sea surface temperature

Water temperature is an important factor in the environment of fish.

It causes the activity levels of fish to increase or decrease, makes fish move into certain areas while avoiding others, and influences feeding and reproductive activity. Temperature data are of interest to those who wish to catch fish or study them. Both fishers and researchers need to understand how temperature affects fish behavior.

Water depth is a major factor influencing water temperature. Since heat comes from the sun, water tends to be warmer near the surface and cooler with increasing depth. Because of this, much of the discussion about how water temperature influences fish behavior tends to center on the surface and the area immediately under it.

However, currents also bring water of differing temperature together, and areas where this occurs can be zones of intense fish activity. Such areas are called oceanic fronts, and their sudden temperature changes encourage the growth of plankton. Plumes of plankton occurring at oceanic fronts attract fish which feed on either the plankton itself or on other fishes that consume it.

Fish are unable to regulate their body temperature, so they are influenced by the temperature around them. If the water is warm, fish metabolism accelerates, feeding and respiration increases, and there is a general increase in movement. If the water is cooler, fish become lethargic and tend to be inactive. However, this is also true for other water creatures such as the insects that some fish eat, and certain fishes have adapted to this fact by specializing in slower kinds of prey. This is why bass and carp fishing is done in winter. These are fish specializing in slow-moving prey, and they are more active in cold water than in warm water. In general, however, most types of fish prefer faster prey and are more active in warmer water.

In areas where water masses of varying temperature meet, fish often begin making eggs and sperm and displaying reproductive behavior such as changing position in the water column and forming schools. Sudden changes in water temperature will sometimes trigger migrations to spawning grounds.

Sea surface temperature


Marine observations