SALMON
BASIC SALMON FACTS & TERMS Are anadromous, meaning that they are hatched and reared in freshwater, but spend part of life in sea before returning to fresh water to spawn. All native Pacific salmon die after spawning, some North Atlantic salmon do not. Genetics: all trout and salmon can be traced to a time when they shared a common gene pool. Pacific trout and salmon are genetically distinct from Atlantic salmon.
While some lake trout can live to be 60+ years old, the lifecycle of salmon rarely extends more than 6 yrs.
SPAWNING BEHAVIOR Rainbow and cutthroat trout generally spawn earlier in the milder climates of more southerly or coastal areas The timing of Pacific salmon spawning varies greatly
Why do salmon and anadromous trout migrate? The benefits outweigh the costs; they take advantage of the abundant food of the ocean. Because of this, they return larger than most of the “local” competition. This allows them to dominate the best spawning locations, and lay many large eggs with yolk that sustains their young for weeks.
SPAWNING BEHAVIOR (con’t) homing instinct aided by celestial navigation and detection of earth’s magnetic fields Once in the home river, the olfactory sense is used
Growth: Determined by interactions between heredity and physical environment constraints Salmon and trout can grow throughout their lifetime. Are cold blooded, and rates of growth and longevity are greatly influenced by water temperature. Metabolic rate increases with higher water temperature, so more food must be consumed. Oxygen levels, salinity, competition, and food availability also impact growth
What they eat: Are generalists and opportunists In fresh water, most rely heavily on aquatic insects, but feeding patterns can vary greatly by season Crustaceans such as shrimp, crayfishes can also be significant
Life Cycle
Life Cycle Reproduce in cold, flowing water by creating excavations in gravel called redds Have relatively large eggs Leave birth stream, go downriver Many stay in coastal estuaries for weeks before seaward migration Ocean life lasts 1-5 years, where large size attained Return to home stream done without feeding