Diel activity rhythm of seabass tracked in a natural environment: Group effects on swimming patterns and amplitudes

Seabass swimming behavior was investigated in a salt-marsh area located along the Atlantic coast north of La Rochelle, France. Seabass is a natural inhabitant of this coastal zone and is farmed there as well. During its 3rd year, seabass can move about either singly or in small groups. Swimming activity of single fish and fish in a group was studied using an acoustic telemetry recording system. This study demonstrates that swimming activity levels and patterns of this species are modified by a group effect. Single fish were mainly nocturnal and fish in a group adopted a diurnal activity rhythm and lower maximum swimming activity levels.