Dredging Had Little Significant Impact on Fish Population, Says Biologist (USA)

According to the data relating to more than 1.2 million fish, originating from 154 different species, sampled within a 10-year study of the St. Sebastian River by the Florida Fish and Wildlife Research Institute, the dredging did not have considerable influence on the fish population.

The study’s findings outlined by Richard Paperno, a marine biologist with the Institute, show that more than 70 percent of the fish caught were anchovy species.

The study initiated in April 2004 in anticipation of the St. Johns Water Management District’s Sebastian River Muck Removal Project, continued through March 2011 keeping track of fish population and sizes through 122 various samples.

Some commercially significant species, such as the snook and drum, were included in the study upon what it was concluded that there were no considerable increases in size or population following the dredging.

“In comparing pre-dredge and post-dredge, the results are very similar. We found no difference in the sizes of the fish we caught,” Paperno said.

Paperno indicated some factors that might have affected the data including the constrained ability to sample using a seine and the increased number and population of freshwater species following the 2004 hurricanes, which reduced the salinity level and resulted in the presence of some freshwater not normally found in the Indian River Lagoon.

The study, in Paperno’s opinion, shows the dredging did not produce long-term consequences for the river’s community structure, however he thinks that the river’s taxonomy should be monitored by conducting further sampling.

A marine biologist with Estuarine, Coastal and Ocean Science Inc., and formerly with the Harbor Branch Institute, Grant Gilmore of Vero Beach, believes that the findings might not be conclusive due to the study methodology. According to Gilmore trawl samples might have provided broader data where the seine method is constrained to depths where researchers could stand.


Dredging Today Staff, November 24, 2011;