Survey Finds 12,000-Plus Horseshoe Crabs In Watershed

BERLIN – A 2020 survey by the Maryland Coastal Bays Program resulted in the count of more than 12,000 horseshoe crabs in local waters.

The Maryland Coastal Bays Program (MCBP) partnered with the Maryland Department of Natural Resources (DNR) and local volunteers to complete a horseshoe crab survey from mid-May to early July. A total of 12,228 horseshoe crabs were counted.

“We usually do not have any expectations for the surveys since the horseshoe crab counts can vary significantly from year to year, however we always hope that we will record high counts,” said Carly Toulan, a MCBP environmental scientist. “This year’s count was twice the amount last year, however it was right around the average count when compared to previous years data.”

She said MCBP conducted four different phases of assessments to count horseshoe crabs between mid-May and early July. Each phase consists of two different surveying times and dates, so crabs are counted a total of eight nights.

“We have a handful of wonderful volunteers who cover three out of the five surveying locations, which are Sunset Island, Homer Gudelsky Park, and the Oceanic Motel,” Toulan said.

She said MCBP and DNR surveyed Assateague and Skimmer Island, since those are protected areas and only accessible by boat. During the survey, staff and volunteers count and record all horseshoe crabs within a 1 meter transect, extending into the water 1 meter from the high tide line.

“On the data sheet we record the number of live male and female horseshoe crabs as well as the number of dead male and female horseshoe crabs,” she said. “This data is later used in our analysis and annual report of the survey.”

MCBP also conducts an annual terrapin survey, which takes place the week after Memorial Day weekend. This year’s survey counted 369 diamondback terrapins. While that number is lower than it has been in years past, Toulan attributes that to weather and COVID-19 concerns. She explained that MCBP had intended to cancel the survey because of COVID-19 guidance, but when the state relaxed restrictions on field work staff decided to go ahead with it.

“Since we decided last minute to conduct the survey, we were unable to reach out to as many volunteers,” Toulan said. “This reduced the number of volunteers for the survey, thus reducing the number of surveys conducted and terrapin counts. Although the numbers are lower than normal, the data is still valuable and can help us determine what areas in the bays terrapins are inhabiting.”

To count the turtles, staff and volunteers conduct water- and land-based surveys.

“For the land-based surveys, volunteers choose a point on land by the water and conduct three separate surveys at that location with each lasting 15 minutes,” she said. “During the 15 minutes, volunteers will count the number of terrapins they spot both on land and in the water.”

For the water-based surveys, staff and volunteers use kayaks, paddleboards, canoes and boats to spot terrapins.

Toulan said the horseshoe crab and terrapin counts were important for various reasons.

“These surveys not only provide insight on population trends, but they also allow us to see where these species are spawning, mating, and living,” she said. “Knowing where the hot spot locations are for these species allows MCBP and partners like DNR to allocate resources and funds to conserve, restore, and protect these locations. MCBP monitors numerous species and overall biodiversity at both current and future restoration sites through seining, fish sampling, surveying, and other scientific methods.”

MCBP also assists partner agencies with similar projects such as subaquatic vegetation surveys (SAV) and annual clam surveys.

About The Author: Charlene Sharpe

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Charlene Sharpe has been with The Dispatch since 2014. A graduate of Stephen Decatur High School and the University of Richmond, she spent seven years with the Delmarva Media Group before joining the team at The Dispatch.