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Health & Fitness

Horseshoe Crabs Are Back in Sandy Hook Bay

Horseshoe Crabs are returning to familiar spawning sites in Raritan Bay and Sandy Hook Bay, a satisfying sight after the destruction last fall from Super-storm Sandy.

The return of hundreds of the ancient horseshoe crabs to their familiar spawning sites in Sandy Hook Bay has begun.

It's a satisfying sight after the destruction to the shore last fall from Hurricane Sandy.

Who knew what to expect? There was a certain amount of vagueness and concern as to how many, if any, horseshoe crabs would show this year, especially given that the loss of shoreline habitat from erosion or the building of bulkheads, beach nourishment projects that can bury and kill adult crabs. Changes in the slope and width of a beach can also affect where and when the crabs gather. Would the aftermath of Sandy have an effect on the mating season?

Volunteers with the Bayshore Watershed Council and students from various local schools, including MAST (The Marine Academy of Science and Technology) were on hand to find out. This was nothing new.

They have been monitoring and studying the movements of this ancient creature for several years. The project began in 2009 as a 5-year study of the population of Horseshoe Crabs in the Raritan Bay/Sandy Hook Bay area. Spawning generally occurs on evening high tides near the full and new moons in May and June.

For the first monitoring event of this season, all seemed to go extremely well for the crabs and the volunteers. Close to 2,000 Horseshoe Crabs were counted at five sites along the Sandy Hook Bay. The sites included Plum Island at Sandy Hook, the mouth of Many Mind Creek in Atlantic Highlands, Leonardo Beach in Middletown Township, near Conaskonck Point in Union Beach, and Cliffwood Beach in Aberdeen Township.

This was the highest amount of crab activity recorded in the study for the beginning of the spawning season in May. It seemed like the need to breed was strong. Many crabs were in mating pairs or in clusters getting ready to create the next generation. When horseshoe crabs spawn, the female will burrow into the sand to lay eggs. One or more male crabs will gather around her. This is called a cluster.

It was a beautiful evening to monitor horseshoe crabs. The air temperature was in the upper 60s and winds were steady at 15 mph from the south. Yet the sand and water were still chilly from a unpleasantly cool spring season. Water temperatures were in the upper 50s.

As the sun was setting and the high tide receded, around 50 volunteers with the Bayshore Watershed Council got to work. One by one, the volunteers came across crabs along the water's edge. 

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With permits in hand from NJ Fish & Wildlife to carry out the study, the volunteers were prepared to get wet and dirty and carried flashlights or headlamps to see in the dark. Across a thousand feet of beach, they counted each crab to estimate the average number of horseshoe crabs at each location along with recording the male to female sex ratio.

Of course, it was not all work. A few big barnacled horseshoe crabs were grabbed for the kids to first fear and then turn to fascination.

Spawning in the bay begins in early May and runs through the end of June. During high tides, horseshoe crabs migrate from deep waters to beaches to spawn. Females will lay thousands of eggs just an inch or so in the sand.

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Males, often hooked to the females backside, will pass over and fertilize the eggs. At low tide, adult crabs go back into the water but may return again at the next high tide.

Horseshoe crab spawning increases on nights with a full or new moon, when gravity is stronger and makes high tides higher. While they are called crabs, horseshoe crabs are closer in relationship to spiders than common crabs.

Horseshoe crabs have been around for at least 350 million years. Yet, there has never been a proper survey done in Sandy Hook Bay. The crabs around here have largely been overlooked by both fishery managers and the public for decades. As a result, there are many questions as to how they are surviving, especially is an urban estuary like New York Harbor.

Do all crabs return to the same beaches every spring to mate and where do the crabs go when the mating season is over? 

The study by the Watershed Council, examining multiple locations throughout the bay, has found some surprising results. The crabs do not return to the same beaches every year.

Instead they often travel to different location around the harbor to find a mate, sometimes even across the bay to New York City beaches, What's more, the ratio of male to female Horseshoe Crabs, typically one to one, is significantly lopsided. For every one female crab that has been found, up to 15 or more males have turned up. The local population is largely unknown in New York Harbor, but it may be declining, especially the female population.

Certainly more research needs to be done to find answers. The data collected by volunteers so far has been important in monitoring changes in numbers of spawning crabs in the bay. Now every spring on several peak spawning days, volunteers, acting as citizen scientists, donate their time to count crabs on key beaches in Sandy Hook Bay in New Jersey.

This is significant since the threats to the long-term survival of horseshoe crabs in New Jersey are numerous. If you are a person of a certain age, then you will remember there being more crabs as a kid.

At the moment the most pressing threat does not come from a predator or from pollution, but from government officials. New Jersey state politicians in Trenton are debating whether to lift a moratorium on harvesting horseshoe crabs that has been in effect since 2006.

Although humans do not eat horseshoe crabs, other species do such as eels and whelks. Fishermen will cut up and use horseshoe crabs as bait to catch local eels and whelks, which in turn are sold to fish markets in Asia and Europe for money. I

t's a global economy and our little horseshoe crabs in New Jersey are part of a world-wide profit margin. Unfortunately, this market has proven to be unsustainable since horseshoe crabs are slow to mature (it takes at least eight years for a male and up to 12 years for a female crab to reach sexual maturity). There is the potential for depletion of local populations.

To keep the moratorium in place on commercial harvesting of horseshoe crabs in New Jersey waters, please send an email to your state senator and state assemblyperson to tell them you are against lifting the Horseshoe Crab moratorium.

The bills in the legislature are not based on science, but on profit  and are short-sighted at best. For more information on the moratorium, please visit this website by local environmentalists in Delaware Bay:  http://myemail.constantcontact.com/ACT-NOW-to-Save-the-Horseshoe-Crab-Moratorium.html?soid=1102026594211&aid=BwHZjjZmjxY

The horseshoe crab spawning survey in Sandy Hook Bay is conducted annually during the spawning season from May to June. The Bayshore Regional Watershed Council coordinates the survey, which helps in the management and conservation of this significant species. We invite anyone who is interested to participate. Volunteers under age 18 must be accompanied by an adult.

For more information on the survey in Raritan Bay and Sandy Hook Bay and to find out how you can become a volunteer, visit www.restoreourbay.org.

For more information, pictures and year-round sightings of wildlife in or near Sandy Hook Bay, please check out my blog entitled, Nature on the Edge of New York City at http://www.natureontheedgenyc.com

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