A new study released by the University of South Florida (USF) concludes that the state’s official shell–the Florida horse conch–is in greater peril than previously thought.
The horse conch is one of the world’s largest invertebrate animals, reaching up to two feet. Unregulated commercial harvesting and the collection of live shells by recreational divers have put its population in a downward spiral.
Just how much of a spiral has yet to be determined, but Florida Fish & Wildlife Conservation Commission (FWC) Research Scientist Stephen Geiger said the latest findings “raise a level of concern.”
An interdisciplinary research team made up of the FWC and current and former USF graduate students reported its findings in PLOS.org. The research concludes that horse conchs have been “intensely exploited by shell collectors, curio dealers and commercial harvest” for more than a century.
Learning more about the Florida horse conch
Sarah Stephenson measures a large lightning whelk in Tampa Bay.
The team has studied the life history of the horse conch, the largest gastropod in U.S. marine waters, including its life span, growth rates, spawning age and number of lifetime spawning seasons. These snails live in shallow sand and weeds in the Atlantic Ocean. Horse conchs do not even spawn until they are six years old and likely do not live past 16 years old. Its typical life span is six to 10 years.
Currently, there is a saltwater products license required to take horse conchs, whose scientific name is Triplofosus gigantea. These invertebrates have no other state protections.
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“It is a cry for a species that needs attention,” Geiger said. “It is a poster child for 1,200 species of snails in Florida, snails in state and federal waters. Nobody is really managing a lot of species.” And some do not need managing, while others do, he said.
“We don’t have a great baseline” of data on the horse conch, he said, but research does show is that there are not as many of the largest specimens in state waters.
“If you go to an oyster reef, there are thousands of little, tiny black snails that probably need no protection. But something like a horse conch, people are harvesting for a variety of reasons.”
“One of the things you see is, it’s not common, but occasionally they (horse conchs) gather in mating groups where there are 20-100 of these very large conchs. You could walk onto the beach and take two or three and eat them. If we can figure out seasonally why that happens and create a season not to take them, say January through March, because they are mating and much more vulnerable.”
“One of the things I can do is point out there are reasons why the species is less common than it used to be and that it is vulnerable to over-exploitation.”
Collecting shells with an eye towards marine life
FWC conducted a survey in the Florida Keys. Here, Erica Levine holds a medium horse conch, probably about the size of a recently mature snail.
For those interested in collecting unoccupied shells, there are several local companies offering shell adventures.
But whether people go shelling on their own or with a company, they should be careful to check each shell for occupancy, Geiger said.
“It’s probably not a huge problem except that the empty shells do form habitat for many creatures. In particular, there are species of hermit crab that can only utilize very large shells to attain their largest size, but many organisms like sponges, barnacles, and oysters rely on shells to settle on,” he said. “The empty shells often serve as dens for things like octopus and small fish that lay eggs in them.”
Removing shells, occupied or not, could make creating regulations and then enforcing those rules more challenging, Geiger said.
“In some places, unfettered harvest for curio and craft trade, of course, does not differentiate live and dead. Prices for collectible shells can be very high, so the temptation to take a live mollusk is also large.”
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Island Boat Adventures is among those companies offering shell collecting adventures. It runs tours to Egmont Key in Pinellas County, an island destination covered in shells and sand dollars. Some typical finds include alphabet cones, whelks, murex, shark eyes, horse conchs, Junonian and Scotch bonnets.
The company notes that it is illegal to take shells containing live creatures. “Yes, you can take your treasures home as long as no one is living in them,” it states on its website. “Many creatures, such as hermit crabs and baby octopus, claim empty shells as temporary homes.”
For those who go on their own, the best time for shell collecting is early morning and after a good storm. Low tide is also prime time for shell collecting.
Some of the best local places for collecting include:
- Honeymoon Island State Park
- Caladesi Island State Park
- Anclote Key Preserve State Park
- Fort DeSoto County Park and Shell
- Egmont Key