Horseshoe Crab Conservation in New England
Ella Ip
Seeing horseshoe crabs being hauled into a tugboat during a marine research field trip sparked an interest within me. Marine biology has always been something I have loved because of the scientific richness of aquatic organisms. That being said, with the mass pollution of Earth’s waters along with the overexploitation of sea creatures living within aquatic ecosystems, we need to pay close attention to environmental legislation being proposed. In the case of the horseshoe crabs, they face being overharvested for medical research and threaten to disrupt the balance of the ecological food chain if we don’t protect them.
The American horseshoe crab (Limulus polyphemus) is a marine arthropod that is more closely related to spiders, ticks, and scorpions than true crabs. Studying fossils have suggested that horseshoe crabs, who share some similarities with modern day crabs, have existed for at least 445 million years. American horseshoe crabs live along the Atlantic coast from northern Maine to the Yucatan Peninsula. Horseshoe crabs have a long lifespan and can live to be as old as 20 years. They generally reach sexual maturity around 9 to 12 years. Similar to other arthropods, horseshoe crabs must molt to grow.
Why are horseshoe crabs important to ecology? Horseshoe crabs deliver hundreds of thousands of eggs during spawning. Only a small fraction of these eggs reach reproductive
Photo: Horseshoe crab
Photo credit: Flickr
maturity, but these eggs also provide useful nutrition to species such as the red knot (a shorebird) and the Atlantic loggerhead turtle among many others along these species' migratory passages. If we reach a point where the species populations become so small, they no longer serve a significant purpose in local ecology, like we saw happen to the Sound’s lobsters.
What is the reason for the horseshoe crab population decline? Recent data studied by Atlantic States Marine Fisheries Commission (ASMFC) suggests that horseshoe crab in the mid-Atlantic region is stable or declining. But, the Delaware trawl survey demonstrates a large decrease in abundance. Additionally, decreasing numbers of migratory shorebirds, such as the red knot, also raise concern about the horseshoe crab population. What are some tell-tale signs linked with a downward trending population? A list of threats facing horseshoe crabs from the IUCN: breeding habitat fragmentation due to coastal development and harvesting, climate changes, shifting predator populations, substandard water quality, rising competition with invasive species, and human harvest for medical experimentation. As aforementioned, horseshoe crabs have long been used as bait in the eel and whelk fisheries along the east coast. Though, according to the ASMFC, after peaking in the 1990s, the number of horseshoe crabs being harvested for bait has declined.
Source: 2019 Horseshoe Crab Benchmark Stock Assessment Peer Review Report
What is Connecticut doing to preserve the horseshoe crabs? The Connecticut Audubon Society is asking state officials to ban the harvest of horseshoe crabs in Connecticut and to expand law enforcement efforts to stifle illegal horseshoe crab harvesting. The season in Connecticut runs from May 22 to July 7, although horseshoe crab fishing is banned in Milford, Stratford, West Haven, and Westbrook. The CT DEEP has issued only 12 licenses, with no plans to issue more. Over the past 18 years, the number of horseshoe crabs harvested in Connecticut has ranged from 12,175 in 2001 to a high of 32,535 in 2008. From 2013 through 2018 the number was about 20,000 per year.
What Can You Do?
Connecticut citizens can aid the efforts of horseshoe crab conservationists by letting local government officials that they support the protection of the crabs and sharing resources that educate others on the integral role of horseshoe crabs in our ecosystem.
Ella Ip is a Sierra Club member and senior at Hopkins School.
Bibliography
"A Change in CT Regulations Could Be A Boon For The Atlantic Horseshoe Crab." Save the Sound. Last modified April 3, 2020. Accessed August 3, 2020. https://www.savethesound.org/2020/04/03/a-change-in-ct-regulations-could-be-a-boon-for-the-atlantic-horseshoe-crab/.
"Connecticut Audubon calls for a ban on horseshoe crab fishing." The Connecticut Audubon Society. https://www.ctaudubon.org/2020/02/connecticut-audubon-calls-for-a-ban-on-horseshoe-crab-fishing/.
"Horseshoe Crab Monitoring." Greenwich Connecticut. Accessed August 3, 2020. https://www.greenwichct.gov/305/Horseshoe-Crab-Monitoring.