The Indian River Ecosystem
Anadromous fish Anadromous fish use the river as habitat for migration, spawning, incubation of eggs, and rearing of young. Anadromous fish are those that live in the sea as adults but return to their natal freshwater streams to spawn. Four species of Pacific salmon (Pink, Chum, Coho, and King), two species of trout (cutthroat and rainbow, also known as Steelhead), and one char (Dolly Varden) spawn in the Indian River. Pacific Salmon die after spawning whereas trout and char may return to the river several times to spawn. (Learn more about the salmon life cycle.)
Pink and chum salmon enter the intertidal and lower segments of the Indian River to spawn from mid-July through September. The fry emerge and migrate to the ocean from late-February through mid-May. Numbers of pink salmon surpass other salmon species in the stream with an estimated 1.3 million fish returning in 2003.
Coho salmon, chinook salmon, and steelhead trout migrate upstream but have not been observed spawning in the park. The primary rearing and spawning habitat for coho salmon, chinook salmon, and steelhead trout is above the Sheldon Jackson College diversion dam. A fish pass along the dam allows upstream access for these species under certain flow conditions. Coho salmon return to the Indian River from late September through November and spawn in upper portion of river. Some spawning chinook but no existing wild populations are thought to be strays from area hatcheries.
Anadromous Dolly Varden enter the river in August, migrating upriver through the park to spawn farther upstream. The fry emerge from the gravels in the spring and disperse throughout the river.
Salmon returning to natal streams to spawn transport nutrients and energy from the ocean to the freshwater environment. These are vital to the overall health of the coastal ecosystems and affect stream productivity. (Learn more about stream ecology.)
The Indian River is also important habitat for resident fish species. Coastrange sculpin, threespine stickleback, and resident rainbow trout live in the river year round.
An aquatic resource survey completed in 1995 revealed that in general, fish habitat suitability in the lower reaches of the Indian River is limited by a lack of pool habitat, few deep pools, and lack of cover. These habitat conditions were directly related to the paucity of large woody debris, the major pool-forming agent, which has an important function in providing habitat cover and density.
Monitoring The staff at Sitka National Historical Park regularly monitor the park's aquatic resources. Biologists snorkel the length of Indian River during the late summer and fall to count the number of spawning salmon. Watch a video clip (.mpg-112 kb) of biologists conducting a snorkel survey.
The Marine Ecosystem
Marine species of fish common to the marine waters of Sitka also inhabit the intertidal and estuarine areas of the park. Inventories of near shore and intertidal waters fishes have found more than 50 species of fish. Download the Inventory of Marine and Estuarine Fishes in Southeast Alaska National Parks during summer, 2001 (PDF) to learn more about the inventory study.
Did You Know?
With 570,374 square miles, Alaska is twice the size of Texas and 1/5 the size of the rest of the United States. It stretches 2,400 miles east-to-west and 1,420 miles north-to-south.