Reduce the number of birds and leash the dogs.

That’s the translation of a technical study released this week by a leading marine biologist which concludes that a flock of invasive cormorants and — to a lesser extent — a group of domesticated dogs are responsible for the high levels of fecal contamination in Sengekontacket Pond.

The study from Dr. Stephen H. Jones, director of the University of New Hampshire Center for Marine Biology, finds that most of the contamination in Sengekontacket can be traced to waste from either cormorants or geese.

High bacteria counts caused the state Division of Marine Fisheries to close down Sengekontacket Pond for shellfishing twice this summer, first in two weeks for June and again in July. The second closure lasted through September. State officials now plan to close the pond to shellfishing for four months during the summer on a permanent basis.

Following the closure, Edgartown shellfish constable Paul Bagnall collected water samples from Sengekontacket Pond and shipped them to the University of New Hampshire center for testing. He also collected samples from Eel Pond and Trapps Pond in Edgartown and Farm Pond in Oak Bluffs.

Strains of fecal-borne microbial, or E. coli bacteria, were isolated from the samples and subjected to a process called ribotyping analysis. The process was able to identify the source of 79 per cent of all isolates collected.

Among other things, the study concludes that 43 per cent of the isolates found at Sengekontacket Pond were from birds, 21 per cent were from dogs and seven per cent were from livestock. The study also concludes that 69 per cent of all isolates found in all four salt water ponds tested were from birds, either cormorants or migratory geese.

The study was based on a total of 48 samples taken during one round of testing over two days from the four ponds. The study concluded that none of the isolates collected were human in origin.

The study found that 33 isolates collected came from birds, which made up 69 per cent of all samples taken and 87 per cent of all samples identified. Three isolates were determined to have come from pets — all came from Sengekontacket Pond — which made up 21 per cent of all samples collected and 30 per cent of all samples identified.

Some shellfishermen this week said the study is proof that cormorants are responsible for the bacterial contamination that forced the closure of Sengekontacket Pond this summer and they advocated the use of lethal force to get rid of them.

“In my estimation we didn’t even need a study — something should have been done a long time ago to get rid of those [cormorants],” said Cooper Gilkes 3rd. “This study only confirms what we’ve known for years — those birds gotta go.”

Mr. Gilkes said he hopes the study will help Island officials convince the federal government that aggressive measures are needed to address the cormorant problem. Cormorants are federally protected by the Migratory Bird Treaty Act.

Despite their protected status, Mr. Gilkes said a majority of Island shellfisherman support getting rid of the cormorants by any means necessary.

“If you ask around I bet ten to one [of the shellfisherman] would be in favor of shooting the birds or [addling] the eggs. We’ve already asked the [federal government] to do something about this problem and they did nothing; something needs to be done and something needs to be done now,” he said.

Edgartown commercial shellfisherman Donny Benefit agreed.

“There are sections of the pond where the [bird droppings from cormorants] are 18 inches deep along the bottom. It’s just criminal what those birds are doing to the pond,” he said.

Oak Bluffs shellfish constable David Grunden said the study proves that cormorants are at least partially responsible for the contamination and the resulting closure of Sengekontacket pond. But he also said more work needs to be done.

“We want to move quickly to address the problem, but we also want to get a lot of people involved and make the right decision,” he said.

Mr. Grunden said a wide range of people should be involved in drafting a plan to address the problem, including spokesmen for the Felix Neck Wildlife Sanctuary, the Martha’s Vineyard Land Bank and the various housing developments along the pond.

Terry Appenzellar, a member of the Friends of Sengekontacket which helped fund the recent study, also advocated a more cautious approach. She said the study is extremely limited in scope and provides no analysis or suggested solutions.

Although the Friends of Sengekontacket have not officially reviewed the report, she said she doubted the group would use its conclusions to justify killing cormorants.

“The study also says that dogs are partially responsible — but I don’t think anyone would support going out and killing dogs. If anything this study is only a very small piece of the puzzle,” she said.

Suzan Bellincampi, director of the Felix Neck Wildlife Sanctuary, which manages Sarson’s Island where many of the cormorants are concentrated, cautioned against placing all the blame on the birds without more testing.

“This was one round of testing and a very limited sample; let’s not all blame the birds before all the facts are in,” she said.