Download - The salmon powerpoint
The Salmon Life Cycle
Hi there, my name is Fred and I LOVE fishing! I was out fishing today and I saw a fish I had
never seen before. My Dad tells me its called
a Salmon. I took a picture, let me show
you!
Salmon
I don’t know much about salmon…I would like to find out more about how they grow up!
Lets start at the very beginning….Eggs
The first stage of the life cycle. A femaleSalmon deposits as many as 10,000 brightpink eggs, about one-fourth inch in diameter.They are laid in the gravel of a stream. Afterabout a month, eyes become visible within
theeggs.
Lets think
Let’s think …..
• To protect them from predators and direct sunlight
• Were you correct?
Answer
Why do you think the eggs are laid in
the gravel of a stream?
AlevinIn late winter and spring, salmon eggs hatch andbecome alevins (pronounced ay-le-vins) .The alevin is a fragile creature with huge eyes and a large yolk sac protruding from its belly. The vitelline vein, running throughthe center of the sac, extracts oxygen from thewater. The at this stage remains under gravel,protected from predators and other hazards. Agood flow of pure water is critical to alevin survival.
Lets think
Let’s think …..
• The orange yolk sac contains a balanced diet of protein, carbohydrates, vitamins, and minerals for the Alevin to live off.
• Were you correct?
Answer
What could the large yolk sac be
for?
Fry
Alevins absorb their yolk sacs and emerge from
the gravel as fry in late spring and summer. About
an inch long, they are easy prey for larger fish.Fry feed on plankton and small insects. At thisstage, important survival requirements includegood streamside cover and an ample food supply.
Smolt
The fry loose their stripes and turn aSilvery colour. At the smolt stage, theyHead downstream. Four to six inches long,They swim seaward in late May during the
spring rains, and enter salt water, wherethey grow to
adulthood.
Adult
Ocean adult salmon spend varied amounts oftime in the sea, ranging up to five years. Theyeat as much as possible and grow rapidly in theOcean feeding grounds.
Spawning AdultUsually in the early summer of their maturing year, salmon begin to head back to their home streams, navigating at least partially by their sense of smell. They stop feeding as they enter fresh water, living on stored body fats. They struggle sometimes for weeks
againstfalls and obstructions to reach the same spawning beds in which
theythemselves were hatched. When a pair of salmon reaches itsspawning ground, the female digs a nest to lay her eggs in. The
maleFertilizes them by covering them with a milky substance known as
milt.The female then covers the eggs with gravel to complete the
spawningprocess. The salmon’s life is finished and within a short time it
dies andthe body drifts downstream, providing nutrients to the stream
systemas it decays
Nest Facts
Nest Facts
• The Salmons nest is also known as a redd
• The redd can be up to 16 inches deep in the gravel.
Lets see how much you have learned
Label the stages of the life cycle