The salmon run is a migration event where mature fish leave the ocean and navigate back to the freshwater streams of their birth. The purpose of this arduous journey is to reproduce, ensuring the survival of the species. This feat occurs in rivers that flow into both the Pacific and Atlantic Oceans, with distinct geographic destinations and biological characteristics defining each basin’s run.
The Anadromous Journey
The movement of salmon from saltwater to freshwater is an example of anadromy, a biological trait where fish spend most of their lives growing in the ocean before returning to spawn in streams. Young salmon hatch in the cold, clear gravel beds of headwater streams, where they spend up to several years maturing before undergoing a physiological change called smoltification. This transition prepares the fish to survive the shift from freshwater to the high-salinity environment of the sea.
After years of feeding and growth in the ocean, a biological signal prompts the adult salmon to begin the return journey. As they approach the coast, the fish rely on their sense of smell, recognizing the unique chemical signature of their natal river. This upstream migration is an immense physical challenge, as the salmon rely solely on stored energy reserves, ceasing to feed once they enter freshwater.
All five species of Pacific salmon (genus Oncorhynchus) are semelparous, meaning they die shortly after a single spawning event. In contrast, the single species of Atlantic salmon (Salmo salar) is iteroparous, capable of surviving the spawning process and returning to the ocean to mature and spawn again in subsequent years. This difference in life history affects the nutrient cycling and population dynamics in their respective river systems.
Major Destinations of the Pacific Run
The Pacific salmon run is the largest globally, involving five primary species in North America:
- Chinook (King)
- Sockeye (Red)
- Coho (Silver)
- Pink (Humpy)
- Chum (Dog) salmon
The vast majority of the run occurs in North America, with Alaska hosting the most prolific returns, such as the Sockeye runs that surge into the rivers of Bristol Bay. The Kenai Peninsula further south sees strong concentrations of Chinook and Sockeye, making it a major destination for both commercial and sport fishing.
Southward, in British Columbia, Canada, the Fraser River system is recognized for its Sockeye salmon migrations, which travel hundreds of miles inland to reach their spawning grounds. The US Lower 48 also hosts runs, with the Columbia River system on the border of Washington and Oregon being a historical destination for Chinook, though populations here are heavily managed due to extensive dam systems.
Across the Pacific, the Russian Far East, particularly the remote Kamchatka Peninsula, is a major destination. The river systems here, such as the Kol and Bolshaya, support healthy wild populations of all six Pacific species, including the Masu salmon, which is primarily an Asian species. Returns sustain large populations of brown bears and Steller’s sea eagles.
Key Locations for the Atlantic Run
The Atlantic salmon run involves only one species, Salmo salar, and is considerably smaller in scale than its Pacific counterpart, spanning rivers on both sides of the North Atlantic basin. In North America, the primary destinations are concentrated in Eastern Canada, where the fish return to the rivers of the Maritimes and Quebec. The Miramichi River in New Brunswick is renowned for its large runs, particularly for fly fishing.
Quebec’s Gaspé Peninsula is home to rivers like the Bonaventure and the Grand Cascapedia. These Canadian rivers often see a mix of multi-sea-winter fish, which have spent two or more years at sea, and smaller, one-sea-winter fish known as grilse.
On the European side, Norway is a destination, with rivers like the Namsen and Alta famous for producing large salmon. Scotland is also a stronghold, with the River Dee and the River Spey attracting fish that have traveled from feeding grounds off the coast of Greenland and the Faroe Islands. Iceland’s rivers offer highly protected and managed runs, with a focus on conservation that helps maintain healthy returning populations.
Seasonal Timing and Viewing Opportunities
The timing of the salmon run varies by species and location, but generally begins in late spring and peaks throughout the summer and fall months. Pacific Chinook salmon are often the earliest arrivals in May and June, followed by the main push of Sockeye and Pink salmon throughout July and August. The Coho and Chum runs typically peak later, extending the run into the late fall, sometimes through November.
Atlantic salmon enter rivers from May through November, with the largest fish often arriving earlier in the summer. Viewing opportunities are abundant, particularly in the Pacific Northwest, where locations like the fish viewing window at the Wildwood Recreation Site in Oregon provide underwater perspectives of the migration. In Alaska, the Sockeye runs in state parks on the Kenai Peninsula offer wildlife viewing opportunities, including bears fishing for the returning salmon.
In the UK, several locations offer the chance to observe the salmon leap, especially after heavy rains raise river levels in October and November. Scotland’s Pitlochry Dam features a salmon ladder, allowing visitors to watch Atlantic salmon bypass the hydroelectric facility on their upstream journey. The Falls of Shin in Sutherland, Scotland, provides a natural obstacle where salmon must leap waterfalls.