Carolina Taraborelli

Allometric relationships between calcified structures and total length of round goby Neogobius melanostomus were determined from a sample of fish ranging in total length from 53 to 152 mm. Each of the 10 allometric equations gave coefficients of determination (r ) that were greater than 0.80 and highly significant. The equations with the most predictive ability were those relating total

We compared round goby (Neogobius melanostomus) population structure and biomass, estimated the quantity of prey consumed by round goby and assessed predation on round goby in two areas of the Bay of Quinte (upper and lower bay) that were invaded by this species two years apart. A bioenergetics approach was used to estimate round goby consumption and to illustrate the influence of changes in the round goby biomass, from May to October in both areas of the bay. Mean round goby biomass was 5 tonnes/km2 for the upper bay and 11.2 tonnes/km2 for the lower bay. Round goby populations were dominated by age-0 to age-2 individuals; older individuals were rare although they constituted a greater portion of total biomass in the earlier invaded lower bay than the upper bay. Estimated round goby consumption was 78.4 tonnes/km2 for the upper bay and 127.1 tonnes/km2 for the lower bay; dreissenids were the most important prey followed by chironomids, zooplankton and amphipods. Diet analysis showed that round gobies were consumed by all predator species analyzed, and constituted a high percentage of stomach content biomass in yellow perch (Perca flavescens), largemouth bass (Micropterus salmoides) and northern pike (Esox lucius). Age structure differences between the upper and lower bay are consistent with those expected between expanding and stable populations.

We assessed round goby (Apollonia melanostoma) density and size structure in two sections of the Bay of Quinte (Lake Ontario) that had been invaded by this species two years apart. Round goby density was assessed with 50 m linear transects, recorded with an underwater video recording apparatus developed for this study that included a depth sounder for maintaining a fixed distance above the substrate. The highest mean round goby densities were observed in the shallowest depth zone (1.5–3 m) at both sites, but there were differences between the sites in the habitat types where the highest densities occurred and there were no significant density differences among habitat types at either site (rock with sparse vegetation, mud with sparse vegetation, sand/mud with moderate vegetation cover). In the upper bay, mean body length of round gobies declined with depth, whereas in the lower bay, mean round goby length was greatest in the deepest zone. Mean body length of round gobies did not differ significantly by habitat type in either section of the bay.