A Plan to Restore Tampa Bay's Scallops

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A Plan to Restore Tampa Bay's Scallops

Every summer, Tampa Bay Watch sponsors “The Great Scallop Search,” where almost 200 volunteers’ snorkel for hours in Tampa Bay, looking for bay scallops and hoping to find evidence the delicious bivalve is making a comeback. (Scallops have long been protected in Tampa Bay and divers only count them.)

The grand total found this year in selected search sites in Boca Ciega and Lower Tampa Bay? Fifty-one.  

In the waters off counties north of Pinellas that have recreational scalloping seasons, each diver is allowed to collect two gallons of the fanned-shaped shells. So, despite the volunteers’ diligence, their quest didn’t find enough scallops to fill even a single bag limit. 

Tampa Bay Watch Executive Director Peter Clark called the results “disappointing,” and noted last year’s red tide probably “affected their ability to repopulate.”

But red tide, Clark stressed, is not the primary culprit.  His environmental nonprofit has held scallop searches since 1996 and most years red tide has not been a factor. Yet the count rarely tops a few dozen. A decade ago, nearly 700 were found, but that encouraging number quickly plummeted.

The initial cause for scallop population collapse is no mystery. Haphazard development and widespread pollution destroyed the scallops’ seagrass habitat.  It’s estimated Tampa Bay lost 80 percent of its original seagrass beds. 

But thanks to state and local efforts to clean up the bay in recent decades, water quality is vastly improved and the number of seagrasses, while still well below historic levels, nearly doubled. The bay now has roughly 40,000 acres of seagrasses, about what it had in 1950, before rapid development claimed much of the shoreline. 

Many fish species rebounded as Tampa Bay’s health improved, but the scallops remained scarce. 

Clark’s conclusion: “We don’t have enough scallops to jump start the population. We just don’t have that critical mass.”

Dr. Joshua Patterson, who works out of The Florida Aquarium’s Center for Conservation at Apollo Beach, is hoping to do something about that.

His solution?  Give the scallop reproductive cycle a boost.

Working with a graduate student, Dr. Patterson, a University of Florida assistant professor of Restoration Aquaculture, collects scallops from Tampa Bay and surrounding regions, which are then taken to a private hatchery.  (There are no publicly run mollusk hatcheries in Florida the state). They are kept at the hatchery until they spawn. Heat and plenty of the microalgae the scallops eat encourage a prodigious spawn. When the larvae become “settlement competent,” meaning they can attach themselves to seagrass, Patterson and his team take then to appropriate habitat for release. 

Patterson and a UF colleague, Dr. Quenton Tuckett recently got a two-year grant from the Tampa Bay Estuary Program’s Tampa Bay Environmental Restoration Fund for scallop releases in Tampa Bay. Working with Florida Sea Grant agent Betty Staugler, he has already conducted releases in Charlotte Harbor, whose scallops had been hard hit by last year’s red tide.

He is hopeful the Charlotte Harbor effort will be effective but he believes the long-term outlook is even better in Tampa Bay. “This could be the sweet spot for the releases because we don’t get a lot of red tide. It is more frequent at Charlotte Harbor.”

Patterson has conducted research on various species at the Center for Conservation since 2014, when it was a single modular building. Now the state-of-the-art complex includes research facilities, a sea turtle hospital and education classrooms. The Florida Aquarium scientists recently became the first to reproduce pillar corals in a laboratory.

 

While Patterson doesn’t work for The Aquarium, he collaborates closely with its scientists. Among his ongoing projects is overseeing a graduate student’s effort to revive the spiny urchin population by growing them in the Center’s tanks. It is critical work. A mysterious disease has virtually wiped out Florida’s spiny urchins, which eat algae that would otherwise smother coral reefs.  Scientists believe the urchins’ disappearance is a factor - along with disease, climate change and pollution - in the rapid loss of Florida’s coral reefs.

Similarly, Patterson hopes researchers eventually can stimulate Tampa Bay scallops out of its population rut. Unlike the spiny urchin, there is no mystery disease here. A big part of the problem, Patterson said, is the mollusk’s “recruitment limitation. There are not enough adults here to produce sufficient larvae.”

He said only a few hundred scallops need to be taken to the hatchery because the hermaphrodite scallop generally spawns twice a year, producing millions of larvae each time.

When taking the larvae to be released “we transport them in five-gallon buckets with aerators. With two or three buckets, we probably have four million or more.”

Still the effort faces obstacles. 

Tampa Bay Watch’s Clark said scallops don’t care for fresh water. With the flow from four major rivers, Florida Aquarium Scallopsdozens of creeks and hundreds of tributaries, Tampa Bay’s scallop habitat will never rival that of the counties that offer salty coastal waters. 

Yet Clark he said historical reports show scallops once were abundant enough in Tampa Bay to sustain a substantial commercial harvest. Like Patterson, he believes the scallops are most likely to rebound in the lower bay, which has higher salinity levels.

Beyond being a delicacy, the bay scallop is a fascinating marine creature. It has brilliant blue eyes along  the outer edge of its shell. And this bivalve can swim, by opening and closing its shell. 

The highly developed abductor muscle that enables the scallop to virtually flap through the water is what provides the tasty bit of meat that can be a such a challenge to free from its shell. 

The scallop, usually found in four to 10 feet of water, needs its eyes and swimming ability to elude more than divers. Stingrays, crabs, whelks, sea stars and other creatures’ prey on them. The bay scallop has a life span of about a year.

The scallop filters microalgae from the water and Patterson said like all filter feeders it helps clean surrounding water, though it can’t rival the oysters’ filtering ability.

Patterson said the placement of the scallop larvae in Tampa Bay will be charted and monitored carefully. Patterson is working with other researchers on a way to genetically identify the hatchery-spawned scallops so scientists will be able to track their contributions to any population increase. 

Patterson is cautious about promising results, but other similar aquaculture techniques are believed to have helped scallops rebound in other counties, though their scallop populations never were as dismal as Tampa Bay’s. 

Overharvesting led the Florida Fish and Wildlife Conservation Commission to prohibit scalloping south of the Suwannee River for a time, but as their numbers recovered areas north of Pinellas were opened, albeit with limited seasons.

Patterson doesn’t envision a major scallop population boom any time soon. Nor does he believe it will ever be able to sustain a major harvest. At best, he thinks, a brief recreational season might one day be possible. 

Now he is focused on placing the hatchery larvae where they have the best chance to thrive, tracking their progress and hiding their location from poachers who could sabotage the entire effort. 

But if scallop revival occurs, it will be a major milestone Tampa Bay’s comeback.”

“The scallop is an indicator species,” Patterson said. “You can’t have them without good water quality.  … And scalloping is such a cultural event in Florida. It’s something the entire family can enjoy.”

With good science and good luck, perhaps the unique joy of scalloping can be returned to Tampa Bay.

ABOUT THE AUTHOR

Joe Guidry, a Tampa native, worked for The Tampa Tribune Company for more than 40 years. He joined The Tampa Tribune Editorial Department in 1984, later became Deputy Editorial Page editor and took over as Opinion Page Editor in 2008, a position he held until the Tribune ceased publication in May 2016. Read more...