Salmon are an iconic fish species that hold tremendous ecological economic and cultural importance. As a keystone species, salmon play an integral role in sustaining the health of aquatic and terrestrial ecosystems across the Pacific Northwest. Understanding why wild salmon are so vital to ecosystems underscores the need to protect and restore their populations.
In this article, we’ll explore the multifaceted importance of salmon and how they uniquely impact food webs, nutrient cycling, habitat, and biodiversity. Losing wild salmon would unravel delicate ecological balances and linkages built over millennia. Let’s dive into why salmon are essential species that literally keep ecosystems running.
Salmon as a Keystone Species
Salmon are a “keystone” species, which means that compared to how common they are, they play a very important role in ecosystems. Salmon populations and their productivity have a direct effect on and support many other plant and animal species in the ecosystem.
Salmon shape their ecosystems both during their ocean phase and freshwater spawning migrations. As juvenile salmon migrate from inland rivers to the ocean they transport key nutrients from freshwater to marine environments. Adult spawners swimming upstream transfer ocean-derived nitrogen and carbon back to nutrient-poor rivers and riparian zones.
This two-way transit of nutrients stimulates growth and production across the food chain Salmon runs act as a conveyor belt that enhances ecosystem fertility in both directions
Marine Nutrient Transportation
The marination contribution from spawning salmon is especially vital for low-nutrient freshwater systems. Salmon obtain over 95% of their biomass during their ocean growth phase. The bodies of adult salmon that come back to rivers to spawn and die send a huge amount of nitrogen and carbon into the watershed.
These marine-derived nutrients fertilize the entire river network, boosting algae and aquatic insect production that feed frogs, fish and birds. Nutrients from spawned-out salmon can account for over half the nitrogen budget in some watersheds.
Salmon runs therefore elevate the productivity of nutrient-limited freshwater and riparian habitats. This marine nutrient subsidy cascades through the terrestrial food web all the way to trees and plants.
Nourishing Riparian Zones
In fact, riparian ecosystems heavily rely on the annual nutrient donation from salmon. Up to a quarter of the nitrogen in some plants along the water comes from salmon eggs.
Trees and plants obtain this nitrogen when they take up nutrients dissolved in salmon-enriched groundwater. This fertilizing effect has been found to accelerate plant growth and boost riparian habitat quality.
Stable isotope studies show salmon nutrients become incorporated into everything from insects to bears and wolves. By stimulating vegetation growth, spawning salmon indirectly support a wide diversity of terrestrial wildlife.
Prey for Wildlife and Humans
In addition to fertilizing the ecosystem, salmon provide a direct protein source that sustains bears, eagles, orcas and other apex predators.
Grizzlies congregate along salmon spawning streams and gain up to half their yearly nourishment gorging on salmon. Eagles, gulls and other birds rely on salmon runs to thrive and rear chicks.
Further downstream, orcas time their movements to intercept salmon returning to rivers to spawn. Several endangered Southern Resident killer whale pods depend almost exclusively on salmon.s also target salmon as a staple food. Coastal indigenous communities like Pacific Northwest tribes have fished salmon runs for millennia as a dietary cornerstone. Commercial and recreational fisheries likewise depend on abundant salmon populations.
Habitat Creation
Spawning salmon engineer the riverbed habitat required for the next generation to thrive. Female salmon use their tails to turn over and clean the gravel river bottom when creating nests for their eggs.
This spawning disturbance process flushes fine sediments out of the gravel, preventing siltation that would suffocate incubating eggs. The nests female salmon actively dig become critical spawning and rearing habitat for the next salmon cohort.
Through redistributing riverbed sediments, salmon runs exert an outsized influence on the physical structure and quality of stream habitats needed to complete their life cycle.
Supporting Biodiversity
The habitat enhancement and nutrients salmon provide as they migrate between ocean and freshwater environments promotes high aquatic biodiversity. Salmon directly and indirectly enable myriad species to flourish, from riverbed insects and algae, to riparian trees and predators.
In fact, salmon act as an indicator species for ecosystem health. Robust salmon runs reveal intact connectivity between diverse marine, coastal, riparian and river habitats. Diverse salmon populations reflect overall watershed vitality.
As a keystone species underpinning ecosystem fertility, salmon occupy a unique niche that regulates biological communities across habitats and food webs. Myriad plants and wildlife depend on sustenance from salmon runs.
