Claire Corlett

Fish Food, Fish Tanks, and More

Facts: The Atlantic Salmon

The Atlantic salmon is an anadromous species. This means that the adults live in the ocean
and return to freshwater rivers to breed. These salmon can be found in the North Atlantic
ocean and the rivers that flow into it. Atlantic salmon spawn in freshwater in the
fall. A female salmon will use its tail to dig a
nest in the gravel where her eggs will be deposited. A female lays an average of 7500 eggs. The gravel nest is called a redd. Over the winter, the eggs develop into small
salmon called alevin. Alevin subsist on their attached yolk sac. In May or June, after the yolk sac is depleted,
the young salmon, now called fry, emerge from their nest. Only a small percentage of eggs survive to
the fry stage. The fry develop into parr with vertical stripes
on their sides for camouflage. Juvenile salmon spend two or three years in
freshwater before migrating to the ocean. Before migration, the salmon undergo a physiological
transformation called smoltification. This transformation into smolts prepares the
salmon for life in a marine habitat. During this process, their gills and organs
change and the fish imprint on the chemical nature of the river. This enables them to find their way back to
the place they were born. They migrate to the ocean to feed, grow, and
mature. The salmon grow much faster in saltwater than
in freshwater. Adults prey on amphipods, krill, and fish
like capelin. The salmon spend one to three years in the
ocean, reaching 2 or 3 ft (.6 to .9 m) long, before returning to their natal rivers to spawn. They must swim against strong river currents
to reach their spawning grounds. They migrate with the help of the earth’s magnetic
fields and their sense of smell. Some lake dwelling populations of Atlantic
salmon do exist, where the adults inhabit lakes and migrate to the surrounding tributaries
to spawn. Many Atlantic salmon die after the first time
they spawn. Very few spawn a second time and even fewer
a third or fourth time. They only live 4 to 6 years. They are preyed on by birds, marine mammals,
and large fish. Commercial fishing for wild Atlantic salmon
in the United States is prohibited. Only farm raised Atlantic Salmon can be found
in the US fish markets. Atlantic salmon farming is controversial because
of the many environment impacts. Chemicals and fish waste from these farms
pollute water systems. The farms also rely on unsustainable industrial
fishing to provide food for the salmon. Accidents sometimes happen where thousands
of farmed fish are released into the ocean due to net failure. Even with fishing restrictions, many populations
of wild Atlantic salmon are still in decline. Their populations are vulnerable to many threats
like pollution and predation by introduced species. Manmade dams and culverts can block access
to their quality habitat. For more marine facts, click the SUBSCRIBE

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