The state Department of Energy and Environmental Protection announced Monday that the prohibition on the taking of alewives and blueback herring from most inland and marine waters in Connecticut has been extended for another year.

This action was initially taken in April 2002, and has been extended each successive year because there has been no improvement in populations of these species during the past year, DEEP said in a news release. The current action by DEEP Commissioner Robert Klee extends the prohibition through March 31, 2018.

“Conserving our wild fish runs is a priority for our agency,” said DEEP Deputy Commissioner Susan Whalen. “We keep looking for evidence that our conservation practices are leading to a recovery, but the data that we are collecting annually tell us that things are not getting better. We have no choice but to maintain the closure of these fisheries.”

River herring is a term used collectively to refer to alewife and blueback herring. Both species are anadromous, meaning they hatch in freshwater, migrate to the ocean to grow, then return to freshwater to spawn. Historically, millions of river herring returned to Connecticut’s rivers and streams each year. More than 630,000 blueback herring were passed over the Holyoke Dam in Massachusetts on the Connecticut River in 1985. By 2006, however, only 21 passed the Holyoke Dam, the lowest number in the history of the Holyoke Fishlift. Numbers have fluctuated since then but have never surpassed 1,000, DEEP said.

Last year, the number of fish that passed the fishlift was only 137. While river herring are not an important food source for humans, they are an extremely important prey source to many species of freshwater and marine gamefish, as well as osprey, bald eagle, harbor seals, porpoise, egrets, kingfishers and river otter, DEEP said.

“The news from other states is encouraging,” said William Hyatt, chief of DEEP’s Bureau of Natural Resources. “River herring runs are increasing in Maine and the state of Massachusetts may consider lifting its restrictions for some of its rivers. But runs in southern New England - especially Connecticut - have not rebounded. Some of our rivers had fewer river herring in 2016 than they did the year before.”

Hyatt noted that river herring return to the rivers from which they originated and segregate into different populations.

“The fact that the species are plentiful elsewhere does not help our rivers, which now have a fraction of what they did 25 years ago,” he said. “We need to protect our populations until they have grown back to a level of abundance that can support harvest without threatening the long-term survival of the runs.”

Biologists from DEEP’s Fisheries Division continue to work with their counterparts from the other northeastern states and the federal government to seek answers for the decline and develop conservation initiatives that will help re-build the populations, DEEP said. In addition, the Fisheries Division continues its other efforts to enhance river herring stocks by transplanting adult river herring into streams where runs have been eliminated or greatly depleted to promote recovery. It also works with conservation groups to removing obsolete dams and building fishways that allow fish to migrate past remaining dams. In 2016, more than 35 miles of freshwater riverine habitat were reconnected with removals of dams in Colchester, Meriden, and Southington, DEEP said. A new fishway was completed on a state-owned dam in Clinton and will begin operation in April when the river herring begin to run.

Non-migratory alewife populations are established in several lakes and ponds in Connecticut. The DEEP prohibition does not include landlocked alewives from Amos Lake in Preston, Beach Pond in Voluntown, Uncas Pond in Lyme and other lakes and ponds around the state with these populations. Alewives in these lakes may still be taken by angling and scoop net as established in state statute and regulation, DEEP said.

j.benson@theday.com