Tide turns for bay scallops, restoration continues in Tarpon Bay

(Photo: Ricardo Rolon/The News-Press)

(Photo: Ricardo Rolon/The News-Press)

Standing in the chest-deep water of Tarpon Bay this week, Eric Milbrandt handed a cage full of bay scallops to Sarah Bridenbaugh aboard a Carolina Skiff.

Milbrandt, director of the Sanibel-Captiva Conservation Foundation Marine Laboratory, and research assistant Bridenbaugh weren't harvesting the tasty mollusks (harvesting bay scallops south of the Pasco-Hernando county line is illegal).

Instead, the caged scallops would be cleaned, counted and measured by Bridenbaugh and interns Krystal Silas, Emily Anderson and Chrissy McCrimmon for an ongoing scallop restoration project.

"Old-timers talk about collecting buckets of scallops in the 1950s and '60s," Milbrant said. "What we're trying to do is re-establish a local population of scallops. We'd like to see a population that can sustain a recreational harvest, but we're quite a long way from that."

Bay scallops used to be so abundant in Pine Island Sound that they supported thriving commercial and recreational fisheries.

In the mid-1960s, however, the area’s scallop population crashed; many people blamed the Sanibel Causeway, which was built in 1963 — the theory is that the causeway islands blocked the flow of the Caloosahatchee River, so fresh water backed up into the estuary and killed the scallops, which die when the salinity drops below 20 parts per thousand.

That theory doesn’t tell the whole story, considering the fact that scallop populations collapsed at the same time all along Florida’s Gulf Coast.

"There is a combination of things," said scallop expert Steve Geiger of the Florida Fish and Wildlife Conservation Commission. "Populations crashed south of Suwannee, and the crash wasn't equal in all places. We can postulate that it was a change in water quality, loss of habitat — there was a lot of dredge and fill and seagrass loss. There was also a larger human population and more harvest."

Southwest Florida had an additional cause: Red tide kills bay scallops, and the traditional red tide hot spot is from Sarasota County to Collier County.

"There are a lot of stressors, a lot of things going on," Geiger said. "Why they're not recovering is a harder question."

Scallop populations remain healthy enough in north Florida to allow a recreational harvest from the Pasco-Hernando county line to the west bank of theMexico City Beach canal in Bay County; Milbrandt said numerous factors might be responsible for scallop populations in that area, including lack of development.

Several organizations are working to help scallops recover in Southwest Florida, including Mote Marine Laboratory, Sarasota Bay Watch and the Charlotte County Extension Service.

Eric Milbrandt, director of the Sanibel Captiva Conservation Foundation marine lab, hands Sarah Bridenbaugh, a research assistant for SCCF, one of their research cages used to monitor bay scallops in Tarpon Bay. (Photo: Ricardo Rolon/The News-Press)

Eric Milbrandt, director of the Sanibel Captiva Conservation Foundation marine lab, hands Sarah Bridenbaugh, a research assistant for SCCF, one of their research cages used to monitor bay scallops in Tarpon Bay. (Photo: Ricardo Rolon/The News-Press)

Eric Milbrandt, director of the Sanibel Captiva Conservation Foundation marine lab, hands Sarah Bridenbaugh, a research assistant for SCCF, one of their research cages used to monitor bay scallops in Tarpon Bay. (Photo: Ricardo Rolon/The News-Press)

SCCF's recovery effort consists of placing juvenile scallops in cages in Tarpon Bay, cleaning and measuring them weekly until they spawn in the summer.

Most scallop larvae settle near where they were spawned, but some travel on tides through passes into the Gulf; then they ride currents and tides and settle in other estuaries.

For the first few years of the restoration effort, SCCF got their juvenile scallops from FWC, which were collected in Tampa Bay.

"We'd meet the FWC guys at I-75 and Jones Loop Road with a cooler and a couple of bubblers," Milbrandt said. "We'd get 300 to 400 scallops, bring them back and put them in cages.

"Last year, a local bait-shrimper called and said, 'Hey, I'm catching a lot of dime-size scallops. Do you want them?'"

Since then, SCCF has been using local scallops caught by the shrimper.

Packed together in cages, the scallops become more encrusted with organisms (this is known as fouling) than in the wild, so an important part of the project is scraping fouling organisms off with the edge of a ponderous ark clam shell.

"The scallops get so fouled that they can't open," Milbrandt said. "They're filter feeders, and if they can't open, they can't feed. We use the edge of a shell instead of an oyster knife because it's softer; a knife could break the scallop's shell."

To assess the abundance of a local scallop population, researchers have created four classifications: sustainable, more than 1 scallop per square meter; stable, 0.1 to 1 scallop per square meter; vulnerable, .01 to 0.1 scallop per square meter; collapsed, 0 to .01 scallop per square meter.

Scallop populations have fluctuated in Southwest Florida's restoration areas; some populations go back and forth from stable to vulnerable.

A bay scallop is displayed on Tarpon Bay off Sanibel Island during a research trip by the Sanibel Captiva Conservation Foundation as part of their scallop restoration efforts. The blue objects inside the shell are the scallop’s eyes. (Photo: Ricardo Rolon/The News-Press)

A bay scallop is displayed on Tarpon Bay off Sanibel Island during a research trip by the Sanibel Captiva Conservation Foundation as part of their scallop restoration efforts. The blue objects inside the shell are the scallop’s eyes. (Photo: Ricardo Rolon/The News-Press)

A bay scallop is displayed on Tarpon Bay off Sanibel Island during a research trip by the Sanibel Captiva Conservation Foundation as part of their scallop restoration efforts. The blue objects inside the shell are the scallop’s eyes. (Photo: Ricardo Rolon/The News-Press)

But the Pine Island Sound population goes back and forth from stable to collapsed.

"It's possible that something has changed in Florida Bay, which provides a source of larvae for Pine Island Sound," Geiger said. "Or maybe there's some stressor we haven't identified. Whatever the reason, whenever the population gets to stable, it falls back to vulnerable. It does go to collapsed sometimes, but it doesn't stay there."

For the most part, Geiger is excited about Southwest Florida's bay scallops.

"I'm concerned that we're not to a level where they're harvestable," he said. "But from a species standpoint, I'm happy. They're not thriving. They're stumbling along, and I have to believe that all these efforts by SCCF, Mote and Charlotte County are having a positive effect."

Like all bay scallops, SCCF's caged scallops die after spawning.

In April, SCCF had 270 juvenile scallops in two cages; through spring and early summer, the death rate was four to five a week, and as the scallops spawned, they died at a rate of 20 a week.

This week, the researchers counted the empty shells of 40 scallops, leaving 156 live scallops in the cages.

"You hate to see them go," Anderson said. "But that's what they do."

Talking scallops

For "Fisherfolk of Charlotte Harbor, Florida," University of Florida, 1996, Robert F. Edic interviewed commercial fishermen about various local fisheries. Here's what a few said about scallops:

  • Bill Hunter: "I used to make money from scallops. Back in the 1930s, we used to get a dollar a bushel. ... You could make twelve or fifteen dollars a day."
  • Esperanza Woodring: "We used to get some to eat up on Tarpon Bay at low water. You used to could go up there and pick them up by the washtub full."
  • Richard Coleman: "There were a lot of scallops around here. Whenever you wanted to eat some, you just dipped them up with a dip net."
  • Raymond Lowe: "We collected them to eat. They were everywhere, all you wanted. Now you can't find one."

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