As the salmon go upstream to the spawning grounds, they may face obstruction from beaver dams. Sluice gates have to be provided so the gravid female salmon can get to the spawning grounds. This is a problem caused by the re-introduction of beavers to the U.K. Sluice gates are opened for the salmon at breeding time. Salmon farms are also possible, in which the fish are non-migratory, but then they have to be fed artificially.
Salmons get the pink color of their flesh from a pigment called astaxanthin. Wild salmon get it from the krill and shrimp they eat, while farmed salmon gets traces of it in kibble (compound feed). If they don't have the pigment, their flesh has a gray color.
Main species change
- "Why do some fish normally live in freshwater and others in saltwater? How can some fish adapt to both?". Scientific American. Retrieved 2021-05-07.
- "Salmon a hit health food in Japan". www.seafoodsource.com. Retrieved 2021-05-07.