Week 9 - Estuaries Review and Salmonids in Estuaries Flashcards
1
Q
Juvenile Estuary Residency
A
- smolts have elevated concentrations of the hormone thyroxine in their plasma
- thyroxine is believed to regulate neurogenesis, and influence neural development in the salmon olfactory system, and facilitate olfactory imprinting
2
Q
Pink salmon
A
-Transient in estuary channels, short residency
2 year life cycle
3
Q
Sockeye salmon
A
- most rear in lakes, minimal time in estuary
- 3-4 year life cycle
4
Q
Chum salmon
A
- resides in the same tidal channel over several days/weeks
- 4-year life cycle
5
Q
Chinoook
A
- Stream and Ocean Types (a continuum, not discrete races)
- Ocean-type fish are smaller, rely heavily on tidal channels for up to 30 d
-Stream-type fish are larger, don’t use tidal channels, shorter estuary residency
6
Q
Fraser River Estuary Study
A
- pink salmon had shortest residency period – a few days
- chum salmon residency was intermediate days
- chinook salmon have longest residency
7
Q
Coho
A
- Nomads move into estuary for rearing year-round
- 3 to 4-yr life cycle
8
Q
What line(s) of evidence suggests that some juvenile Chinook salmon rely on estuary habitats for an extended period of time before migrating off-shore?
A
- Chinook salmon were recorded using tidal channels - presence detected over time, increasing fork length and growth
- Mark and recapture surveys saw juvenile chinook return to tidal channels over several tide cycles
9
Q
Two life functions carried out by juvenile Pacific salmon in estuary habitats?
A
- Need to undergo physical transformations from freshwater to saltwater fish as juveniles
- Need to undergo physical transformations from saltwater to freshwater fish as spawners
- Consume prey and grow large enough to migrate to the ocean
- Imprinting on their natal streams(concentrations of the hormone thyroxine =facilitate olfactory imprinting)
