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Bidding bye-bye to baby bivalves

By SUZANNE WENTLEY
suzanne.wentley@scripps.com
September 10, 2006

They're all grown up and ready to move out.

This week, the 98,000 oysters scientists and waterfront homeowners started raising in mesh bags in June will be scattered over natural reefs in the St. Lucie River to augment the struggling local population.

Heather Holberger, a research assistant at the Florida Oceanographic Society, said the project — designed in connection with Research Aquaculture, a Hutchinson Island-based business that grows clams and oysters — has been a success despite the recent dip in salt levels in the river water.

"It came back up right when I was figuring how to move them," she said. "They're plenty big enough."

Oysters can survive for about a week in water with salinity levels as low as three parts per thousand, but they thrive when the salty conditions range from 15 to 30 parts per thousand, she said.

Recently, the salinity levels have been about six parts per thousand in the South Fork and about four parts per thousand in the North Fork, because of the recent heavy rains.

Because the oysters were growing in mesh bags that floated with plastic PVC pipe underneath homeowners' docks, moving the oysters to deeper reefs will benefit them, Holberger said.

"The oysters are closer to the surface of the water," she said. "When they're at the bottom, it will be a little saltier."

This week, Holberger and volunteers will retrieve the half- dollar-sized oysters from the docks of about 30 waterfront homeowners, replace the worn and muck-covered cages and give each dockowner 500 baby oysters to rinse and monitor.

The grown oysters will be scattered over five quarter-acre sections of nearby natural oyster reefs in the St. Lucie Estuary.

The local scientists have applied for grant money from specialty license plates to map the reefs and monitor the oysters' size and density to see if the project successfully adds to the local population.

This week, Stuart-based Hydro-Engineering and Mapping Inc. will map the reefs, while Tom McCrudden of Research Aquaculture will start growing more baby oysters for a replacement this December, Holberger added.

"The oysters did fine," she said. "They don't need that much attention."

WANT TO HELP?

The Florida Oceanographic Society is looking for dock-owners along the St. Lucie River's North Fork and middle estuary to help raise oysters.

Call Heather Holberger at (772) 225-0505 ext. 112.