden and Sharma 2016;Hansen et al 2017;Rypel et al 2018).…”

“…Climate change in particular is rapidly changing the fisheries ecology of lakes in Wisconsin and elsewhere (Lynch et al 2016;Winfield et al 2016;Hansen et al 2017). The dynamics of fish populations and communities are strongly regulated by temperature; thus, climate change is rapidly re-organizing fisheries (Tonn 1990;Lyons et al 2010;Magee et al 2018;Myers et al 2018;Rypel et al 2018).…”

Predicting Impact of Climate Change on Water Temperature and Dissolved Oxygen in Tropical Rivers

“…Future climate change indeed will impact the species composition of tropical rivers, leading to a dominance of warm water species that are able to adapt to a low DO concentration level and a consistently high water temperatures condition. As suggested by Hansen et al [66], warm water species can quickly adapt to climate change compared to cold-water species. Understanding the effects of climate and predicting the effects of future climate change on water temperature and DO concentration on the river ecology is critical for effective resource management [67].…”

Large-scale modeled contemporary and future water temperature estimates for 10774 Midwestern U.S. Lakes

“…Preliminary methods used to model lake temperatures for 2,368 lakes in Wisconsin, USA were described in brief in previous publications 16,17 . Here we document the entire modeling process, highlighting improvements and updates to the modeling approach.…”