School of Salmon
We have 6 different species of Pacific ocean Salmons, they are sockeye (Oncorhynchus nerka), coho (Oncorhynchus kisutch), pink (Oncorhynchus gorbuscha), Chinook (Oncorhynchus tshawytscha), chum (Oncorhynchus keta), and masu (Oncorhynchus masou). First five species spawn in northwest American rivers, while masu salmons are found in Japan and Korean rivers.
Fall is a good time for most of pacific salmons to spawn. They start to come to rivers of Washington State (USA), Canada and Alaska (USA). If lucky enough, we could spot schools of them enter the river, swim upstream to find spawning ground.
Why do we able to see the fish swimming in the river? The answers are: river has clear water, fishes color is red which contrast to their environment background and because the size of fish so big, where the length may reach 1.5 meter and weight around 50s kg.
The big size due to spending most of their times in the rich ocean, where they eat abundance of food to increase their body mass until gain maturity. Why color of salmons is red? It is because they eat small organisms (shrimps) which contain a pigment called “carotene”. This pigment changes color of salmons from white to pink or red.
Salmons will spawn in the same river where they were born. They find the river by magnetoception, then use their smell sensory to search the exact spawning ground. Unfortunately, females will die after spawning. The eggs are hatching and going downing stream slowly until reach suitable size to go to ocean. The repeat cycle of live will begin after several years later.