Quahogs | Oysters | Soft Shell Clams | Mussels | Scallops | Crayfish

Bay scallops differ from clams and oysters in that they retain the ability to move actively throughout their lives. The juveniles will attach themselves to underwater eel-grass or algae through extruded filaments known as byssal threads. The Eelgrass offers protective isolation from many predators crucial during early life stages, and then settle-out within or adjacent to the vegetation. Their ability to move and remain above the sediment as they mature makes them less prone to bottom predation. Bay scallops eventually lose the tendency to attach themselves; they dwell on the bottom as adults, manipulating themselves through "jet propulsion" by forcefully closing their valves. Scallops less than one year old (determined by the annual growth ring) are considered seed and may not be harvested.

The bay scallop, as with other shellfish, has two shells, or valves, with the "laying" shell (the one the scallop rests on)being lighter in color and having a byssal notch or foot groove. The outer surface of a scallop shell exhibits prominent ridges and furrows, which radiate from the beak to the free margin. During the winter months, the scallop does not grow and a heavy concentric line, similar to that of a tree's annual ring, forms. Growth begins again in the spring and it is this ridge that determines the age of a scallop.

Scallops, unlike quahogs and soft clams, have only one adductor muscle, commonly referred to as the "eye." Bay scallops are hermaphroditic; all individuals possess male and female sex organs and produce both sperm and eggs.

Bay scallops spawn in response to increases in water temperature in the spring, beginning at approximately 61 degrees F., although spawning may be induced artificially in the hatchery by increasing water temperatures; 68 - 84 degrees is the spawning range, with 74 - 76 degrees inducing spawning within fifteen minutes after placement. Bay scallops have the capacity to spawn repeatedly over a period of weeks, depending upon external conditions.

Scallop larvae go through two distinct developmental stages, during which the mortality rate is at the highest point in the life cycle. The embryonic, or sub-veliger stage is the period prior to development of a shell; the post-embryonic, or veliger stage is the period during which the larvae have developed shells but prior to attainment of full development. During this pre-adult stage, the larvae are capable of both digging and swimming.

Once the scallops "set" by way of attachment to an available surface with byssal threads, they have reached the dissoconch ("two shelled") stage and are approximately 1/3 " in size. The scallop does not reach its full internal and shell development until the plicated stage, where the radiating ridges characteristic of the adult scallop develop. Bay scallops have a much shorter life-span than do oysters, clams, or mussels. Most bay scallops do not live beyond two years and they may reach sexual maturity within six months. They also retain their free-swimming (through jet-propulsion, expulsion of water through the "ears" coupled with shell closure) and locomotive abilities, which mandates that cultivation be off-bottom, in enclosed nets, bags, or cages.

Bay scallops, like other shellfish, are filter feeders. Unlike clams, who feed from below the substrate, scallops use their gills to siphon diatoms and other planktonic matter from the surrounding water.

Scallops are not as likely to act as a vector for disease as other shellfish because the adductor muscle is the most common food product. Pathogens are typically transferred through the food chain as the result of eating the whole shellfish, including the gut, where pathogens typically accumulate. However, consumption of whole and roe-on scallops has increased dramatically over the last two years, leading to increased risk of food product contamination.

*Information found at the Massachusetts White Paper