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Horseshoe Crab Survey

CIB Volunteers Take the Lead Counting Horseshoe Crabs!

Joshua Blockstein, Trevor Gibson, Dylan Greer (left to right) helped the James Farm Volunteer Horseshoe Crab Survey team tag horseshoe crabs on the beach at James Farm.

Each year, horseshoe crabs come ashore by the thousands to spawn on the sandy beaches of our Bays around the full moon and new moons in May and June.

Researchers from all over the world travel to Delaware to observe this annual phenomenon on the beaches of Delaware Bay, but much less was known about the horseshoe crab spawning population on the Inland Bays.

In 2008, the Center for the Inland Bays partnered with Dr. Doug Miller at the University of Delaware, School of Earth, Ocean and the Environment in Lewes to begin to answer questions about horseshoe crab spawning in the Inland Bays.

Our data has shown that the Inland Bays are host to a significant horseshoe crab spawning population and that spawning density at surveyed Inland Bays sites approach those found in Delaware Bay surveys.

Volunteers are needed for the 2015 Survey!

If you would like to participate in the 2015 Survey, you can contact Team Leaders directly or send an email to volunteer@inlandbays.org.

Click link for 2013 results: 2013 Horseshoe Crab Survey Annual Report


2015 Horseshoe Crab Survey Information
 Site Survey Times & Dates
 Survey Protocol & Team Contacts
 Liability Waiver
 Random Quadrat Tally Sheet
 Total Quadrat Tally Sheet
 Tagging Procedure
 Beach Site Data Sheet

The annual Horseshoe Crab Survey is one of the volunteer citizen science projects at the CIB.



What’s it like to do a Survey?

In the spring, on the first full or new moon in May at high tide, volunteers will meet on six beaches around the Inland Bays. With flashlights in hand, bug repellent in their pockets and old sneakers on their feet, they’ll carry equipment down to the water’s edge.

Each site has a volunteer leader and a team of volunteers to assist. Working teams of three or more; two handling the equipment and counting, and one keeping dry to record the data, they work their way down the beach. The teams count horseshoe crabs in a 1-meter quadrat (measuring square), ‘leap-frogging’ along the length of the beach. These random samples are used to estimate the number of horseshoe crabs per width of beach, the total number of females nesting on that beach, and the male:female sex ratio.

Map of the Horseshoe Crab survey locations (click to enlarge).

If you are interested in participating in the 2015 Survey, check out the Survey Times & Dates and the map for the location closest to you. You can contact the Survey Team Leader directly or contact our Volunteer Coordinator at volunteer@inlandbays.org or call 302-226-8105.

If you wish to participate in the Survey, please bring a completed Liability Waiver for each individual or family member participating in the Survey and give it to the Team Leader. Individuals under the age of 18 must have an adult chaperone on-hand at all times.

Click here to view a power point: The Importance of the Inland Bays Beaches as Horseshoe Crab Nesting Sites — Kat McCole and Doug Miller, UDCMES

View Horseshoe Crab Survey Brouchure»

Data for the Horseshow Crab Studies

 2011 Horseshoe Crab Survey Results
 2010 Horseshoe Crab Survey Results
 2009 Horseshoe Crab Survey Results
 2008 Horseshoe Crab Survey Results
 2008-2010 Chart of Spawning Horseshoe Crabs
 2008-2010 Chart of Adult Female Horseshoe Crabs

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