Saving the Horseshoe Crabs for the Birds

Sometime in mid-May, Beth Freiday hopes to see New Jersey’s bayside beaches turn a dusky olive color.

“At the peak of horseshoe crab spawning season, the beaches are almost green from the quantity of eggs and crabs covering the sand,” explains Freiday, a U.S. Fish and Wildlife Service biologist based in New Jersey.

While green beaches are an interesting sight in their own right, it’s what they signify that Freiday cares about – an abundance of crab eggs for migratory shorebirds like the threatened rufa red knot to feast on during their stopover in the Delaware Bay.

The beaches along Delaware Bay are some of the most critically important stopover sites for migratory shorebirds, many of which are undergoing alarming declines. Without a jumbo snack of horseshoe crab eggs, these birds might not make it on their long-distance migration.

To help, the U.S. Fish and Wildlife Service is working at numerous sites along the Delaware Bay to restore beaches and improve conditions for spawning horseshoe crabs, thereby helping support migratory shorebirds.

Horseshoe crabs spawning in Delaware Photo credit: Gregory Breese/USFWS

Fortifying Beaches

At one such site, Freiday is coordinating a partnership with the American Littoral Society and others to restore a 1.5-mile stretch of New Jersey shoreline severely damaged by Hurricane Sandy. These beaches saw a loss of 2 to 3 feet of sand, with the sand pushed so far above the high tide line that spawning crabs could no longer reach it.

To remedy this, the partners are trucking in sand from a local sand mine and moving it onto the beach with a bulldozer, using lightweight pieces of equipment to spread it. Work started at the end of March at Cooks and Kimbles Beaches in Cape May County and is expected to last until mid-April.

All told, approximately 12,000 cubic yards of sand will be spread across the two beaches, which together span 5.5 acres.

“We’re very careful of ecological and historical resources at the sites,” says Freiday, noting that the most environmentally appropriate methods are used for replacing the sand.

While Hurricane Sandy initially wiped out these beaches, Freiday says the problem is persistent.

“Since Sandy, we have had some destructive winter storms that move sand from the beach into the adjacent marsh,” she explains. “This leaves not enough sand on the beach for crabs to spawn, and the sand that is moved into the marsh is no longer accessible for crab spawning.”

It might be something to get used to with a changing climate. The mid-Atlantic Coast is expected to experience some of the fastest rates of sea-level rise in the United States, with more intense storms like Hurricane Sandy battering coastlines.

Restoring Cooks Beach in New Jersey Photo credit: Elizabeth Freiday

Connecting the Dots

Horseshoe crabs are not endangered, though they are under harvest restrictions in New Jersey and Delaware. They experienced a rapid decline from overharvesting in the 1990s. Then came Hurricane Sandy, which demolished 70 percent of New Jersey’s key horseshoe crab habitat.

Since horseshoe crabs don’t start breeding until at least 9 years of age, population increases might not be noticeable for a while. But the good news is they produce upwards of 100,000 eggs in a season – as long as they have access to the sand habitat they need.

Freiday’s team is planning to have all the sand spread and ready for spawning horseshoe crabs by April 15.

“We don’t know exactly when the horseshoe crabs will come up onto the beaches to lay eggs – it all depends on water temperature,” explains Freiday. “We usually estimate May 1, but this year the water is warmer so it could be sooner. We want to be ready.”

After the horseshoe crabs come in to lay eggs, the migratory shore birds will show up – hopefully by the thousands. And the tourists soon follow.

Ultimately, restoring these beaches will not just benefit horseshoe crabs and migratory shorebirds, but also the people who live, work and recreate here. Benefits to people include greater protection from storm surges, improved beach areas for public recreation, and the economic benefits of beach and wildlife-related ecotourism, valued at $522 million in New Jersey’s Cape May County alone.

Endangered rufa red knot at Mispillion Harbor, Delaware. Credit: Gregory Breese/USFWS

Horseshoe crab eggs provide a vital food source for rufa red knot and other shorebirds Photo credit: Gregory Breese/USFWS

This restoration work is being funded by the Department of the Interior through the Disaster Relief Supplemental Appropriations Act of 2013. Partners include the Fish and Wildlife Service, the American Littoral Society, the New Jersey Department of Environmental Protection and the Army Corps of Engineers. Additional work has been coordinated with the National Fish and Wildlife Foundation NFWF and the Conserve Wildlife Foundation of New Jersey.