AUGUSTA – State officials voted Thursday to hold an annual catch-and-release fishing season in the fall for Atlantic salmon on the Penobscot River after the success of last year’s experimental fishery.

The Maine Atlantic Salmon Commission also kept alive the hopes of some avid anglers by directing its staff to evaluate the risks of holding an early-spring fishing season on the Penobscot.

But officials cautioned that any salmon season is contingent on enough adult fish returning to the river during spring and summer spawning runs. And so far this year, the numbers are well below normal.

“The restoration program … comes first. It has to,” said Dick Ruhlin, chairman of the commission.

George Lapointe, commissioner of the Maine Department of Marine Fisheries, joined Ruhlin on Thursday in voting to approve a monthlong season for sea-run Atlantic salmon to be held every fall on the Penobscot between Bangor, Veazie and Eddington. The board’s third member, Inland Fisheries and Wildlife Commissioner Roland “Danny” Martin, was not present Thursday.

The future fall seasons will be modeled after an experimental season held last September and October. Nearly 250 fishermen bought special licenses for the season, although only one salmon was hooked and landed.

As in last year’s season, anglers participating in a fall fishery will be restricted to using artificial flies with the barbs snipped off or flattened to minimize damage to the fish. Any salmon that is landed must be released immediately without removing the fish from the water.

Officials can close the river to fishing at any time – signaled by red flags flying in predetermined locations – in order to protect the last significant run of Atlantic salmon in U.S. waters.

“The great thing about the regulatory system being put in place is we have the flexibility about whether to hold a fishery,” Patrick Keliher, executive director of the commission, said after Thursday’s meeting. “We could fly red flags for any reason.”

During a public hearing held earlier this month, more than a dozen anglers – many of them longtime members of the three Bangor-area salmon fishing clubs – lent their tacit support to a fall fishery. But the fishermen were outspoken about their belief that Maine can hold a fishing season in the spring, when salmon are more plentiful and energetic, without harming the fish population.

In response, Ruhlin and Lapointe directed commission staff to analyze the risks of holding a season during May, assuming the same restrictions as the fall season. If approved for next year, it would be the first spring salmon fishing season in Maine since 1999.

Of course, all of Thursday’s talk about fishing seasons, fall or spring, could be for naught if more adult salmon don’t start showing up at the Veazie fish trap on the Penobscot.

Slightly fewer than 500 salmon have been counted in the fish trap so far this spring and summer, which is nearly 300 fewer than this time last year and significantly below average for recent years. More alarming, biologists are 170 females short of their goal for supplying brood stock to federal hatcheries.

Joan Trial, the commission’s lead biologist, said she is hearing similar reports from biologists elsewhere along the Atlantic coastline.

“Are they late or are they just not coming? I don’t know what to tell you,” Trial told the board. “We’ll know at the end of the year.”

Keliher said there isn’t a magic number for how many adult fish will be needed before commission staff will recommend opening the river to fishermen during the fall season. One key is whether biologists have enough brood stock to meet demand at the hatcheries that produce more than a million baby salmon for Maine rivers annually.

“It will play into the decision of whether we hold it or not,” Keliher said.