DIAMONDBACK TERRAPINS have benefited from recent protections.
Once on the decline, the only turtle that thrives in brackish Texas coastal waters is under the protection of a law that prohibits its possession.
The diamondback terrapin was threatened by commercial harvest in the early 20th century for use in a popular turtle soup. Even after that trend ended, terrapin numbers continued to decline as they lost habitat, got caught in traps intended for blue crabs and faced continued harvest pressure. That changed in 2007, when a new regulation made it unlawful for people to “knowingly take or possess a diamondback terrapin (Malaclemys terrapin) or their eggs” unless they have a scientific, educational or zoological permit.
The turtles play an important role in the ecosystem, in part by acting like scavengers, feeding on sick or dead invertebrates like snails, clams, mussels, shrimp and crabs.
“The terrapins will feed on the sick ones, the weak ones, the ones that are easier to pick off from the rest of them, and by taking those out, they actually increase the vitality and quality of the prey population, and reduce competition for resources for the rest,” says Paul Crump, Texas Parks and Wildlife Department herpetologist.
This terrapin gets its name from its diamond-patterned upper shell, or carapace. The color of the carapace varies from brown to black; the plastron, or lower shell, is a lighter color. Its skin can range from dark gray to white, flecked with black spots. Males often have darkly colored spots and black markings on their upper jaw, resembling a mustache.
The terrapins thrive in the brackish, semi-salty water found in estuaries on the coast of Texas. While they live in salty water, they drink fresh water. After a rain, they will drink the fresh water flowing on the surface of the bay.
“When it rains, the turtles engorge and store water subcutaneously in tissues, and when they are hydrated, they look puffy,” Crump says.
Terrapin males are smaller (5-6 inches) than the females (9 inches). Generally, the terrapins are solitary unless they are mating in the water. The female lays four to 18 eggs in a tear-shaped nest on land.
Although terrapins are no longer harvested in most areas, they often enter crab traps and drown. Mesh traps shaped like cubes with four entrances on the sides are dropped down to the bottom of bays with bait to attract crabs.
“You can imagine the situation — you’ve got an air-breathing turtle prowling around and looking for crabs and there’s a trap on the bottom of the bay next to one of the islands or hangouts,” Crump says. “These guys go into the crab traps looking for the crabs to eat, but they get trapped and can’t get out and drown.”
In May 2018, an abandoned commercial crab trap with 82 dead terrapins was found at Bolivar Peninsula.
The deaths could have been prevented if the trap had been fitted with a contraption called an excluder, a requirement by law on commercial traps.
Each February since 2002, the Texas Parks and Wildlife Department has hosted the annual Abandoned Crab Trap Removal Program when crab harvesting is shut down. All crab harvesters are supposed to remove their traps and bring them up to code. TPWD coastal biologists examine each trap brought in for any evidence of diamondback terrapin mortality.
“We have a voluntary program where people can get turtle excluder devices for free to put on their crab traps,” Crump says. “They will actually keep turtles out of the trap and still alive.”
Earl Nottingham | TPWD
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