BOSTON – Massachusetts and New Hampshire officials filed a joint lawsuit Tuesday against the federal government, opposing new laws aimed at protecting valuable fish stock by limiting the number of days fishermen are allowed at sea.

The rules, called Framework 42, count each day in two heavily fished areas off the Gulf of Maine as two days, while allowing one-to-one fishing days at sea in an area of Georges Bank used mainly by fishermen from southern New England. The rules were set to take effect Wednesday.

“We have fought against these regulations every step of the way and we will continue to do so because of the damage they will do the lives of Massachusetts fishermen and the fishing industry,” Massachusetts Attorney General Tom Reilly said in a statement.

In addition to hurting commercial fishermen financially, Reilly said the restrictions Framework 42 imposes could lead to overfishing in other areas as people try to recoup their losses. That, he said, would put Framework 42 in violation of the Magnuson-Stevens Act which is aimed at balancing fishery conservation with management.

Teri Frady, a spokeswoman for the National Oceanic and Atmospheric Administration’s northeast regional office, said Framework 42 is not a drastic change from interim regulations that fishermen had previously been working under, which gave them a 1.5-to-one day at sea ratio for certain areas. And, Frady said, the new regulations slightly increase the area that can be fished on a one-to-one day ratio.

“We believe that the framework meets all the legal requirements and that it is necessary to rebuild the stock,” she said Tuesday night.

Framework 42 uses a number of measures – from how many days a fisherman can spend at sea to what type of nets a boat can drag – in an attempt to conserve particularly vulnerable species of cod, yellowtail and flounder.

The two-for-one counting of fishing days will affect an inshore region of the Gulf of Maine and area near the coast of Southern New England and Long Island.