The Round Goby or Neogobius Melanostomus

The round goby, Neogobius melanostomus, is a non-native species of fish. They are known for their aggressiveness and their signature black spot on their dorsal fin. Originally found in Eurasia, specifically the Black Sea, Sea of Azov, and the Caspian Sea. They are able to inhabit both freshwater and salt water, making their ability to thrive almost anywhere possible. After first being discovered in the St. Clair River in 1990, the invasive species now calls the Great Lakes of the United States home. It is believed that the round goby was first brought here by international shipping vessels. In a matter of 14 short years, they were able to inhabit all five great lakes and are starting to travel inward. The round goby is affecting the ecology of the Great Lakes and there have been several environmental impacts. There is also evidence that the round goby is increasing its range in unpredicted ways (Kornis et al., 2012).

The spread of the round goby so quickly is thought to have been due to a large degree of genetic variation and multiple areas in which they were accidentally brought to the United States (Kornis et al., 2012). The feat of spreading so quickly is also due to their high success rates of fertilization and egg hatching. Round gobies have been known to be multiple spawners. They are able to spawn every three to four weeks during the months of April through September. The male will guard approximately 10,000 eggs from multiple females. Nest guarding from predators helps their rate of success, which has been measured as high as 95% (Charlebois et al., 1997).

The round goby has been studied primarily for its environmental impacts. Round goby are consuming smaller fish as prey, but also the eggs of larger fish (Kornis et al., 2013). Specifically, in the St. Lawrence, researchers who compared the populations of invertebrates before and after the invasion of the round goby found a statistically lower macro invertebrate predator biomass as the concentration of the round goby increased (Kipp and Ricardi, 2012). This is decreasing the numbers of its larger fish predators, but also food sources for fish of the same size and other aquatic animals. As adults, round gobies are filling the niches of native species and also taking over spawning grounds.