Archives of The Cold Blooded News

The Newsletter of the Colorado Herpetological Society

Volume 31, Number 11;   November, 2004

Gems of the Chesapeake:
Northern Diamondback Terrapin Malaclemys terrapin terrapin

by Marguerite Whilden

Diamondbacks may live as long as 50 years, though at seven years old a male is considered mature, can weigh about a pound, and be four inches along the plastron. The female terrapin matures by twelve years old and can weigh up to seven pounds, reaching lengths of nine inches long. Water temperature and food supply play a role in growth rates; in warmer waters terrapins stay active, feed longer, and hibernate less.

Terrapin mating occurs in May. In June and July. Females lay up to 13 light pink, leathery textured eggs in sand or loam covered nests on shore. Hatching occurs August-October, depending on temperatures. The sex of hatchlings is also determined by the nest temperature; a higher nest temperature produces more females.

Only 1-3% of the eggs laid produce a viable hatchling. When the hatchlings emerge, they are only an inch long and on their own. Their survivorship in the wild is currently unknown but is believed to be equally low. Hatchlings are a favorite food with herons.

The terrapin like, other turtles, has a strong beak rather than teeth. It is a predator more than a scavenger. The carapace or top shell of the Maryland terrapin may be light brown, bluish gray or black, and the plastron is yellow to olive in color. The top shell is covered with thin, shiny scales called scutes, and on some Malaclemys, there are black concentric rings which led to the nickname "diamondback." The skin of terrapins is its "fingerprint", in that no two animals are alike. Black spots and dashed or curly lines create a strikingly unique design.

Diamondbacks are strong climbers and have webbed feet enabling them to swim fast. How far they move throughout Chesapeake Bay is unknown. Studies have shown that adult terrapins may remain in a rather small area for most of their life.

There are several references to "Terrapin" as a grand dish as early as 1800. In any case by the turn of the century, terrapin was a much desired food item for the famous Terrapin Soup or Stew and the terrapin fishery was well established. In 1938, a candidate for Governor jokingly promised voters a "terrapin in every pot".

Nowadays, not many Marylanders have a taste for terrapin or the stomach for preparing them. Still, commercial fishery continues in Maryland and interest in the terrapin as a food item may be gaining as multi-cultural markets expand in the U.S. and Canada. Commercial fishery is prohibited from catching terrapins with a plastron length under of six inches. This presumably may result in a mostly female catch which could impact the breeding female population. In Maryland, terrapin season closes May 1 - July 31 to allow for mating and nesting.

Natural predation by foxes, crows, raccoons and humans is on an increase near terrapin habitat, while the ideal terrapin nesting habitat continues to be diminished by natural erosion, development, and shore erosion protection measures. Beach cleaning techniques also crush nests and increasing boat traffic is an issue. A major threat to the terrapin population is the crab pot fished in shallow waters.

By law, commercial pots are prohibited from the tributaries and pots can only be fished in the deeper waters of the main bay. However, Maryland waterfront property owners were permitted use of up to two of the crab pots at their property off their piers or shoreline regardless of location, main stem bay or shallow tributaries, 24 hours a day, 7 days a week, during the crab season. Unfortunately the "non-commercial" or "homeowner" crab pot is where the curious terrapin is unintentionally captured and drowned.

In 1999, Maryland passed legislation that requires the installation of by-catch reduction device (BRD) in all non-commercial crab pots in an effort to reduce terrapin death in crab pots. Today, the distribution and abundance of the terrapin in the Chesapeake Bay remains unknown and the future of the terrapin population lies exclusively with Marylanders.