Clam Dredging: A Rebuttal to ShoreRivers by Marc Castelli


I am responding to the op-ed on clam dredging by Mr. Horstman. A reply is necessary because there were many missing and mishandled facts, to the point that it was beyond opinion and became erroneously misleading, which is a concern.

Beginning with some broad concepts, it is easy to take pot shots at an industry that few have ever taken the time to study and physically witness. Criticism outside the realm of actual knowledge becomes noise. But the public often responds quite well to noise, marching to it and cheering. So, while you have the freedom of speech to say what you want, there is a responsibility when speaking as an executive director to have facts for the public you are addressing. The reader likely looks to you, in your position, as an authority on the subject, but in fact, you are not sharing the whole story about clamming.

This is common in op-ed pieces: people set themselves up as an expert, but they aren’t. More often than not you end up misleading your membership with hysterical hyperbole. Why are simple facts about how the clam fishery interacts with the environment and natural resources so hard to find in the media? Is it because you, one of the Bay’s environmental “guardians” offer misinformed comments that will try to sway public opinion against clamming? Many of that industry’s best speakers are busy trying to make a living on the water and keep up with the pace of changes forced on it by outside pressures. Simply put they just do not have the time to respond to misleading op-ed pieces. I do.

I’m concerned that Mr. Horstman has never spent the day on a clam dredge asking questions of the very people he apparently wants to do away with. There is much to learn about clamming yet he hasn’t done the needed homework. Confirmation bias is not a healthy lifestyle. I will address the many issues in his latest op-ed on clamming. The quotes will be in their entirety. The italics are my words.

Photo by Marc Castelli

Hydraulic dredging for clams in our rivers is on the rise. This is accurate but carries the tone in his op-ed of a “problem,” as if clamming has increased upon a depressed population. Yet, dredging is on the rise because clam populations have risen significantly. A healthy harvest is supported by a healthy population. Many of us have witnessed the damage this practice causes. What damage? There are no specific details, only opinion. Who witnessed it? Where? This is noise. I hear the cheers and footsteps.

Clamming licenses in Maryland sharply increased over the past few years from just 8 in 2013 to over 30 in 2016, perhaps signifying a modest comeback of the softshell clam and reflecting the increasing popularity of clams as crabbing bait. There are numerous problems with Mr. Horstman’s “expertise” here. It is true that licenses have increased and this is due to an increase in clams. But he mentions a modest comeback. In fact, it is significant. He mentions soft shell clams, but in fact, razor clams have also increased. He links the increase in licenses to soft shell clams, but it is also due to razor clams. He mentions an increasing popularity of razor clams as crab bait, but in fact, they have been popular as crab bait for years.

Similar to oysters, clams are a vital filter feeder and a key component in the ecological food chain. While it is true that soft clams are filter feeders it is not correct about razor clams which are deposit feeders. Unlike oysters that live many years, even over 10, clams are short-lived and are difficult to “save” over time.

Historically the clam population has been decimated by overharvesting and disease. Not quite correct as the softshell clam industry was booming for many years since the 1950’s. Harvest was vigorous and the population didn’t decline from that. The steep decline in the late 1900’s to early 2000’s was due to the widespread and virulent disease, clam neoplasia, not overharvesting. High water temperatures have also depressed the softshell clam populations and caused die-offs at times, as the clam in Maryland is at the southern limit of its range.

Without a DNR management plan, the clam population is now at risk of another serious population downturn. Mr. Horstman offers no meaningful information for this claim, no evidence on the linkage between the clam stocks and the lack of a clam management plan, and no data about the imminent loss of clams. He states the population is NOW at risk. Data, please? In fact, the populations naturally vary, decreasing and increasing over time. Harvest numbers will reflect that. But to link a natural decrease to a lack of a clam management plan is nothing more than biased overreaching to sway the public. A discussion of the current clam management plan can be found further on in this piece. Downturns are related to many natural conditions already mentioned, including predation that can wipe clean many clam areas.

Clams are not like oysters – they do not live long. The soft shell clam reproduces twice a year.

