Katmai's Fish Species

Sockeye salmon swarm in Brooks River
Spawning sockeye salmon swarm together at the mouth of Brooks River.

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From bringing large numbers of brown bears to areas for bear viewing, and creating great recreational fishing opportunities, the different species of fish are a crucial part of Katmai’s ecosystem. They have great local economic significance, and provide exceptional visitor experiences.

No matter when or where you visit, fishing in Katmai requires extra care and responsibility to protect the wildlife and experience.
sockeye salmon swarm

Sockeye Salmon (Oncorhynchus nerka)
A predictable eruption occurs at Katmai National Park and Preserve annually as salmon burst from the northern Pacific Ocean and into park waters. Sockeye (also known as red) salmon return from the ocean, where they have spent two or three years. Navigating first across the open ocean, and then up rivers, lakes, and streams, they return to the headwater gravel beds of their birth to deposit their own young before dying. Their size, averaging 5 to 7 pounds, varies proportionally to how long they spend feeding at sea.

The salmon run begins here in late June. By the end of July, a million fish may have moved from Bristol Bay into the Naknek system of lakes and rivers. Salmon stop feeding upon entering freshwater, and physiological changes lead to the distinctive red color, humped back, and elongated jaw they develop during spawning. The salmon spawn during August, September, and October. Stream bottoms must have the correct texture of loose gravel for the eggs to develop. The stream must flow freely through winter to aerate the eggs. By spring the young fish that have just hatched, called "fry" or "juveniles," emerge from the gravels and migrate into the larger lakes, living there two years. The salmon then migrate to sea, returning in two or three years to spawn and begin the cycle once again. Salmon provide food for the bears, bald eagles, rainbow trout, and directly or indirectly for the other creatures that forage along these streams. Find out more about sockeye salmon in Katmai.

Rainbow Trout in river

Rainbow Trout (Oncorhynchus mykiss)
Cousin to the salmon, rainbow trout are found throughout Katmai’s rivers and are native to the Pacific Coast of North America from Alaska to Mexico. The diet of rainbow trout varies from insect larvae and pupae to algae. They typically spawn in streams and rivers with steady water flow and gravel bottoms. Rainbow trout can live up to 11 years and can grow to 6-16 inches (15-40 cm) long.

Lake Trout in net underwater

Lake Trout (Salvelinus namaycush)
Lake trout are native to Canada, Alaska, the Great Lakes, New England, and parts of Montana. They are a predatory fish and are at the top of the aquatic food chain, eating other fish. Lake Trout prefer cooler water between 40-55 degrees Fahrenheit (4-13 degrees Celsius). The average adult weighs 9-10 pounds (4-4.5 kg) and can live up to 25 years of age.

Researchers examining lake trout
Southwest Alaska Network (SWAN)
SWAN is analyzing lake trout to monitor mercury concentrations in lakes throughout Katmai. This long-term monitoring project is working to find the source, natural or not, of mercury in Katmai’s pristine aquatic ecosystems.

Learn more about the Southwest Alaska Network.

Last updated: November 7, 2019

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