THIS STORY HAS BEEN FORMATTED FOR EASY PRINTING

Seeing sea stars - and lots of them

Shellfish predator's population surging

Boston.com article page player in wide format.
By Beth Daley
Globe Staff / June 15, 2009
  • Email|
  • Print|
  • Reprints|
  • |
Text size +

SANDWICH - The five-armed creatures appeared by the thousands last Sunday at Scusset Beach State Reservation - spiny-skinned organisms so resilient that if one of their arms gets lopped off, it grows right back.

A starfish invasion is underway.

Enormous mats of the spiny creatures are infesting pockets of New England waters from Narragansett Bay to Cape Cod Bay this spring, charming beachcombers but tormenting some fishermen who worry they could devour the region's bounty of oysters, scallops, clams, and mussels. Starfish have little economic value - even seagulls gag when eating them - but their colorful skin and iconic shape bring squeals of delight from children and have made them a popular trinket in beachside tourist shops.

"They are multiplying like no one's business," said Peter Melanson, owner and founder of the Sakonnet Oyster Company Inc. in Little Compton. R.I. "They smell all the shellfish . . . it drives them crazy."

While theories abound about why starfish populations appear to be spiking, scientists acknowledge it is largely a mystery. Radical population shifts occur naturally in scores of species, from lynx to lobster. Yet researchers are only now unraveling the complex relationships and influences that govern their cycles of abundance.

It's not clear how widespread the invasion is because so few scientists study starfish. News of the population uptick is coming via reports from divers, fishermen, and spring beachgoers. State divers in Buzzards Bay were startled two weeks ago to find vast carpets of starfish - each creature 4 to 5 inches across - stretching 100 yards along the sea floor. Some fishermen in Narragansett Bay are hauling up an increasing number of starfish. Workers dredging contaminated shellfish in upper Mount Hope Bay between Rhode Island and Massachusetts also are seeing more. And last week at Scusset, overjoyed children armed with nets and buckets scooped up dozens of smaller starfish to show parents and take home as mementos.

They are properly called sea stars because they aren't fish, but have also been called the opossum of the sea - very much alive when they seem so dead. The region's starfish, which probably live three to four years and range in color from yellow-orange to purple-brown, are found in deep waters but can move to shallow areas to munch on tiny snails and a slew of shellfish.

How they eat those shellfish can repulse even the most hardy fisherman. Suction cups affix the sea star's arms to the clamped shell of an oyster, mussel, scallop, or clam. The starfish's powerful muscles slowly open the shell. If the slit is even paper thin, the creature pushes its stomach out of its mouth into the opening to excrete digestive juices and then consumes the dissolved material. One US Fish Commission report in 1900 described a starfish that ate 50 young clams in six days - and increased in size 300 percent.

"It is totally disgusting to see," said Robert Rheault, executive director of the East Coast Shellfish Growers Association.

Starfish were once so despised that Massachusetts and Rhode Island placed bounties on them. Clyde MacKenzie, 78, a National Marine Fisheries Service biologist who grew up on Martha's Vineyard, remembers people getting about 50 cents a bushel for them during the Depression. Farmers would come to the docks and load the starfish into wagons to fertilize their farmland.

Fishermen, meanwhile, would drag "starfish mops" - iron bars with large pieces of cotton at the end - along the sea floor to snag the spiny animals. Hauled back on board, the starfish were plunged in hot water to die.

"Sometimes fishermen would try to get rid of them by chopping them up with an ax and throwing them overboard, but you'd actually just get more" in the sea because they can regenerate, said Michael Rice, a professor of fisheries and aquaculture at the University of Rhode Island. Oyster farming was a big business in Rhode Island in the late 1800s and early 1900s, and maps were printed each year to show starfish abundance.

The Hurricane of 1938, along with pollution, helped end the oyster heyday in Narragansett Bay, and scientific interest in starfish waned. Some fishermen said starfish numbers plummeted along with the oysters. Now, scientists say they see only glimpses of starfish boom and bust cycles. The last starfish boom was eight to 10 years ago.

"It's really cyclical," said Terry O'Neil, a Massachusetts marine fisheries biologist who came across a giant pack of starfish on top of bay scallop beds in Buzzards Bay two weeks ago. "I've never seen so many starfish there before," he said, "but I have seen it in Cape Cod Bay - and the next year they are gone."

Some scientists believe starfish numbers are related to how shellfish populations did the previous year; a good shellfish year could spark a lot of starfish the next. Others wonder whether this year's population surge might be related to a reported decline in spider crabs, a starfish predator, or to changes in water temperature. Others say people just might be happening upon yearly localized events that often go unnoticed under the water surface. At Scusset, the best guess is that prevailing easterly winds drove the sea stars to shore.

"Everyone has their pet theory why - but an exact cause? We don't have it," said Dale Leavitt, associate professor of marine biology at Roger Williams University in Bristol, R.I.

Shellfishermen say that they have not been too bothered by the increase, but that starfish in general are a pervasive problem. Melanson, however, says he chooses to see their comeback as a positive sign.

As he hauled up a seaweed- and barnacle-covered cage filled with tiny oysters in thick mesh bags from the Sakonnet River last week, life teemed on it. About 20 starfish clung to the cage and to the largely impenetrable oyster bags.

With better controls on pollution, he said, the water is cleaner and luring back species - ones people want and ones they don't.

"There is more of everything now," said Melanson. "You could see it as a win-win situation."

Beth Daley can be reached at bdaley@globe.com.