Andrew S. Bumps


Presentation: 10:45-12:00, Kennedy Union Ballroom



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Round gobies (Neogobius melanostomus) are small, benthic fish native to the Black and Caspian Seas that are now invasive around Europe and the Great Lakes. Male gobies exhibit alternative reproductive tactics, in which guarders invest energy into body size and nest protection, while sneakers are smaller and invest in sperm production to sneak into nests to fertilize eggs. Our study investigated the influence of environmental factors on the ratio of sneaker to guarder males and the influence of this ratio on aggressive and exploratory behaviors. We used GoPro footage, minnow trap collections, and environmental observations from 4 nearshore sites around Beaver Island, Michigan. Reproductive tactics of individual male specimens were determined using gonadosomatic index and length. Our results show that interstitial space, wave action, weather, density, and temperature appear to impact the ratio of sneaker to guarder males. Based on video footage, the percentage of guarders and aggression both increased with density, indicating possible correlation. In addition, smaller gobies were more exploratory than larger ones, indicating that male alternative reproductive tactics may strongly influence goby behavior. Our study demonstrates a highly variable, environmentally-driven structure of round goby populations, which in turn likely influences their ecological role in these nearshore ecosystems.

Publication Date


Project Designation

Independent Research

Primary Advisor

Karolyn M. Hansen

Primary Advisor's Department



Stander Symposium, College of Arts and Sciences

Institutional Learning Goals

Scholarship; Practical Wisdom

Round goby male reproductive tactics: connections to environmental factors, and impacts on behavior.