Salmon are amazing fish that undertake incredible journeys between the ocean and rivers to complete their life cycle. But what exactly do these iconic fish eat while they reside in freshwater rivers and streams? In this article, we’ll take a detailed look at the diet and feeding habits of juvenile salmon living in riverine environments.
An Overview of The Salmon Life Cycle
Salmon are anadromous fish meaning they hatch in freshwater migrate to the ocean to feed and mature, and then return to their natal rivers and streams to spawn. Juvenile salmon may spend anywhere from a few months to over a year in their home rivers before heading out to sea. This time spent in the river is a crucial period that shapes their development and survival. Access to an abundant food source is vital for fueling the growth that allows them to transition to the ocean.
While in the river, salmon go through several life stages, each with slightly differing dietary needs:
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Alevins – Newly hatched salmon that still carry a yolk sac for nutrients As they absorb the yolk, they start to emerge from the gravel and begin actively feeding.
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Fry – Young juvenile salmon that have fully absorbed their yolk sac and now rely completely on external food sources. This stage lasts for several months and is key for rapid growth.
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Parr – Larger juvenile salmon with parr marks along their sides. Some species may spend over a year in this stage, continuing to feed and grow, before migrating
Why Juvenile Salmon Need A Nutrient-Rich Diet
The food juvenile salmon eat in the river provides the energy and nutrients needed to fuel the physiological changes required for surviving in salt water. Key developments supported by their freshwater diet include:
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Muscle growth for swimming strength to migrate and regulate osmosis.
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Enzyme and hormone production for maintaining water and salt balance.
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Immune system fortification to handle pathogens and stressors.
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Sufficient fat reserves to endure lengthy ocean migrations.
Without access to plentiful food sources, juvenile salmon may fail to thrive and never make it to the ocean.
The Main Components of The Juvenile Salmon Diet
So exactly what are the primary food items juvenile salmon feed on in river environments? Research shows their diet consists mainly of:
Aquatic Insects
Insects make up the bulk of food eaten by juvenile salmon in rivers. The most common insects in their diet include:
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Mayflies – Abundant near the water surface. Salmon target mayfly nymphs as they rise to the surface during hatches.
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Stoneflies – Prevalent in clean, highly-oxygenated water. Salmon eat the nymphs.
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Caddisflies – Found on the stream bottom in larval and pupal stages. A prime salmon food source.
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Blackflies & Midges – Smaller insects. Provide nutrients when other insects are scarce.
Salmon consume all life stages of these aquatic insects, including eggs, larvae, pupae, and adults. The protein obtained from this insect-based diet facilitates rapid muscle growth.
Crustaceans
Small crustaceans that live on the stream bottom supplement the insect diet of juvenile salmon. These include:
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Gammarus (Scuds) – Abundant source of protein and fat. Frequently eaten by salmon fry.
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Copepods – Tiny crustaceans that provide essential fatty acids when abundant.
Other Organisms
Depending on habitat and availability, salmon may also feed on:
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Terrestrial insects that fall into the water
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Fish eggs and larval fish
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Small fish like sculpins and dace
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Aquatic worms, leeches, snails, and zooplankton
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Detritus and algae
How Salmon Feed in The River
To capture their prey, salmon employ a range of feeding strategies and behaviors, including:
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Darting and lunging to grab insects floating on the surface film.
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Picking insects and crustaceans from submerged rocks and vegetation.
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Digging in gravel and cobble to uncover benthic organisms.
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Consuming terrestrial insects trapped in the surface film.
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Chasing after detectable moving organisms like fish and amphibians.
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Gulping down drifting organisms in the water column.
Juvenile salmon are active and aggressive feeders. They will eat voraciously when food is abundant to maximize growth. During periods of colder temperatures or low flows, feeding activity may decrease significantly.
Key Factors Influencing Food Availability
The availability of prey organisms in a river system depends on diverse environmental factors, including:
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Water quality – Food sources diminish when pollution, sedimentation, or low oxygen levels impact insect populations.
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Water temperature – Warmer waters tend to increase insect growth and activity.
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Stream habitat – Riffles, pools, and woody debris provide optimal habitat for aquatic insects.
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Flow regime – Fluctuating flows influence insect displacement and concentration.
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Seasonality – Insect abundance and salmon growth change throughout the year.
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Climate patterns – Drought, flooding, and thermal changes affect food webs.