Protecting wild salmon means protecting ecosystem resilience. Salmon declines degrade habitats, biodiversity and ecological linkages. Maintaining free-flowing, clean rivers full of spawning salmon is key to ensuring healthy functioning ecosystems for all species, including humans.
Why do salmon migrate up rivers?
Seven types of salmon live in the Pacific Ocean. Five of these species live and breed in water in North America. These species are Chinook, Coho, Chum, Sockeye, and Pink salmon. The largest species of salmon lives in the Atlantic Ocean – the Atlantic Salmon. The Chinook salmon is the biggest type of Pacific salmon. It can get up to 5 feet long and 126 pounds heavy. The smallest salmon species is the Pink salmon, which only reach about 2. 5 feet long and weigh up to 12 pounds. These important fish depend on the connectivity between oceans and rivers for a key component of their lifecycle. Salmon spend most of their lives in the ocean, where there is a lot of food and nutrients. They are called anadromous fish because they can swim back to land. In other words, they swim up river mouths and lay their eggs upstream, where they are safe from marine predators. Strong currents and rapids make it hard for salmon, but every year they swim tens to hundreds of miles upstream to spawn. They do this in big rivers like the Columbia and the Fraser as well as in many small rivers that reach the coast. Salmon usually choose to lay their eggs in riffles, where the water is shallow and moving quickly and rough. Their nests are called “redds,” and they are small depressions in the gravel river bed that the female salmon makes with her tail. She makes a shallow hole where she can lay her eggs by fanning her tail over the gravel. This causes the gravel to rise up from the river bed. To protect the eggs from being eaten, she swims upstream of the nest and spreads out more gravel to cover them. Because of this unique spawning behavior, salmon need coarse river gravel with a diameter up to 4 inches. This size of gravel not only protects the eggs, but it also lets water flow through and gives the eggs the oxygen they need to grow. Female salmon typically die within a week after laying their eggs because spawning is so taxing. For example, the Pacific salmon lives in the ocean for many years before migrating up rivers to spawn. However, they die after laying their eggs, so they only spawn once in their lifetime. Because these salmon die in upstream parts of rivers, the plants and animals in the area benefit from the nutrients the salmon brought in from the ocean. In this way, the salmon life cycle helps the different ecosystems that live along the Pacific Northwest coast.
Why Are Salmon Important To The Ecosystem
Salmon are vital for the economies of coastal communities, especially those in the Pacific Northwest. Wild salmon also play a critical role in ecosystem heath, from the ocean, to mountain streams and forests. It is eaten by more than 130 animal species, like the Orca whale and the Grizzly Bear. The protein and nutrients in salmon are good for them. People also eat a lot of salmon, especially people who live along the coast and have fished for salmon for thousands of years. Wild salmon went out of many rivers in the 20th century because of overfishing, habitat loss from things like building dams, and pollution in the water. Salmon populations are going down, which is making people unhappy. This has led to calls to return river systems to their natural states so that salmon can return to mountain streams.
Salmon’s life cycle and their incredible impact on our ecosystem
FAQ
Are salmon important to the ecosystem?
What would happen to the ecosystem without salmon?
How important is salmon to the economy?
What is the significance of salmon?
Why is salmon important to humans?
Salmon are not only important to humans–they are also interconnected with other animals, such as Southern Resident killer whales. When planning salmon fisheries, co-managers consider the conservation needs of the salmon species, their relationships with other organisms, and the larger ecosystem connections with salmon.
Why is salmon important in a stream?
The amount of salmon in a stream has been shown to be an indicator of the density and diversity in species of birds in the surrounding ecosystem. Pacific salmon populations are important for the survival of diverse and large assemblages of resident and migratory birds, and their disappearance would mean the decline of many bird species.
What role do salmon play in the ecosystem?
Throughout their life cycle, salmon fundamentally transform the way ecosystems function, creating the foundation of watersheds by playing the roles of both predator and prey, and by releasing important nutrients back in the ecosystem after they spawn. Allan, J. D., M. S. Wipfli, J. P.Caouette, and A. Prussian. (2003).
Why are Pacific salmon important?
Pacific salmon are keystone species, and play an essential role in the health and function of ecosystems. Salmon benefit other species as food and their bodies enrich habitats through the cycling of nutrients from the ocean to freshwater streams. Ocean Swimming Salmon. Credit: Shutterstock