Back in 1970, Quebec fisheries officials stocked muskellunge in a small lake, reportedly in an attempt to provide a viable sport fishery in response to requests from anglers. Those same officials thought that muskies were sedentary, territorial and wouldn’t migrate.
They were wrong.
By the 1980s, muskies had begun turning up in the St. John River — Lac Frontiere, the stocked lake, is a headwater lake of the river’s Northwest Branch — and today, they have migrated at least as far as Grand Falls, New Brunswick.
Maine anglers have been targeting the large muskies for more than a decade, and a sport fishery has bloomed. Still, that fishery came at a cost: Native fisheries, including once-outstanding brook trout fisheries in the river, have collapsed. In addition, muskellunge have migrated into the lower Allagash River, a tributary of the St. John, and threaten brook trout there.
Maine fisheries biologists recently got a much-needed bit of good news, however, as the U.S. Army Corps of Engineers completed a study that was nearly six years in the making. Its conclusion: The upper reaches of the Allagash River are safe — for now — from naturally migrating muskies.
The section of the river targeted by the study was Allagash Falls, a majestic set of rapids about 13 miles upstream from the confluence of the Allagash and St. John rivers. Biologists suspected that Allagash Falls served as a natural barrier to upstream migration by muskies, but sought the expertise of the Army Corps of Engineers in 2004. A recent visit to the falls during low-water conditions showed that the falls will, in fact, stop migrating muskies.
“That was our gut feeling, that the falls were indeed going to be a barrier,” said Dave Basley, regional fisheries biologist for the Maine Department of Inland Fisheries and Wildlife said on Friday. “The fish hadn’t gotten up in there for a number of years [after] they’d been stocked in Lac Frontiere, and they’ve been in the St. John River itself.”
Basley said muskies have been caught just below Allagash Falls, though, and the DIF&W wanted to make sure that the falls were as effective at stopping migration as they suspected.
“Just to be able to answer all the questions with a straight face, we wanted to have this study team come in,” Basley said.
Smallmouth bass also live in the St. John River, and study team members focused on the swimming ability of bass as they tried to assess Allagash Falls as a barrier. The premise: Bass are stronger swimmers and better jumpers than muskies, so if bass couldn’t bypass the falls, neither could muskies.
Study participants determined that any barrier that was higher than six feet, or that consisted of water flowing faster than 15 feet per second, would be impossible for bass to surpass.
And Allagash Falls passed both of those tests at every water level that was tested, according to the study.
If the study had found that Allagash Falls was an insufficient barrier, some form of mitigation would have been proposed, Basley said.
“I would guess that we would have sought approval through the Allagash [Wilderness] Waterway and the various stakeholders who have an interest in that waterway to try to alter those falls,” Basley said. “Based on the velocities and the drop, it appears that we’ll be safe.”
There is one part of the falls that is still a matter of concern, Basley said.
The main stem of the river carries about 75 percent of the water through the falls. A back channel carries another 25 percent. And the Army Corps of Engineers discovered a potential long-term problem in the back channel.
“There’s some loose rock in that channel,” Basley said. “Should some of that rock, through ice action and high water, get dislodged and get moved downstream, we should be aware that there could be a lessening of the pool and maybe [the creation of] a ramp that would allow fish access up through the back channel at favorable water conditions.”
Basley said that an Allagash Wilderness Waterway ranger will take yearly photographs from a predetermined point so that biologists and the Army Corps of Engineers can monitor the situation on that back channel and act if it appears that a ramp is forming.