Aspects of the biology of Engraulis australis (White, 1890), the southern anchovy

Abstract

Aspects of the biology of the southern anchovy - Engraulis australis (White, 1890) from New Zealand are examined, 1000 specimens are used. Analysis of 895 stomachs containing food shows that E. australis predominantly feeds on Zooplankton. Calaniold copeoods, Euphausids and Mysids represent the bulk of this. Phytoplankton contributes a third of the diet comprised predominantly of diatoms. With increasing length E. australis consumes larger prey items. No significant differences were found in the diet of males and females. The diet composition of E. australis appears to be strongly associated with mouth size and gill raker structure. Comparison between E. australis and S. neopilchardus, S. muelleri and S. antipodum shows that gill raker structure may be species specific. Competition may occure between these species. Ageing was by otoliths though this was restricted because of calcification from the strong preservative (formalin). Ageing results along with length-weight measurements indicated a similarity in growth between males and females. Visual examination of the gonads shows that E. australis spawns during late spring and summer. A 4 stage gonad maturity scale is described. 10.5% of E. australis examined were infected by parasites. These were a nematode anisakis sp. and a unidentified cestode. The history of, and potential for a commercial industry based on New Zealands clupeoid fish is discussed.