How Do Salmon Swim Upstream?

Salmon are amazing fish that can swim hundreds or even thousands of miles upstream against strong currents to reach their spawning grounds, This incredible feat allows salmon to reproduce and perpetuate their species But how exactly do they accomplish such a difficult journey?

Why Salmon Swim Upstream

• Salmon are anadromous meaning they are born in freshwater rivers and streams migrate to the ocean to mature, and return to freshwater to spawn.

• They have an incredible ability to return to their exact place of birth to reproduce after spending years roaming the ocean.

• Salmon fry need cool, oxygen-rich freshwater to hatch and survive. Spawning grounds high up in river systems provide the best habitat.

• The lower, wider parts of rivers are more easily accessed by predators. Shallow spawning grounds upriver are more protected.

• imprint on the scent of their natal stream as fry before migrating downstream. As adults, they follow this scent back upstream to reproduce.

The Incredible Distances Salmon Swim

• Some salmon species swim upstream for hundreds of miles from the ocean to reach spawning grounds.

• Atlantic salmon may journey over 6000 miles in the ocean before returning to home rivers. Some swim 200 miles upriver from the mouth to spawning grounds.

• Pacific salmon like Chinook swim 280 miles from the ocean up the Columbia River to Idaho.

• The average salmon manages 14 miles upstream per day. In optimal conditions, over 20 miles per day is possible.

How Salmon Power Upstream Swimming

• Salmon cease feeding during upstream migration to conserve energy. They live off fat reserves for the journey.

• Their bodies undergo physical changes to become streamlined and efficient for extended swimming.

• Salmon alter their heart rate and metabolism to maximize oxygen delivery to muscles.

• Salmon bodies are designed for burst swimming to overcome obstacles like rapids and waterfalls.

• Salmon may jump up to 12 feet vertically to clear obstacles like dams and waterfalls.

Unique Salmon Adaptations

• Salmon use magnetic fields to navigate during migration. This guides them across vast ocean distances.

• They have a highly acute sense of smell that allows them to identify their natal stream.

• Salmon alter their kidney function to thrive in both fresh and saltwater environments during their life cycle.

• Powerful tails, streamlined bodies, and other adaptations make them superb swimmers over long distances.

• Salmon can swim up to 7 body lengths per second, achieving speeds of up to 25 miles per hour.

Swimming Upstream Is An Arduous Journey

• Salmon stop feeding and slowly deteriorate during the upstream migration. Many die before spawning.

• They must leap up waterfalls, swim through rapids, and circumvent obstacles like dams along the way.

• Swimming against strong currents requires tremendous effort. Some salmon become utterly exhausted.

• Pollution, warm water temperatures, and low oxygen levels can exacerbate the challenges.

• Bears and other predators await salmon on the spawning grounds, winnowing their numbers.

The incredible ability of salmon to locate their birthplace and swim enormous distances upstream against all odds to spawn and propagate their species is one of nature’s greatest wonders. After this mighty effort, the salmon’s life cycle is complete and soon comes to an end. But the next generation of their offspring will repeat the journey in a testament to instinct, endurance, and the power of evolution.

Salmon migrate upstream to spawn during different months depending on the species and specific location. Generally, the salmon run, which is the period when they swim upstream, occurs in the fall, from September through November. However, some salmon species, like spring-run Chinook, may migrate as early as April through July.