Conserving Salmon Food Webs
Protecting the freshwater food sources juvenile salmon rely on involves conserving the aquatic and riparian habitats that support the organisms salmon feed upon. This requires an ecosystem-based approach that addresses water quality, stream complexity, fish passage, flow management, climate resilience, and invasive species. By taking a food web perspective, we can gain a deeper appreciation for salmon as keystone species interconnected with their environment. Their remarkable life cycle ultimately hinges on access to the rich food resources of their home rivers and streams.
The hatchery salmon diet
Salmon raised in CIAA hatcheries are fed fish feed from Bio-Oregon, a commercial supplier of fish food. This feed comes in different sizes and combinations of nutrients to follow salmon through their growth.
Hatchery food is made with fish meal and fish oil as well as supplemented vitamins to ensure healthy fish. This fish meal and oil can come from different sources, including scraps from commercial processors used to produce these feeds. The rest of the feed production comes from small ocean fish that breed rapidly, such as herring, sardines, and mackerel.
The salt water salmon diet
In the sea, salmon become predators, feeding on a wide variety of creatures. Once in the ocean, a salmon’s main goal is to avoid getting eaten while eating lots to get ready for their migration back to the spawning grounds.
Salmon continue to eat similar foods as they ate in the freshwater, such as zooplankton and crustaceans, but they expand their palate to include small squid, eel, and lots of shrimp.
In many ways, salmon become what they eat in the ocean. Consider the differences between coho, king, and sockeye fillets, particularly their color.
The pink or red color in salmon flesh comes from carotenoids, a natural pigment present in many vegetables such as carrots, tomatoes and pumpkins. Crustaceans such as shrimp and crabs contain high levels of carotenoids.
It makes sense that crustaceans make up the majority of the sockeye’s preferred diet, resulting in that distinct red flesh color. On the other hand, coho and king may feed partially on crustaceans but they also enjoy other small fishes, resulting in flesh that is more orange.
The Salmon’s Life Mission | Destination WILD
FAQ
FAQ
What is the best bait for salmon in the river?
The best bait for salmon is definitely herring. All-day every day herring will catch salmon. People hook up herring as plug-cut herring or whole herring. As long as the bait is spinning it will catch fish. Using the whole herring is faster and easier.
What feeds the Salmon River?
Known as “The River of No Return,” the Salmon River originates in the Sawtooth and Lemhi Valleys of central and eastern Idaho; snows from the Sawtooth and Salmon River Mountains in the south and the Clearwater and Bitterroot Mountains in the north feed this river.
What is salmon’s favorite food?
… similar foods as they ate in the freshwater, such as zooplankton and crustaceans, but they expand their palate to include small squid, eel, and lots of shrimpJun 8, 2023
What are salmon predators in rivers?
Young salmon are especially vulnerable to predators during their freshwater and nearshore rearing and migration stages. Native fish such as pikeminnow and cutthroat trout, as well as introduced species such as bass and walleye, are known predators of salmon.
What do salmon eat in fresh water?
In fresh water, young salmon mostly eat small insects such as mayflies, stoneflies, caddisflies, blackflies, and riffle beetles. Sometimes they eat small amphibians and fish. READ SOMETHING ELSE
What do juvenile salmon eat?
In freshwater environments, juvenile salmon often consume zooplankton, insect larvae, and small fish. As they migrate to the ocean, their diet transitions to include larger prey such as krill, herring, and other small fish, which are vital for their growth and development.
What do captive salmon eat?
Still, the captive salmon are fed by the farm operators in addition to eating naturally occurring foods like zooplankton. In salmon farming operations, the most common food served to the growing fish is dry pellets colloquially called “salmon pellets.”
Do salmon eat squid?
Squid. These foods include both ones that salmon eat in freshwater as well as in the ocean. Generally speaking, salmon spend the first portion of their lives in freshwaters where they grow up in streams and rivers. Salmon return to these places to spawn years later when they reach maturity.
What animals eat Atlantic salmon?
In the ocean, Atlantic salmon are eaten by: Large predatory fish like Atlantic halibut, Atlantic bluefin tuna, swordfish, and striped bass. Greenland shark, mako sharks, porbeagle sharks, and other sharks. Seabirds such as the Northern gannet. Various seals (harp, grey, harbor, etc.). Toothed whales like killer whales, dolphins, and porpoises.
Do salmon eat flies?
In the interim, salmon move into the ocean if they are not one of the landlocked species. While in freshwater, salmon mostly eat the insects that were listed such as mayflies and caddisfly larva. As adults, they are larger and more capable hunters, and different foods become available to them in the ocean.