Impact of environmental factors on survival of larval and juvenile Cape anchovy Engraulis encrasicolus (G.) in the southern Benguela upwelling region, determined from hatchdate distributions: implications for recruitment

摘要: March larval and May juvenile Cape anchovy of the unusually strong 1999/2000 year-class were collected off South Africa. Age estimates obtained from daily increment counts on otoliths using light microscopy for larvae (14-70 mm standard length, SL, n = 193, 92% success rate), scanning electron juveniles (52-110 80, 22% rate). Differences between hatchdate distributions related to prevailing temperatures. showed slight modes in October/November 1999 January/February 2000, each a month later than (September/October November/December). Thus, mortality rates hatched after mid-December seem have been higher. Large areas warm water (19-26 ◦ C sea surface temperature) Agulhas Bank, mid- November indicated conditions conducive spawning reduced offshore advection products. A period upwelling, is likely increased availability planktonic food older larvae; also causing dispersal younger patches required by these, possibly leading starvation during upwelling. The critical thus seemed be at first-feeding.