On Horseshoe Crabs and Clammers


 As I See It,
Bill Sargent, The Daily News of Newburyport, Edition August 4,

“June 24 was a warm, sultry summer day. The afternoon sun glinted off the tightly packed cottages that dotted Great Neck and two tall wind turbines spun in the onshore breeze. The full moon would be in four days and we were still in the proxigean tides so several dozen clammers were bending over their rakes taking advantage of the extremely low water.”

“It was not difficult to imagine what these flats looked like 500 years ago. Great Neck would have been covered with a scattering of long houses surrounding fields the Agawam kept open through yearly burning and kept fertilized by alewives from the nearby Ipswich River. By June the fields would already be covered with subtle green clusters of corn, squash, and beans, the three sister crops that sustained their ancestors for untold generations.”

“The clammers would have been mostly women then, bantering back and forth as they dug clams with sticks and loaded them into long dugout canoes instead of into today’s aluminum skiffs.”

“The thing you wouldn’t have heard were clammers complaining about the “f’ing” horseshoe crabs. I felt like I was back in the ‘50s on Cape Cod after the state had declared horseshoe crabs shellfish predators and encouraged Cape Cod kids to turn in horseshoe crab tails for a two-cent-per-tail reward.”

“We even had a Labrador retriever who had picked up the habit by watching us catch the crabs. Jake would spend all day wading in the shallows until he felt a crab with his paw, then he would plunge his head down below the surface, grab the crab by the tail and haul it up the beach.”

“When the crab righted itself and started to crawl, Jake would dig a hole in front of the hapless creature and wait for it to tumble in. Then Jake would bury the crab and return to the water to search for more crabs. He taught three generations of dogs to catch horseshoe crabs, but by the third generation, they would just haul the crabs up the beach and bark at them all day. But now we know that horseshoe crabs feed primarily on worms, detritus and tiny gemma gemma clams that look like quarter inch quahogs but are actually full-sized adults. More significantly we now know that if you keep a horseshoe crab in the wild and only bleed it once a year for biomedical purposes, it is worth more than $3,000 over its lifetime. So today’s shellfishermen would be killing an animal worth $3,000 to protect an animal worth only a few bucks a pound.”

“But some of the old timers never got the memo and continued to impale horseshoe crabs on their rakes, spilling out the crabs’ cobalt blue blood that is worth $30,000 a quart when it is used to test for often fatal bacterial diseases like spinal meningitis and toxic shock syndrome.”

“Such random killing has had a negative impact on both the crabs and the endangered shorebirds that feed on their eggs. But the last time anyone did any kind of systematic count of horseshoe crabs in Plum Island Sound was in 1952. That was when Carl Schuster was measuring the width of horseshoe crabs in estuaries from Maine to Florida.”

“On July 27, 1952, he caught and measured more than 1,000 adult horseshoe crabs in the sound in the morning and about the same number in the afternoon.”

“He discovered that horseshoe crabs are largest and most plentiful in Delaware Bay and get smaller and less plentiful as you go both north and south. He also discovered that Plum Island Sound has the smallest horseshoe crabs of any on the East Coast because of fresh water from the Merrimack and Parker rivers and our cool northern waters.”

“But today you would be hard put to catch 50 crabs — let alone 2,000 — behind Plum Island Sound in one day. If the existing crabs are not killed their populations could bounce back quickly because each female lays about 4,000 eggs a day for four days on both the new and full moon high tides.”

“What we need are accurate counts of both the breeding adults and their immature offspring. This can be done in the spring when the adults are spawning, and in the fall when the immature have cast off their empty shells.”

“Both are perfect exercises for citizen scientists. In the spring the volunteers could count the number of male and female crabs mating in a designated section of beach. In the fall, volunteers could count the number of shells cast off by immature crabs along a 50-foot section of the wrack line. Their numbers could range from less than a dozen crabs shells for an unsustainable breeding population to several hundred shells for a healthy population.”

“Several volunteer groups are planning to work with the state to get these numbers and to initiate a program to collect horseshoe crab eggs and raise them in tanks until they are large enough to ward off predators.”

“After horseshoe crabs reach about an inch across they have few predators, but as eggs and part of the plankton they are like tiny little ice cream cones. Birds, fish, and mammals all like to eat them. It will be interesting to see whether this exercise will have enough impact on Plum Island Sound’s natural population of crabs to appear in the data collected in the potential spring and fall crab surveys.”


Copyright © 2018 The Daily News of Newburyport, Edition 8/4/2018

Photograph Copyright © 2018 Sandy Tilton

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