Fish (schooling)

Avg. speed

3 kn

A large school of fish breaking the surface is one of the clearest signs of an active feeding event, often with predators driving them from below and seabirds working them from above. Schools of species such as sardines, anchovies and mackerel can stretch for kilometres and shift shape in an instant as the fish move as one. For the sailor they are a valuable navigation cue, since concentrations of bait fish usually mark underwater structure such as banks, reefs or upwellings beneath the surface. Schooling is a survival strategy in itself, a moving wall of bodies that confuses predators and reduces any individual fish's odds of being singled out.