On Wednesday, Maine Department of Marine Resources employees stocked the Piscataquis River near the Abbot-Greenville town line with 25,000 salmon smolts.
It could be decades before it is known whether this effort has borne results.
"And it's worth a little bit of time on all of our parts to be involved in their restoration, to be active and to ask questions about what we're doing to protect them in our own towns," said Penobscot Indian Nation Fisheries Program Manager Dan McCaw
The Piscataquis River is one of the tributaries of the Penobscot. Although it was heavily fished for decades, the last full season of Atlantic salmon fishing on the Penobscot took place in 1999.
According to Sean Ledwin, director of the DMR's Sea Run Fisheries Division, now is the right time for this project.
"This watershed has probably twice as much salmon habitat of any of the other watersheds in the Penobscot, which itself is a large watershed for salmon," he said.
Twenty years ago, in 1999, Atlantic salmon were placed on the endangered species list.
The biologists said the smolts released Wednesday will place a natural GPS marker in the river and return to the Piscataquis as adults to spawn.
"This is really the best spot for us. They'll continue to move up and spawn. They're going to look for ... they'll be imprinted to the drainage and they'll look for some good spawning gravel to spawn in when they return," Oliver Cox of the U.S. Fish and Wildlife Service said.
Salmon restoration efforts are being conducted at several areas across eastern and Downeast Maine, including along the Machias river basin.