NEU TL 76 001 C 3 ' ,~ ggg ggpgLSPJ Placopecten magellanicus! gag COFVONN merciallyoff the coastof Maine,eastern Canada and on the GeorgesBank. Twoother scallopsare fished commercially in the UnitedStates the bayscallop found in shallow watersfrom Cape Cod south to the watersoff NewJersey and the calico scallop, a southernscallop, fished.commercially off the Carolinasand Florida. However,the sea scallopis the largestscallop fishery and was the third mostvaluable fishery in Maine in 1975. Seascallops are foundall alongthe Mainecoast in the mainestuaries and bayson beds of gravel,sand oz pebbles;however, commercial fishing is generally limited to the Penobscot Bay area. Some HINGE of Maine's fishermen also fish for scallops offshore on the Georges Bank.

The shells valves! of the sea scallop are fan-shaped with a straight hinge and wings at each side of the hinge. Manyof the scallop species have radial ribs the scallop shell most usually pictured in art and architecture is similar to that of the bay scallop!; however, the sea scallop shells are relatively smooth. The bottom shell is usually flatter and light colored while the top shell is convex and tannish. Concentric rings mark periods of growth, and if the scallop undergoes a serious disturbance, its shell will be marked with a shock ring. Scallops growing on Georges Bank where there is extensive dredging may have very distinct shock rings.

Clams and oysters are known to be sedentary, but not the sea scallop. The scallop perfected jet propulsion long before man.With the useof its adductormuscle which is thepart of the scallopyou eat!, it opensand closes its valves,forcing water out through two openings near the hinge. This movementis most generally used as anescape mechanism. However, it canalso move in the oppositedirection. This is madepossible because the scallop has a curtainlikemantle edgewhich the scallop holds firmly in placeas it opensand shuts its valves.The mantleprevents the water from shooting through the hinge, and thus the scallop moves for- ward. It looksas if it werebiting thewater as it moveS.By controlling the muscles of its mantleflap, the scallopcan move in anydirection. Despiteits greatmobility, tagging experimentsdo not showany migrational habits.

Another unusual feature of the scallop is its eyes. AGE RINGS Along the edge of the mantle the scallop has as many as fifty blue eyes, eachcontaining a cornea,lens andretina. Theyprobably cannot. form an imagebut are very sensitive .Il to light. If a fish shouldcause a shadowand scare the scallop, it's valveswill snapshut andthe scallop will swimrapidly away. While resting on the bottom, the scallop's valves are not closed tightly but are held open bv the triancular elastic cushion on its hinge. Commercial fishing for sea scallops began in Maine in the 1880's. The scalloper to~@[email protected] of a coarsemesh bag made of wirerings. Mainefishermen generallyuse a 4-foot drag, although3-foot tandemdrags have been popular.. Thescal- loper tows the dredgefor about 15 minutesand then pull it up. Thesedredges are estimatedto haveonly 54 to 15%efficiency. The openseason for catching sea scallops in Mainewaters is from November1st to April 14th. Thewaters are cold then, making the scallops sluggish and less able to swimaway from the dredges. Divers can also gather scallops commerciallyduring the season,usually in rocky areaswhich the dredge cannot reach. Scallopsfeed on microscopic plants andanimals in the water. Theyuse their cilia and mucusto collect the food from the water as it passesthrough the mantle cavity.. ...Spawningtakes place fromlate Augustto early Octoberand perhaps throughout the summerin inshore waters. The eggsand spermare emitted.into the water and fertiliza- tion takes place. Thetemperature of the water at the time of spawning C and10 C seemsto be the ideal temperature range conducive to spawning! seemsto have a great deal to do with the abundanceof the scallop landings six years later in coastal waters. However,water temperaturedoes not seemto affect scallopson the GeorgesBank....The lengthof the scallop'slarval periodhas not beendetermined. As it changesto adult form,the youngscallop will often attachitself to a solid substrate shells, etc.! by byssalthreads; however, this attachmentcan be releasedwhen desired and the scallop swimsaway.....In a givensize scallopthere may be greatvariability in the size of the muscle.....Scallopsas large as 225mm 9 inches! in height and210 mm 8'x inches! havebeen recorded in Mainewaters, but generally those dredgedare 125mm and 175mm inchesto 7 inches!in width. Sometimesthe adductormuscles will be 2 inches across...... Only 10%of the scalloper's catch maybe scallops of less than 76 mm inches!in diameter...... Thescallop is a coldwater creature end does not thrive in water temperatures above 20oC.

Abbott,R. Tucker. Kin domof the Seashell. NewYork: CrownPublishers, Inc., l972. Baird.,Frederick T. Meat.Yield of MaineScallo s, PectenMa ellanicus. Reseaz'ch Bulletin 416, Dept. of Sea.and Shore Fisheries. February 1954. Baxnes.R. D. Invertebrate Socio . Philadelphia: W. B. SaundersCo., 1963. Dow,Robert L. TheMaine Sea Scallo Fishe . FisheriesCircular 419. Departmentof Sea and Shore Fisheries, Augusta, Maine. 1956. SeaScallo Fishe . The Encyclopediaof Marine Resources. NewYork: Van Nostrand Reinhold Company, 1969. Merrill, ArthurS. andHaskell S. Tubiash.Molluscan Resources of the Atlantic and Gulf Coastof the United.States. Proceedingsof the Symposiumon Mollusca, Part III> 1970, pages 925-948. "Scallops," Knc clo edia Britannica, 1971, Vol. XIX.

Preparedfor MaineSea Grant bv JaneD. Simonds.ADDITIONAL COPIES may be obtained by writingPaul D. Ring,Extension Marine Specialist, Ira C. DarlingCenter, Walpole, ME 0457.

RECEIVED NATIONAL SEA GRANT DEPOSITORY PELL LI8RARY BUILDING NATIONALSEA GRANT DEPOSiTORY 6/76 URI, NARRAGANSETTB Y CAINPUS 0 NARRAGANSETT,R I 02882