Trends in body condition of native piscivores following invasion of Lakes Erie and Ontario by the round goby

Abstract

1. Biological invaders can provide a highly abundant novel prey, yet the effect this has on the body condition of native predators is unknown. 2. Since invading the Laurentian Great Lakes over two decades ago, the round goby (Neogobius melanostomus) has become an important food source for many native species. 3. We used long-term data from Lakes Erie and Ontario (1993À2012) to create quantile regression models of mass-length relationships for populations of four native predators: smallmouth bass (Micropterus dolomieu), yellow perch (Perca flavescens), walleye (Sander vitreus) and burbot (Lota lota).Model-based estimates of changes in mass-at-length following the invasion were used to compare the effects of round goby on relative trends in body condition. Water temperature data were also included in the models, to investigate its effects on body condition. 4. The condition of smallmouth bass increased after the invasion, varying in magnitude between lakes and among size classes. Condition of yellow perch changed variably in direction and magnitude, depending on the quantile of the mass-length relationship examined and fish length, whereas that of walleye increased only for larger fish in Lake Ontario. Minor increases in mass-at-length were observed for the smallest length class of burbot, while the body condition of burbot in the largest length class decreased during the study period. 5. Mean summer water temperature did not differ between pre-and post-invasion time periods in Lakes Erie and Ontario, although water temperature was a significant predictor of body condition. 6. Changes in body condition may have implications for additional population and life history characteristics. Future research should investigate the effects of the round goby on growth, age at maturity, fecundity and survival of native predators.

The diet of reservoir perch before, during and after establishment of non-native tubenose goby

“…an increasing number of large adult perch appear to have switched their main foraging habitat from open water to the littoral riprap zone, resulting in an increased intake of fish overall and, possibly, reduced predation on chironomids and cyprinids in favour of the tubenose goby. It has been suggested that, by altering energy flow through the aquatic food web, gobies could potentially affect the growth rate (Hensler and Jude, 2007) and body condition (Crane et al, 2015) of native predators. In turn, as predatory fish alter their feeding habits in response to changes in prey availability (Roseman et al, 2014), native species production may also be altered through top-down effects, the effects being especially strong if the predator specialises on novel prey species.…”

What do we really know about the impacts of one of the 100 worst invaders in Europe? A reality check

“…Smallmouth bass predation on round gobies is higher in areas with earlier goby invasion, which can be explained by predator-learning ability (Brownscombe and Fox 2013). In Lake Erie and Lake Ontario, increases in smallmouth bass growth and condition following round goby invasion have been found (Steinhart et al 2004b;Reyjol et al 2010;Crane et al 2015). For white bass, there has been no consistent trend in increased growth after round goby invasion .…”

“…Round goby impacts on yellow perch (P. flavescens) have been extensively studied in the Great Lakes area (9/53; Table S2). Impacts are life stage dependent and include competition for food in the juvenile stages (Duncan et al 2011;Crane et al 2015) or one-sided predation by adult yellow perch on round gobies Lee and Johnson 2005;Truemper and Lauer 2005;Truemper et al 2006;Campbell et al 2009;Reyjol et al 2010;Taraborelli et al 2010;Crane et al 2015). The strengths of both interactions depend on the complexity of habitat structure, biotic factors, and round goby density (Reyjol et al 2010).…”

“…If predation occurs in the adult stages, round goby as novel food item can be beneficial for yellow perch. Round gobies may provide an energetic advantage over traditional prey: foraging costs should be lower when predators feed on abundant goby prey than on less-abundant and presumably harder-to-catch native prey , thus leading to a higher mass-at-length for larger yellow perch ([27.5 cm total length TL, Crane et al 2015).…”

“…Adult smallmouth bass (Micropterus dolomieu), largemouth bass (M. salmoides), rock bass (Ambloplites rupestris), and white bass (Morone chrysops) prey on round goby Dietrich et al 2006;Hogan et al 2007;Campbell et al 2009;Taraborelli et al 2010;Brownscombe and Fox 2013;Crane et al 2015). Smallmouth bass predation on round gobies is higher in areas with earlier goby invasion, which can be explained by predator-learning ability (Brownscombe and Fox 2013).…”