Today’s clam population mirror those of oysters, resting at about 1% of historic levels. This is just hype. No one knows for certain what the clam population was or is. The oft-repeated 1% claim for oysters is not a set-in-stone statistic either. It is based on many unsupported assumptions. Linking clams with the oyster plight is a ploy. The marching continues.

The practice of harvesting clams with a hydraulic dredge is akin to underwater strip mining. While it is an aggressive form of harvesting it is not strip mining. Mr. Horstman’s linking the two just serves to heighten the hysteria he is trying to create.

He goes on further to claim that, high-velocity jets of water strip away the river bottom. No, they don’t. To strip away means that the river bottom no longer exists. High-velocity jets of water will actually crush the shells of clams. What right minded clammer would be so destructive? Clam rigs fluidize the bottom dislodging clams which will float and then be carried onto the conveyor belt. Much of the larger grain sediment (sand, grit, pebbles, for example) that is stirred up actually falls through the chain of the belt back to the bottom within seconds. Clamming is not a high-speed process. The boat and dredge move very slowly ahead. Pump and boat engines usually run a little more than idle. Too much power to either will destroy the rig’s pump and crush the clams. If Mr. Horstman knew better he could say that as the boat moves, large amounts of sediment dislodged by the dredge can actually settle back onto the river bottom, leaving a shallow depression. But then I doubt that he has ever actually been on a clam dredge. I have and have spent many an hour nursing a backache from picking clams from the conveyor. It is long, repetitive back-breaking work with few if any breaks. Reading, asking questions of everyone concerned and hands-on experience with first-hand observations is how I have learned the little I do know about clams.

He goes on to claim that a clam dredge will leave a trench that can be two feet deep and three feet wide. It is obvious he did not talk with a clammer. First off, he describes the path of a clam dredge that will dig down two feet and be three feet wide as a trench. He leaves the reader with the notion that a dredge digs a trench and does not replace sediment along the dredge’s path. But as stated above, sediment partially refills the affected area. Most clam bottom is not suitable for dredges that are three feet wide, some dredge heads are 18 inches in width. While there are 36-inch dredges, such pieces of equipment are suitable for sandy bottom only. Not all clam bottom is sandy.

He claims, the action of the dredge causes major damage to the river floor. That is an exaggeration and is not accurate. The bottom does not sustain major damage. Instead, it is emulsified, but then the sediment quickly resettles. Benthic organisms then recolonize the bottom. The river floor is not “gone” or “dead” after clamming. Clams can even come back and in some instances are thicker. Who would know this? A clammer would be able to see this. The first-hand empirical knowledge of a waterman is vast.

He asserts that dredging causes irreversible damage to submerged aquatic vegetation(SAV). Yes, grasses will be uprooted, but this is why clamming is prohibited in SAV beds. Safeguards are in place. Additionally, clam rigs don’t work well in grass beds. The grass not only clogs the belt but the intake as well and takes too much time to clear away the grasses in order to pick the clams from the belt. Officials in his position should not use op-ed opportunities to misinform the public. Executive directors should value opportunities to factually inform the public, not raise the temperature on these issues. Facts are stubborn creatures. They do not go away.

He does state factually, that sediment plumes are visible from clammers. Yes, there are sediment plumes. Depending on the type of bottom, the plumes will not stay suspended for any great length of time. But, has he ever spent the time to watch just how long such a plume remains suspended in the water column?

Mr. Horstman states that according to multiple studies, hydraulic dredging is catastrophic to SAV beds and that the sediment plumes kill oyster spat in surrounding areas. SAV beds are seriously impacted IF a dredge goes in them, but designated SAV beds are legally off limits to clamming and as stated above clammers avoid clogging their rigs with grass. Additionally, note that SAV has increased over the past few years during which clamming has also increased, significantly. The two can co-exist. In fact, long-term trends in SAV (available online) show no linkage with clam harvest levels. As for oyster spat mortality, there is no definition of “surrounding areas”, leading the reader to think that spat in a large area is killed by clamming. In fact, a study was done to determine limits on clamming found that impacts on oysters occurred up to 75 feet away from the dredge. Maryland decided to create 150 ft. setbacks from oyster beds. That is actually twice the distance noted in the study. But, in reality, there is even a greater safeguard. The boundary line of an oyster bar is from where the 150 ft. is measured. The actual oyster bar population is within the boundary of the bar such that the oyster population is likely hundreds of feet more away. If a clammer is found to have an oyster on his boat, he is ticketed and faces a huge fine. Very crafty writing Mr. Horstman: sparse on facts, but a lot of noise.

