Groton — A “long overdue” change in a federal program offering shellfishermen insurance coverage for storm-related losses should boost Connecticut’s aquaculture industry, the region’s congressional delegation said Tuesday.

The change, adopted Dec. 15 by the U.S. Department of Agriculture, extends coverage to shellfishermen who eschew the use of containment devices — bags, cages, pens — in the production of such mollusks as oysters, clams and mussels. Previously, the Noninsured Crop Disaster Assistance Program, or NAP, applied only to growers of aquaculture species maintained in controlled environments.

“This is a celebratory day,” Sen. Richard Blumenthal said during a news conference in UConn-Avery Point’s Marine Sciences Building. He was joined by Sen. Chris Murphy and Rep. Joe Courtney,

D-2nd District, as well as leaders of the Connecticut Sea Grant program.

Blumenthal said he had been lobbying for the change since he was Connecticut’s attorney general and that “year after year” the USDA had rejected the argument that eligibility for disaster-related insurance coverage should be extended to all shellfishermen, regardless of the harvesting methods they employ.

USDA data indicates that 70 percent of mollusk producers use the no-container, “on bottom” production method, including most oyster growers on the East Coast. It is the most common practice among Connecticut shellfishermen.

Blumenthal said weather disasters that can devastate crops are the “new normal” and that “crop losses that occur under water deserve the same protections as crops grown on shore.” Shellfishermen, he said, “are no less courageous and entrepreneurial than farmers who till the soil on land.”

The Connecticut senators met this summer with members of the Noank Aquaculture Cooperative to discuss the issue, and Courtney pursued it with USDA officials.

Blumenthal said the USDA’s delay in revising the regulation was “inexcusable.”

Under the change, the NAP coverage for mollusks not planted or seeded in containment devices will only extend to losses “caused by a named tropical storm, typhoon, or hurricane,” according to a summary published in the Federal Register.

The summary notes that Hurricane Irene and Superstorm Sandy caused significant losses for mollusk growers in 2011 and 2012, respectively. At the time, the majority of growers did not have NAP coverage, and if they had, they would not have had any losses that met the NAP eligibility requirements then in effect.

Murphy said he learned that shellfishermen typically operate on “small, decreasing margins,” and that “one uninsured catastrophe” can wipe them out.

“We have some 40-odd (aquaculture) businesses operating on the Sound,” he said. “Not so long ago, it was in the hundreds. This change will ensure that Connecticut keeps and expands its business.”

Courtney said the new NAP rules also would increase coverage levels to 65 percent of production at 100 percent of market value.

“It’s going to stimulate farming all across the country,” he said.

b.hallenbeck@theday.com

Twitter: @bjhallenbeck