10 Years of Good Turns
‘reTURN the Favor’ Helps Horseshoe Crabs Get Back on Their Feet
Spawning horseshoe crabs along Delaware Bay beaches.
The Wetlands Institute’s horseshoe crab rescue program, reTURN the Favor (RTF), celebrated its 10th season this year, and the RTF volunteers have a lot to be proud of. This dedicated team of horseshoe crab heroes has developed into a key piece of the conservation puzzle, with more than 150 trained volunteers contributing to the recovery of a keystone species in the Delaware Bay this year alone.
Though horseshoe crabs are commonly found on beaches and in bays along the East Coast – including around Sea Isle City – the largest concentration of spawning horseshoe crabs in the world is found in the Delaware Bay. This population experienced a substantial decline resulting primarily from overharvesting and habitat degradation. Many other species within the local ecosystem are affected by this decline, as horseshoe crabs play a significant role in the food web. Their eggs and larvae are food for many species of finfish, all crab species, and several gastropods including whelks. The horseshoe crab’s most important ecological role is its connection to the survival of migratory shorebirds.
Each May, hundreds of thousands of shorebirds make a stopover on the Delaware Bay beaches on their way from South America to their breeding grounds in the Arctic, timing their two-week rest to coincide with the horseshoe crab’s spawning season. In order to complete the long-distance migration, which can exceed 9,000 miles, shorebirds rely on nutrient-rich horseshoe crab eggs to double their body weight and replenish depleted energy reserves. As the number of horseshoe crabs has declined, so has the availability of eggs for consumption. Shorebird populations that rely on the food source are also plummeting, especially the red knot, a federally designated threatened species whose survival is critically dependent on the recovery of the horseshoe crab population.
In addition to being essential to the ecosystem, horseshoe crabs also play a critical role in human health and have directly impacted most people alive today. A solution called limulus amebocyte lysate produced from the blood cells of horseshoe crabs is used to test for the presence of bacteria in injectable drugs, vaccines, and implantable devices. The crabs are harvested to have approximately one-third of their blood removed for this purpose. Although the crabs are returned to the water alive, there is an estimated 10-15% mortality rate associated with this practice.
Although New Jersey has a complete moratorium on the harvest of horseshoe crabs for anything other than biomedical uses, other states still harvest horseshoe crabs from the Delaware Bay to be used as bait for the conch and eel fishing industries.
Changes in the condition of beaches and nearshore habitat have also impacted the population of this long-lived species. During typical spawning activity, an estimated 10% of the population succumbs as a result of stranding. While coming ashore they can be easily overturned by waves, and are then vulnerable as their soft undersides are exposed to the sun and to predators. It is likely the amount of loss from stranding has increased due to erosion of beaches from rising tides and rougher waters. These erosional conditions create hazards, as rubble from past infrastructure is exposed and horseshoe crabs risk becoming trapped in structures such as jetties, groins, outfall pipes, boat ramps, houses, bulkheads, riprap, and bin blocks, or in the adjacent dunes and marshes.
reTURN the Favor volunteer on a rescue walk.
Overturned horseshoe crabs in need of rescue.
The RTF program was introduced in 2013 to address these forms of stranding mortality and to bring more awareness to horseshoe crab conservation. Volunteers are trained by conservation professionals to properly rescue overturned and trapped horseshoe crabs that would otherwise succumb to dehydration or predation on 18 beaches along the Delaware Bay. The program provides each volunteer the opportunity to take direct conservation action by saving the lives of horseshoe crabs one at a time, while the combined effort of all volunteers contributes to the recovery of a keystone species in the local ecosystem.
Devoted volunteers go out on the beaches to rescue at all hours, often in the middle of the night, and endure challenging conditions and biting insects to make their rescues. It is labor-intensive work, especially on nights when there might be more than 1,000 crabs to rescue just on one section of beach. But volunteers agree that the hard work is worth the reward of saving lives and contributing to the conservation of many interconnected species.
RTF also gives volunteers a sense of community as they share a passion for what they do, and many close friendships have been born out of the program. Volunteers share photos, experiences, triumphs, important information, articles of interest, and anything else horseshoe crab-related on an RTF Facebook group. These posts keep volunteers connected and motivated throughout the season, and a party at the end of the season allows volunteers to get together and celebrate their achievements.
In addition to rescuing the crabs, volunteers collect important data to support habitat restoration. Over the past 10 years, beach restoration along the Delaware Bay has become one of the most significant strategies to protect spawning habitat for horseshoe crabs and foraging habitat for migratory shorebirds. The data collected by RTF volunteers has played a vital role in that work by identifying beaches in need of rubble removal and/or sand replenishment. Program coordinators recently developed an interactive map for biologists and the public to visualize program data including key hazards and beaches to prioritize restoration projects and effort.
The RTF program has grown significantly in the past decade as its message reaches more people each year and volunteers become more dedicated to the work of conservation and outreach. The enthusiasm of the volunteers to spread the word and share their passion as horseshoe crab ambassadors has played a huge role in the growth of the program. In its first year, the program started with six walk leaders who contributed 45 volunteer hours over 43 individual walks and saved close to 5,000 horseshoe crabs. Those numbers have steadily increased each year, as shown by the same statistics from 2021: 107 walk leaders, 2,605 volunteer hours, 867 individual walks, and almost 153,000 crabs rescued! In total (not including 2022 data) more than 840,000 crabs have been saved.
Horseshoe crabs trapped behind an old bulkhead.
The Wetlands Institute’s partners associated with this program include the Executive Office of Western Hemisphere Shorebird Reserve Network-Manomet, Conserve Wildlife Foundation of New Jersey, Citizens United for the Maurice River, Friends of Cape May National Wildlife Refuge, The Nature Conservancy, New Jersey Audubon Society, and New Jersey Fish and Wildlife. Each partner coordinates one or more of the program’s beaches to offer support to the volunteers. Some of the partners, including The Wetlands Institute, offer public walks to introduce the local community, as well as long-distance visitors, to the program. These public walks have resulted in recruiting a number of long-term volunteers who get hooked right from their first walk.
Anyone interested in becoming a volunteer can attend a training session in the spring. These group sessions typically are held in mid-to-late April, and will be posted on the website when dates are available. To learn more about the program and explore the new interactive map, visit returnthefavornj.org.
The RTF program is currently supported by Ocean Wind (An Orsted and PSEG project) and the Marshall Reynolds Foundation.