Fisherman Lou Williams sees plenty of harbor porpoises, usually swimming in small pods well away from his boat, unlike the herds of lookalike dolphins that get close enough to ride his vessel's wake.
A place Williams doesn't see many porpoises is his nets.
"It's a rare occasion," said Williams, 55, who fishes out of Gloucester. "I don't think more than a couple this year."
But federal regulators say far too many porpoises in the Gulf of Maine are drowning in fishing gear, specifically the stationary nets that Williams and other fishermen use, called gillnets.
The estimated fatalities are so high, they triggered a provision in federal rules that will close a busy fishing ground that extends from Gloucester to southern Maine to gillnets for two months annually, starting this Oct. 1.
Some say the fishermen bear much of the blame for the closure. The porpoise can be avoided by equipping the nets with so-called pingers, which make periodic beeps that drive the porpoises away. All gillnetters are supposed to have working pingers at the corners of each of the nets they string together, but federal regulators said fishermen who use the affected area had only a 41 percent compliance rate.
"The industry has done itself a great disfavor, at least this segment of the industry, by not going up full bore ... with compliance," said David Pierce, a member of New England Fishery Management Council.
Fishermen are trying to maintain functioning pingers, but it's difficult to tell when the devices break down, said Mike Russo, a fisherman who spoke at a council meeting last week. The closure was coming at a terrible time for an industry struggling to survive various new restrictions, he added.
"Once you cut the head off of someone, it's hard to sew it back on," Russo said.
The porpoise, which lives off waters from Maine to North Carolina, is often confused with the dolphin, but the animal has some key differences in appearance. Porpoises are stout, dolphins tend to be leaner. The dolphin has a curved dorsal fin, while a porpoise's is triangular. Dolphins have elongated beaks, while porpoises have smaller mouths.
Both animals are among those protected under the federal law behind the coming closure.
The harbor porpoise is not rare, with a population estimated between 60,000 and 90,000.
But to keep the population healthy, the Marine Mammal Protection Act allows only a certain number of porpoises to be accidentally caught and killed annually.
Right now, the annual nationwide limit is 703, and the law requires regulators to bring the average down to a tenth of that, about 70 deaths annually, said David Gouveia, the marine mammal program coordinator the National Oceanic and Atmospheric Administration's Northeast office.
But federal researchers say 883 porpoises were snared on average annually between 2005 and 2009, the most recent years numbers are available.
Gouveia said a key to bringing down the rate is making sure all the required pingers on gillnetters are working. If even one pinger on a string holding, say, 10 nets isn't working, the porpoise might think there's a gap between the nets, which are each about 300 feet long. The animal then gets snagged trying to swim through a gap that isn't there.
So a team of regulators, fisherman and environmentalists devised rules and penalties that require independent observers on fishing boats to monitor whether all the pingers are working, he said. The observers also record the rate at which the fishermen accidentally catch the porpoise — another sign whether their pingers are functioning.
In the Gulf of Maine between September 2010 and May 2011, observers found pingers working properly on only 41 percent of observed hauls and that gillnet fisherman were snaring porpoises at a rate more than twice as high as what was allowed.
As a result, the coming Gulf of Maine closure was ordered.
Some of the roughly 40 affected boats are based in New Hampshire and Maine, but the majority is based in Gloucester. Fishermen there dispute both the high accidental catch rate and the low compliance rate.
Jackie Odell of the Northeast Seafood Coalition, a Gloucester-based fishing industry group, said 1,400 pingers were purchased for about $100,000 by a local fishing preservation fund to ensure the entire fleet was covered.
Williams said everyone he knows has functioning pingers, and questioned whether there would truly be dire consequences if one or two don't work on several strings of nets.
He also questioned the need to shut down a crucial fishing area to help a robust population of porpoise, comparing it to penalizing a driver for hitting a deer.
Williams said he lands about 50 percent of his annual catch of bottom-dwelling groundfish during October and November, when the shutdown is scheduled. According to federal numbers, fishermen pulled in about $4 million in revenues during that period over the past two years.
The loss is huge in an industry that's fighting for its future as it faces significant cuts in key stocks such as cod in the Gulf of Maine and yellowtail flounder in Georges Bank. There's also no obvious end to the annual closure to protect porpoise, since the requirement to reduce accidental porpoise deaths down to 70 per year looks a long way off. The team of regulators, fisherman and environmentalists that devised the closure could conceivably decide there are better alternatives to shutting down the area, but they don't meet until this fall.
At the fishery council meeting last week, the council passed a motion to ask the team to meet "immediately," so that it can quickly consider ways to avert a shutdown for the gillnetters.
"This is a very, very serious issue for a number of people in a number of states," said council member David Goethel, a New Hampshire fisherman. "The fall is way too late."