He further claims that while there are regulations aimed at prohibiting hydraulic dredging in SAV beds, some dredging is allowed in and near oyster sanctuaries. He obviously chooses to be ignorant and to keep his readers ignorant of the setback distances and regulations mentioned above that protect oysters and oyster bars, including those in sanctuaries. Why?

He goes on to say, additionally, it is getting more and more difficult to determine where SAV beds are located as they continually change and many large SAV beds are not mapped at all, leaving them vulnerable to this destructive practice. Hidden in his message is actually the need to better manage SAV beds. Nothing wrong with that. Maybe his association could let go of some of the many thousands of dollars they have and fund a state survey of SAV beds. What he barely conceals is that he wants clamming prohibited.

Horstman states that hydraulic harvesting is currently 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, scrape and gouge the river bottoms, producing thousands of pounds of sediment pollution. What a picture he has painted with these adjectives. He is sadly mistaken in portraying the clam industry as being in operation day after day. It is only for 6 days a week (Mon.-Sat.), weather and market permitting, from May 14 to Nov. 1 they get to start at sunrise and have to put the clams out by no later than 3 in the afternoon to avoid unhealthy spoilage and no later than 1 hour after sunset from Nov. 1 to May 14. This is a market-driven industry and the winter months do not see a consistent market for soft shells. I have already discussed the fact that while there is a plume, much of the dislodged sediment actually settles back to the affected areas. Does Mr. Horstman know that a strong blow, lasting for days will suspend silt over huge areas of rivers, far more than clamming will? That resuspended silt came from the land (not clamming). Most associations such as the newly formed one he is the executive officer of, have projects already in place to investigate and mitigate land sources of silt. Perhaps a more vigorous pursuit of those would be more productive than these op-eds.

We think, he states, it’s time 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. What damage? He doesn’t cite details. SAV damage is regulated already by the closing of SAV areas where no hydraulic harvesting is allowed, and oyster bars are separated from clamming. There has been a successful clam management plan in existence for many decades. There is a boogeyman under the bed. Noise, cheers, and marching.

Clams today, he says, represents a tiny portion of the Bay’s seafood harvest. He doesn’t even speak to the immense value of clams for crab bait. He missed discussing a major importance of clamming. I’m sure he is an excellently skilled director, but he has much to learn about clamming. As the demand for clams increases, we should answer some important questions before clam dredging grows into an even larger problem. I have to wonder if he knows the differences between soft clams, piss clams, hard clams, white clams, mannose and razor clams? Warning – it is partly a trick question. These are just the market clams that live in the Bay and the tributaries. All together clams represent a huge economic value chain that runs from many of Maryland’s fishing communities out through the state. Instead of recognizing this value, and the safeguards that lessen various issues, clamming is by definition, according to Mr. Horstman, a “problem” from the get-go. I think the problem is unsubstantiated comments and open bias when good judgment, data, and reason should prevail.

Our rivers are virtually choking from sediment. How is that possible when we have been reading for the past year or so that water quality is the best it has been in years? Watermen can see it firsthand. I guess it is hard to see such things from behind a computer in an office.

Our rivers are already listed by the EPA as impaired for sediment pollution, among other pollutants. Is he claiming clam dredging is responsible for the sediment overload and other pollutants? Try checking land-based sources of sediment.

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 our natural resources, to benefit all stakeholders while ensuring a healthy and sustainable clam population? When these policy and executive directors have doubts about the issues they always trot out the same old tired arguments and go over the top with their hyperbole. Where are the factual components of their arguments? You can’t have a discussion with someone who just wants to set the world on fire all the time. He talks about a sustainable clam population but he never even hints at a sustainable fishery. By all appearances, his goal is to put an end to clamming. Also, where is “all” the underwater life that gets choked out? All? That’s total. There is no data in his piece that any gets choked out.

