Salmon (kill me) Flashcards
What are sea-run fish?
Fish that migrate from fresh water (home) to the ocean
What are diadormous fish?
migrate between salt and fresh water
- 1% of world’s fish species
- must change physiology due to water chemistry changes
Anadormous fish live their adult life in _____ water and migrate to _______ to spawn & hatch
salt to rivers & lakes
What fish are anadromous?
salmon, herring, striped bass, etc.
What are the three stages of a salmon life cycle?
- River Cycle
- spawn
- eggs buried in redds (nests in coarse gravel)
- after 1 yr the eggs hatch!
- stay here for a total of two years - Estuary Cycle (brackish water)
- Ocean Cycle
- migrate here to mature
- stay here for two years before returning to home rivers to spawn again
The four Hs
- Harvest
- commercial fishing (typically overfishing is a huge issue that leads to salmon decline) - Habitat
- accès to clean, high quality habitat without having to swim through dams - Hatcheries
- solution to degradation caused by dams
- limited success - Hydropower
- problem for fish who are working to swim up stream
What do salmon need?
A) cool, unpolluted water
B) Gravel bedded rivers to lay eggs
C) Hydrographs in sync with life cycle
- Spring flooding to carry juveniles downstream, yet not disrupting spawning beds
D) Woody debris and overhanging tree
- Shade
- Safety from predators
- Create side channels (where juveniles can hide during floods)
Hatcheries were designed to…
replace stocks of salmon
- adult salmon comes up to its home river to spawn and instead of laying eggs in the gravel beds, they are captured and the eggs are incubated in a hatchery instead
What are the pros of hatcheries?
- unlike the in the wild, a majority of salmon eggs are hatched (they are protected)
- hatchery fish are stronger and bigger due to being consistently fed
- Hatchery salmon are less genetically diverse
When do hatcheries yield returning adults?
- when good habitat and good water quality are available hatcheries can be used to replenish depleted stocks
- when habitats are lost due to dams
What are farmed salmon?
fish that spend their whole life in aquaculture facilities
What are wild-caught salmons?
caught in wild, you don’t know whether if they are hatchery fish or from the river themselves
Pacific salmon include which breed?
Coho, Chinook, Sockeye, and Pink
> 60% of world’s commercial salmon comes from ________
aquaculture
Why did salmon evolve to spend adult life in the oceans? (Why are they anadromous)
- oceans have more food than coldwater rivers
Hydropower and dams
Problem #1: Barrier to migration upstream
Solution:
- Fish ladders
- Fish elevators
- Dam removal
Problem #2: Barrier to migration of juveniles swimming out to sea
Solution:
- Ladders and elevators do not work
- Run-of-the-river dams <25 ft tall, so fish can swim over
- Dam removal is also always an option
Problem #3: Juveniles diverted to irrigation canals and ditches
Solution: screens over inlets
Problem #4: Mortality in power turbines
Solution: screens
Problem #5: Changed flow, migration slowed by reservoirs & more juveniles die by predation before reaching ocean
Solution:
- trap & truck
- spill water from reservoirs during migration
How do we create suitable living areas?
Study your answer on the problem set
How do forest ecosystems help salmon?
A. All of these answers
B. Riparian trees provide shade, cooling summer water temperatures
C. Riparian trees fall in the river, providing cover for fish
D. Wood in streams leads to increased depth ad velocity variability in channels
All of the above
How do salmon fertilize forest ecosystems?
carcasses provide marine-derived nutrients
What river bed sediment grain size do most salmon species need for spawning habitat?
gravel
Your supermarket is selling wild-caught Chinook salmon from Alaska. Where did it hatch?
A: a hatchery or a riverbed
B: a riverbed
C: a hatchery
D: a fish farm
A: a hatchery or a riverbed
