Atlantic Salmon in the Gulf of Maine

Atlantic Salmon

Salmo Salar

Austin Davis

Fish have always been a part of my life. Every year my dad and I would trek 12 hours to Ennis, Montana for an annual fishing trip with his friends and their families. Although, I loved the thrill of catching the brown trout and rainbow trout that inhabited the rivers we fished, it got old after a while. I can remember it was always a dream of mine to branch out an explore other rivers with bigger and stronger fish, particularly those that housed chinook and kokanee salmon. Additionally, salmon has always been a staple of my diet. As the famous fish fling of Pike Place Market demonstrates, seafood is a huge part of the culture of my hometown, Seattle, Washington; consequently, salmon seems to be a fan favorite. Still, aside from my fascination in these fish, they make up a large portion of U.S. seafood consumption, which itself is on the rise. According to the United States Department of Agriculture, salmon accounts for 16% of seafood consumption in the U.S.; this level of consumption is only behind shrimp at 27%.  Unfortunately, heavy consumption of Atlantic Salmon, among other things, has had a detrimental impact on these leaping sea creatures. Of particular concern are the Atlantic Salmon populations in the Gulf of Main (GOM).

Description and Ecology:

These silver-blue fish, which are coated along the sides with black dots are unique fish, even among other salmon species. On average they range from 8-10lbs in weight and 28-30in in length; although there have been multiple reported catches of Atlantic Salmon weighing over 100 pounds (“American’s Seafood...”, Kantor). These measurements place them in the ranks as one of the largest species of salmon. The large biomass of Atlantic Salmon is important for their survival, particularly during their reproductive cycles. Adult female salmon lay nests of eggs, called “redds”, in the gravely bottoms of rivers. These eggs remain buried in the gravel until they hatch, usually during March and April. These eggs hatch into baby salmon, which are known as “sac fry”. The fry feed on plankton and small invertebrates under the gravel until they are ready to emerge and grow into the “parr” stage of salmon maturity. Parr continue feeding, growing, and maturing while the adult salmon continue to rear and spawn other juveniles. In fact, females will lay close to 7,500 eggs on average every 2-3 winter reproductive cycle while only 15-35% will survive (“Atlantic Salmon (Salmo Salar)”, NOAA). One of the things that sets the atlantic salmon apart from other salmon is that they “anadromous”, meaning that they are usually able to live after spawning. During these reproductive cycles, the adult salmon receive very little to no food. They rely on their fat and muscle stores for the energy required to reproduce and survive during this time, as well as to climb up to 200 miles upstream to their spawning grounds. Aside, the name “salar”, which means the leaper, stems from the Atlantic Salmon’s ability to jump almost 12 feet out of the water in order clear obstacles like rapids and small falls that stand in their way during their trek back upstream (video). Once the juveniles have undergone “smoltification” they are ready for their long marine migration downstream out into much of the NW Atlantic Ocean. Here they feed—on small fish, squid, eels, and shrimp—and intermingle with Atlantic Salmon populations around the world before returning home after another 2-3 winters at sea. One of the most astonishing feats of the Atlantic Salmon is their ability to navigate back to their original spawning grounds. They use smell cues to find the rivers in which they originally were born. In addition to anadromous salmon there are land-locked salmon which migrate between rivers and lakes, leaving out the oceanic portion of migration. Visit the Atlantic Salmon Restoration website for a more in depth description of their life and migratory processes.

Geographic and Population Changes:

 The distribution of Atlantic Salmon includes rivers and the Atlantic Ocean within temperate to sub-polar latitudes. There are three generally recognized groups of Atlantic Salmon: North American, Baltic, and European. The North American group is of particular conservation concern. “Historically the North American group ranged from northern Quebec southeast to Newfoundland and southwest to Long Island Sound” (NOAA). Before the 19^th century Atlantic Salmon runs in New England occurred throughout almost every major river north of the Hudson. Unfortunately, by the 19^th century these salmon were extirpated from 3/5 rivers boasting the largest populations. Furthermore, by the mid-20^th century Atlantic Salmon in the U.S. was largely limited to the eastern third of the coast of Maine. As I said before, this particular recovery plan focuses on the Gulf of Main (GOM) distinct population segment (DPS). The GOM DPS stands as the only segment that supports native, wild Atlantic Salmon populations in the U.S., all of which are extremely low. In fact it is estimated that only 42% of the historical population. The GOM DPS has been further delineated into 3 Salmon Habitat Recovery Units (SHRU’s) in order to adequate distribution of Salmon populations to accommodate metapopulation dynamics.  

Listing Date and Type of Listing:

Atlantic Salmon populations in Maine have been designated as a species of concern since 1997. Unfortunately, the precaution wasn’t heeded and the GOM DPS was listed as an endangered species under the provisions of the Fish and Wildlife Service (FWS) in November 2000. The dire situation the species found itself in continued to worsen and Altantic Salmon throughout Maine, outside of the GOM DPS, were listed as endangered under the Endangered Species Act in September 2006. Then in June 2009 critical habitat was designated for the GOM DPS by the NOAA. The biological features for critical habitat of Atlantic Salmon include: oxygenated pools with cover, clean and permeable gravel, cool water with diversified food resources to support rearing, freshwater and estuary migration sites free of barriers to support migration, among other factors.

