For a sound development of fisheries on the world’s remaining unused resources an evaluation of the potentials is needed, both to encourage interest and to provide guidance for timely management. The type of information required is not limited to stock potentials but should include main features of fish biology, behavior, catchability, size, quality, etc.The possible methods and sources of information are of two kinds: indirect and direct. Indirect methods make use of information on the oceanography and basic productivity of sea areas and of ecological relations. Examples are mapping of upwelling areas, charting of observations of basic productivity, and stomach content studies.Direct methods base themselves on quantitative observations of any stage of the resource itself, thus including egg, larval, and postlarval surveys, exploratory fishing, acoustic surveys, aerial scouting, and observations from vessels engaged in other primary tasks. The advantages and limitations of these various methods and the conditions for their successful use are discussed and compared.
Prolactin Influences Different Aspects of Fish Biology