Archive for August 2017

2017 Horseshoe Crab Monitoring and Tagging Recap

Horseshoe Crabs Spawning at Plumb Beach © Jennifer Kepler

Horseshoe Crabs Spawning at Plumb Beach © Jennifer Kepler

Another great horseshoe crab monitoring season has come and gone. It was quite an incredible year for horseshoe crabs in Jamaica Bay, with huge numbers of spawning horseshoe crabs at our four sites: Plumb Beach East and West, Big Egg Marsh, and Dead Horse Bay. While numbers are still preliminary, peak spawning appears to have taken place in the beginning of June. On June 11, we had 351 crabs at Plumb Beach East (in our quadrat samples), 59 at Plumb Beach West (in quadrat samples), and 1,313 at Dead Horse Bay (total count). Big Egg peaked slightly earlier, with 284 crabs in quadrat samples on May 27. While Big Egg’s numbers were down slightly from last year, overall numbers and spawning densities increased at all the other sites.


This was our ninth year collecting data on horseshoe crabs, an important food source for shorebirds like the threatened red knot, in Jamaica Bay. Our horseshoe crab monitoring and tagging efforts are part of a larger project run by the New York State Department of Environmental Conservation and Cornell University Cooperative Extension.


Our friends from National Park Service, who monitor horseshoe crabs at Great Kills in Staten Island, had an amazing year as well. They reported finding over a thousand crabs in just one night­—more than they’d seen in an entire season in some previous years.


With the help of a record 206 volunteers, including groups from Patagonia, Metropolitan Society of Natural Historians, Atlas Obscura, and the Trinity School, we tagged 800 horseshoe crabs in Jamaica Bay over the course of 12 nights this summer. We learned that 70 of those tagged crabs were resighted later in the season, almost always at the same beach where they were originally tagged. Every year shows us how important these locations are for spawning crabs that use the same beach repeatedly over the course of two months—and continue to come back year after year.


Of the 17 horseshoe crabs tagged at Plumb Beach West that were seen again, seven of them were resighted at Plumb Beach East. While this is still technically the same beach, it is interesting to learn that the crabs moved within this site during spawning season from the less populated west end to the more populated east end. No crabs tagged at the Plumb Beach East moved to Plumb Beach West.


Horseshoe Crab with Tag # 366741 © Debra Kriensky

Horseshoe Crab with Tag # 366741 © Debra Kriensky

We also resighted 20 horseshoe crabs tagged by our program in earlier years. Eight of them were tagged by us in 2016, seven in 2015, four in 2014, and one in 2013. There were also a handful of tags resighted in Jamaica Bay that were not part of our program; we’re anxiously waiting to hear where and when they were deployed.


Thank you to all of our volunteers who came out and helped with monitoring efforts this year. We of course couldn’t do this without the help of our outstanding site coordinators: Phil Cusimano, Christine Nealy, Ann Seligman, and Dottie Werkmeister. These dedicated individuals put a tremendous amount of time into making each survey go smoothly. We also want to thank National Fish and Wildlife Foundation’s Five Star and Urban Waters restoration program, Bank of America, FedEx, Patagonia, Williams Companies, and Investors Bank for their support of this year’s monitoring.


We are already looking forward to next year, which will be our 10th year tracking these amazing and important creatures!


-Debra Kriensky, Conservation Biologist