Cause of Listing and Main Threats:

As the only region supporting native, wild Atlantic Salmon the GOM DPS has become increasingly reliant on conservation efforts to keep it afloat. Possibly the biggest threat to Atlantic Salmon in the U.S. are dams which can fragment habitats by creating barriers to passage as well as serve to cause high rates of mortality among Atlantic Salmon. Barriers to passage occur when the fish are migrating back upstream to spawn. Contrarily, when the salmon trek back downstream they are subject to having to travel over the spillway of the dam, through a downstream fish passage built into the dam, or through power-generating turbines. The highest rates of mortality occur when fish pass through the turbines. Dams also have indirect effects on Atlantic Salmon through habitat changes. Another significant factor listed in the recovery plan is inadequate regulations of damns. While many dams are not even fully functional anymore and still do not provide for fish passage, not much is being done by Federal Energy Regulatory Commission (FERC) to change this. These two factors require conservation efforts in the rivers and estuaries, but a third significant threat is the survival of Atlantic Salmon in the NW Atlantic Ocean. Marine survival is poor because of things like predation, starvation, diseases and parasites, changing ocean conditions (rising sea temperatures), and overfishing. In recent years, climate change is beginning to become even more of a problem because as salmon go back to the rivers in which they hatch the water temperatures of these rivers are rising too high for redds to survive.

Description of Recovery Plan:

The recovery plan was set forth, in 2009, with the ultimate goal of improving the long-term viability of the GOM DPS Atlantic Salmon population. To achieve viable salmon populations (VSPs) conservation biologists used Shaffer and Stein’s “3r’s” principles: resilience (population health), redundancy (distribution), and representation (genetic diversity). The main focus of this recovery plan is for viability in the freshwater environment of the DPS as factors involved in marine survival under continued examination; although, it should be mentioned that marine survival is the biggest driver for population trends in the GOM DPS. Measurements of population viability, habitat availability, and threat abatement are the 3 fundamental aspects of Atlantic Salmon conservation. In order to assess the success of this recovery plan these 3 aspects must be addressed in terms of the 3r principles.

-Population viability involves increasing the abundance, productivity, and distribution of native, wild Atlantic Salmon. By increasing the abundance and productivity of the populations the resilience of the populations to natural events and other threats will strengthen. Increased Abundance will also provide for increased genetic diversity (representation). While Atlantic salmon do tend to spawn in the same areas each reproductive cycle, limited straying can also help genetic mixing as well as the distribution (redundancy) across the 3 SHRU’s. Analysis has allowed scientists to determine that each SHRU needs at least 2,000 adult salmon returning to spawn in order to achieve rangewide population viability.

-Habitat Availability is important, especially has manmade structures continue to bar salmon from reaching their spawning grounds. Without adequate available habitat in each of the SHRU’s salmon will not be able to spawn which has direct effects on resilience, redundancy, and representation. Scientists have determined that a minimum of 30,000 HU’s per SHRU is necessary in order to achieve desired results.

-Threat abatement is necessary for these other two aspects to increase. Lets take, for example, the threat of dams and manmade structures. These structures decrease the availability of habitat by restricting salmon on their upstream journey to spawning grounds. They also decrease the population viability by accounting for high mortality rates as salmon migrate to the oceans.

By evaluating these conservation aspects and establishing measures to deem them adequately conserved, a four-phase approach has been developed highlighting the key steps in the Atlantic Salmon Recovery Plan:

Phase 1: identify the threats to Atlantic salmon and characterize the habitat needs of the species

Phase 2: use conservation hatcheries to ensure that the GOM DPS persists long enough for the recovery plan to take its course

Phase 3: Use hatchery salmon to help increase the abundance, distribution, and productivity of naturally reared salmon. At the end of this phase delisting should be possible

Phase 4: Achieved when there is a self-sustaining wild population distributed across all 3 SHRU’s .

What you can do:

After being overfished for decades and more recently subject to manmade impediments, Atlantic Salmon populations in the U.S. are at dangerously low levels. Conservationists can only do so much with the resources they are constrained to. Reaching out to others like government officials and conservation agencies is a way to get the conversation started. Staying informed and up to date will give you a perspective on how to help out. Lastly, any donations to efforts help. Visit http://oceana.org/marine-life/ocean-fishes/atlantic-salmon and scroll to the bottom of the page to help out.

Additional resources:

·       “Atlantic Salmon.” Oceana, oceana.org/marine-life/ocean-fishes/atlantic-salmon.

·       “Atlantic Salmon.” U.S. Fish and Wildlife Service, www.fws.gov/fisheries/fishmigration/atlantic_salmon.html.

·       Fisheries, NOAA. “Atlantic Salmon (Salmo Salar).” NOAA Fisheries, 14 Jan. 2015, www.nmfs.noaa.gov/pr/species/fish/atlantic-salmon.html.

·       Kantor, Linda. “Americans' Seafood Consumption Below Recommendations.” Americans' Seafood Consumption Below Recommendations, 3 Oct. 2016, www.ers.usda.gov/amber-waves/2016/october/americans-seafood-consumption-below-recommendations/.

·       “Life History and Ecology.” Atlantic Salmon Recovery Project, atlanticsalmonrestoration.org/resources/documents/atlantic-salmon-recovery-plan-2015/recovery-plan-pages/life-history-and-ecology.

·       U.S. Fish and Wildlife Service and NOAA-Fisheries. 2016. Draft recovery plan for the Gulf of Maine Distinct Population Segment of Atlantic salmon (Salmo salar). 61 pp.