Angler‐Caught Piscivore Diets Reflect Fish Community Changes in Lake Huron

Abstract

Examination of angler‐caught piscivore stomachs revealed that Lake Trout Salvelinus namaycush, Chinook Salmon Oncorhynchus tshawytscha, and Walleyes Sander vitreus altered their diets in response to unprecedented declines in Lake Huron's main‐basin prey fish community. Diets varied by predator species, season, and location but were nearly always dominated numerically by some combination of Alewife Alosa pseudoharengus, Rainbow Smelt Osmerus mordax, Emerald Shiner Notropis atherinoides, Round Goby Neogobius melanostomus, or terrestrial insects. Rainbow Trout Oncorhynchus mykiss (steelhead), Coho Salmon Oncorhynchus kisutch, and Atlantic Salmon Salmo salar had varied diets that reflected higher contributions of insects. Compared with an earlier (1983–1986) examination of angler‐caught predator fishes from Lake Huron, the contemporary results showed an increase in consumption of nontraditional prey (including conspecifics), use of smaller prey, and an increase in insects in the diet, suggesting that piscivores were faced with chronic prey limitation during this study. The management of all piscivores in Lake Huron will likely require consideration of the pervasive effects of changes in food webs, especially if prey fish remain at low levels. Received December 19, 2013; accepted June 30, 2014

The diet of reservoir perch before, during and after establishment of non-native 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. An example of the type of effect such predation can have was documented in the Gulf of Gdańsk, where a shift to predation on non-native round gobies (40.7% mean contribution) appears to have resulted in the inclusion of Pomatoschistus spp.…”

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

“…Round goby is not an important food item for lake trout in Lake Michigan, although consumed in small numbers (Jacobs et al 2010). In contrast, round goby is the most important lake trout food organism in Lake Huron (Roseman et al 2014), and the second most important food item for large lake trout in Lake Ontario in 2004 (Dietrich et al 2006). Another study in Lake Ontario, conducted four years later, found that round goby contributed substantially to the diet of all length classes of adult lake trout (Rush et al 2012).…”

“…Some walleye eggs were found in Lake Erie round goby stomachs, but the authors suggest that these eggs were ingested by accident by round gobies foraging on dreissenids (Roseman et al 2006). The contribution of round goby to walleye diet ranges from around 10% of diet in Lake Erie , 30% frequency of occurrence in Lake Ontario (Taraborelli et al 2010) and Lake Huron (Roseman et al 2014), to around 50% frequency of occurrence in Lake St. Pierre in the St. Lawrence River (Reyjol et al 2010). …”

Diet analysis of burbot (Lota lota) from eastern Lake Michigan: 1996–2012

“…(Jude et al, 1992;Cookingham & Ruetz, 2008). Round goby are rapidly becoming an important forage species for piscivores in the Great Lakes, including birds and fishes (Jacobs et al, 2010;Johnson et al, 2010;Roseman et al, 2014;Tucker & Seefelt, 2014). Annual mortality estimates for round gobies in Lake Michigan during the late 2000s ranged from 79 to 84%, raising the possibility that round gobies were already under predatory control (Huo et al, 2014).…”