Native Lake Sturgeon eat more fish (and sooner) in response to Round Goby invasion: A silver lining to an invasive cloud?

Species invasions are ubiquitous in ecosystems across the world, and the Laurentian Great Lakes ecosystem is no exception. Round Goby, a small benthic fish species, have invaded each of the Great Lakes, spreading to Lake Ontario by 2002. The Great Lakes are home to a number of native fish species that are imperiled and of high conservation interest. One of these is the Lake Sturgeon, of which relatively few relict populations still persist, and for which population densities are far below historical records. This paper presents evidence that invasive Round Goby in Lake Ontario are not only eaten by Lake Sturgeon, a large-bodied benthic consumer and putative invertivore, they’ve allowed Lake Sturgeon to shift feeding ecology toward increased predation on fish at smaller size and younger age. The net effect of Round Goby on Lake Sturgeon in this system is still poorly understood: the effects of other species interactions between Round Goby and Lake Sturgeon, and the indirect effects of shifting food web structure on Lake Sturgeon are unknown. However, the shift in feeding ontogeny we document may actually have a positive effect on Lake Sturgeon access higher-quality prey (namely Round Goby) at smaller size and younger age; thereby eating more fish, and sooner. This highlights the complexity of ecosystem responses to species invasions. Though Round Goby have had a strong negative overall effect on the Great Lakes system, the shift in Lake Sturgeon feeding ecology we observe may have a positive effect on this native species.

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Jacobs, G. R., Bruestle, E. L., Hussey, A., Gorsky, D., & Fisk, A. T. (2017). Invasive species alter ontogenetic shifts in the trophic ecology of Lake Sturgeon (Acipenser fulvescens) in the Niagara River and Lake Ontario. Biological Invasions, 10(5), 1533–1546.