The most confusing statement is his conclusion. Our rivers belong to all of us. The current hydraulic practices hurt more of us than they help. Bizarre to say the least. Who is “us” in his mind? Sounds like it is people opposed to clamming. His piece clearly casts clammers as the enemy and not part of “us”, but in fact, the Bay belongs to them too. They are part of us.

He encourages action for the benefit of all of the stakeholders. What action does he want his readers to consider? I would hope that self-educating from many different angles would be part of that process. But here he is minimizing and marginalizing the incredible economic benefits that are woven all through the value chain that is Maryland’s commercial fishery. The word resource has never in my years of researching Bay resources been used to describe sea nettles. Yes, they have a part in the ecosystem but no one wants to interact with or protect them. That fact alone tells you that the words, natural resource, implies human need and interaction. I can only assume that Mr. Horstman does not eat crab or clams and would like for others to follow his example.

Make your own mind up after doing the research. Do not just got to websites that confirm your bias. Question your assumptions, try to find the facts for the larger picture. It is never as simple as Mr. Horstman would have you believe.

Marc Castelli is an award winning painter and photographer of the Chesapeake Bay and those who work on the water.

Letters to Editor

  1. ShoreRivers Staff and Board says:

    The following is in response to Marc Castelli’s opinion article on the ShoreRivers’ executive director, Jeffrey Hortsman in a January 25th op-ed in the Spy Hydraulic Dredging for Clams on the Rise, as is the Damage.

    Marc’s response to ShoreRivers’ op-ed shows a significant difference of opinion in what we as a community know about the clamming fishery, its environmental impact, and its economic significance. This conversation furthers the need for a scientific assessment of the clam population and the environmental effects of hydraulic clamming, as well as stakeholder discussions that consider the knowledge and opinions of scientists, watermen, environmentalists, and concerned citizens.

    So, we are calling for public stakeholder meeting with the Maryland Department of Natural Resources, who manages this fishery, to review these issues and we hope Marc will attend.

    We know that clamming on Eastern Shore rivers is on the rise and that hydraulic dredging for clams causes damage to the local ecosystem by destroying underwater grass beds, stirring up sediment, and altering the benthic landscape. ShoreRivers believes in managing our fisheries with a science-based understanding of the impacts to water quality, habitat, and fishery populations. We have an opportunity now, while the fishery is relatively small, to develop regulations that protect our natural environment while preserving the fishery.

    We agree with Marc that clamming licenses are on the rise, significantly. In the past, many oyster watermen voiced concerns when DNR increased the number of oyster licenses issued. Some suggested that limiting licenses could have helped both the watermen and the oysters. With clamming efforts now growing, we can learn from the experiences of the oyster fishery and take the opportunity to proactively discuss clamming license numbers and limits.

    Marc and ShoreRivers agree that we could better monitor and manage our submerged aquatic vegetation (SAV) in order to avoid damage by clamming efforts. Currently, state-designated SAV beds are legally off-limits to clamming. However, these maps are a decade’s holdover a decade old, and we know from aerial monitoring that grass beds across the Chesapeake Bay have significantly increased. We need to update the state SAV maps to reflect the current documented spread of underwater grasses.

    The clam fishery once produced well over 400,000 bushels a year, and by late 1970s the fishery had become basically non-existent. However, in the past few years, we have seen a modest rebound in the fishery, of 5,000 bushels in 2015 and 10,000 bushels in 2016, according to the Department of Natural Resources. As this fishery rebounds, we should be proactive in establishing science-based regulations that protect our natural resources and the right that we all have for clean water and healthy rivers. We should also note that hydraulic dredging is not allowed in Virginia and Maryland’s coastal bays purportedly due to the environmental damage it causes.

    The ShoreRivers Staff and Board

  2. David Lloyd says:

    Wow. Many words leading to my conclusion: he attacks Mr. Horstman with lots and lots of words which, every now and then, may make sense. Otherwise, I am not impressed by attacking factual presentations with claims that “it is all designed to hurt those depending on the waters for their living.”

