The Benthic Feeding Ecology of Round Goby Fry

Abstract

Larval and juvenile stage events play a dominant role in regulating the ultimate recruitment strength of fish populations. As such, the feeding ecology of early life stages are useful for interpreting the proximate causes of recruitment variability. This study provides the first targeted study of the early juvenile (“fry”) diet of the round goby (Neogobius melanostomus, Pallas 1814), a prominent Great Lakes invasive fish. Previous accounts of the diets of round goby fry in the Great Lakes have been based upon by-catch from nocturnal, pelagic studies. Alternatively, we sampled diurnally (day) in diverse benthic environments including open lake, embayment, and stream sites. It was typical for the local diet of round goby fry to feature a primary prey type which contributed >50% to the total diet. Primary prey varied between four types: harpacticoid copepods, chydorid cladocerans, chironomid larvae, or ostracods. An ontogenetic diet shift from harpacticoids to chydorids was suggested between 6 – 26 mm SL. The dominance of benthic prey types in the diet of round goby fry further supports the notion that dreissenid-induced benthification in the Great Lakes is beneficial for round gobies.