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Life Cycle of Salmon
Transcript of Life Cycle of Salmon
Life Cycle of Salmon
Challenges of the Life Cycle
The growing smolt eventually becomes
the ocean going adult. During the ocean phase
salmon leave the near shore waters and head
to the cold, open ocean. In the ocean, salmon
travel in large, loose schools, and feed on small
fish, krill, and crustaceans. They remain in the
ocean for 2 to 8 years
After the salmon
hatch it is
known as an
Alevin. The Alevin
does not yet
have a fully
formed mouth or digestive system. Instead it lives
off the nutrients provided from its yolk sac.
begins life as an egg.
The eggs in this photo
are called eyed eggs
because the eye spot is
visible. This is also an
indicator that the egg is
viable, meaning that it is
growing life. Eggs will hatch between for 4-16 weeks.
The maturing parr makes
its way downstream to
the estuary. The salmon
transition from living
in freshwater to living in saltwater, through a
process called osmoregulation. At the end of the
transformation the salmon becomes a smolt.
smolts loose the parr marks and turn
Salmon leave the ocean, swim
back up the river, to the same
gravel redd that they were born in; spawn and
then die from exhaustion. The carcass, is super important to the overall ecosystem, as well as the next generation of salmon. The carcass provides nutrients to the forest, and young salmon also feed on the invertebrates that break down the carcasses.
Plants and animals have
predictable life cycles.
Challenges of the Life Cycle
Redd (Gravel Nest)
Slide 5: http://cache2.artprintimages.com/lrg/49/4921/REU9G00Z.jpg
Slide 9: http://www.beautifulpacificnorthwest.com/images/cohosmolt2.jpg
Even More Photo Content
Slide 13 and 14
Slide 15 and 16
Slide 17 and 18
Slide 21 and 22
Slide 23 and 24
Slide 25 and 26
Slide 28 and 29
Slide 31 and 32
Slide 43 - hyperlinked image
Slide 13, 15, 17, 19, 21, 23, & 25
Slide 28 & 31
sound clips http://www.fws.gov/video/sound.htm
Slide 51 - 66 http://wfrc.usgs.gov/outreach/salmon.html
More Photo Content
And Finally the Last Page of Photo Content
Salmon have a hard life?
Human activities that
degrade or diminish habitat
are the primary cause of salmon decline.
U.S. Fish & Wildlife Service
Federal agencies have a
fundamental responsibility under
the Endangered Species Act to
prevent extinction and foster
recovery of threatend salmon species.
For every 8000 eggs produced, 4500 alevin survive, from which 650 fry survive, from which 200 parr survive, from which 50 smolt survive, from which only 2 spawning adults survive (who produce thousands of eggs).
Q: Why do salmon die
after they spawn?
USGS Questions and Answers About Salmon
A: Salmon use all their energy for returning to their home stream, for making eggs and digging the nest. Most salmon stop eating when they return to freshwater and have no energy left for a return trip to the ocean after spawning. After they die, other animals eat them (but people don't) or they decompose, adding nutrients to the stream. Steelhead trout, however, continue to eat in freshwater and many survive and return to the ocean. These fish can grow another year and then return to spawn again.
Q: How do salmon know where their home is when they return from the ocean?
Scientists think they can tell directions in the ocean by the earth's magnetic field acting like a compass. When they find the river they came from they start using smell to find their way back to their home stream. They build their "smell memory-bank" when they start migrating to the ocean as young fish.
Why are there so few salmon left?
A: In the Pacific Northwest, salmon populations are doing very poorly. There are many reasons for this. Logging an area around a stream reduces the shade and nutrients available to the stream and increases the amount of silt or dirt in the water which can choke out developing eggs. Dams cause fish to die from the shock of going through the turbines and from predators which eat the disoriented fish as they emerge from the dam. Fishing is another source of death that can contribute to the decline of salmon. The weather also affects the amount of food that is available to salmon in the ocean.
A: Yes, most salmon can be seen migrating during the fall (September through November). Steelhead trout migrate in the summer and winter but don't spawn until spring and are harder to observe than salmon (because the water is higher in spring and they don't change color).
Q: Are there specific seasons in which salmon can only be found?
Q: How many species of salmon are there?
A: There are eight species of Pacific salmon: chinook, coho, chum, sockeye, pink, steelhead trout, masu and amago salmon (two Asian species).
There are three generally recognized groups of Atlantic salmon: North American, European, and Baltic.
Q: What happens if a salmon cannot find its stream?
A: Some salmon will try to find the right stream until they use up all their energy and die but most would simply try to find other salmon to spawn with. These fish stray into other streams to spawn if they are lucky.
Q: How long do salmon usually live?
A: 2 to 7 years (4 to 5 average).
Once the yolk sac is fully
absorbed, the salmon
emerge from the gravel
as fry, and begin to move about and feed on their own. Some salmon fry species start swimming toward the estuaries, while other species of salmon wait months, even years, before heading downstream.
The next stage of salmon
development, is the parr
stage. It is characterized
by the vertical bars that
develop on the sides of their bodies. These bars, or parr marks, help camouflage the small fish from predators. This stage can last months or years, depending on the species.
Slide 19 and 20
Slide 42 http://www.water.ca.gov/recreation/locations/oroville/FeatherRiverTour/images/fish_ladder_profile.jpg
Slide 34 http://img123.imageshack.us/img123/1751/sarovardamindiayb1.jpg
Q: What can we do to save salmon?
A: Some things we can do to save salmon are to protect their stream habitat, help restore streams that have been damaged, reduce fishing, and help find ways to increase salmon survival through the dams.