Salmon Life History and Ecology

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Salmon Life History and Ecology

• Generalized life history
• Overview Anadromy, Homing, Semelparity
• Niches streams to oceans
• II. Salmon diversity
• Species
• Genetic diversity (Ch. 6)
• III. Ecology
• Streams food, predators, reproduction, nutrient
  cycling
• Oceans food, mortality

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I. Generalized Life History
Reprod. Potential (eggs/adult)

• A. Overview

of successful offspring
Factors affecting sustainability
Mortality ( of returning adults)
Salmon Life Cycle
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Slightly more detailed life history
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Scale of salmon home range
Pacific Northwest
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Scale of salmon home range
Pacific Northwest
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3 Unique Aspects of Salmon Life Histories

• Anadromy start in fresh water, migrate to salt
  water, return to fresh water. (contrast
  catadromy)
• 2. Homing return to natal stream to spawn
• 3. Semelparity reproduce once before dying
  (contrast iteroparity e.g., cutthroat
  steelhead)

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Cool biology anadromy and physiological
alteration

• - Body fluids are saltier than surrounding water
• - Gain too much water and loss critical salts.

• Solutions
• Specialized cells in gills transport Cl-
• Kidneys

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Cool biology anadromy and biochemical alteration

• Need right physical conditions for physiological
  changes.
• Timing of migration coincides with physiological
  changes
• Fry ? Smoltification ? smolts (migrating) ?
  adaptation in brackish water (mixed salt and
  fresh).
• River flow rates matter (dams affect this
  greatly).
• - Estuaries are very important as rearing and
  acclimation habitat.

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Human modification of estuaries
Squalicum Harbor Marina
Padilla Bay
http//apps.ecy.wa.gov/shorephotos/scripts/bigphot
o.asp?idSKA0323
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Tradeoffs in anadromy

• Benefits
• i. freshwater sites are relatively safe for eggs
  and juveniles
• ii. large ocean pasture, greater populations
• 2. Costs/risks
• i. Dependent on conditions across a wide range
  of ecosystems
• ii. multiple migrations expose individuals to
  multiple risks

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Cool biology - homing

• How do salmon find their home stream from the
  ocean?
• Mechanism olfactory imprinting - different
  smells of home stream.
• As migrating smolts waypoints

Olfactory rosette
Homing behavior olfactory cues to swim up or
downstream
Quinn 2005
Quinn 2005
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Cool biology - homing

• Population consequences
• - Leads to reproductive isolation of different
  subpopulations.
• - Reproductive isolation allows for adaptation
  to local conditions
• - Salmon tend to have high genetic diversity
  within species.

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Cool biology - homing

• How many salmon stray vs. home (degree of
  fidelity)?
• Straying happens (1-10 of individuals)
• Important for recolonizing streams after
  disturbances (or for restoring streams).
• Recolonization is most likely to be successful if
  individuals are from similar streams/habitats

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Semelparity Salmon reproduction
Sockeye males competing for a mate
Chum pair spawning
Female chum digging nest (redd)
Quinn 2005
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Better enjoy it, cause then you die
Quinn 2005
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Semelparity Tradeoffs

• Benefit/selection High growth low probability
  of survival for multiple migrations ? do it while
  you can
• 2. Costs/risks all eggs in one basket,
  literally. Disturbance (natural or human-caused)
  could destroy an individuals chance of passing
  on genes.
• 3. Interacts with straying

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Semelparity consequences with Salmon

• Net transfer of nutrients from ocean to stream
• Important food source for
• - many terrestrial animals (bears, eagles,
  scavengers)
• - aquatic organisms (including those that salmon
  eat)
• May contribute significant fertilization to
  riparian vegetation
• Positive feedback? Are more salmon necessary for
  more salmon?

Quinn 2005
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Niche concept, as applied to salmon

• Stream -
• Temperature
• Water flow
• Reproduction (gravel size)
• Ocean
• Temp PDO

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II. Salmon Diversity

• Species
• 1. The different species

Plus Masu salmon (O. masu) in Japan
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2. Life history variation among species

• a. Time in freshwater

Quinn 2005
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2. Life history variation among species

• b. Time, location in oceans

For example Chum 2 years, open ocean Chinook
4-5 years, open ocean Sockey continental shelves
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B. Genetic diversity with species

• Species reproductively isolated
• Metapopulations local breeding populations
  linked by occassional immigration (genetic
  mixing)
• Demes local breeding populations
• Stocks units of fisheries management

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Chinook metapopulation
Klamath river
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