Wednesday, July 4, 2012

Scientists ponder mollusk mystery – why scallop numbers vary

From TampaBay Online:  Scientists ponder mollusk mystery – why scallop numbers vary

In the shallows primeval, the delicate scallop danced a graceful ballet — like a Disney cartoon — pirouetting across the hip-deep waters along the Florida's coastline from West Palm Beach to Pensacola, its dozens of bright blue eyes scanning the seascape for predators.

That was long before predators wore masks and snorkels and Speedos.

Scallop season opens today, and there are mollusks in the legal hunting areas, though maybe not quite as many as last year.

Each year, state biologists count scallops in the month before the season opens. This year the counters totaled an average of 36 scallops in a 656-square-yard spot around Homosassa and Crystal River. That's just below the average of 41 spread over the past eight years.

The mysterious thing about scallops is this: Populations in areas where they are known to flourish fluctuate wildly from year to year, and scientists admit they really don't know why.

In 2001, biologists counted nearly 300 scallops in that same marked area near Homosassa; three years later, in the same spot, they counted five.

"Very fickle," said Norman J. Blake, a retired professor of biological oceanography at the University of South Florida's College of Marine Science in St. Petersburg, referring to scallop populations.

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The ping-pong numbers are not all due to human intrusion, though it does appear that wherever humans are, scallops tend to go elsewhere. That's why the current concentrations of scallops stretch from Pasco County up around the Big Bend and west to the Panhandle. South of Pasco, where they have to share the water with more humans, boats and pollution, scallops aren't so plentiful anymore.

When God created scallops, said Blake, who oversaw USF's scallop restoration project in the mid-1990s, he put them everywhere along Florida's southern and Gulf coasts, but gradually they have disappeared.
They were decimated in Tampa Bay and Charlotte Harbor in the 1950s, when commercial trawlers dragged the sea bottom, scooping up just about every last scallop there.

The state subsequently banned commercial scalloping.

Blake said there is no single answer as to why scallops disappeared in some parts of the state. "It's real complicated," he said.

It may have to do with human interference: dredging, building spoil islands that interfere with currents and doing other things that affect the sensitive sea grass environment in which scallops breed and live.

"It's not any one of those things by themselves," Blake said, "and we're really not sure if it's any of those things at all."

The briny truth, he said, "is that wherever people go, scallops disappear."

Undoubtedly, it doesn't help that scallops are delicious grilled, broiled or baked.

Still, because of an intense effort in the mid- to late 1990s spearheaded by Blake and his research at USF, the scallop population between Anclote Key and Crystal River has rebounded and seems robust even though the numbers vary widely from year to year.

That project propagated scallop larvae in the marine lab and set them free in specific areas. Larvae also were captured in devices placed in scallop-rich areas and relocated to spots with little or no scallops.

In 2001, scallop counts around Homosassa were the highest ever recorded, a remarkable turnaround from the 1990s. Scallop populations from Pasco County to the Suwannee River had crashed, forcing the closure of the state's popular scallop season in that area to be suspended for seven years.

But that's not to say the scallop population will be high year to year. A hurricane or tropical storm in the fall, when scallops spawn, could wipe out a population for years, Blake said.

"Some years are good," Blake said. "Some years are not."

This year, Tropical Storm Debby may have bounced the bivalves around from one spot to the next but shouldn't have an effect on the population when snorkelers hit the waters on Sunday, he said.

Holly Wagner of Hernando Beach can't wait to get her goggled face in the water.

She and her husband, Ron, are just a 20-minute boat ride to the Gulf from their home.

"We are going out on opening day, definitely," she said. "We just go out the channel and start scalloping. It's a lot of fun. It's good exercise and good eating. It's a good sport for families because you're only in four to six feet of water."

The first day usually finds scallopers all over the place. "You could walk from boat to boat out there," she said.

Scallop yields last year were very good, and she's hoping for the same this year. Like any fishing trip, scalloping depends a lot on luck.

"If you hit the right spot, you can get (your limit) in 15 minutes," she said. "If it's a slim day, you can spend three or four hours trying to get your limit.

"The best scallop area is in three to 10 feet," she said, over a bottom that is sandy and grassy. "We usually find our limit in one to two hours. We have limited out in 30 minutes with five people in the water. It's not fun to limit out too soon."
* * * * *
Scientists say scallops were first harvested in Florida by indigenous people a century ago.
Rules governing the hunt are strict.

The southern boundary is the Pasco-Hernando county line and extends out nine nautical miles from the coastline to Mexico Beach. Scallops taken outside that area are illegal bounty. You can't even have them in your boat if you dock in Pasco County after a scalloping hunt, according to the Florida Fish and Wildlife Conservation Commission.

The limit is two gallons of unshucked scallops per person per day and no more than 10 gallons per boat. Each person can take no more than a pint of shucked scallops, and a boat can't have more than a half gallon of scallop meat.
Scallopers must have a Florida saltwater fishing license.

The season typically lasts into the second week of September.

Steve Geiger, a marine scientist with the state's Fish and Wildlife Research Institute in St. Petersburg, said the season may open to less than stellar reviews.

"It may be off a little in most places," he said, and that's just the way the scallop falls.

"They are a one-year species," he said, "and if anything happens at any stage of the life cycle, that can result in a big variation."

But the mollusks do rebound in healthy populations, he said. Scallops lay millions of eggs. "They are very fecund," Geiger said. "It doesn't take that many to rebound in areas with healthy populations. They seem to rebound better after down years and generally bounce back in a year or two."

A stable population has been established around Crystal River and Homosassa. Though the number of scallops fluctuates greatly from year to year, they always seem to rebound after a sparse year, and that's what makes it a viable species in that area.

He said attempts to restore scallop populations closer to home have been more difficult.

"Tampa Bay and Sarasota," he said, "are not responding to our restoration efforts."

Someday, will there be scallops bobbing along the bottom of Tampa Bay?

"I'd love to see it," he said. "It's part of our goal to return populations to sustainable levels. It's a challenge. It is possible.
"I don't want to say it will never happen."


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