Food Habits of Fall-Collected Age-0 Walleyes in Eastern South Dakota Glacial Lakes

Food habits of age-0 fishes can influence their growth and survival prior to the first winter (Hoxmeier et al. 2006, Shoup and Wahl 2011). Ontogenetic diet shifts in juvenile piscivorous fishes result in a transition in consumption from zooplankton to macroinvertebrates and eventually fish throughout development (Mittelbach and Persson 1998). Certain food items may be more energetically beneficial to fishes than others as consumption of prey fishes may lead to faster growth rates of predators, decreased overwinter starvation, avoidance of competition, and reduced predation risk (Werner and Gilliam 1984). By the time age-0 walleyes (Sander vitreus) have reached lengths of 60–80 mm total length (TL), their diets are predominantly composed of fish (Priegel 1969, Quist et al. 2002, Galarowicz and Wahl 2005). Previous studies have examined age-0 walleye food habits in South Dakota in a limited number of waters at various times and the majority of fall diets were composed of fish (Beck et al. 1998, Blackwell et al. 1999). Fathead minnows (Pimephales promelas), rainbow smelt (Osmerus mordax), yellow perch (Perca flavescens), darters (Etheostoma spp.), and gizzard shad (Dorosoma cepedianum) have all been documented as regionally important prey fish species for juvenile walleyes (Jackson et al. 1992, Beck et al. 1998, Blackwell et al. 1999, Pelham et al. 2001, Uphoff 2012). Although generalized feeding ecology of walleye during early life stages has been investigated, previous studies have only examined food habits in either a controlled setting or limited number of waters, thereby potentially overlooking spatial differences in feeding ecology. Therefore, this study examined food habits of age-0 walleye collected during fall across a range of eastern South Dakota glacial lakes

Diets of double-crested cormorants in the Lake Winnebago System, Wisconsin

Double-crested cormorant Phalacrocorox auritus Lesson (cormorant) populations have increased throughout the Great Lakes region of North America causing concern related to the impact of cormorant predation on fish communities. A recent decline in yellow perch Perca flavescens (Mitchill) abundance within the Lake Winnebago System, Wisconsin, USA, prompted an assessment of cormorant diets to evaluate potential effects of cormorant predation on the sportfish community. Diets were collected from 883 cormorants (417 from Lake Winnebago and 466 from Lake Butte des Morts) between 2015 and 2017. Cormorant diets on both waterbodies consisted mostly of freshwater drum Aplodinotus grunniens Rafinesque and gizzard shad Dorosoma cepedianum (Lesueur). Yellow perch and walleye Sander vitreus (Mitchill) observations were infrequent and represented \u3c 5% of cormorant diets by weight each year. Under current conditions, cormorant predation likely has minimal impact on the Lake Winnebago sportfish community, but more research is needed to assess potential impacts on Lake Butte des Morts

FOOD HABITS OF FALL-COLLECTED AGE-0 WALLEYES IN EASTERN SOUTH DAKOTA GLA- CIAL LAKES

Food habits of age-0 fishes can influence their growth and survival prior to the first winter (Hoxmeier et al. 2006, Shoup and Wahl 2011). Ontogenetic diet shifts in juvenile piscivorous fishes result in a transition in consumption from zooplankton to macroinvertebrates and eventually fish throughout development (Mittelbach and Persson 1998). Certain food items may be more energetically beneficial to fishes than others as consumption of prey fishes may lead to faster growth rates of predators, decreased overwinter starvation, avoidance of competition, and reduced predation risk (Werner and Gilliam 1984). By the time age-0 walleyes (Sander vitreus) have reached lengths of 60–80 mm total length (TL), their diets are predominantly composed of fish (Priegel 1969, Quist et al. 2002, Galarowicz and Wahl 2005). Previous studies have examined age-0 walleye food habits in South Dakota in a limited number of waters at various times and the majority of fall diets were composed of fish (Beck et al. 1998, Blackwell et al. 1999). Fathead minnows (Pime- phales promelas), rainbow smelt (Osmerus mordax), yellow perch (Perca flavescens), darters (Etheostoma spp.), and gizzard shad (Dorosoma cepedianum) have all been documented as regionally important prey fish species for juvenile walleyes (Jackson et al. 1992, Beck et al. 1998, Blackwell et al. 1999, Pelham et al. 2001, Uphoff 2012). Although generalized feeding ecology of walleye during early life stages has been investigated, previous studies have only examined food habits in either a controlled setting or limited number of waters, thereby potentially overlooking spatial differences in feeding ecology. Therefore, this study examined food habits of age-0 walleye collected during fall across a range of eastern South Dakota glacial lakes

Ways of working

Ways of working details the development of workshops for primary age children focusing on the giving and receiving of feedback during selected tasks. This is the first stage in work on peer coaching skills with this age group. The paper discusses the rationale for the chosen tasks and the changes made to the workshops through the experiences with different groups of children. The paper ends with reflections on the process by the researchers from different backgrounds and suggests ways of moving forward with this area

