Effects of Enhancing Pontoons on Abundance of Fish: Initial Experiments in Estuaries

We investigated whether it was possible to increase abundances of fish associated with pontoons by increasing the available shelter. The physical complexity of the undersides of pontoons was enhanced by adding 7 m² units made up of artificial seagrass leaves. Abundances of fish from these pontoons were compared with those from normal pontoons. The total number of fish, number of species and number of recently settled fish were significantly higher on enhanced pontoons than on unenhanced pontoons during December, but not October. The number of recently settled fish on pontoons was low compared to simultaneous settlement of fish in nearby natural habitat. Possible reasons for this were the position of pontoons in the water column, their movement in relation to tides and currents, and shading.