State fisheries biologist David Boucher isn’t willing to admit defeat to invasive bass in the Rapid River drainage of Upton and Township C.

Lower Richardson Lake’s Middle Dam is the only obstacle preventing bass from migrating to other large lakes in the Rangeley Chain of Lakes. The Rangeley fishery has long been noted for its brook trout and landlocked salmon.

Smallmouth bass are competitors to and predators of brook trout, but not so much on salmon, which are more tolerant of bass, according to Boucher. Unlike brookies, salmon are not native to the drainage. They were introduced there in the late 19th century.

“The end result is that the numbers of trout less than 12 inches long are going down, and down and down, whereas, at the same time, the numbers of bass are going up, and up and up,” Boucher said by phone Thursday in Strong.

“It’s going in a direction we don’t want to see it go,” he added.

Illegally stocked downstream in the mid 1980s in Lake Umbagog, bass quickly established themselves there. By the late 1990s, they migrated upstream and took hold in the 3.2-mile-long Rapid River.

“The best hope we have to keep bass out of the rest of the Rangeley chain is public education. That’s probably the best tool in our toolbox. Nothing else seems to be working. The Rapid River situation is a dramatic example of what can happen when people willy-nilly move fish around,” Boucher said.

For brookies, the river is the most important part of the waterway because it’s where wild trout spawn. Now, it’s also where they’re competed with bass and salmon for food and space.

Stomach content analyses made in 2003 and 2004 in more than 100 bass taken from Lake Umbagog, Rapid River and Pond in the River revealed that insects and crayfish were the most frequent food sources for bass, rather than juvenile bass, trout or salmon.

Despite the relatively small sample used in the analyses, Boucher said he believes bass predation on trout fry is a frequent occurrence.

“We don’t yet have daily or weekly samples, but there is clearly predation,” he said.

In 2000, the Maine Department of Inland Fisheries and Wildlife unsuccessfully tried to reduce bass populations in the waterway by liberalizing bass harvests from the river and the 512-acre Pond in the River, which also provides habitat for certain life stages of Rapid River trout.

But most efforts by the Rapid River Coalition, a collection of conservation and sporting groups and state fisheries biologists, have been information gathering to better determine actions.

“The public demands that we try and we work for the public and the resource, so, as an agency, we will do everything we can that’s practical and makes sense, cost-wise and effort-wise. We just have to try to protect trout whenever and however we can, and give them every possible edge, but we know we’re not going to do a hell of a lot to the bass,” Boucher said.

The latest approach involves raising the river level gradually from its base rate of 300 to 400 cubic feet per second to 1,200 cubic feet per second. This will be done at night by Florida Power and Light operators at Middle Dam, starting in the third week in June, when bass fry are hatched and start rising off nests.

“It’s my brainchild. It really is our best opportunity,” Boucher said of the flow bursts.

The high-water flush won’t affect young brookies because the trout fry will be a few inches long then and have a higher mobility than bass fry, he added.

But, other than possibly creating temporary nest abandonment, flow bursts won’t affect bass in Pond in the River.

“Beyond that, there’s not much else on the table. I’ve always been interested in doing directed electro-fish removal of bass in June when trout are most vulnerable to bass, but the flow study holds much more promise in controlling bass, so, we’re going to get that going first,” Boucher said.

For more info

To learn more about the Rapid River bass situation, visit www.brookie.org/site/pp.asp?c=liKVL3POLvF&b=1737055

and www.maine.gov/ifw/fishing/reports/index.htm