Watersheds
It Takes A Healthy Watershed To Raise Fish
Alaska is huge landscape blessed with an abundance of fish and aquatic resources, but to maintain these resources, we must
maintain healthy watersheds
with a diversity
of habitats. Resident fish species, such as rainbow trout and burbot depend on healthy watersheds for their entire life cycle
and anadromous fish, such as salmon and hooligan, also depend on
watersheds for all of their important life functions. We must understand watersheds and freshwater fish
habitat needs so we can preserve, protect and maintain Alaska's valuable
aquatic resources.
Fish depend on watersheds for one reason: SURVIVAL. Individuals must survive to maintain the population, and populations must survive to maintain the species. Fish habitat needs for survival include: feeding, escape, overwinter, spawning, and migration. Different species and different life stages of each species have different habitat needs and these needs change with the different seasons. Just as people use their community to find food, security, seasonal activities, socialization/ recreation, and safe transportation, different species and life stages of fish use different parts of their watershed to find habitat for food, escape (security), overwintering, spawning, and migration.
What is a WATERSHED? A watershed is an entire region (or "basin"), which
drains into a river or river system. A watershed typically includes several sub-basins with components from the mountains to the
sea: glaciers, tributaries, lakes, wetlands, and estuaries. A watershed is like a factory that makes fish. Different parts of
the factory (habitats) have different functions, but each part depends on the other parts and all of the parts work together to
produce a product (fish). The raw materials for this factory are abundant clean water and nutrients with organic matter from the
streambank and associated vegetation (i.e., "riparian area"). Where
anadromous fish are found, they are an especially valuable addition to watershed productivity because they feed in the ocean where
they accumulate "marine nutrients" which are released into the watershed
after they die, stimulating the food chain.
Where in a watershed do fish find habitats? Different species spawn in different parts of a watershed and at different times and the young of different species prefer different parts of the watershed for rearing. Fish find escape habitat for security from predators and floods throughout the watershed, usually around overhanging banks, space between rocks, woody debris, and irregular, complex shorelines. Most species use deep pools, space between rocks, and woody debris as critical overwintering habitat.
Migration corridors connect fish habitats in the watershed and allow each species to access different seasonal habitats.
Fish passage between feeding, overwintering and spawning habitats is critical
for the survival of individuals and life stages.
Healthy riparian areas, including streambank vegetation and wetlands, are critical for watersheds, too. These provide structure for the streambanks and supply woody debris that becomes in-stream habitat. Riparian areas provide connectivity within the watershed between aquatic and terrestrial habitats and connectivity up and downstream through the watershed. Healthy riparian areas provide vital habitats for wildlife, birds, and plants, which also depend on the watershed the entire year.
Healthy, complex, diverse, watersheds provide a wide variety of habitats that sustain a diversity of species at all life stages throughout the year.
If you would like more information concerning Watersheds, please email DFG.DSF.StreambankRehab@alaska.gov.