Progress report for FNE23-039
Project Information
Aquaculture is on the rise. In the not-so distant future, regulation and population collapse in the current wild fishing industry will drastically change how Maine seafood is produced and consumed. Here in Maine, there are 3,478 miles of coastline, much of which is very well suited to shellfish farming. Hard clams, which are native to these waters, need to be further explored as a viable commercial shellfish crop. The issue with clam farming at the moment is that the systems are expensive and cumbersome to stock and restock through the nursery and harvest phases. The objective of this project is to trial a new gear method that is substantially more cost effective and is much easier to handle at large scale. The key component to our method is a trawl-like linear tube mesh material planted in the muddy substrate, replacing the hard clam bags that are typically utilized (think 900' long sock rather than a string of pillowcases). We will document and analyze each step of the project and publish our findings on our website as we go. We will also utilize our social media platforms (mainly Instagram, which is currently the primary way for shellfish farmers to share information) to encourage discussion around our approach. The rapid growth of the aquaculture industry is also supporting numerous new publications where we will share our findings, as the community is eager for new systems and methods that utilize improved technologies.
This project seeks to test a simplified and cost-effective approach to clam farming by building a low-cost, high volume hard clam farm, using inexpensive, off the shelf, non-custom gear. Added benefits also include:
- Farmers will be able to utilize unused portions of their lease, which are too muddy to grow other shellfish such as oysters and scallops.
- Farmers will be able to shorten the required nursery phase by planting the young clams out at 5mm rather than 15mm, saving on labor.
- Simplified equipment required for all operations of the clam farm, adding to simpler planting and harvesting methods. Farmers will also be able to keep track of stocking densities and total expected harvest rates with ease.
- Significant reduction of initial gear investments required to grow clams at commercial scale, making it easier for aspiring farmers to enter the industry.
- Low visible impact, low carbon footprint and the obvious filtering capabilities of clams to clean the water, keeping local ecosystems healthy
There are thousands of acres of the Maine coast full of phytoplankton and nutrients that were once inhabited by soft shell clams, but the appearance of the green crab has decimated our soft shell culture. Maine was once a leader in soft shell clam production, and it once produced more revenue from clams than from lobsters. The ability to grow soft shell clams has been tried using different types of gear to protect against green crabs with limited success. However, it is my belief that we can grow hard clams, Mercenaria mercenaria or "quahogs", in the state of Maine with simple techniques that I am experimenting with on my farm with the opportunity for great success. Hard clams are also native to New England and can ward off the green crabs very well; we just need to learn how to farm them commercially in cold waters.
The environmental plusses to growing hard clams are many.
- Clams are filter feeders and clean the water as they grow.
- Clams store a great deal of carbon in their shells; every clam you eat results in 3 grams of carbon removed from the atmosphere.
- The amount of fossil fuels to build and maintain a clam farm such as mine are extremely low.
Maine’s hard clam market is nascent, whereas in the southern states and southern New England they are widely consumed and sought after. 25 years ago in Maine, almost no one was eating and growing oysters. and now look how popular they are! I believe that hard clams could be the new oyster, and the market is already ready.
There are a hard clam farm practices in place, but they rely upon expensive and specialized equipment which make a high point of entry for new clam farmers. The most exciting part about this project for me is the gear needed to grow clams with this new method is extremely inexpensive compared to traditional gear, and is immensely labor-saving.
For a very small amount of money, it should and could produce clams at a high volume which would in turn create valuable income for working families along the coast in a time where it's becoming increasingly difficult to make a living on the water. For an Island community like ours on North Haven, developing sustainable businesses like this is extremely important. Currently, over 70% of the island families in Maine make their income from lobster fishing in some way. The state of the lobster industry is in flux through rising sea temperatures and draconian policy. Developing alternate ways of income for island families that can also improve water quality and provide climate solutions is my way of giving back to my community and providing for my young family who would like to continue to make a living on the island.
I would like the opportunity to develop these ideas further and share them with my fellow aquaculture community.
Cooperators
- - Technical Advisor
Research
As an innovative alternative to the standard material used to grow clams, we plan to use 1800 ft rolls of polyethylene mesh, cut in half to form 900 foot long "clam tubes". This mesh is traditionally used in the lobster industry for bait bags, and is cost-effective and widely available. I came up with a method of sliding the material onto a 16 ft length of PVC pipe, and pouring the 5mm seed clams through the pipe and into the mesh tube. Stocking densities are 400 clams per 4 ft of mesh tube. A stainless steel snap is attached at 4 ft intervals to separate each 400 clam segment. This snap serves two purposes, one, dividing the baby clams by groups of 400, and also weighing down the mesh with the clams into the mud. Each end of the mesh will be anchored to the bottom of the salt pond with appropriate sized moorings. The deployment of the baby clams in mesh takes no specialized equipment.
