Temperature Temperature Water temperature is a major controlling factor for all aquatic life. There is a narrow temperature band at which cold blooded animals can live and if stream temperatures increase, decrease or fluctuate too widely, this can severely affect the metabolic activities of these organisms.
Temperature affects the amount of dissolved oxygen and salmonids require high oxygen levels.
They can only live in cool temperature environments with high oxygen concentrations. They can take being banged around and last a long time in the field. However, any type of thermometer that gives accurate and consistent readings will suffice. Temperatures along a stream site should be taken at least 10-15 feet apart at two different locations. Leave the thermometer in the water for at least 30 seconds and read it while still in the water if possible.