A number of conservation groups have combined their clout to push for further restrictions on midwater trawling in the herring industry.

The groups - including the Pew Charitable Trusts, the Conservation Law Foundation, the CHOIR Coalition of Chatham, Earthjustice, Greenpeace and the Ocean Conservancy - believe trawlers, which use large nets to catch herring, threaten the ocean's ecosystem by reducing the amount of herring, which are food for many marine species.

"Herring are the most important fish in the ocean," said Steve Weiner, chairman of the CHOIR Coalition. "Nearly all of our commercially and recreationally important fish stocks rely on herring as a key component of their diet."

David Ellenton, general manager of Cape Seafood Inc., could not be reached for comment for this report, but previously told the Times there is no evidence to support an assertion that mid-water trawlers greatly harm the herring population. He also pointed to catch limits established in 2000 and to a voluntary moratorium on weekend fishing.

Cape Seafoods, located on the Jodrey State Fish Pier, processes herring from three trawlers, the Challenger, the Endeavor and the Voyager, all owned by Western Sea Fishing, which land a total of between 15,000 and 18,000 metric tons of herring annually.

Peter Baker, the Herring Alliances campaign manager of the Pew environment group and former chairman of the CHOIR Coalition, said the trawlers pose a hazard to marine wildlife, such as tuna and whales, that may be feeding on herring as the nets pass through the schools.

In a statement released last week, the the Herring Alliance said its goals are:

* to establish catch limits that leave sufficient herring in the ocean as forage for other marine predators;

* to regulate herring trawling by creating buffer zones and time and area closures that minimize catching other species, (bycatch), and avoidi localized depletion to ensure sufficient herring is available; and

* to monitor and minimize bycatch of commercially and recreationally important fish stocks, including juvenile or spawning herring and depleted herring and groundfish, as well as whales, seals, dolphins and porpoises.

The groups and many of the key people in the Herring Alliance individually have advocated for tighter restrictions on herring trawling.

"This isn't about being anti-the herring fishery, it's about fishing in such a way that is sustainable and respects the fragility of the ocean's resources," said Ray Kane, vice chairman of the CHOIR Coalition and a commercial tuna fisherman from Chatham.

Baker and a number of others now involved in the Herring Alliance went to Washington in March to advocate for more funding for federal observers on herring trawlers. He said about 30 percent of hook-fishing vessels have observers, while about 1 percent of trawlers have observers.

Last year, the New England Fishery Management Council added an amendment to the herring management plan that bans mid-water trawling in a large area of the Gulf of Maine from June through September starting this year. And in March, the federal fishery council approved the amendment for inshore trawling in the waters known as Area 1A.

This change means that vessels cannot use trawl nets, funnel-shaped nets pulled behind the boat to catch fish, in the large inshore Area 1A, which stretches from Cape Cod to the Canadian border. Vessels using purse seine gear, which is cast around a school, pulled upward and cinched at the top before being lifted out of the water, can still fish inshore.

The National Fishery Management Council is considering lowering the catch limit to 45,000 metric tons in area 1A, following a September reduction by the New England council from 60,000 metric tons to the current 50,000 metric tons.

Regulations set a hard limit on the total amount of herring that can be landed in a year. Most other species have individual catch limits for fishermen as well, but the entire fishery does not close once the catch limits have been reached. For the entire inshore area - comprised of four sections called 1A, 1B, 2 and 3 - running from Nantucket to the Canadian border and about 50 miles from shore, the total catch is 145,000 metric tons.

After a crash in the herring stock in the mid-1970s, restrictions placed on fishing for herring led to a rebound. Both sides of the debate agree that overfishing is not occurring on herring.

In the United States, herring is used mainly as bait for lobster traps. Ellenton has previously told the Times that a reduction in the amount of herring landed during the summer could drive up lobster bait prices. Herring also is sent to overseas markets for food.

Landings of pelagics - which are fish that swim midway between the surface and the ocean floor and include herring - have steadily increased in Gloucester over the last few years, hitting 126.9 million pounds last year from 46.8 million pounds in 2001. The value of the landings nearly quadrupled from $2.5 million in 2001 to $9.1 million in 2006.

The weight of groundfish, which include cod, haddock and pollock, was stagnant from 2001 to 2005, hovering between 17 million pounds and 18 million pounds. Its value increased slightly over that time, reflecting price increases for a scarcer resource, rising from $17.2 million in 2003 to $19.6 million last year.