Tagging Crabs – Tricky, but Worth it!

In late May, a group of Defenders of Wildlife volunteers headed down to the Delaware Bay shore to tag horseshoe crabs.  These crabs are a fundamental part of the Delaware Bay’s ecology, and are essential to the life cycle of migratory shore birds, including the highly imperiled red knot. The red knot makes one of the longest yearly migrations of any bird: Nearly 10,000 miles, from the southern tip of South America to its breeding grounds in the Arctic!  The Delaware Bay is an important stop as they feast on horseshoe crab eggs to regain their strength before they continue on their journey north.  Historically, horseshoe crabs have been used as bait for fishing eels and whelk, and due to their declining number, there is a temporary ban on fishing horseshoe crabs in New Jersey. Their spawning is the only time during the year that they come ashore, and unfortunately this season is just a few short weeks in May and June – leaving us with a very small window of time to monitor the health of this species that so many others depend on.

Our evening began when 20 volunteers met for dinner in Cape May Courthouse.  Over pizza and salad, guests listened to Shane Godshall of the American Littoral Society and Laura Chamberlain of Celebrate Delaware Bay speak about their work tagging and monitoring horseshoe crabs.  Yaron Miller, Defenders’ Director of National Outreach, and I shared ways members can help support the Endangered Species Act, the highly successful legal lifeline for thousands of imperiled species. Our volunteer projects can make a big difference on the ground, but without the protections granted by the Endangered Species Act, the imperiled wildlife we’re working to help would be in much more danger.

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After dinner, the group split up and headed to two beaches: Cook’s Beach and Pierce’s Point. In total, we were able to tag 425 horseshoe crabs! These tags will allow scientists to monitor Delaware Bay crab populations, which will support the scientific research of the crab and shorebird populations. As we walked onto the dark beaches, we used our headlamps to scan the shoreline and were treated to the sight of hundreds of crabs spawning.  The females dug down into the sand while the males gathered around to fertilize the eggs – a ritual that these “living fossils” have completed each year for millions of years. Volunteers were able to tag the crabs and help with monitoring their numbers along the beach.  As the tagging was wrapping up, the crabs finished their spawning and began to retreat back into the ocean.  It was a rare opportunity and we were all thrilled to be a part of this important study!

Julia Millan Shaw is the Philadelphia Metro. Outreach Representative for Defenders of Wildlife