Shell Shock!

Conch are a type of sea snail whose soft bodies are protected by a hard spiral shell (see Conch Anatomy). “There’s this massive shell, and the most adorable eyes you can imagine peeking out,” says biologist Andrew Kough of the Shedd Aquarium in Chicago, Illinois.

Herds of queen conch graze along the seafloor among the hundreds of islands that make up the Bahamas. They eat tiny plant-like organisms called algae that grow among the seagrass. Conch also help keep their ecosystem in balance, eating dead seagrass and supporting a diverse mix of other animal species.

Conch are a type of sea snail. A hard spiral shell protects their soft bodies (see Conch Anatomy). “There’s this massive shell, and the most adorable eyes you can imagine peeking out,” says Andrew Kough. He’s a biologist at the Shedd Aquarium in Chicago, Illinois.

Hundreds of islands make up the Bahamas. Around them, herds of queen conch graze along the seafloor. The animals eat algae. These tiny plant-like organisms grow among the seagrass. Conch also help keep their ecosystem in balance. They eat dead seagrass and help support many different animal species.

Conch get around by pushing a claw against the seabed—a slow process that makes them easy to grab. “Conch live in shallow waters, and they can’t run away,” says Kough. Fishers can harvest large numbers from a herd in one fell swoop.

Traditionally, conch collectors reached the animals by snorkeling or holding their breath in a free dive. That limited the number of shellfish people could gather. But today, with the help of specialized breathing gear, people can dive longer and deeper to collect many more conch.

Conch push a claw against the seabed to get around. It’s a slow process. That makes them easy to grab. “Conch live in shallow waters, and they can’t run away,” says Kough. Fishers can quickly harvest large numbers from a herd.

To reach the animals, conch collectors used to snorkel or hold their breath in a free dive. They could gather a limited number of shellfish. But today, special breathing gear is available. It allows people to dive longer and deeper to collect many more conch.

A few years ago, a group of scientists including Kough completed surveys of queen conch populations in the Bahamas. Boats slowly towed researchers wearing snorkels, who examined nearly a million square meters (10 million square feet) of seafloor at 42 sites over a period of several years. “Being dragged behind a boat counting conch isn’t for everyone,” jokes Kough. “But you get to see huge amounts of the ocean bottom, and it’s very peaceful.”

A few years ago, a group of scientists counted queen conch in the Bahamas. Kough was one of them. Boats slowly towed the researchers, who wore snorkels. The scientists covered nearly a million square meters (10 million square feet) of seafloor at 42 sites over several years. “Being dragged behind a boat counting conch isn’t for everyone,” jokes Kough. “But you get to see huge amounts of the ocean bottom, and it’s very peaceful.”

When the researchers compared their latest data with previous conch surveys going as far back as the 1980s, “we saw a steady decline,” says Kough. “It was really startling.” In some places, the number of adult conch had plummeted by more than 90 percent. And the average age of conch at many sites had also decreased. The findings suggest that fishing has reduced the number of adult conch, leaving mainly juveniles behind.

That could signal a big problem, because adult conch are the only ones able to reproduce and replenish the species’ numbers (see Conch Life Cycle). If fishers remove too many adults, the conch population may not be able to sustain itself. In shallow waters that are easy for fishers to reach, there may already be too few animals left to reproduce successfully.

The researchers looked at earlier conch counts going back to the 1980s. When they compared their new data with these older counts, “we saw a steady decline,” says Kough. “It was really startling.” In some places, the number of adult conch had dropped by more than 90 percent. And the average age of conch at many sites had also decreased. The findings suggest that fishing has reduced the number of adult conch. Mostly juveniles are left behind.

That could be a big problem. Only adult conch can reproduce and restore the species’ numbers (see Conch Life Cycle). If fishers remove too many adults, the conch population may not be able to keep up. That might have already happened in shallow waters that fishers can easily reach. Too few animals may be left there to reproduce successfully.

Despite the concerning changes scientists have observed, they say there’s still a chance to protect the conch’s future—and preserve its important role in Bahamian culture. A recent study by Kough and Lundy found that marine protected areas, where fishing is banned, are home to more mature conch. “The protected zones were where all of the breeding was happening,” says Kough. The offspring of those conch drift into surrounding waters where fishing is allowed, helping to repopulate them. Creating more protected areas could give the Bahamas’ entire conch population a big boost.

Another option is updating fishing regulations. Right now, fishers can legally collect conch whose shells have developed a “lip” that flares outward. That usually happens when the animals are a few years old. Scientists suggest that a more effective conservation policy would require waiting until the lip grows to a certain thickness— indicating that conch have reached adulthood. “Research shows that the lip has to be at least 15 millimeters [0.6 inches] thick before conch have a chance to reproduce,” says Lundy. That would give the conch population a better chance of rebounding, while allowing the fishing industry a reasonable supply. And instead of removing conch from their shells at sea, fishers would bring them ashore in their shells so regulators can verify their catch.

Scientists are concerned about these changes. But they say there’s still a chance to protect the conch’s future and its important role in Bahamian culture. In marine protected areas, fishing is banned. A recent study by Kough and Lundy found that more mature conch live in these areas. “The protected zones were where all of the breeding was happening,” says Kough. The offspring of those conch drift into nearby waters where fishing is allowed. This helps restore conch numbers there. Adding more protected areas could give the Bahamas’ entire conch population a big boost.

Another idea is to change fishing regulations. Conch develop a “lip” on their shells that spreads outward. This usually happens when the animals are a few years old. Right now, fishers can legally collect conch that have a lip. Scientists suggest a new rule to help conservation. It would require waiting until the lip grows to a certain thickness. That means the conch have reached adulthood. “Research shows that the lip has to be at least 15 millimeters [0.6 inches] thick before conch have a chance to reproduce,” says Lundy. The conch population would have a better chance to recover, and the fishing industry would have a reasonable supply. And fishers wouldn’t remove conch from their shells at sea. Instead, they would bring the animals ashore in their shells. Then regulators could check their catch.

Late in 2020, the Bahamian government began debating such regulations in a new bill. The proposed law would also make it illegal to export conch to other countries and give officials the power to limit fishing to certain months of the year. These changes might not be popular with some fishers but could help ensure their industry doesn’t collapse over the long term.

Although the fate of conch in the Bahamas remains uncertain, scientists like Kough and Lundy are optimistic about the animals’ survival. “Conch is a part of the culture that is deeply cherished,” says Kough. “We definitely don’t want people to stop eating conch. We just need to find ways to make those traditions sustainable.” Lundy adds, “People here—including the fishing community—want to protect this resource to make sure it’s available far into the future.”

Late in 2020, the Bahamian government began working on a new bill. Officials considered regulations on things like lip thickness. The new law would also make it illegal to export conch to other countries. And it would allow officials to limit fishing to certain months of the year. Some fishers might not be happy about this. But the changes could help to keep their industry from collapsing over time.

The future of conch in the Bahamas remains uncertain. But scientists like Kough and Lundy are hopeful about the animals’ survival. “Conch is a part of the culture that is deeply cherished,” says Kough. “We definitely don’t want people to stop eating conch. We just need to find ways to make those traditions sustainable.” Lundy adds, “People here—including the fishing community—want to protect this resource to make sure it’s available far into the future.”