Watch where you step this spring! Horseshoe crabs (Limulus polyphemus) are beginning to crawl ashore on beaches around Sandy Hook Bay, Raritan Bay, Jamaica Bay, and other shallow estuarine sites around New York Harbor to mate on full and new moon evenings in May and June.
Yet another spawning season for Horseshoe crabs has commenced, an annual rite of spring that has connections going back for more 450 million years. For all those Jurassic Park movie fans, that is 230 million years before the first dinosaur!
Known as “living fossils,” Horseshoe crabs are harmless, ancient creatures that have been effectively unchanged through time. They are more closely related to spiders and scorpions than to crabs, but are really a prehistoric family of animals unto themselves.
In late April, Horseshoe crabs begin their migrations from deeper ocean waters into estuaries to breed. First to arrive are often males, waiting for available females to appear at beaches. Sort of like a primitive singles bar, minus a colorful tiki bar.
But alcohol isn’t needed here. When a single female crab crawls out of the surf, she will release chemical cues called “pheromones” that will help to attract a male to breed. A male will then grasp a single female from behind with special appendages shaped like tiny boxing gloves located on the end of the first pair of his walking legs. With a male in tow, they will move together in the intertidal zone, the area on a beach that is above water at low tide and underwater at high tide, to deposit and fertilize between 60,000 and 120,000 lime green eggs in batches within wet sand.
In approximately, two weeks to a month the eggs will hatch. The youngsters will be about the size of a human fingernail and will look like a near–replica of an adult, though tailless. The small crabs will leave the eggs and head straight to the water where they will grow in sandy shallow areas around an estuary. It will take the next 8 to 12 years for a crab to mature sexually before it can migrate back to bay beaches to breed.
Although the largest population of spawning Horseshoe crabs in the world can be found in Delaware Bay, the nearby busy and bustling waters of New York Harbor has a population of crabs too. Around here, few people welcome this incredible natural wonder. Those that do, though, will often know when and where to find them by the dozens, hundreds, and perhaps even thousands along the shore.
Volunteers with the Bayshore Regional Watershed Council, an environmental group dedicated to improving water quality and restoring wildlife habitat along Raritan Bay and Sandy Hook Bay, have been monitoring Horseshoe crab populations along the southern shore of New York Harbor in Monmouth County, New Jersey since 2009. The goal of the study has been to obtain a better idea of the spawning population of this aquatic species, and to ascertain if the population is stable, increasing, or decreasing.
So far, results of the study show a population of Horseshoe crabs that are less than robust. Females are on the decline.
In 2009, the watershed council counted in total 495 total female crabs (both single and in mating pairs) along Raritan Bay and Sandy Hook Bay across a thousand feet of beach at five sites. Yet, in 2016 only 217 female crabs were counted at the same monitoring sites. The single female population also decreased from 96 to just 15 in total during this time period.
Compare the data to a surprising growing male population of Horseshoe crabs. In 2009, there were 679 male crabs counted at monitoring locations in total (both single and in mating pairs) in Raritan Bay and Sandy Hook Bay. This number increased in 2016 to 1,016. The single male population also increased from 251 to 769.
An enormous inequality between the sexes, which has had a rippling effect on spawning activities for the Horseshoe crab population too. It takes two to make a baby. Swimming pairs (crabs seeking a place to lay eggs) decreased from 265 in 2009 to 130 in 2016 and burrowed pairs (crabs in the process of laying eggs) decreased from 276 to only 50 pairs in 2016.
What could be causing such a dire decline in females? Humans and money of course. Increased harvesting of Horseshoe crabs in New York State waters threatens their population. New York is the only state along the Atlantic Coast of the United States that has not placed a total moratorium on harvesting Horseshoe crabs during their important breeding period.
Females are repeatedly harvested more than males. Female Horseshoe crabs are about thirty percent bigger than males, thus they have more meat. Adult females also often carry eggs, which will make better bait.
Since 2009, New York State’s commercial quota for horseshoe crabs has been around 150,000 crabs, with a certain amount of these captured crabs coming from Raritan Bay and along the south shore of Long Island.
But there are also an undetermined amount of crabs in New York being harvested illegally. In May 2013 two men from Brooklyn were arrested for stealing 200 horseshoe crabs from an island, locally known as the Ruffle Bar, in Jamaica Bay, Queens. The two men were each charged with taking wildlife without a permit and disturbing wildlife breeding practices in a national park.
