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Published byPeregrine Rose Modified over 8 years ago
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List 3 reasons why it is important to preserve freshwater fish species.
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Salmon, Steelhead & Rainbow Trout The Salmonid Family
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Steelhead & Rainbow Trout Appearance: Steelhead Distinct dark spots on back and fins Square shaped dorsal fin Color: - dark silver when at sea; pinkish color when in rivers Length - up to 45 inches Weight - up to 36 pounds Rainbow Dark spots on back and fins Square shaped dorsal fin Color: - light silver or gold with iridescent pink stripe on sides Length - up to 16 inches Weight - up to 8 lbs.
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Salmon Appearance Up to 46 inches in length Up to 65 pounds Dark silver at sea but can be bright red during spawning Males may develop aggressive features such as hooked jaw and bright red color during spawning
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Where are they found? Coastal areas and inland rivers from southern California to Alaska Steelhead & Salmon are called anadramous because they spend part of their lives in rivers and part of their lives in the Pacific Ocean
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Salmon & Steelhead Life Cycle
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Eggs 1 cm diameter Black eyespots Light to dark orange Needs: Cold, flowing water Gravel & pebble streambed Oxygen Only 10% survive to hatch (in nature)
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Alevin Feed on yolk sac No gills - gets oxygen through vitelline vein Avoid light so stay hidden in rocks Rocks & gravel must be free from sediment or alevin will suffocate No fins so can’t swim
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Fry Grow fins so swim freely (usually at night to avoid predators) eat small insects parr marks help to camouflage Need vegetation to hide Fast moving water with riffles May begin imprinting
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Dangers Safety predators, river rocks, warm water overhanging trees
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Smolt (salmon & steelhead) Anadramous - migrate to ocean as adult Swim downstream to estuary (nutrient-rich wetlands) loses parr marks and turns dark silver in color Adapt to live in salt water May spend 1 to 4 years out at sea
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Adult Salmon and Steelhead up to 4 years at sea Eating to gain size and strength Up to 70 pounds Up to 52 inches Dark silver
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Spawners Migrate back to homestream to spawn Recognize homestream by scent of minerals in water Sometimes travel 100s of miles Don’t eat Must swim against river’s current
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Spawners Females create a redd (nest) by sweeping away gravel - lay eggs Males fight over fertilizing eggs with milt Male and female salmon die after spawning. Steelhead may migrate back to ocean to repeat cycle
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Trout Life Cycle Same stages as steelhead and salmon except they are not anadramous They never migrate to the ocean Do not go through the smolting stage Live in streams, rivers and freshwater lakes
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Inadequate stream flows cause water to warm Warm water does not hold as much dissolved oxygen as cold water Salmonid Species are threatened due to many environmental problems
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Chemical waste from industry, agriculture and homes contaminates water
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Blocked access to spawning streams due to dams Dams are built to provide water for: agriculture Hydroelectric power residential use to provide land to be developed residential or commercial use
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Human activities that discharge sediment and debris into waterways Sediment warms water and slows current Fills in spaces between rocks in streambed, suffocating young fish Caused by construction; development and residential activities
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Fish hatcheries help with the spawning of migrating fish whose waterways are blocked As spawning steelhead swim upstream, the hatchery ladder attracts fish into the hatchery
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Fish are routed into the spawning area through gates
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Eggs are released from females Male milt (sperm) are mixed with the eggs.
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Steelhead that are considered young enough to spend time in the ocean, then spawn again are released back into the river.
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