Schooling behaviour of jack mackerel, Trachurus declivis (Jenyns), observed in the Tasmanian purse seine fishery

摘要: The seasonal, lunar and diurnal changes in schooling of jack mackerel were examined using log-book information collected from an industrial fishery off the east coast Tasmania between 1985 1989. School size increased significantly spring to autumn. ratio surface subsurface schools encountered by also changed seasonally. Surface predominate during summer, whereas become more frequent was predominantly a day no effects on catch rates or fishing intensity detected. Catches mainly comprised mackerel, although redbait (Emmelichthys nitidus Richardson) blue (Scomber australasicus Cuvier) significant by-catch. In almost exclusively composed but other seasons mixed found. Data presented, together with evidence sources, suggest that availability may be closely related feed.