1. As the oyster industry expands in Maine, new aquaculture farmers are running into several problems. Obtaining a lease can be difficult if there are any objections to the visibility of floating gear. Many lease applications have been stalled due to waterfront property owners objecting to floating gear and access to their moorings and docks. Bottom culture of clams will not have these issues, as the amount of floating gear required for operations is significantly reduced compared to oyster, scallop, kelp, and mussel operations. This simple difference will open up more opportunities for farmers to utilize their lease acreage, whether they choose to plant clams underneath their floating oyster gear, or in new areas that would not be able to be leased for floating oyster culture due to high boat traffic.
2. The biggest advantages with this mesh are its ability to hold 5mm clam seed, which reduces the time in the upweller (aka. nursery phase), and gets the baby clams into the mud quickly, which is their preferred environment. In discussing this with my mentor, Dana Morse, the biggest hurdle in building a clam farm has been how to handle the small clam seed the first year, as the growth rates are not fast enough in Maine to get it to a larger size in the first summer. This small mesh gear solves that problem.
3. Harvesting the clams after three years of bottom growth will be done with relative ease, as the mesh tube full of clams is easily handled without expensive boats or hydraulics. We run our aquaculture operations in the salt pond with an 8'x16' plywood barge that we made on-farm in three days. We expect that this simple vessel will be more than adequate for running this expanded clam farm operations. One other asset to farming clams in mesh tubes is that you can pull up the tube by hand, and simply empty enough product out of the tube to fill the market that you have for that week without disturbing the other clams.
4. The upfront cost of the bagging mesh material is $280 per 1800 ft roll which equals 23 cents a square foot, as opposed to the other standard materials for clam operations (of which we have experimented with on-farm for several years) which are upwards of $3 a square foot. This is a huge cost savings in labor and materials.
5. Hard clams are bi-valves, which are the ocean's natural filterers. They filter harmful algal blooms, detritus, and microorganisms, which make them an integral part of a healthy ocean ecosystem. A single little-neck clam can filter 4.5 gallons of water per day, whereas large clams can filter as much as 50 gallons per day! In terms of water quality, clam farms yield a net benefit to the ecosystem they are grown in. Additionally, Clam shells are 12% captured carbon by weight. Clams offer a climate-friendly, high-protein food source, because they often have lower greenhouse gas (GHG) emission footprints than do the equivalent products farmed on land. The GHG emissions per unit of protein produced by aquaculture generally compare favorably with most livestock production and some wild-caught fisheries.
Put simply, with this grant, we are hoping to develop scalable climate solutions that feed our communities and contribute to sustainable working waterfronts.
Learning Outcomes
All of us involved with the clam project (Zeb, Kaleb and myself), had positive experiences with the knowledge gained through this project.
Since it is a 3 year project, we still have yet to come to conclusions and create the outreach we plan to conduct around the project.
However, we have expanded our oyster farm tours to include the clam farm operation. The oyster co gives tours with an average of 6 people / week throughout the summer. Each tour was shown the clam operation, and there was great excitement and engagement with the tours.
Project Outcomes
We are just 8 months into this 3 year growing cycle, so the jury is still out on our methods. When we bring the clams up in the spring, we will be able to see mortality and growth rates.
We were able to forgo the cost of stainless steel snaps, because we substituted them with zip ties. We discovered that the clams in the tubes provided enough weight for them to silt themselves into the mud without the snaps. Zip ties of course are much less expensive than the stainless steel snaps.
This summer we experienced unprecedented rain events throughout the summer. Due to rain closures, we were only able to sell product for 18 days from May to December. This wet summer lead to slower growth rates for our seed in the upweller than we've seen in previous years. In September, we were able to grade and plant about 30% of the seed that was big enough to be planted in the 3mm mesh tubes into the pond. The remaining 70% we kept in the upweller to put more growth on before planting. On October 9th, we experienced 6 inches of rain in 24 hours - an unprecedented amount of rainfall for our area. Because fresh water is less dense than salt water, it all collected at the top of the salt pond where the clams were growing in the upweller. Working quickly, we got as much clam seed into alternative small mesh bags that we had on hand at the farm, and planted them on the other side of the dyke in a tidal inlet, in hopes that the water there would be saltier. Unfortunately, the greencrab pressure and the slightly rockier substrate was not ideal for the baby clams, and we likely had an 80% mortality rate with the clams placed there.
Up until the major rain event in October, even though it was a very wet summer, the clams had 0% mortality in the upweller. Any time you put shellfish into a contained space (tubes or bags), this has the benefit of creating a safe space for the shellfish but can also restrict the flow of the water and the mobility of the seed while growing. We won't know the true mortality of the clams in the pond until the ice goes out in the seed. I do believe this method and our findings will be very valuable for other clam farmers in the area.