Distribution and abundance of fishes relating to artificial aquatic macrophytes in the tidal Potomac River

Previous studies suggest that several species of fishes associate with the structurally complex habitat created by aquatic macrophytes in the littoral zone. Aquatic macrophytes provide complex habitat and serve as a refuge for numerous aquatic organisms, particularly fishes. A two-year study evaluating distribution and abundance of fishes associated with artificial submersed aquatic vegetation in the tidal Potomac River. Artificial aquatic macrophyte beds of three different densities (low, intermediate, high) were sampled with electrofishing gear semimonthly during the growing season. The artificial macrophytes were pillar-type and for comparison, pillar-type natural macrophyte stands (Vallisneria americana) were sampled. These comparisons indicate that the artificial macrophyte beds were very effective in terms of attracting fishes. A total of 1,021 fishes representing eighteen species were collected. White perch (Morone americana), pumpkinseed (Lepomis gibbosus), and bluegill (Lepomis macrochirus ) were the most frequently sampled fishes in the artificial plant beds. These fishes were significantly more common in the artificial habitat blocks than in nearby barren sediment controls. A significant positive relationship was found between bed density and abundance of fish. Banded Killifish ( Fundulus diaphanous) was the most frequently sampled fish in the natural beds. The natural macrophyte beds contained slightly fewer fish than the artificial beds and, in one case, the difference was significant.; The major species of fishes examined in the present study (the top 85% of the electrofishing catch) exhibited: (1) a preference for structurally complex habitat over barren bottom areas, and (2) a preference for intermediate and high levels of habitat complexity over low levels and barren bottom areas. Comparisons of artificial and natural grass beds indicate the artificial habitat attracted a greater abundance of fishes than the natural habitat. Seasonal dynamics were analyzed, with mixed results, but are most likely one of the dominant factor influencing fish behavior in the tidal Potomac River.