  3. Alice Jane Lippson says:

    I am so glad Mr. Castelli has answered the article by Mr Horstman that appeared in the Talbot Spy. I was a research scientist at the Chesapeake Biological Laboratory in Solomon’s in the60s and70s when the hydraulics dredge was invented and the subtidal soft clam populations were feasibly harvested. Previous soft clams were primarily harvested in New England in tidal flats bared when the tide receded. This was an opportunity for a new seafood industry. Before legalizing clammy no the state instituted a in depth study of the impacts to the environment and to the well established oyster industry. A statewide mapping of the oyster areas and potential cramming beds was implemented.

    If you have been on our rivers you must have seen the floats that say.Clam Line which designated where that clambers could only clam from that line to shore. There were many other laws and regulations that were instituted to protect our oyster and make clamming environmentally stabilized. After all these years I cannot believe the ignorance of Mr. Horstman about the history of the efforts in Maryland to enable both oystering and clamming to-reside side by side.

  4. Jeffery McPherson says:

    There is such anger in this article I can hardly take it seriously. It does not take a scientist to see the destruction of a clam dredge. I have witnessed many a sediment plume from a clam dredge and those sediments can be suspended for days. The sand may settle out fast, but the silt and clay will stay suspended for a long time. That sediment will choke out SAV and other filter feeders in the area. I have seen dredging troughs on my echosounder and they are easily visible.

    Those conditions desired by clam dredgers are also the same conditions desired by SAV. Relatively flat, shallow, sandy areas. This means that fringe areas that could have a low density of SAV can be easily damaged. A clammer may not want to dredge through a dense bed of SAV, but dredging through sparsely populated SAV areas would be no issue. This is something that cannot be easily enforced or policed.

    As with any activity occurring in public areas we must consider whether the economic benefits from dredging clams outweighs the environmental impacts caused by their operation. I feel that their destructive nature is directly opposed to the majority that like to boat, fish, and swim on our waterways.

    • There is no way that you see the troughs on your “echo sounder”. I’ve been working on the water for 30 years and I have never seen a trough on a depth finder from caused by a clam rig. That is just a ridiculous thing to say. Clamming is correctly managed now and has been since the sav bed legislation was passed. The real reason people want clammers to go away doesn’t have anything to do with its environmental impacts. The real reason is because people that have a lot of money are buying waterfront homes and they don’t think that they should have to listen to a Diesel engine at 6 in the morning right outside they’re new 5,000,000 dollar mansion. Think I’m wrong? Look at why they shut hard shell clamming down in the back bays of ocean city for exactly that reason. The dnr literally destroyed an entire industry just so people didn’t get bothered by the noise. You can’t make this stuff up.

    • John mcmillian says:

      Yes this guy knows just as little as Jeffrey Horstman. There are no tracks visible from clam rigs, the bottom naturally changes everyday anyway. These clam boats have worked the same area since the 50s with no loss in clam population or effects on the bottom. The water is more clear then it has been in a very ling time and these clam boats are operating all over. No sediment plume ever lingers. Don’t believe me, do your own research. I’ve seen it first hand. Sediment plumes happen whenever we have heavy rains, strong winds. Ive even seen sediment plumes after large amount of boat traffic in eastern bay on weekends. Its natural and it happens 24/7 365.

  5. Marc Castelli says:

    I’m sharing these photos to be as part of that conversation and hoping to take some of the one sided hysteria out of it.

    They are of the waters in the Chester River on Friday the 16th of February. As you can see the water is still carrying huge amounts of sediment from the rains nearly a week ago. More sediment was dumped in the river last Friday the 9th and on, Saturday the 10th than any amount that could have possibly been put there by the total amount of clammers in the past 20 or so years.

    When looking at these please make sure to remark on the colors of the water and the suspended sediment that is still in it. Top shot is the wake of the fishing vessel Southpaw.Second shot is the bow wave of the same fishing vessel. Third shot is the water draining from the live tank of the same vessel. This water is drawn up from the Chester River. Fourth shot is the live tank water draining out through the stern scuppers of the fishing vessel Southpaw.

    The real question is; Why now after all of these years of a strictly managed clam industry are these people wasting their hysterical efforts on beating a dead horse? These are my photos taken on the days mentioned above.

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