Bioacoustic Traps for Management of Round Goby

PROJECT OVERVIEW
The round goby is an invasive fish that is rapidly spreading throughout the Great Lakes. One reason for its rapid expansion is that round goby outcompetes native fish through its ability to spawn throughout the spring and summer in contrast to native fish, which only spawn once a year. Interrupting this reproductive cycle in some way could be used to help halt further expansion of round goby and control existing populations. Scientists from the University of Minnesota - Duluth are using this appropriation to develop and test a method for trapping these fish using sounds that mimic those that male gobies use to attract females to the nest.

OVERALL PROJECT OUTCOME AND RESULTS
The bioacoustics of the round goby population in the Duluth-Superior Harbor were investigated over the course of three summers. The goal of the project was to assess the behavior and the sound production of this invasive species to develop a fish trap to target this invasive species. Fish were found to move offshore during the winter and thus subsequent concentrations were thought to have great potential for collection. However, fish were found to be inactive the majority of the winter and did not produce sound. Sound production coincided with the resumption of swimming activity and feeding in late spring with vocalization first recorded when water temperature exceeded 8 degrees C, which correlated with the initiation of spawning. Two choice experimental trials succeeded in attracting the fish to sound sources using both pure tones and round goby vocalizations, indicating that fish can find the origin of sound. Several different traps were produced and bioacoustical field trials were conducted. We were able to capture, for the first time, round gobies in unbaited traps using sound as the only stimulus and observed many round gobies approach sound sources but fail to enter the traps. As they readily enter the same traps when baited, it was concluded that although sound is an effective attractant, it is not the only sensory modality that round goby use to approach calling males. Future experiments that would combine sound with a large sexually mature fish and/or pheromones could significantly increase the number of fish that enter the trap and could prove to be an effective strategy.

PROJECT RESULTS USE AND DISSEMINATION
Project manager collaborated with the Great Lakes aquarium to produce a audio video exhibit on invasive fish. Two master's students, Jared Leino (degree pending) and Elise Cordo (degree in progress), received funding from the project and five undergraduate students received funding for summer research. Additionally several manuscripts are in preparation and will be submitted for publication.