More recently, a woman was arrested on an island in Jamaica Bay for illegally harvesting seven Horseshoe crabs on April 30, 2017. The women told Officers with the United States Park Police that she was harvesting crabs for her business. The body parts of Horseshoe crabs in some parts of the world are considered to be an aphrodisiac for men and can command a high price.
Typically, horseshoe crabs are harvested as bait for the American eel and Channel whelk fisheries. Fishermen will use the body parts of female Horseshoe crabs as bait to attract eels and whelks, locally known as conch.
Eels and whelks are highly valued in Asia and Europe for human consumption. Harvesters in the United States have turned to the American eel and Channel whelk fisheries to make money and meet the diverse needs for seafood in oversea markets.
It's a global economy and our Horseshoe crabs in New York Harbor and along Long Island are often seen as bait and profit. In about 20 years, the price for a single horseshoe crab has jumped from .25 cents to more than $5.00 per crab.
In addition to bait, Horseshoe crabs are harvested by the medical industry for their cooper based blood, which turns blue when exposed to air. Horseshoe crab blood has remarkable antibacterial properties and enormous medical value that makes certain no impurities exist in medicines. The U.S. Food and Drug Administration (FDA) requires all intravenous drugs and vaccines, and any medical device, such as replacement hips, hearts, pacemakers or knees, coming in contact with the human body to be first tested through the crab's blood for bacterial toxins, such as toxic shock syndrome, meningitis, and typhoid. As a result, millions of people survive each year in the United States due to the clotting characteristics of the Horseshoe crab’s blue blood.
Unfortunately, the medical benefit for humans is not always a benefit for the crabs. Horseshoe crabs are supposed to be caught, bled (about 30% of the blood from each crab is taken), and then returned to waters where they were found, but not all make it. According to author Alexis Madrigal in a February 26, 2014 article in The Atlantic entitled, The Blood Harvest, “between 10 and 30 percent of the bled animals, according to varying estimates, actually die.” In addition, “bleeding a female Horseshoe crab may make it less likely to mate, even if it doesn't kill it.”
Environmental scientists, John Tanacredi and Sixto Portilla, also tell us from a technical research paper published in Changing Global Perspectives on Horseshoe Crab Biology, Conservation and Management, 2015, that many crabs taken from New York waters to be bled by the medical industry are often not returned to New York. From research on Horseshoe crab populations from Brooklyn to Montauk from 2003 to 2014, they found that numerous crabs permitted by the State of New York to be harvested and taken to Massachusetts to be bled for the medical industry are often released “to local waters in Cape Cod, not back in NYS waters as required” by their permit. In the end, “many of those animals are re-harvested for bait and sold back to NYS fishermen at an average cost of US $5/crab.”
With all this legal and illegal action, it is no wonder the harvesting of Horseshoe crabs, especially females, has had a negative impact. It has limited the distribution and breeding of the crabs, resulting in localized population declines. It’s not an easy life in New York Harbor, and the Horseshoe crab population could locally disappear if nothing is done to safeguard the species in New York State waters.
New Jersey has instituted a moratorium on harvesting Horseshoe Crabs in 2007, but there is no such law in New York State. People are still able to harvest crabs. This action puts the crab population under severe threat in Lower New York Bay, Raritan Bay and Sandy Hook Bay.
The potential loss of Horseshoe crabs will have a disastrous impact to migratory shorebirds. The fatty eggs of Horseshoe crabs provide an important food source for many migratory shorebirds, including red knots, ruddy turnstones, and sanderlings, as they continue their journey northward to breed in the Arctic. If the population of Horseshoe crabs disappears in New York Harbor it could result in the loss of these migratory animals as well, or maybe even lead these animals to starve.
We need your help! Please send emails to both Governor Andrew Cuomo and the New York State Department of Environmental Conservation to tell them to provide greater protection for horseshoe crabs. Success hinges on making sure New York State restricts the harvest of Horseshoe crabs, especially female crabs, in local waters.
We need to strongly urge people in Albany to put a moratorium on Horseshoe crab harvesting to protect these prehistoric animals before it’s too late.
Moreover, please share the blight of the Horseshoe crab with friends and family. We need to make sure lots of people are aware that protecting Horseshoe crabs in New York is absolutely necessary to ensure their survival in estuarine places like Raritan Bay, Sandy Hook Bay, and Jamaica Bay.
Hopefully, with greater awareness and public support, coupled with increased conservation efforts, Horseshoe crabs, the ancient mariners of New York Harbor will once again fill beaches for many spring seasons to come. It would be great if we could protect the crab so they might endure for another 450 million years!