The initial, rapid expansion of the invasive round goby (Neogobius melanostomus) throughout the Great Lakes drainage was largely confined to lentic systems. We recently observed round gobies ascending two tributaries of the St. Lawrence River. The expansion of gobies into small lotic environments may place ecologically similar species at risk. Fantail darter (Etheostoma flabellare) is one of the several benthic species of the New York Great Lakes drainages that are threatened by round goby invasion. We examined the habitat use and diet composition of fantail darters and round gobies in Mullet Creek, a third-order tributary of the St. Lawrence River, NY, USA. The objectives of this study were to determine the degree of habitat and diet overlap between fantail darters and round gobies in a tributary of the St. Lawrence River. Gobies and darters co-occurred at 22% of capture sites. Of the four habitat variables examined (cover, depth, substrate and velocity), only depth use was significantly different with gobies using deeper habitats than darters. Among the two species and size classes sampled (large vs. small), large darters had the most restricted habitat use requirements. There was variation in round goby and darter diet composition, but only moderate diet overlap occurred between fantail darters and round gobies (Cλ ¼ 0.43). Conditions in Mullet Creek were appropriate for the evaluation of possible spatial and dietary competition between round goby and native darters. Early detection and management of round goby invasions is critical to maintaining ecological integrity of lotic ecosystems in the St. Lawrence Valley.

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Seines are simple and effective fish collection gears, but the net mesh size influences how well the catch represents the fish communities. We designed and tested a hybrid seine with a dual-mesh bag (1/4 00 and 1/8 00 ) and compared the fish assemblage collected by each mesh. The fine-mesh net retained three times as many fish and collected more species (as many as eight), including representatives of several rare species, than did the coarser mesh. The dual-mesh bag permitted us to compare both sizes and species retained by each layer and to develop species-specific abundance correction factors, which allowed comparison of catches with the coarse-mesh seine used for earlier collections. The results indicate that a hybrid seine with coarse-mesh wings and a fine-mesh bag would enhance future studies of fish communities, especially when small-bodied fishes or early life stages are the research focus.

American eel (Anguilla rostrata), a once common species, is now in decline throughout much of its native range in North America. There is little information on the role of American eel in river food webs. A better understanding of the diet and ecological role of American eel will help in the conservation of this important species. During autumn 2009, eel and aquatic invertebrate samples were collected from Hannacroix Creek, a tributary of the Hudson River, in Albany and Greene counties, New York, USA. Eel diet was analyzed by the eel size and time period (day or night). A high proportion of eel stomachs were empty (73%). Eel diets varied among size classes and day and night feeding periods (p ¼ 0.001). Diet overlap was significant between small and medium eels caught both during the day ( ¼ 0.71) and at night ( ¼ 0.84). Nocturnal diet and nocturnal invertebrate samples were similar ( ¼ 0.65), indicating a preference for bottom feeding during the night. Mayfly nymphs were the major prey consumed in each period by all size classes. Among eels that fed, nightfeeding eels had the greatest stomach weight (as a percent of total body weight). The swim-bladder parasite, Anguillicoloides crassus, was also observed in eels of all size classes with nearly 50% afflicted.