Horseshoe crabs: Precious resource that deserves protection

Thanks to Tim Prudente for his article on horseshoe crabs and their importance to saving human lives (“How the coronavirus vaccine relies on Maryland’s strangest fishery: horseshoe crabs,” Dec. 31). This species’ copper-based blood is used to produce limulus amebocyte lysate (LAL) to test all injectables and implants for pathogens, safeguarding medicinals such as coronavirus and flu vaccine and saving human lives.

My fascination with these prehistoric survivors led me as a state senator in 1993 to sponsor and gain passage of legislation requiring the first management plans for their conservation in Maryland. Later, as vice president of American Bird Conservancy, I spearheaded efforts to gain protections coast-wide.

These armored arthropods are true living fossils having changed little over their 400 million years. They are in need of stronger conservation measures as unregulated slaughter has reduced numbers radically. A century-long slaughter stopped in the 1960s for fertilizer and livestock feed.

But a second wave started in the 1990s, this time for bait, primarily for conch and also for eels and catfish. This over-harvest reached 2.6 million crabs in 1999 and significantly reduced crab populations affecting migrating shorebirds who feed on its excess eggs. Delaware Bay hosts the largest spawning population of any of the world’s four species of horseshoe fueling the second greatest concentration of shorebirds in North America each spring.

The crab slaughter continues with around 800,000 crabs killed in 2019. From 2013 to 2019, about 5.8 million crabs were taken for bait with Maryland allowing more than one million of those. Maryland and other states should follow New Jersey’s 2007 lead and end this slaughter.

In 1998, a coast-wide management plan was adopted by the coastal regulatory agency with a biomedical mortality threshold of 57,500 crabs. If exceeded, it was supposed to trigger reductions of this mortality. The threshold has been exceeded every year since 2007 with the exception of 2016 while the board has done nothing to reduce this mortality. This problem is exacerbated by the targeting of the much larger females.

Landings for bleeding have increased sharply to a record 748,376 crabs in 2019 up from 221,738 in 2001. As your reporter points out, a synthetic has been developed based on cloning crab blood and is in use in other countries as a substitute in testing the purity of biomedicals. Wildlife groups and pharmaceutical giant Eli Lilly are pushing for this substitution from U.S. Pharmacopeia.

The indomitable horseshoe crab faces many other threats including loss of sandy beach habitat and oil spills. Limulus Polyphemus has survived five great extinctions. Let us show respect for our elders and work to assure that it survives the current sixth great extinction, the only one caused by humans.