How Body Size and Food Availability Influence First‐Winter Growth and Survival of a Stocked Piscivore

Abstract

The first winter of life can play an important role in the success of age‐0 fishes. First‐winter survival is often size dependent, with larger fish exhibiting higher survival than small fish. Cohorts of age‐0 saugeye female Walleye Sander vitreus × male Sauger S. canadensis stocked into Ohio reservoirs exhibit overwinter shifts toward larger body sizes; however, it is unclear whether growth, size‐dependent mortality, or size‐dependent emigration underlie this phenomenon. Saugeye may experience low prey availability during the overwinter period, making them especially vulnerable to starvation. Furthermore, survivors emerging from winter in poor energetic condition may experience reduced spring foraging success and growth. We used a combination of overwinter PIT tag studies in the field and overwinter outdoor pool experiments to understand these direct and indirect effects of winter on survival and size distributions of cohorts of saugeye. Using PIT tags to allow us to track growth of individuals in reservoirs, we found that saugeye of all sizes increased in length over winter, there was no evidence of size‐dependent overwinter mortality, and rates of emigration out of the reservoir were greater for large saugeye than small saugeye. Thus, only growth rate, and not mortality or emigration biased toward small fish, can explain the observed overwinter shift in size distributions. In pool experiments, we found no direct effects of winter on survival, even in the complete absence of food, and no negative consequences of starvation over the winter on the ability of saugeye to resume feeding in the spring. Our results suggest that shifts in size distributions of first‐year cohorts over winter are driven by growth rather than mortality. Neither direct effects of first winter on survival nor indirect effects mediated through effects of starvation on future foraging ability are important in recruitment success of saugeye in Ohio reservoirs. Received March 18, 2014; accepted June 30, 2014

The divergent effects of moderate climate warming on the gut microbiota and energetic state of cold-climate lizards from open and semi-closed microhabitats

“…With the same survival, warming temperatures enhanced the growth rate, which is considered to have a beneficial effect on individuals and populations (e.g., Buckley et al, 2017 ; Hao et al, 2021 ; Liu et al, 2022 ). A higher growth rate allows for a larger body size before winter and enhances the survival rate over winter in ectotherms, especially for cold-climate species (e.g., Steiger, 2013 ; Kallis and Marschall, 2014 ; Lu et al, 2019 ). At the same time, we found enhancements in the sprint speed under a warming climate in both lizard species in this study ( Figures 2A,B ).…”

The effect of water temperature, prey availability and presence of conspecifics on prey consumption of pikeperch (Sander lucioperca)

“…In largemouth bass (Micropterus salmoides), swimming during the spring was affected by the winter food supply (Ostrand et al 2005). According to Kallis and Marschall (2014), starvation of age-0 saugeyes (female walleye × male sauger Sander canadensis) before entering the winter season resulted in a higher prey consumption rate following the temperature increase. The overall trends of these reports presume the importance of the prey availability to the temperate predators, including pikeperch, during and after wintering.…”

“…Depending on latitude, the winter season poses one of the biggest challenges for predatory fish triggering substantial changes of physiological functions, as a temperature decline forces them to rely more on internal energy storage to meet metabolic requirements (Ostrand et al 2005). Coldwater piscivores are well adapted to winter, however, they are rather sensitive to low prey availability in the following spring (Kallis and Marschall 2014), when their metabolic demand increases faster than their feeding rate, creating a risk of starvation (Rall et al 2010;Fussmann et al 2014).…”

Community series in the wildlife gut microbiome and its implication for conservation biology, volume II

“…With the same survival, warming temperatures enhanced the growth rate, which is considered to have a beneficial effect on individuals and populations (e.g., Buckley et al, 2017;Hao et al, 2021;. A higher growth rate allows for a larger body size before winter and enhances the survival rate over winter in ectotherms, especially for cold-climate species (e.g., Steiger, 2013;Kallis and Marschall, 2014;Lu et al, 2019). At the same time, we found enhancements in the sprint speed under a warming climate in both lizard species in this study (Figures 2A,B).…”