August 14, 2020 — The following was released by NOAA Fisheries:
NOAA Fisheries Atlantic salmon researchers have found that Atlantic salmon abundance can increase as more young fish and returning adults survive their encounters with dams. Also, progress in rebuilding the population will depend heavily on continuing stocking of hatchery fish raised especially for this purpose. This information is based on a life history model and new information on changes in the Penobscot River watershed.
The remaining remnant Atlantic salmon populations in the United States are located in Maine, with the largest population in the Penobscot River. Numerous factors play a role in salmon recovery — from predation and habitat degradation to pollution and climate change. The two most influential factors are survival of fish as they navigate dams in the river, and survival during the marine phase of their life. Atlantic salmon are born and remain in fresh water for 1-3 years and migrate downriver through estuaries into the sea. Then they spend 1 to 2 years at sea before returning to the river where they were born to spawn.
“Our findings indicate that Atlantic salmon abundance can increase as survival at dams from the lower to the upper watershed increases. Hatchery supplementation will be necessary to sustain the population when survival is low in egg-to-smolt and marine life stages,” said Julie Nieland, a salmon researcher at the science center’s Woods Hole Laboratory in Massachusetts and lead author of the study. “Increases in survival during both of these life stages will likely be necessary to attain a self-sustaining population, especially if hatchery supplementation is reduced or discontinued.”