The Jersey Shore, the Red Knot, and the Horseshoe Crab

While we have all been under lock and key for the last two months, something amazing has been happening outside. Nature has taken over.

Air pollution has decreased dramatically in the Northeast. Nests of the Leatherback Turtles in Thailand are at their highest levels for 20 years. Ocean life has increased due to the lack of global shipping activity. And depending on what you read, there has been an increase in red knot and horseshoe crab activity off the coast of New Jersey.

A recent article on Forbes.com reports that horseshoe crab and red knot populations have stabilized during the important spawning season for the crabs and the migration period for the red knots. Meanwhile, another article, this one from the public media outlet in Philadelphia, has reported numbers of horseshoe crabs and red knots have dropped precipitously this year.

I have not been to the Jersey Shore this year, so I can’t say which is accurate. It is important to remember, however, that the red knot and the horseshoe crabs are both important parts of the New Jersey ecosystem and the two species are intertwine at the Jersey Shore.

A red knot at the Jersey Shore. source: NJDEP Division of Fish & Wildlife

In 1999, the red knot was listed as a threatened species in New Jersey under the New Jersey Threatened Species Act. As a result of the Red Knot Status Assessment in fall 2006, the U.S. Fish and Wildlife Service announced the red knot as a candidate for federal listing and the Committee on the Status of Endangered Wildlife in Canada recommended listing the red knot as endangered in April 2007.

Each spring, red knots migrate from wintering areas as far south as the southern tip of South America, to breeding grounds in the Canadian Arctic; 20,000 miles round trip. The red knot is one of the longest-distance migrants spending over six months of the year migrating back and forth between wintering and breeding areas.

The Delaware Bay is an essential part of the red knot’s spring migration because it is the center of the Western Hemisphere’s only population of horseshoe crabs. Horseshoe crab eggs are quickly metabolized into fat by the red knots. That fat store allows these small birds to double their body weight in approximately two or three weeks.

The Delaware Bay is the last stop before they make their way to their arctic breeding grounds. The fat they add to their body mass by filling up on the eggs of the horseshoe crabs allow red knots to survive, continue courtship, mating, and egg laying until food becomes available.  Without a sufficient fat reserve, their survival is at risk.

So if you head to the Jersey Shore and see a red knot, consider yourself lucky. If you see a horseshoe crab, make sure it isn’t on its back. What is most important is that you enjoy them from afar whenever possible and know you are witnessing a unique relationship that only happens at the Jersey Shore.