Larval Abundance in Relation to Stock Size, Spawning Potential and Recruitment in North Sea Herring

摘要: In recent years the idea that larval abundance estimates provide valid (relative) measures for spawning stock size has become more generally accepted in North Sea herring research (Anon, 1971b, 1972). The application of this stock-size parameter was promoted by increasing difficulties encountered using catch-effort statistics rapidly changing fisheries. use data purpose presupposes absence major variations egg and mortalities between over longer periods. Provided these do not differ greatly areas, would also allow a comparison local stocks (given length composition fecundity data) (Zijlstra, 1970; Anon, 1971a, b). As is supposed to be related stock, it provides finally useful stockrecruitment studies (Burd Holford, 1971). realization probable value as tool population initiated an international collaboration improve collection coordinated surveys with standardized methods (Boetius McKay, Saville, Wood, 1971; Schnack, 1972; Zijlstra,