Maine’s Atlantic Salmon Commission moved a step closer Thursday to reopening the Penobscot River to salmon anglers this spring.

Buoyed by an overwhelmingly positive response to last fall’s month-long season, commission members asked staff biologists to study the risks of holding a two- to four-week fishing season for sea-run Atlantic salmon in the spring of 2007.

Depending on the results of the risk assessment, commission staff could hold public hearings on the spring catch-and-release season early next year.

The three-member Atlantic Salmon Commission board would have final say whether to reopen the Penobscot to the first springtime salmon angling in Maine since 1999. And board members made clear Thursday that they plan to carefully weigh the risks before and err on the side of the fish.

“I want to see the information. I haven’t made a decision about a spring season,” said George LaPointe, commissioner of the Maine Department of Marine Resources and a member of the salmon board. “I am moving slowly.”

Board members, commission staff and representatives of various salmon fishing clubs all described the experimental fall season as a success, despite the fact that only one fisherman managed to hook and land a salmon. The fish was released unharmed.

Commission chairman Dick Ruhlin, a longtime member of Maine’s salmon clubs, said he was “delighted” to hear the fall anglers’ sincere interest in protecting the fish that had brought the fishermen back to the Penobscot.

“When people love a resource they are going to protect that resource and fight for it very strongly,” Ruhlin said.

Commission staff are still compiling the fishing reports that the 241 salmon fishing license holders were required to submit. As of Thursday’s count, anglers reported making nearly 250 fishing trips averaging about 31/2 hours each.

The majority of those who bought salmon licenses were Maine residents. However, the 35 non-Maine residents who filed reports spent, on average, more than $200 a day on their trip. Maine residents spent about $30 in fishing-related expenses per trip, according to the reports.

While only one fish was hooked and landed, commission staff reported that more than 50 adult salmon went through the fish trap on the Veazie dam that month. The dam is located just upriver from the stretch of fishable water.

Joan Trial, a commission biologist, said staff had predicted that one to four salmon would be caught during the fall season based on historic fish populations at that time. So Trial expressed confidence Thursday that staff will be able to estimate anticipated catches during a spring season.

The big question is how many salmon likely would die after being hooked by a fisherman as a result of injuries, exhaustion or other factors.

Most adult salmon begin their spawning rituals in the spring. The silvery, glistening fish are typically strong, fat and looking for a mate – not food – as they leave the open ocean and enter their birth rivers. Wild, adult salmon from Maine can grow to 20 pounds or more.

That makes them among the most prized catches for anglers from around the globe. It is also why commission staff would expect to see many more fishermen casting fly lines into the Penobscot in the spring than during last fall’s season.

Nearly 1,050 adult salmon were counted in Penobscot River fish traps this year, the vast majority of those arriving during the spring. That is up slightly from 2005 and about 120 higher than the five-year average.

But it is still a pittance compared to the tens of thousands that historically clogged the Penobscot during spawning season. The Penobscot accounted for more than 90 percent of all adult salmon returns in Maine in 2006 and represents the only significant-size wild population of Atlantic salmon in the United States.

Nonetheless, commission staff and board members said populations of fish known as “the leaper” remain fragile. A representative of the National Oceanic and Atmospheric Administration underscored that point Thursday by saying the federal government is still weighing whether to designate the salmon populations in the Penobscot, the Kennebec and other large Maine rivers as threatened or endangered.

The federal government already has designated eight salmon populations in smaller Maine rivers as endangered.

Commission staff will estimate mortality rates during their risk assessment for the spring season.

Ralph Keef, a member of local salmon clubs, said he was pleased with the prospect of a spring fishery. Keef said the experimental fall season demonstrated that the commission can carefully regulate fishing to protect the fish and that anglers will follow the rules.

Patrick Keliher, executive director of the commission, said the state could attempt to minimize the impact on the salmon by limiting license sales or restricting fishing to times when fish are less likely to bite.

“We based the fall season on science and if we do something in the spring, it is going to be based on science,” Keliher said.