The Round Goby ( Neogobius melanostomus) in Pennsylvania Tributary Streams of Lake Erie

The round goby ( Neogobius melanostomus) has successfully colonized the Great Lakes, where it appears to be out-competing and possibly displacing native fish species. Movement of the round goby into tributary streams of Lake Erie could further jeopardize native species. Sampling was done by electrofishing in six Pennsylvania tributary streams of Lake Erie from June 2000 through October 2001. Round gobies were collected from four of the six streams sampled: Elk Creek, Walnut Creek, Twentymile Creek, and Sixteenmile Creek. The most extensive colonization has occurred in Elk Creek where round gobies comprised 17.1% of the total number of fish where they were present, and occurred as far as 2.25 stream km upstream from the mouth of the creek. Round gobies fed almost exclusively on aquatic insects, and the most important insects in the diet were chironomid larvae. Female round gobies matured at 1+ years old. Individual fecundity ranged from 86 to 591 eggs, and increased with fish length. The plasticity of the diet, high fecundity, and aggressiveness of the round goby may make it a threat to native species in Pennsylvania tributary streams.