Sand-covered cobble means lost revenue to fishermen
BY PETER B. BRACE INDEPENDENT WRITER
Bass fishermen call it cobble. Cobblestone-size rocks in scattered clumps can be found in 15 to 20 feet water, out to about 1,200 feet offshore about a half-mile north to half-mile south of Sankaty Head Lighthouse.

In these underwater rock gardens of glacial moraine, according to Nantucket's commercial and charter striped bass fishermen, are all the marine yummies that bass love to nosh on. Crabs, sand eels and sand dabs like to hide beneath this cobble along with juvenile lobster. Strong tidal currents wash schools of squid through this area and winter and yellow flounder breed here.

Whether on the menu or not, many sea creatures use this ocean habitat for shelter from predators, working the barren sandy bottoms just off Nantucket and breeding. Some of those creatures are the striped bass that charter fishermen promise to their clients and that commercial striped bass fishermen depend on during the summer.

But now, both of these seasonal livelihoods are apparently in jeopardy with the proposal from the Siasconset Beach Preservation Fund to rebuild the beach with 2.6 million cubic yards of sand from a shoal west of Bass Shoal, about three miles off the beach. The beach would be re-nourished at five-year intervals or as major storms dictated.

The fishermen say the construction of this wider beach, designed to protect real estate along Baxter Road and sections of public beach from washing away, will smother the cobble areas and put them out of business.

Future seaward enhancements might aid the beach in accreting out more than 1,000 feet, further hampering the habitat.

"It's why those fish are there," said Charter Fishing Captain Josh Eldridge of Monomoy Charters. "In our 20 years of fishing I don't know of any other cobbled bottom [around the island] that will hold fish like that does. It's the kingpin of the whole show."

At the second meeting of what will likely be a multi-part public hearing for the Siasconset Beach Preservation Fund's notice of intent filed with the Conservation Commission, Eldridge and other fishermen gave the engineers an earful of their dire predictions for the future of their business should this beach nourishment go forward.

"So you're telling me that my bottom has to suffer so you can do this project, because you can't come up with a better alternative?" Charter Fishing Boat Captain Bobby DeCosta asked at the meeting.

Nantucket fishermen are not alone in their protectiveness of this habitat. In his Jan. 22 letter to Massachusetts Environmental Secretary Ian A. Bowles concerning SBPF's proposal, Paul J. Diodati, director of the state's Division of Marine Fisheries, said a full recovery of this habitat from the first phase of nourishment could take a decade.

"Although very little literature exists on the magnitude of impact or recovery success of cobble following beach-fill activities, studies of recovery following impacts from commercial fishing suggest recovery periods of six to 10 years," said Diodati. "Given the estimated project life of five years, it is unlikely that habitat functions and values will have returned to preconstruction levels before the next cycle of construction impact. For the purpose of evaluating this project, such impacts are unavoidable only as a function of the chosen construction technique."

Coastal Engineer Gordon Thompson of Coastal Planning & Engineering of Boca Raton, the project engineer, explained that the most likely sand dredging ship for the job would be a hopper dredge. It uses a large arm with a rectangular opening at the business end that does the sucking. It is capped with a grate to filter out the larger rocks. The sand is then pumped into the open hold of the ship. When full with 3,000 to 6,000 cubic yards of sand, the dredge steams toward shore and connects via onboard flexible pipe to a pump station which pumps the sand in a slurry onto the beach through a 30- inch pipeline resting on the bottom.

Thompson showed four corridors that the pipeline would pass through from the pump station to the beach. DeCosta did not like what he saw.

"It's not just the cobble. Everyone's talking about the damn cobble," he said. "It's the bottom of the cobble It's essentially a northern reef. Where you have your pipeline set up will not work for the fishermen, I can tell you right now."

Offshore, the fishermen are also worried about the scour from the dredge's propeller, which could be sitting about 30 feet down into the water as it fills with sand.

Charter captains are also concerned about turbidity - the clarity of the water given the amount of sand and other debris. Although Thompson said the turbidity plumes are gone 30 minutes after dredging stops and that it is no worse than that produced during ocean storms, fishermen believe the dredge's fouling of the water would make it tougher for them to find the fish away from the cobble.

Thompson said the project would take five months during the summer and fall seasons with crews working 24 hours a day. The dredge, which can work in seas no rougher than six to seven feet, would need 150 days on the water to mine enough sand for the project. To haul the 30-inch pipe needed to pump the sand from the pump station and then down the beach would require 130 truckloads to the site and 130 back

off island when the job is done. I