Spawning areas and larval distributions of anchovy &lt;em&gt;Engraulis encrasicolus&lt;/em&gt; in relation to environmental conditions in the Gulf of Tunis (Central Mediterranean Sea)

Rafik Zarrad,Alberto Garcia,Hechmi Missaoui,Romdhane Mohamed Salah,M'Rabet Ridha,El Abed Amor,Jarboui Othman,Francisco Alemany

doi:10.3989/scimar.2006.70s2137

Abstract

Early life stages of anchovy were investigated in the Gulf of Tunis by means of four seasonal surveys carried out from summer 2002 to spring 2003. Anchovy eggs and larvae were found all year round, but they were much more abundant in spring and summer. In spring, the main spawning area was located in the north of the Gulf, to the west and southwest of Zembra Island. In summer, higher egg and larva abundances were also observed to the southwest of Zembra Island, but secondary spawning grounds were detected in the vicinity of the mouths of the Rivers Majreda and Meliane. No direct correlations between sea surface temperature (SST), salinity (SSS) and chlorophyll a and the horizontal distribution of eggs and larvae were observed. However, egg distributions in all seasons and larval distributions in summer and autumn were significantly related to depth. The temporal variation of temperature seems to control the spawning intensity and the beginning of spawning seems to be triggered by the increase in SST.

Highlights

IntroductionThe stock fluctuations of small pelagic species (e.g. sardine and anchovy) are often attributed to the relative success of recruitment
The stock fluctuations of small pelagic species are often attributed to the relative success of recruitment
While Engraulis encrasicolus spawning of the Iberian Peninsula have been extensively studied and related to the main productive events in the different areas, the information is very scarce for the northern African waters

Summary

Introduction

The stock fluctuations of small pelagic species (e.g. sardine and anchovy) are often attributed to the relative success of recruitment. The variability of this success takes place in early life stages through the action of environmental factors. Tion) play a key role in this success, which combines to yield favourable reproductive habitats for small pelagic fishes and other species (Agostini and Bakun, 2002). The enrichment assured by Rivers Rhone and Ebro and the development of the deep fluorescence maximum influence northwestern Mediterranean anchovy (García and Palomera, 1996; Olivar et al, 2001; Sabatés et al, 2001; Lloret et al, 2004)

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Discussion

Conclusion