DELMARVA ALMANAC

Protecting Our Diamondback Terrapins

by Dave Wilson

Dave Wilson and a couple of friends to tell us about the Diamondback Terrapin.

Dave Wilson:
Our guests today are Scott Smith with Jen Rafter. As we heard last time, Scott Smith is a Wildlife Ecologist for DNR’s Natural Heritage Program where he has worked with birds, reptiles, and amphibians for 26 years. Jen Rafter is the Technical Coordinator for the Maryland Coastal Bays Program. She oversees their terrapin monitoring program as well as tracking the program’s environmental progress and coordinating climate adaptation and resilience activities. You two, welcome.

Scott, I want to start with you. Can you discuss the biology of terrapins? What they eat, where they live, where they go in the winter?

Scott Smith: " "The diamondback terrapin is the only species that lives in brackish water--in salt ponds, salt marshes, near the beach. Terrapins are adapted to excrete the excess salt in their system which would be lethal to a lot of other turtle species. They have really three main habitat criteria. They need beach areas for nesting, marsh habitat for the juveniles and for feeding and they need open water areas, deeper open water for females, and near shore areas for males and juveniles.

Dave Wilson:
Can you talk a little bit about what terrapins eat?

Scott Smith:
"Sure. Terrapins are kind of a diet specialist. They are what we call a molluscivore that means they feed on mollusks or shellfish and so snails and clams and mussels are a big part of their diet. But they also opportunistically feed on a lot of other things such as different types of crabs. And there's even some suggestion that they will intake eel grass seeds while feeding on other things and they're responsible for helping to spread eel grass around in the marsh area. "

Dave Wilson:
Terrapins have quite a history in Maryland starting with their sustainable harvesting by Native Americans which was followed by waves of more aggressive harvesting for food and for the pet trade until 2007 when the Maryland legislature stepped in and banned commercial harvest of the species. Dave Wilson: How does DNR currently track of their populations in the state?

Scott Smith:
"So we have a number of ways we keep track of terrapins. First off we have a really great relationship with Dr. Willem Roosenburg from Ohio University who's been studying terrapins in Maryland for 25 plus years, starting with a long-term population study in the Patuxent River. Now he's working on Poplar Island in Talbot County. Turtle populations trends are hard to track unless you track them over long periods of time because they are so long-lived so there's huge value for us in looking at his data and him sharing his dated with us. We also have been coordinating a Statewide Terrapin Headcount Survey where scientists and citizen scientists go out on the water in boats and count terrapins in the spring. "

Dave Wilson:
Yeah I know one of the things that precipitated that was the concern about crab pots and they're getting caught and killed in crab pots. Maybe you can elaborate on that.

Scott Smith: "Sure. The crab pot that we have now was first developed in the Chesapeake Bay in Virginia and it was adopted in the 1940s here in Maryland. Right off the bat waterman noticed that they were drowning and killing terrapins and fish and other things and so its use was banned in the 1940s by the legislature and then when it came back in to use a couple of years later it was only allowed to be used in deeper water habitat. Right now in our regulations from a commercial standpoint crab pots can’t be used in water that's less than 4 feet deep and so the idea there is to keep them out in deeper water where you're not going to impact the larger number of terrapins."

"However in the 1970s regulations were passed that allowed their use by recreational crabbers, i.e. shoreline landowners in those same tributaries where we know we have large terrapin populations and thus over the years there’s been many records and reports of crab pots being filled with dead terrapins. So in 1999 after research was done again by Dr. Roosenburg, we adapted regulations to require terrapin excluder devices or what we call BRDs, (bycatch reduction devices) from recreational crab pots and those have been a help. But our problem right now is that we're not seeing as much use by the public as we would like."

Dave Wilson:
Scott, what other threats might they face?

Scott Smith:
"Like any other species, terrapins face problems with habitat loss and habitat fragmentation. Because shoreline habitats are so important to them the development of our shorelines and shoreline hardening (basically rip rap) and other types of shoreline stabilization measures, while they're great for the landowner, they basically keep the terrapins from their ability to access nesting habitat."

"Besides recreational crab pots there's road mortality, there's boat strikes, and of course there's the threat by global climate change and sea level rise on their important marsh and beach habitats.
Jen Rafter: " "We talked about how terrapins face threats from crab pots and this often becomes a problem when there's ghost crab pots that have been cut loose from their lines from boaters that hit them accidentally. In addition to not being good for the boat, this causes the crab pot to be free drifting and loose and those crab pots become self-baiting. As animals enter more animals enter to prey on them and terrapins as air breathers need access to oxygen and often drown in ghost crab pots."

Dave Wilson:
I think I read that the program had an abandoned crab pot with a lot of terrapins in it just a couple weeks ago.

Jen Rafter:
"That's correct. A crab pot was brought in with over 20 dead terrapins in it. "

Dave Wilson:
Can you tell me a little bit about the Maryland Coastal Bays Program work with terrapins?

Jen Rafter:
"Since 2011 as part of the Maryland Terrapin Working Group that Scott heads the Maryland Coastal Bays Program has helped organize volunteers to conduct citizen science terrapin surveys. We do the surveys in the spring when the terrapins emerge usually the week after Memorial Day. This spring 27 volunteers sited over 400 terrapins and the surveys take place via motor boat, kayak, or canoe, even stand up paddle boards. And also for the past two years people have done land surveys using spotting scopes."

Dave Wilson:
Is there an easy way for people to get involved in that? Is there a website or phone number?

Jen Rafter:
"Sure. You can give me an email at .(JavaScript must be enabled to view this email address) or call 410-213-2297, ext. 105 and you can also go to mdcoastalbays.org and there's a link on our homepage for the terrapin project."

Dave Wilson:How about turtle excluder devices? Is there a way to get those on crab pots if people are interested?

Jen Rafter:
"That's a great question. The Maryland Coastal Bays Program actually has free bycatch reduction devices or terrapin excluder devices through a grant from the Community Foundation of the Eastern Shore and if you're interested in getting some of those give Sandi an email at .(JavaScript must be enabled to view this email address) and we will be happy to help you out with those as long as supplies last."

References:


Maryland State Reptile - Diamondback Terrapin
Diamondback Terrapin - Malaclemys terrapin
Maryland Coastal Bays Program
Diamondback Terrapins - Maryland Sea Grant
MD legislators ban commercial harvest of diamondback terrapins