Cephalopod Species in Mozambican Waters Caught in the “Mozambique 0307” Survey: Distribution, Abundance and Assemblages

Abstract

—The present paper reports for the first time for Mozambique waters the distribution, abundance and species assemblages of cephalopods in the outer shelf and upper/middle slope (100 – 700 m depth) from data collected in spring of 2007 during the “Mozambique 0307” bottom-trawl survey. A total of 129 hauls were performed following a random stratified sampling scheme in the different sectors and bathymetric strata. The biomass estimates were computed by the sweptarea method. Cephalopod species accounted for 8.4% of the total biomass captured, with a total of 50 species belonging to 13 families. The most important families in terms of species richness were Octopodidae and Sepiidae with 10 representatives each. The most abundant species was theomastrephid Nototodarus hawaiiensis, present in all sectors. The second most abundant species in terms of biomass was Sepia acuminata, followed by the Veladona togata (Octopodidae) mainly between 400 and 600 m depth. The highest biomass estimates were recorded in the sectors named Bazaruto B and Boa Paz, between 200 and 400 m depth. Species assemblages were analysed with the Bray-Curtis similarity index and the group average clustering method was applied, revealing three cephalopod assemblages : the shelf community (100-200m), a wide transitional zone between shelf edge-upper slope (200-600 m) and the middle slope (600-700 m), mainly characterised by Sepia species, Nototodarus hawaiiensis, and Histioteuthis species, respectively. The diversity indices showed a higher diversity in Sofala, in the north of the study area, and inthe shelf community in all sectors. Keywords: Mozambican waters, assemblages cephalopods, shelf community, upper-middle slope