FREEPORT — If you have eaten at Harraseeket Lunch and Lobster, you may have spotted a little white tent down on the dock. If you were to look a bit closer, you would find a sign for a shellfish nursery. Barely 10-feet square, this tent is the headquarters for extensive shellfish research being conducted by the Downeast Institute for Applied Marine Research and Education, a non-profit research organization.

This year, there are six different experiments going on in different locations spanning several of Freeport’s coves and areas up into the Harraseeket River. DEI’S scientists have brought their expertise from their headquarters in Washington County to design experiments to explain the loss of Casco Bay’s shellfish resources.

As you may be aware, landings of soft-shell “steamer” clams in Casco Bay declined nearly 70 percent in the last 10 years, and this decline coincides with an unprecedented rise in the water temperatures of the Gulf of Maine.

When we experienced a huge spike in water temperatures in 2012, clammers saw record numbers of green crabs, an invasive and voracious predator, swarming their bags of clams. Since then, many scientists, managers and harvesters have been working hard to figure out how to combat the problem.

The effort in Freeport began back in 2013 when the town invested a substantial amount to study why vast areas of flats were seeing such dramatic decreases in the once plentiful steamers. They consulted scientists, including Dr. Brian Beal of DEI. After that initial launch, DEI secured funding to continue this research to develop methods to sustain and enhance production of soft-shell clams in Casco Bay.

In the four years since the project began, there has been a lot going on — 24 separate experiments at 100 different field sites! Each year the design and purpose of the experiments builds upon the experiences and results of the previous year, allowing researchers to continue answering questions posed by nature and the people who rely on shellfish for their living.

As Field Research Coordinator Sara Randall explains, ”The one thing that really separates DEI’s applied field experiments in Freeport from other research that’s been conducted on Maine’s mudflats is the scale of the research and how that affects our confidence in the findings. The more times we replicate a treatment, the closer the results take us to the truth. It’s been a lot of hard work, but it’s also been fun and what we have learned is groundbreaking.”

Dr. Brian Beal and clammer Adam “Fluff” Morse. Photo by Sara Randall

One of the primary goals of the research was to figure out how to improve the survival of the seed or baby clams. In year one, they tried predator deterrent fencing around large areas of mudflats. But they found the high levels of labor and cost required to install and maintain the fences in the deep intertidal mud meant this technique was not the best option for clam protection.

They then tried netting over the area to protect planted clams. That, too, wasn’t enough as the netting proved ineffective at thwarting another amazingly proficient predator of soft-shell clams — the milky ribbon worm. Dr. Beal noted, “nowhere have I encountered milky ribbon worms in the densities we have in Freeport.”

This finding led researchers to test whether the presence of bloodworms deters milky ribbon worms from preying on soft-shell clams.

Another question they investigated was whether there was adequate juvenile clam settlement on the mudflats. To determine this, researchers put out “recruitment boxes,” empty wooden boxes protected with mesh on the bottom and top. This mesh is fine enough for the tiny baby clams to fall through as they settle out of the water column, but too fine for predators to get through.
At the end of the field season, scientists opened the boxes to find loads of clams — in some locations as high as almost 1,400 per square foot! They compared those amounts to the number of clams in unprotected areas of the mud right next to the recruitment boxes and found that very few baby clams survived outside the boxes.

The results show that there’s plenty of seed settling onto our flats, but it needs protection from predators to survive to harvestable size. Warmer waters give the edge to predators, especially green crabs. As Sara summarized, “Our most important finding from the four years of experiments is that predation is the most important factor impacting clam survival.”

The whole point of this research is to figure out ways to enhance the local shellfish population. Improving survival rates is what matters to both the ecosystem and to the harvesters. To that end, several members of the Maine Clammers Association have been involved in this project from the beginning, sharing valuable knowledge about local resources as well as assisting with the research. Clammers stand to benefit from the new techniques that are being discovered and are hopeful they can sustain and improve their harvest.

There will be a lot happening under the little white tent over the next several weeks as the researchers take the boxes out of the water for the season. They have to sieve and sort what is inside and count and measure the contents. It is wet, muddy, work, but also is a lot of fun. I got to join a group from Brunswick High School last year and plan to go again this year. If you’re interested in volunteering, you can contact Sara Randall at [email protected].

Or, if you aren’t into getting muddy and wet, you can read about these experiments in a lot more detail at www.downeastinstitute.org/freeport.htm. It’s a really neat project that I look forward to hearing more about as they literally sift through the results of the 2017 experiments this summer and fall.