Studies on the Effect of Dredging Operations Upon Fish and Shellfish

Ingle, Robert

Investigations were made to determine the effects of dredging operations upon fish and shellfish in the vicinity of Great Point Clear, Alabama. Damage to scalefish and motile crustacea was not observed, even within 25-50 yards of an active dredge. Shellfish were not found to suffer damage when suspended from dredge itself. Damage due to larger particles of mud occurred on bottom in immediate neighborhood of dredge, but did not extend beyond 400 yards. In most cases this distance was much less, in some cases being about 75 yards. Because momentary conditions of tide, speed of current, speed of dredging vary, and variations exist in various bay bottoms, every situation merits separate consideration. Controlled dredging is suggested as the best solution. By this method the dredging activity is coordinated with local conditions, spatial and temporal. In the areas under consideration (West Florida and Alabama), controlled dredging should begin to operate at 400 yards distance from live oyster reefs. There is some evidence that dredging stirs up organic detritus resulting in a beneficial effect to shellfish and crustaceans.