Salmon Life Cycle
Each species of Salmon live a very different life cycle.
Life span among the 5 species is between 2 and 9 years.
Life span among the 5 species is between 2 and 9 years.
Chum Salmon
Chum Salmon live a unique life cycle and it can vary greatly depending on the stock of fish and environmental conditions.
Year One Nov – March
Incubation
In November through to December Chum Salmon spawn, depositing their eggs into nests, also known as “redds” in the streams gravel. The average Chum female can carry up to 3,000 eggs. Once deposited, depending on stream conditions, it can take up to four months for the eggs to develop and hatch into alevins. Alevins are newly hatched fish that carry a portion of their yolk sacks underneath their abdomen. The young fish are 1-1.5 inches in length, and during this stage the yolk sack will feed the young fish for about a month.
In most streams and rivers the survival rate from egg to alevin is ~7-8%, it is important to note that in urbanized streams this number is expected to decrease drastically due to many factors, such as: deforestation, storm drain run off, pollution, channelization and loss of stream complexity. The most negative effect to the fish at this stage are high flows due to storm drain run off and channelization, this causes the nests or “redds” to be washed out and the eggs are sent down stream without protection.
Migration
When the fry have finished consuming their yolk sack they have transitioned to the fry stage. Chum fry move downstream toward the ocean, the estuary of the stream or river right away. In some cases a few outliers may remain in the stream until the end of the summer. Without the cover of woody debris, rocks and other areas of shelter in the streams, fry use the numbers defense tactic and join each other in groups called schools. The young fish grow and develop in shallow waters, gradually moving to deeper waters, and then finally migrate to open waters. Birds and larger fish are the main predators during this time, the fry are especially vulnerable during the transition from freshwater to salt water as the predators wait in the estuaries for their arrival.
By the end of summer the fry range from 4 – 6 inches in length, at this time most of the fry will begin migration to open water. It is also possible that some of the fry will stay nearshore for an additional year before migrating to open waters.
Year 2
For most, their second year is spent heading up to the Gulf of Alaska, here they will feast on a bounty of plankton, shrimp, small squid and smaller fish.
Year 3
The fish continue to feed and develop, about 1/3 (33%) of the remaining fish will begin their journeys back to their home stream to spawn in the coming fall. Some will stay a second year to grow and feed, while a small portion will actually spend a third year feeding and developing into even larger fish.
3 Year Old Spawners
These fish average around 2 feet in length, or 60cm, and weigh approx. 8lbs on average. Spawning begins in early October and is usually finished by the end of November.
Spawning begins by the female selecting suitable spawning gravel on the streambed for nest construction. Fertilized eggs are deposited into pockets of the nest or “redd.” Males compete to spawn with the females, the pockets of fertilized eggs in a redd may have different suitors. The spawning process can take up to 10 days and the female will guard the redd until she succumbs to weakness and dies.
4 Year Old Spawners
Out of all the fry that began their ocean journey four years ago, the majority – or 60% of the original school will begin their journey back to their stream.
5 Year Old Spawners
Around 10% of the original school of fry stick it out for a 5th year in the ocean, these fish average 3ft in length and weigh 12lbs on average.
In very rare circumstances 1% of the original school of fry will spend a 6th year in the ocean.