FOOD HABITS OF FALL-COLLECTED AGE-0 WALLEYES IN EASTERN SOUTH DAKOTA GLA- CIAL LAKES

Food habits of age-0 fishes can influence their growth and survival prior to the first winter (Hoxmeier et al. 2006, Shoup and Wahl 2011). Ontogenetic diet shifts in juvenile piscivorous fishes result in a transition in consumption from zooplankton to macroinvertebrates and eventually fish throughout development (Mittelbach and Persson 1998). Certain food items may be more energetically beneficial to fishes than others as consumption of prey fishes may lead to faster growth rates of predators, decreased overwinter starvation, avoidance of competition, and reduced predation risk (Werner and Gilliam 1984). By the time age-0 walleyes (Sander vitreus) have reached lengths of 60–80 mm total length (TL), their diets are predominantly composed of fish (Priegel 1969, Quist et al. 2002, Galarowicz and Wahl 2005). Previous studies have examined age-0 walleye food habits in South Dakota in a limited number of waters at various times and the majority of fall diets were composed of fish (Beck et al. 1998, Blackwell et al. 1999). Fathead minnows (Pime- phales promelas), rainbow smelt (Osmerus mordax), yellow perch (Perca flavescens), darters (Etheostoma spp.), and gizzard shad (Dorosoma cepedianum) have all been documented as regionally important prey fish species for juvenile walleyes (Jackson et al. 1992, Beck et al. 1998, Blackwell et al. 1999, Pelham et al. 2001, Uphoff 2012). Although generalized feeding ecology of walleye during early life stages has been investigated, previous studies have only examined food habits in either a controlled setting or limited number of waters, thereby potentially overlooking spatial differences in feeding ecology. Therefore, this study examined food habits of age-0 walleye collected during fall across a range of eastern South Dakota glacial lakes

Effects of Simulated Cold Fronts on the Survival and Behaviour of Yellow Perch Perca Flavescens Yolk-sac Fry

Acute reductions in water temperature (i.e. cold fronts) may influence larval fish survival directly via limits on physiological tolerance or indirectly by acting as a sublethal stressor. The primary objective was to quantify survivorship of yellow perch yolk-sac fry exposed to two different temperature declines (4 and 8°C) and compare survivorship to that of perch fry under ambient temperatures representative of natural conditions. Behaviour of yolk-sac fry following temperature declines was also qualitatively assessed. Mean survival in the control, −4, and −8 treatment tanks was 90, 91 and 97%, respectively, and no significant differences in percent survival were observed between the control and the −4 treatment (ts = −0.10; df = 7; P = 0.93), the control and −8 treatment (ts = −1.85; df = 7; P = 0.11) or the −4 and −8 treatments (ts = −1.33; df = 7; P = 0.22). Observations of yellow perch eggs and fry behaviour following temperature declines differed among treatments. Any remaining eggs in the control treatment and −4 treatments continued to hatch during the experiment, and fry were documented swimming throughout the water column in all tanks. However, in the −8 treatment, any eggs that had not hatched remained inactive and all fry within all −8 treatment tanks ceased swimming activity and settled to the bottom of the tanks once the temperature reached 3.9°C. Fry remained at the bottom of the tanks for the entire 48 h simulated cold-front. Fry resumed swimming activity once water temperatures began to increase (by approximately 6°C). Results indicated that drops in temperature (i.e. cold fronts) similar to or greater than those found in small impoundments did not cause direct mortality of yellow perch during the yolk-sac fry (post-hatch larvae) stage. Although an acute drop in temperature may not induce sudden high mortality, it may be a sub-lethal stressor, leading to increased starvation or predation risk

Influence of Smallmouth Bass Predation on Recruitment of Age-0 Yellow Perch in South Dakota Glacial Lakes

We estimated the influence of predation by Smallmouth Bass Micropterus dolomieu on recruitment of age-0 Yellow Perch Perca flavescens in two northeastern South Dakota glacial lakes. We estimated a likely range in consumption of age-0 Yellow Perch using Smallmouth Bass diet information from two time periods when age-0 Yellow Perch constituted high (2008) and low (2012 and 2013) proportions of Smallmouth Bass diets, and bass population size estimates as inputs in a bioenergetics model. The proportion of age-0 Yellow Perch consumed by the Smallmouth Bass populations was determined by comparing estimates of consumption with estimates of age-0 perch production. During 2008, age-0 Yellow Perch constituted between 0% and 42% of Smallmouth Bass diets by weight, whereas during 2012 and 2013, age-0 perch constituted between 0% and 20% of bass diets by weight. Across both lakes and time periods, production of age-0 Yellow Perch ranged from 0.32 to 1.78 kg.ha -1 week -1. Estimates of Smallmouth Bass consumption measured during the same intervals ranged from 0.06 to 0.33 kg.ha -1 week-1, equating to consumption of between 1% and 34% of the available Yellow Perch biomass. Given current conditions relative to Smallmouth Bass abundance and consumption dynamics and production of age-0 Yellow Perch, it does not appear that Smallmouth Bass predation acts as a singular factor limiting recruitment of age-0 Yellow Perch in our study lakes. However, future research and management initiatives should recognize that the long-term impact of Smallmouth Bass predation is not static and will likely fluctuate depending on environmental (e.g., temperature) and biotic (e.g., trends in macrophyte abundance, predator and prey population structure and abundance, and predatory fish assemblage dynamics) characteristics