Why salmon migrate

They reside in lakes, never making the marine migration. They generally do not grow as large as sea-run fish, averaging between 12 and 20 inches long. In fresh water, young salmon mostly eat small insects such as mayflies, stoneflies, caddisflies, blackflies, and riffle beetles.

Sometimes they eat small amphibians and fish. Just before adults migrate to estuaries to begin the spawning migration, they stop eating altogether. In freshwater, juveniles are eaten by a variety of fish smallmouth bass, striped bass, Northern pike, slimy sculpin, etc. Atlantic salmon are also caught for consumption by humans in targeted aboriginal or traditional First Nations fisheries.

The largest Atlantic salmon was pounds and 60 inches. However, depending on how long they are at sea, adults returning to the Gulf of Maine rivers typically weigh approximately lbs and are inches long after 2 years at sea.

The maximum recorded age was 13 years old, but most Atlantic salmon that survive to reproduce live 5 to 8 years years in fresh water, years in the marine environment. Almost always.

While some straying has been documented, most spawning salmon return to the river in which they were born and sometimes they even home to the very stream of their birth. Generally from 2, to 7, depending on the size of the female larger females have more eggs , or about eggs per pound of body weight.

The Endangered Species Act ESA is a law passed in that provides for the protection and conservation of species that are at very high risk of going extinct. This means that they are in danger of extinction throughout all or part of their range. Before construction of dams in the early s, more than , Atlantic salmon returned to U. There are many reasons why U. Atlantic salmon population abundances are so low.

There are three primary causes:. Salmon are raised in hatcheries to supplement natural production in rivers. Atlantic salmon are endangered and are currently unable to produce enough juveniles under natural conditions in the rivers to support their populations. Therefore, juveniles are raised in hatcheries to various stages i. Then they are stocked in the rivers so that they can migrate to sea then return to spawn after a few years. This gives scientists and managers more time to figure out how to restore thriving populations to Gulf of Maine rivers again.

From , releases of hatchery-raised Atlantic salmon smolt to supplement natural production in the streams of the Gulf of Maine resulted in adult spawning returns of approximately 0. This low return rate is the result of numerous factors including high mortality in the river from downstream passage barriers and low marine survival.

Fish passage is essential for adult salmon to be able to travel upriver to spawn and for salmon smolts to be able to travel down river to reach the sea. This means that adults can go six months without food while transferring body fats into their gametes for reproduction.

Salmon hear using low frequency sound waves which vibrate through the water to a row of sensory pores called lateral lines on the sides of the salmon. Salmon in their saltwater phase travel an estimated 18 miles a day, but they are capable of maintaining an average of 34 miles per day over long distances. Salmon can migrate more than 3, kilometres upstream through freshwater to spawn Yukon River. That is comparable to driving halfway across Canada.

Salmon often travel 50 kilometres per day on their spawning journeys. This is equivalent to running more than a marathon every day! Salmon can jump up to two metres to cross obstacles in rivers — the same height some Olympic athlete can jump. A typical orca eats 25 kilograms of salmon a day. For the resident orcas in B. Then they may travel downstream for a bit, until they encounter that home stream smell again. The more they sense the smell of their birthplace, the more they swim upstream.

There are still many unknowns in the famous story of the salmon swimming upstream. Evidence exists that salmon from different reaches of the same river will tend to migrate to the same stretch where they originated. But do they return to the very same nest site where they were hatched? How close do they get? At some point, that urge to return home will be up against other factors: selecting a nest site, selecting a mate, using remaining energy stores.

Interested in learning more about salmon migration and salmon in general? Join us for the Cedar River Salmon Journey to talk to trained naturalists while watching salmon spawn! Click here for remaining dates, times, locations and directions. Our programming continues with your help.