DAY 6: Tuesday August 19, 2003
I began my day in Matunuck with a boat trip out to one of the scallop study sites. The Salt Pond is really a wonderful place and it was nice to experience it on a boat! Our objective was to retrieve several spat lines that had been deployed earlier in the summer.
Spat lines are used to collect scallop spat. The lines are about thirty feet long and have twenty spat bags (mesh bags about the size of a 50 pound onion sack) attached about every four or five feet. The spat bags are stuffed with a material called netron and they have a piece of lead line on the bottom to prevent them from floating on the surface horizontally. A float is attached to every other bag and from a distance the sight of several spat lines look like a flotilla of seagulls. The lines were deployed about a month ago in areas that have historically been productive scallop beds and close to eelgrass.
The spat bags follow the same line of reasoning as the remote setting gear used in the oyster shell bags. Bay scallops, along with all of our other inshore bivalves are temperature dependent spawners. When the water temperature starts to increase in the spring, the young scallops thoughts turn to romance, well sort of, the increase in temperature triggers gonadal development. It turns out that the bay scallop is a functional hermaphrodite, wait until the kids hear that one! When the scallops release their gametes into the water, fertilization is by chance and within 24 to 48 hours, the fertilized egg develops into a planktonic veliger. The veliger stage of the bay scallop lasts from ten days to two weeks, after which the veliger looks for suitable attachment substrate. In the case of the scallop, the substrate of choice is eelgrass.
Eelgrass populations have not done too well in the last few decades. Between several blights that wiped out acres of once thriving eelgrass beds in the 1950's and 60's and all of the excesses of the last twenty years, essentially way too much nutrient enriched runoff, there are far fewer places where scallop veligers might find attachment substrate. Many shellfish biologists are convinced that the loss of eelgrass in our coastal salt ponds has had a devastating impact on the bay scallop population.
The spat bag was developed as an artificial attachment alternative to eelgrass. The veliger drifts or swims through the mesh bag, bumps into the netron, mistakes the netron for eelgrass, and attaches. The spat bag provides some protection from predation and allows for a steady stream of phytoplankton filled water.
When I was new to Rhode Island and landed my first teaching job, I remember spending a fall weekend with some friends in Scarborough who were also new to the state. While cruising around, we noticed quite a few wetsuit clad people with bushel baskets lying face down in the Great Salt Pond. We found out these people were scalloping and having more time on our hands than money, decided we should scallop too. At this point in my marine education I didn't know a scallop from a clam. Two of us found some wet suits, some bushel baskets and an old wind surf board. We put our baskets on the board and paddled out in tandem to join the crowd. Within 25 minutes we had both gotten our limit of one bushel per person. There was no way to know that we had just participated in the last really big scallop harvest ever in the Great Salt Pond. It was 1985, and there hasn't been a year like that since.