Science for Everyone


Researching Down Under​

Post by Bailey Moritz, Scallop Research Intern

The boat is loaded and we’re reading to hop in the water!

Scallop survey dives in and around Muscle Ridge have begun! Cait and I have gotten out on a lobstermans boat several days so far and more days to come. Meeting our captain and his lobster boat at the dock at 7am, we step over bait totes and down the steep metal ramp with our scuba tanks and equipment. Ideally, 4 dives get done in a day. Once we reach the dive site, a 100m transect is laid down with cement blocks and buoys on either end. Fighting against our awkward fins and the rolling of the boat to maintain balance, we hit the water and descend on the transect, down the length of which we will record the number of scallops and crustaceans we see, We’ll also collect the scallops we encounter in collection bags to be brought topside for tissue sample processing and later shell analysis. The bags can get heavy if the site is rich in scallops, so we have to control our buoyancy accordingly.

As it may sound, the survey methods themselves are quite straightforward. Lay out a 100m transect on land and the task is rather simple. But as this has been my first experience with underwater research, I’ve learned that there are definite complications to take into consideration as you descent for a scientific dive.

Jim, the fisherman who took us diving, demonstrates how to shuck a scallop. We’ll keep the adductor muscle for sampling, which is the part people eat. 

Barnacles and seaweed often cover the top of the scallops. This one is a female, indicated by the pink, egg filled gonad.

One of the critical factors for underwater research are the limitations that come with diving. We can only stay down as long as we have sufficient air in our tanks, so the scope of data collected has to fit within that timeframe. As anyone who has gone for a swim in Maine lately can attest to, the water is not warm and since we are diving in wet suits, we eventually get too cold to stay underwater. Tides impact the depth at which each site sits, changing multiple times a day. Some days, the tide and currents are moving strongly and we can get carried off to the side of the transect or just carried right over the top without time to collect any data! The other day, we attempted to do a dive survey, but storms the night before had kicked up a lot of mud and sediment, and the bottom was just too dark and murky to see your hand in front of your face, let alone any scallops. Visibility becomes one of the biggest factors in this type of research.

Another challenge underwater is the ability to write. Fun fact; pencils can write underwater! Because of this helpful perk of the yellow No. 2, we are able to use “writing cylinders” on our wrists, which are a segment of PVC pipe with waterproof data sheets and a pencil taped on, to collect data. Since hand signals can only go so far, they also allow us to write notes to each other if there is a change in the plan or a point of confusion.

Scallop dive surveys will continue into the fall, and we’re crossing our fingers for some sunshine and good visibility going forward!

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Desperately Seeking Spat Bags

Some of the bags were completely covered in fast growing seaweed!

Dripping with muddy water and covered with tiny dancing skeleton shrimp, we spent the day searching for and hauling up lines of spat bags. Cait deployed them this past October, so they have been collecting scallop larvae for the past 9 months. A spat bag is constructed of 2 layers of mesh; the outside green layer having very small netting that only larval stage scallops can enter and exit through, and the inside blue layer with larger netting that they can attach and grow on. 5 bags are tied to a line with a cement block on one end and buoys on the other, suspending them at different depths throughout the water column. Soon, we’ll count all the scallop spat in the bags to gain an understanding of how many scallops are entering these areas and how much settlement might be occurring around Muscle Ridge. The bags don’t select for species, so we’re sure to find lots of little clams and mussels as well. 

Keeping the pile of spat bags cold and wet with ocean water

It takes a whole team of eyes to hunt down the right color in the sea of buoys.

Lobstermen generally don’t leave their traps out during the winter and you can see why. The buoys were harder to spot with the colors washed off and some of the bags looked more like we had undertaken seaweed aquaculture! Luckily our fantastic captain, Skip, had a knife handy to clean the outside of the bags as we hauled them up. Strong winter storms can also push the cement blocks across the ocean floor, far away from the GPS point where they were dropped, making it a challenge to find them again. In the end, we recovered 5 of the 12 lines, which luckily included all 3 lines that had the HOBO temperature loggers tied to them! To keep them wet and out of the hot sun, we covered them in burlaps sacks soaked in seawater. After multiple transfers in and out of the water, the spat bags made it on the boat out to Hurricane Island, where we’ll start counting those adorable little scallops.

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