Autumn larval fish assemblages in the northwest African Atlantic coastal zone

Abstract

A study on the assemblage composition and vertical distribution of larval fi sh was conducted in the southern area of the Moroccan Atlantic coast in Autumn 2011. A total of 1 680 fi sh larvae taxa were identifi ed from 21 families. The majority of the larvae were present in the upper layers. Clupeids were the most abundant larvae taxa followed by Myctophidae, Gadidae and Sparidae, hence the larval fi sh assemblages (LFA) were variable in diff erent depth layers. Total fi sh larvae showed a preference for surface layers, and were mainly found above 75 m depth, with some exceptions. The maximum concentration of fi sh larvae was concentrated up to 25 m essentially above the thermocline, where chlorophyll a and mesozooplankton were abundant. Spatially, neritic families were located near the coast and at some off shore stations especially in the northern part, while oceanic families were more distributed towards off shore along the study area. Cluster analysis showed a segregation of two groups of larvae. However, a clear separation between neritic families and oceanic families was not found. Multivariate analysis highlighted the relationship between the distribution of larvae of diff erent families and environmental parameters. Temperature and salinity seem to have been the factors that acted on associations of fi sh larvae. Day/night vertical distributions suggest there was not a very signifi cant vertical migration, probably due to adequate light levels for feeding.

The Moroccan Ichtyoplankton - A General Overview

“…34 Taxonomic clusters were identified including the families of the following pelagic clusters: Clupeidae, Engraulidae, Carangidae, Scombridae and Trichuridae with an abundance of Sardine eggs and larvae [17]. In 1998 (March-July) two campaigns were carried out in the southern Atlantic between Cap Blanc and Cap Boujdour to assess the Hydrological Parameters and their importance on the distribution of ichthyoplankton, this assessment indicated a difference between the coastal and off-shore stations [18], during later years [19] have confirmed these results in their study, which indicates that the more the direction is offshore, the more the abundance of ichthyoplankton decreases, with a preference of larvae for the upper layers, they were able to identify 21 families with the most abundant taxon and that of the Clupeidae.…”