Part 2, Sec. 2B2e
Sanctuary Resources - Natural Resources
Sea Turtles

e. Sea Turtles

Although four species of sea turtles have been recorded in Gulf of Maine waters, only two, the leatherback and the Atlantic ridley, are seen with any regularity. All species are currently listed as either threatened or endangered.

Atlantic, or Kemp's ridley (Lepidochelys kempi). Atlantic ridleys are observed in waters off Massachusetts as juveniles, having either swum or drifted north in the Gulf Stream from hatching areas off the southern coast of Mexico. Juvenile ridleys generally measure 10" to 12", and weigh around seven pounds. Southern New England waters are important feeding grounds for ridleys and are thus considered important habitat for this endangered species. Each fall (generally between November and January), as Cape Cod Bay water temperatures decline, a number of ridleys regularly strand on Cape Cod due to cold-stunning (Prescott, 1986). Cold-stunning occurs when water temperatures fall below 12 degrees C (57 degrees F), and turtles are unable to swim or digest food. Between 1977 and 1987, a total of 115 juvenile ridleys were found stranded on Cape Cod beaches (Danton and Prescott, 1988).

Leatherback (Dermochelys coriacea). The endangered leatherback is a regular summer visitor to the waters around Cape Cod, the Gulf of Maine, and Nova Scotia. This is the only species of sea turtle that colonizes cold waters for feeding activities, which include jellyfish (notably the lion's mane jellyfish), comb jellies, salps, and other jelly organisms abundant in these waters during the summer. The largest and heaviest of all extant reptiles, leatherbacks may grow to ll feet in length and weigh up to 1,900 pounds. Turtles observed in the area between Cape Cod and Newfoundland are generally single, mature animals, frequently measuring more than six feet in length and weighing over 1,000 pounds. Of all sea turtles, leatherbacks appear to migrate the farthest in search of summer food; Western North Atlantic leatherbacks breed anytime between April and November along beaches in Central and South America (with very occasional nesting activity noted in southern Florida). Females usually nest only every other year, during March and April, and may not migrate as far north as males during breeding years. This may explain why most leatherbacks observed in the Gulf of Maine are males. Sightings off Massachusetts are most frequent during late summer (July through September). The turtles usually first appear in the Gulf of Maine between May and June, and are most frequently seen in the Gulf's southerly coastal waters. In the autumn, the turtles move further offshore and begin their migration south for the winter (Payne, et al., 1986).

The physiological adaptations of leatherbacks to pelagic environments make this species poorly-equipped to deal with obstructions in shallow waters. Leatherbacks regularly become entangled in fishing nets and lobster pot lines, situations which are compounded by this species' inability to either maneuver easily or to swim backwards. In addition to these problems, leatherbacks have been reported to die from intestinal blockage following consumption of plastic bags, which they presumably mistakenly identify as jellyfish. Collisions with boats also occasionally result in leatherback mortality.

Loggerhead (Caretta). Although loggerhead sea turtles are the most widespread and numerous species along the eastern seaboard, they are generally absent in shelf waters north of Cape Cod, including Cape Cod Bay and the Gulf of Maine. Water temperature is the primary factor in marking Massachusetts as the northern tolerance limit for this endangered species. Following nesting activity, loggerheads disperse northward, and there are limited sightings along outer Cape Cod and the islands during mid-summer through fall. Occasionally, loggerheads become trapped inside Cape Cod Bay in late fall and winter, resulting in cold-stunning and death.

Green (Chelonia mydas). Juvenile green sea turtles are rare summertime stragglers as far north as Cape Cod Bay. This endangered species generally is found in waters warmer than 20 degrees C.

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