TIERRA VERDE — The water was clear Saturday, making it easy to see waves of dark green sea grass where the golf-ball-sized shellfish were said to be hiding.
But while water quality has improved in Tampa Bay and grass beds have expanded by hundreds of acres a year, a mystery is why the scallop population, which ought to be growing, too, continues to struggle.
More than 200 people set out from Fort De Soto Park in boats and kayaks to help the nonprofit Tampa Bay Watch conduct a survey of these swimming shellfish across a broad area stretching to downtown St. Petersburg.
It was the 20th year of the Great Bay Scallop Search, which has tracked the success of efforts started in the 1980s to reintroduce scallops into Tampa Bay after they had vanished from the area.
The record number — 674 — was collected in 2009. Subsequent red tides and winter freezes might have caused the bivalves’ numbers to plummet. Last year volunteers counted less than a dozen.
Peter Clark, president of Tampa Bay Watch, said rainy weather probably skewed last year’s total, but it still was surprisingly low and the count has been less than 20 for several years.
On Saturday, though, the sun was bright and the scallop searchers were hopeful.
For the first hour, there were scant signs of life.
“I found a handful of shells; broken, dead ones,” volunteer Jason Bird said.
Bird and his friend, Nathan Shawen, snorkeled along a 50-meter transect line in 3-foot-deep water, combing the grass below.
Each volunteer group was responsible for scanning two half-mile grass beds. They swam or shuffled along the transect line using their feet, their eyes and a PVC pole to detect the shellfish.
Clark says they feel like a flat golf ball.
“They’re out here,” he said.
“I’m always optimistic at the beginning of the search.”
Andy Harris has volunteered for the scallop search for the past three years with his catamaran sailboat. As a frequent fisherman in the bay, he also is optimistic.
“I do a lot of fishing, so I know the water is getting cleaner. I really think one of these years there’ll be a lot of scallops and that’ll be really cool,” said Harris, a Tampa resident.
Harris brought along his daughter, Rachel, and her friend, Shelby Freeman, both Plant High School sophomores.
Rachel has yet to see a live scallop. “I didn’t get any last year,” she said.
One problem, Clark says, is there might not be enough of a concentration of scallops for their population to thrive.
Every fall, he said, when cold fronts make water temperatures shift, scallops release millions of sperm and eggs into the water within a few days. But if there are only a handful of scallops in close proximity, few will be spawned, he said.
Halfway through Saturday’s search, there was positive news.
“Hey, I found one. It took me five years to find one live one!” said volunteer Bill Marois, who paddled up to Clark’s boat in a kayak.
As the boats returned to shore for lunch, Clark gathered a preliminary count: 51.
“Which is much better than we’ve done the past couple years,” he said, adding the scallops were spread over a broad area.
“I still think we’ve got a long way to go in Tampa Bay,” he said.