PORTLAND – Fishermen say they are seeing more herring returning to the Gulf of Maine where a ban on trawlers that drag nets through the water has been in effect through the summer.

“There has been lots of sea life, and it kind of amazes me,” Daniel Fill, captain of a Rockland-based fishing boat, told a daily newspaper. “I have seen fish where I haven’t seen them for years. They’re in nice, big bunches for miles.”

Other purse seine herring fishermen, whale-watching companies and tuna fishermen are reporting similar observations. They also say they see more seabirds, dolphins, tuna and seals, which feed on herring.

Their reports contrast with what was seen a year earlier, when more trawlers, sometimes working in pairs, cut through the water dragging nets for herring. In the meantime, a ban on midwater herring trawlers has been in place in Gulf of Maine coastal waters.

The New England Fishery Management Council’s ban extends 50 to 60 miles offshore and lasts from June 1 to Sept. 30. It doesn’t affect fishing boats that use purse seine nets that encircle the fish when they come to the surface to feed at night.

The restriction was put in place in response to pressure from conservationists, tuna fishermen, lobstermen and sporting and whale-watching boat companies, which said the big nets that go deeper in the water break up herring schools and disrupt their breeding behavior.

Naturalist Zack Klyver of Bar Harbor Whale Watching, who supported the ban, said he’s now seeing a dozen whales a day in a section of the gulf where the ban has been in place and no whales were sighted a year ago.

“I think the ban has made a big difference,” said Klyver.

Despite the observations of those who work on the water, scientists say it may take months or years to see whether the ban on midwater trawlers has had any effect.

The ban has had its critics, including owners of midwater trawlers, who say the rule is based more on politics than science.

“This is about a big agenda to eliminate fisheries and trawler fisheries worldwide,” said Jeff Kaelin, a political consultant for the Portland-based 113-foot trawler Providian. “They found a small group of trawlers and kicked us off. We were not big enough or organized enough.”