PORTLAND – Operators of Maine’s salmon farms say they are taking steps required by state officials to stop the spread of a virus that is killing thousands of fish in eastern Maine.

State rules went into effect Monday for 90 days. They include a quarantine that bans aquaculture boats from entering or leaving Cobscook Bay, unless they are cleaned and independently certified.

Monthly testing for infectious salmon anemia in Cobscook Bay and reporting to the state will also be required.

“The industry fully supports making these guidelines mandatory,” said Jeff Kaelin, a spokesman for Heritage Salmon Inc. of Eastport, which has several aquaculture pens on the Canadian border in Cobscook Bay.

The Maine Department of Marine Resources last week announced the strict regulations aimed at controlling the spread of ISA. The disease kills fish, but is harmless to humans.

The industry already has taken precautions, such as scrubbing and disinfecting boats.

More than 700,000 farm-raised salmon have been destroyed since July to stop the spread of ISA. Those fish would have been worth $12 million at maturity and accounted for 6 percent of the total number of farm-raised fish, officials said.

Twelve companies operate 26 farming sites in Maine. They employ about 900 workers directly, and 300 more in allied fields, such as transportation.

Sebastian Belle, director of the Maine Aquaculture Association, said the arrival of ISA will slow the industry’s growth. But he said it was too early to estimate the financial impact of the disease.

ISA was identified in March in Maine and has been spreading since.

Belle said the risk of the disease spreading will diminish as the weather cools because ISA transmission declines in cold water.

Job losses stemming from ISA may also be limited because fall and winter are slow times for the industry, he said.