Age and Growth of Round GobyNeogobius melanostomusin the Upper Detroit River

Abstract

The round goby Neogobius melanostomus has quickly become one of the most abundant benthic fishes in the Lake Huron–Lake Erie corridor of the Laurentian Great Lakes since it was first discovered in the St. Clair River in 1990. We describe the age, growth, and size structure of the round goby population from samples collected in the upper Detroit River. Round gobies were collected using an otter trawl about every 3 weeks during spring, summer, and autumn 1996. Age-1 fish were found to be the most abundant group in the population, and fish size within a given age-group was highly variable. Both males and females were found to be maturing younger and at smaller sizes than in their native range. Marginal increment analysis of otoliths revealed that annulus formation occurred in late May–early June. Although mean size of fish differed significantly with sample date (P < 0.001), there was little increase in mean size from May to October. Age-1 fish had a larger growth than age-2 fish. Mean annual growth for age-1 males (37 mm) was greater than for females (33 mm), but size ranges overlapped. Early maturity and rapid growth are two factors that may ensure the continued expansion of the round goby throughout the Great Lakes.