Horseshoe Crab Egg Surveys Expand to More NY & NJ Bays

Littoral Society staff have been digging on beaches along Raritan Bay and Shark River for horseshoe crab egg density surveys.

Recently, American Littoral Society staff have been crawling on beaches along the Raritan Bay and the Shark River.
 
Why have we been on our hands and knees, pawing through sand at these places? To count tiny eggs - little bigger than the grains of sand in which they are buried - which have been left by living fossils.
 
These egg density surveys can provide crucial information toward the effort to protect horseshoe crabs, a species that is crucial to the health of our bays and has survived unchanged for more than 300 million years.
 
Such surveys have been conducted for years along Delaware Bay beaches. But thanks to new funding, the Littoral Society has partnered with the NJ Delaware Bay Shorebird and Horseshoe Crab Project and Susan Linder, a field scientist with the Horseshoe Crab Recovery Coalition and Wildlife Restoration Partnerships (HCRC/WRP), to expand these vital surveys into Raritan Bay and Jamaica Bay.

Horseshoe crab eggs mixed look like little gray balls mixed with sand.

Here at the Littoral Society, our commitment to protecting horseshoe crabs is as enduring as these ancient mariners themselves. In 2008, we and partners campaigned for and won a New Jersey moratorium on harvesting horseshoe crabs from the Delaware Bay. After Hurricane Sandy struck, we began restoring Delaware Bay beaches critical for crab spawning. Most recently, we have joined efforts to have the crabs placed on the endangered species list, and to convince the Atlantic States Marine Fisheries Commission - which manages fishing quotas for 15 Atlantic coastal states - to stop permitting bait harvesting of any horseshoe crabs.
 
Horseshoe crabs are not just ancient mariners navigating coastal waters for millions of years; they are ecological linchpins. In addition to their eggs providing a crucial food source for migrating shorebirds (including the Rufa Red Knot), their unique blood of contains a substance that has been crucial in medical testing to detect bacterial contamination. While horseshoe crab blood can be taken without killing crabs, there is mounting evidence that the methods used by biomedical companies to bleed the crabs are also contributing to the population decline.
 
What role does counting horseshoe crab eggs play in this ongoing effort? They give us a direct snapshot of horseshoe crab spawning success on specific beaches. By counting the number of eggs on the surface and buried egg clusters, we can understand how intensely horseshoe crabs are using these areas for reproduction. That data tells us not just if they're spawning, but how much they're spawning.
 
Such detailed information is critical, especially within the context of the historical decline of horseshoe crab populations. Decades of overharvesting for bait and their unique blue blood (used in biomedical testing) have significantly impacted their numbers. Understanding current egg density helps us gauge population health, identify critical spawning hotspots, and monitor the effectiveness of restoration efforts.

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A cluster of horseshoe crab eggs found during a survey.

Members of our staff were trained in the precise methods for conducting these surveys around lunar cycles between May and June 2025. For the Raritan Bay surveys, our team has already completed two rounds, meticulously visiting four key beaches: Cliffwood Beach, Atlantic Highlands, Sandy Hook (Plum Island), and Shark River.
 
During each visit, staff go to GPS locations along the beach, then take samples in a 9-meter transect, carefully sifting through the sand for both loose eggs on the surface and deeper, buried egg clusters.
 
So far, we've been thrilled to find both types of eggs at three of the four beaches, and we're eagerly anticipating the third round of sampling during the upcoming full moon tidal cycle.
 
This invaluable data directly informs our ongoing efforts to protect horseshoe crabs, allowing us to pinpoint crucial spawning grounds and advocate for targeted conservation strategies, ensuring these remarkable creatures continue their ancient ritual for generations to come.

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