Atlantic Salmon And Ocean Ecology

Atlantic salmon spawned in Maine rivers migrate through estuaries, the Gulf of Maine, the Scotian Shelf, the Labrador Sea and eventually to the coast of Greenland before returning home to spawn. This journey is about 5,000 miles—about the same distance as a round trip between New York City and Los Angeles!

Acoustic Tagging

To monitor the river, estuarine, and nearshore migration of Atlantic salmon, we place acoustic tags in fish and acoustic receivers in the environment. These tags emit an ultrasonic signal that the receivers hear and record when a tag is detected. Collaborators from the Ocean Tracking Network and the U.S. Animal Telemetry Network help extend our monitoring network south to Florida and north to Labrador, Canada.

This information helps us:

• Reconstruct Atlantic salmon migration routes
• Identify where and when fish are located in these varied environments
• Help determine the environmental conditions during migration
• Track deaths of tagged fish 

Satellite Tagging

Monitoring salmon movements with acoustic tags presents challenges in the open ocean. To overcome these challenges, we put pop-off satellite tags on adult Atlantic salmon in Greenland. Salmon are captured with rod and reel, fitted with a tag and released.

The tags collect temperature and depth data as well as light intensity data during the migration. We use this information to reconstruct the salmon’s migration route. We can also obtain information similar to that we get from acoustic tagging, but from fish migrating from Greenland to their natal river to spawn. We collaborate with the Atlantic Salmon Federation and Fisheries and Oceans Canada on this work. 

Insert tagging video here:

https://videos.fisheries.noaa.gov/detail/video/6032339995001/tagging-adult-atlantic-salmon-in-greenland?autoStart=true&q=greenland

Atlantic Salmon Age and Growth

The environments that Atlantic salmon inhabit may affect their growth and survival. Examining a fish’s scales tell the story of its growth over time. In our image analysis laboratory, we extract these stories by examining growth patterns in Atlantic salmon scales to interpret the growth histories for these sampled fish. 

Generally speaking, fast growth may be associated with increased survival of Atlantic salmon and slow growth is often associated with lower survival. We have a long history of studying Atlantic salmon growth, especially in the marine environment. The Gulf of Maine Research Institute has been a major collaborative partner on these projects.

Other Diadromous Species

Our tagging studies on Atlantic salmon have given us insight into the lives of Atlantic salmon. We also plan to learn similar details about other diadromous species. 

For example, inshore Atlantic cod populations may depend on the annual spring migration of spawning river herring for a source of highly nutritious prey after a long winter. As individual river restoration projects like ongoing efforts in the Penobscot River are completed, diadromous fish populations will increase. We are monitoring to see if the river restoration will increase prey availability and positively impact regional marine species health and viability. 

Since 2010, we have partnered with the Maine Department of Marine Resources’ Inshore Trawl Survey. We collect and analyze stomach samples from potential predators of diadromous fish from Maine’s coastal waters in order to better understand the long term impact of river restoration on diadromous fishes.