By Lucy Williams
Throughout the summer weeks you will find our educational programs on our main pier. Front and center, students, educators and researchers are sorting through muck, squishy tunicates, skeleton shrimp, and piles of clams. The goal is to find juvenile scallops in these green and blue mesh bags, called spat bags.
Research Assistant Sam Poratti and (then) Research Intern Lucy Williams sorting spat on Hurricane in 2021
Every year in September, our research team sets out spat bag lines at twelve locations surrounding Hurricane and the Muscle Ridge. Last year, our Director of Education, John Van Dis, set out some additional educational spat bags with Belfast and Oceanside schools in October. These lines are usually retrieved in the late spring and organized on our aquaculture site. Our spat bag research is an undertaking that takes the entire summer for students, participants, the occasional island visitor, and the research team to sort through. While collecting the juvenile scallops, we count the precise amount of living scallops, measure a percentage of them, and account for other species present in the bags such as tunicates, sea stars, and mussels.
However, for commercial scallop farms like Pen Bay Scallops, the process is much faster and does not include precise counting, measuring, and biodiversity analysis like we do on Hurricane. Commercial farmers are usually most interested in the amount of scallops collected year to year wherever they set their bags. With dual commercial and research applications, spat bags are a great teaching tool for introducing students and interested growers to scallop aquaculture and the unique qualities of the animal that make farming different (and maybe a little more complex) from other bivalves.
On May 16th, Pen Bay Scallops farmers Marsden and Bob Brewer hosted the Eastern Maine Skippers Program, a high school collaboration with Maine Center for Coastal Fisheries, as well as a few interested farmers for sorting their spat bags with the help of the Hurricane Island Research team. We were able to boat over from Rockland to Stonington in the morning fog in our new vessel, Sunny. On the Stonington public dock, three groups sorted through ten bags received by the Brewers from the approximate 200 they set out each year. Madison Maier, Aquaculture Manager on Hurricane, devised a scheme for estimating the total amount of scallops per bag. For perspective, our first few bags this season have had 170, 243, and even 434 scallops per bag. Pen Bay Scallop’s spat bags averaged 4,038 per bag!
Logan Leach (left) and Emery Leach (right) sort through the netron mesh from one of the Brewer’s spat bags and the juvenile scallops fall into the barrel to be measured (right image).
To get this estimate, students collected 10 mL of scallops by scooping up from the piles of scallops that came out of every bag or by individually picking them up. Once they had 10 mL, they counted the total number of scallops that filled that 10 mL volume. Three measurements were made for each bag and the average number of scallops in 10 mL was calculated. Then, the total volume of scallops for each bag was measured using 1000 mL graduated cylinders. Once the total volume of scallops was obtained, the students simply multiplied the number of scallops in 10 mL by the number it would take to get to the total volume.
The total scallops in each bag ranged from 1700 scallops to 7160 scallops. The total scallops collected in all 10 bags was estimated to be 40,380! That is a lot of little scallops! Marsden and Bob, with the help of the students, sorted the juvenile scallops by size and then put them in appropriate gear for them to grow up on their commercial aquaculture lease near Crotch Island.
