GREENWOOD – The Maine Department of Inland Fisheries and Wildlife is adopting a rainbow trout stocking program for only the second time in more than 30 years.

Because rainbow trout are not native to Maine, the department is erring on the side of caution, selectively stocking certain waters so they don’t displace native and wild brook trout and salmon, according to MDIF&W Director of Fisheries Jeff Boland.

“Some of us have been pushing for rainbows and to consider a state program,” Boland said Wednesday by phone in Augusta. “Six to eight years ago, we laid the groundwork for it and identified a very clear study with an experimental program. Now that we’ve reached the end of the study, we’ve decided it will become one of our stocking programs.”

According to Sebago Region assistant regional fisheries biologist Jim Pellerin, a study that evaluated the relative performance of rainbow trout, brook trout and brown trout, found that rainbow trout have the potential to produce:

• Longer-season fishing opportunities.

• Better-size quality fisheries.

• A limited number of trophy-sized, 18-inches trout without sacrificing overall catch rates.

However, Pellerin stated in a Monday report that rainbows as trout still have limitations, and will only produce longer season put-and-take fisheries of slightly larger size quality in waters with extremely marginal water quality.

“On certain marginal waters currently managed for brook trout, the replacement of put-and-take brook trout stocking programs with rainbow trout could improve angling opportunities for cold water sport fish in Maine,” Pellerin said.

From 20,000 to 25,000 rainbow trout eggs were purchased for the study, which tested rainbow, brown and brook trout stocked in 10 or 12 ponds. The study included three parts: hatchery performance comparisons among all three species, field performance comparisons of browns and rainbows, and field performance comparisons of brookies and rainbows, Pellerin said.

The last portion evaluated the field performance of Eagle Lake strain rainbow trout and Maine hatchery strain brook trout in four small trout ponds: Jaybird in Hiram, Lily in New Gloucester, Long in Denmark and Overset in Greenwood.

“Overset was reclaimed about eight to 10 years ago, then restocked with brook trout, and it became one study water that did very well with rainbows,” Boland said.

There are 15 to 20 waters now stocked with rainbow trout, but the plan is to stock them in 15 or more waters annually.

Costs to grow rainbow trout will be about the same as that incurred to raise brook or brown trout.

“As eggs, they’re quite inexpensive. Most of our fish are raised a year to year-and-half in the hatchery. Rainbows will be no more expensive than brook or brown trout,” he said.

In the late 1970s, the state discontinued its first rainbow trout stocking program due to problems getting suitable eggs and other issues, Boland said. Then, about eight or nine years ago, the state experimented with genetically altered rainbow trout, but now there’s a push to restart the program.

“Overall, rainbows performed very, very well compared to browns and brook trout. They were caught six times more often. I think people will enjoy them. We’ve already had a couple of positive comments,” Boland said.