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It's mating season for horseshoe crabs, and state wildlife officials want beachgoers to help watch.
By RON MATUS, Times Staff Writer
© St. Petersburg Times, published April 23, 2003
All over Tampa Bay, males hopped up on hormones are scrapping with each other beachside, vying for females who will show them the time of their lives.
When the hook-up happens, state officials want you to watch.
Then they want you to tell them about it.
In this case, the love-struck beachgoers are horseshoe crabs, those dark, scuttling creatures with helmet-like shells.
Scientists fear crab populations are shrinking because of their popularity as bait for eel and whelk, which Asian consumers crave. But to find out for sure, they need more details -- including where, exactly, crabs do the deed.
Even first-time crab-watchers will recognize the ritual when they see it, said Dan Warner, a staffer with the Florida Marine Research Institute in St. Petersburg.
Boy meets girl, grabs her by the shell and holds tightly until the eggs drop.
Make that, boys, plural.
"You'll see a lot of males swarming around the mating pair," he said. "They'll crawl all over and try to get in there."
In 1998, the Atlantic States Marine Fisheries Commission, based in Washington, D.C., approved a horseshoe crab management plan that requires all 15 member states to identify spawning beaches. Florida scientists began last year, but this year they made a bigger push for public help.
Crabs in Florida are not under the same pressures as those in mid-Atlantic states, where more than 1-million are scooped up each year by dredges and trawlers, and environmental groups are pushing for a moratorium. Here, the annual harvest is less than 10,000.
But scientists say it's still important to pay attention.
Horseshoe crabs are a vital link in the food chain, especially for shore birds.
In Florida, mating grounds are vulnerable to sea walls and other development.
"They need the habitat," said Braddock Spear, who coordinates the commission's management plan. "If you build on one of their most important beaches, you could wipe out the population in that year."
As a species, horseshoe crabs are 250-million years old, meaning they were propagating even before the dinosaurs.
Mating season lasts from March to June, drawing inspiration from high tides and beaches with low-wave action. The best time to spot mating crabs is a few days before and after a full moon. Night is best, but crabs aren't shy about daylight.
Prime viewing spots include the beaches along the Courtney Campbell Parkway; Fort De Soto Park and Honeymoon Island State Park in Pinellas County; and Picnic Island Park and Apollo Beach Nature Park in Hillsborough County.
Last year, Warner saw more than 100 at the same time in Phillipe Park in Safety Harbor. Two weeks ago, dozens swarmed the shallows just off Ballast Point Pier in South Tampa. "Mommy, those two are stuck together," a boy said as he and his mother walked along the sea wall.
Mommy offered an embarrassed smile and pulled him away.
Typically, the female crawls out of the surf, dragging the male behind her. Then she'll dig a shallow hole above the high tide line and plop down thousands of pearl-sized eggs. The male fertilizes them.
In two to four weeks, hatchlings dash for the sea. If they're lucky.
Shore birds snap up the eggs, which for some species are critical fuel during migration. Environmental groups fear some bird populations in New England have plunged since the 1980s, when bait harvesting began to escalate.
Humans depend on horseshoe crabs, too.
More than 200,000 are caught each year for the biomedical industry, which uses copper-rich crab blood to determine if human vaccines or implants such as heart valves are contaminated by bacteria.
Since crab blood clots in the presence of the bacteria, screeners can use it to weed out bad batches of medicine.
Use of crab blood became widespread in the late 1980s. Before then, screeners used live rabbits.
Unlike the rabbits, most of the blood-donor crabs survive the ordeal.
Some, perhaps, wind up in secluded spots in Tampa Bay, doing their best to keep the species going.
In late March, Jamie Sullivan and her family puttered down a canal in Tampa Shores in their boat, looking for a spot to picnic. But they couldn't slide their boat on to shore because the place was crawling with crabs.
"We were in awe," Sullivan said.
Last year, she spied crabs in the same area and dutifully reported her findings to the state. A few weeks later, she noticed the babies that dribbled over the beach.
"There were gazillions," she said.
Exactly what the scientists want to hear.
-- Ron Matus can be reached at 226-3405 or matus@sptimes.com .
Horseshoe crab surveys can be filled out at www.floridamarine.org. To locate the survey, search the site for "horseshoe crab." For more information, call 727-896-8626, ext. 3132.