Transport of anchovy, Engraulis capensis Gilchrist, eggs and early larvae by a frontal jet current

Abstract

Anchovy Engraulis capensis is the main contributor to the South African purse-seine fishery. Eggs are spawned at the eastern limit of anchovy fishing operations in warm, well-mixed water of low productivity. Recruitment follows a regular pattern with juvenile fish appearing in the catches 250 km north of the spawning ground. A strong shelf-edge frontal jet is a regular summer feature of the area. The ability of the jet current to entrain quantities of anchovy eggs and transport them in the direction of the recruitment ground was shown in October 1976 using a free-drifting parachute drogue. Deterioration of the frontal system and consequently the jet current (with northwest wind) was observed in November 1976. Starvation mortality of early-stage larvae remaining in the spawning ground or carried eastwards by current reversal under northwest wind conditions would be expected to be relatively high compared with larvae transported to the productive upwelling area where recruitment normally occurs.