Florida’s horse conch is closer to extinction than expected

The conch, one of the world’s largest invertebrates, is traditionally battered and fried in the Caribbean. The animal’s shell is famously used as a horn for long distance communications in Polynesia. Since 1969, the horse conch has been an official symbol of Florida and has been used to promote tourism in the sunshine state. But now, the animal inhabiting the shell is slipping toward extinction.

Unregulated harvest of the gastropod has led to a drop in population, and this decline turns out to be greater than scientists realized. Previously, it was believed that conchs could live for up to 50 years. A new study led by researchers at the University of South Florida tells a different tale.   

The new research shows that the horse conch lives for only an average of 8 to 10 years, reaching reproductive maturity at 6 and giving birth to 28,000 offspring annually. A record breaking two-foot-long conch shell in Bailey-Matthews National Shell Museum was found to be only 16 years old. Even with the large amount of offspring, the study shows that fewer conchs are replaced each year than are harvested. 

“Our research shows that horse conch reproduction is less likely to keep pace with intense harvest than previously thought,” said study lead author Greg Herbert, an associate professor in the USF School of Geosciences. 

“Horse conch populations are important. They create habitat for other species by leaving empty shells of dead prey around for fish, crabs and other animals to use as homes. They also contribute to the unique experience that we have in Florida of being able to go to the beach and seeing one of the largest seashells in the world at the water’s edge.”

The researchers estimated the age of conchs by chemically analyzing the layers in the animal’s shell. They found that males grow slower than females and mature at a smaller size. The experts also discovered that females start laying eggs at the age of six.

The researchers analyzed data from Florida Fish and Wildlife Commision (FWC) to determine population trends over time. They found a decline from a peak conch harvest of 14,511 in 1996 steadily dropping to a mere 67 in 2020. 

“We still know very little about how many horse conchs exist and where their preferred habitats or what their optimal environmental conditions are,” said study co-author Stephen Geiger, research scientist at the FWC. “Because we have no dedicated funding for more than 1,500 species of mollusks found in the waters that surround Florida, we continue to seek grants that enable us to study their biological traits, including those that will help managers decide if some species are in need of better protection.”

The research is published in the journal PLOS ONE,

—

By Zach Fitzner, Earth.com Staff Writer