Save habitat for migration

By Tim Dillingham

and Kelly Mooij

Every spring, one of the most spectacular natural phenomena in the world occurs on quiet beaches of New Jersey's Delaware Bay. It is a critical pit stop in the migration of several shorebird species.

In the spring, their arrival is timed with horseshoe-crab spawning, as the crabs come ashore to lay millions of energy-rich eggs in the sand. The meeting is far from chance, having evolved over thousands of years. It is a ritual critically important to one shorebird, the red knot, which has just been added to the federal endangered species list. The spring meal provided by the bay's horseshoe crabs is literally keeping the red knot from going extinct.

Without being able to fuel up on horseshoe crab eggs, red knots can't complete a 9,300-mile one-way trip to their breeding grounds. But overfishing has led to steep declines in the horseshoe crab population since the mid-1990s. And that reduced food supply has led to the recent decline of red knots.

Recovery of the horseshoe-crab population is critical to the recovery of red knots. A 2008 moratorium on harvests in New Jersey is an important component of this recovery and must remain in place. Currently, horseshoe-crab egg numbers are far below what is necessary for population recovery, clear evidence that the moratorium is still needed.

Before the severe population declines, the spring congregation of horseshoe crabs and shorebirds along the Delaware Bay was compared to impressive wildlife spectacles on Africa's Serengeti. The second-largest congregation of migrating shorebirds in North America also creates benefits to the local economy. A study in 2000 estimated the economic impact of tourism around shorebird migration at nearly $13 million per season in New Jersey and the overall shorebird migration viewing on the Delaware Bay generating $34 million annually. This figure is projected to rise to $58 million annually if the Delaware Bay shorebird populations recover.

The U.S. Fish and Wildlife Service is in the process of identifying critical habitat for the species. They will also evaluate activities that would adversely impact red knot feeding and resting opportunities, such as disturbance of the foraging shorebirds, which causes them to move away from their food source and costs them energy needed to survive their migrations.

On the beaches, the birds are very sensitive to people, dogs, and other activities. New Jersey and the local communities have long worked together to ensure that people and dogs stay off the foraging areas during the shorebirds' stopover. Importantly, local residents have become leading advocates for this stewardship strategy.

One activity being evaluated for its impact on the migration process is commercial oyster aquaculture. If improperly sited, this relatively new industry could harm both horseshoe crabs and red knots.

The operations work from a rack system, placed in intertidal waters. Daily maintenance via all-terrain vehicles across beaches with feeding or resting red knots could create a significant disturbance. The racks themselves, placed in the intertidal zone, may prohibit horseshoe crabs from reaching their spawning habitat. A careful assessment involving many stakeholders, including government agencies, oyster growers, and conservation organizations, is required.

The American Littoral Society, in partnership with other conservation organizations and the state, has, since Superstorm Sandy, brought millions of both public and private dollars to several Bayshore beaches and their adjacent communities to restore their storm-buffering capacity, as well as to repair storm damage to horseshoe crab and shorebird habitats. We must continue to ensure that activities conducted on these beaches are consistent with and not detrimental to the habitat restoration.

We believe there is a way to ensure a strong oyster aquaculture industry in the Delaware Bayshore while protecting the areas most critical to shorebirds. By using the portions of the aquaculture development zone, which will have the least impact on the horseshoe crabs, and consequently on the red knot and other migrating shorebirds, we can meet the goals of the industry while protecting these species and the ecotourism industry that depends on them.

As virtually the entire North American population of red knots uses the shores of the Delaware Bay during their migration, New Jersey plays a critical role in the future of this species. There is no other food but the crab eggs in sufficient abundance that can support the birds on their journeys. There is no other place but the Delaware Bay that offers them the opportunity to adequately refuel.

Protection measures such as the horseshoe-crab moratorium must remain in place, while activities that may adversely affect the red knots or the crabs require an assessment that is conducted in an open and stakeholder-inclusive process. In the end, our stewardship of these species may determine their continued existence.