Hydraulic dredging for clams in our rivers is on the rise. Many of us have witnessed the damage this practice causes. Clamming licenses in Maryland have sharply increased over the past few years, from just eight in 2013 to over 30 in 2016, perhaps signifying a modest comeback of the soft-shell clam and reflecting the increasing popularity of clams as crabbing bait. Similar to oysters, clams are a vital filter feeder and key component in the ecological food chain. Historically, the clam population has been decimated by overharvesting and disease, and, without a Department of Natural Resources (DNR) management plan, is now at risk of another serious population downturn. Today’s clam populations mirror those of oysters, resting at only about 1% of historic levels.

The practice of harvesting clams with a hydraulic dredge is akin to underwater strip mining. High velocity jets of water strip away the river bottom, leaving trenches that can be two feet deep and three feet wide, while a mechanical conveyor belt attached to a long metal arm churns through the newly-cut river bottom collecting clams. This action causes major damage to the river floor and irreversible damage to submerged aquatic vegetation (SAV) beds, ripping up their roots and leaving large sediment pollution plumes in its wake. According to multiple studies, hydraulic dredging is catastrophic to SAV beds and the sediment kills oyster spat in surrounding areas. While there are regulations aimed at prohibiting hydraulic dredging in SAV beds, some dredging is allowed in and near oyster sanctuaries. Additionally, it is getting much more difficult to determine where SAV beds are located as they continually change and many large SAV beds are frequently not mapped at all, leaving them vulnerable to this destructive practice.

Hydraulic clam harvesting currently is allowed year-round and the practice is increasing without any assessment of the growing environmental damage it’s causing. Day after day, these hydraulic machines scour, scape and gouge the river bottoms, producing thousands of pounds of sediment pollution. We think it’s time for to develop a clear management plan for this valuable species, taking into consideration clam populations, their immense value to the ecosystem, the residual damage of hydraulic harvest, and the views of all stakeholders. Clams, today, represent a tiny portion of the bay’s seafood harvest. As the demand for clams increases, we should answer some important questions before clam dredging grows into an even larger problem.

Our rivers are already listed by the Environmental Protection Agency (EPA) as impaired for sediment pollution, among other pollutants. Our rivers are virtually choking from sediment. So, the first question we might ask is: Should we continue to allow hydraulic dredging in impaired rivers when we know it causes catastrophic SAV damage and creates large areas of sediment pollution capable of killing oyster spat and all the underwater life it chokes out? The second question might become: Are there better ways to protect and manage our natural resources, to benefit all stakeholders, while insuring a healthy and sustainable clam population? Our rivers belong to all of us. The current hydraulic harvesting practices hurt more of us than they help.

Jeffrey Horstman
Executive Director
ShoreRivers, Inc.
jhorstman@shorerivers.org
443.385.0511