Trammel net fishing in Jeddah: species composition, relative importance, length-weight and length-girth relationships of major species

Abstract

Efficiency and selectivity of trammel nets used in Jeddah fisheries were assessed in terms of species composition and catch per unit effort. The index of relative importance was estimated for each species. Trammel nets of three inner-panel mesh sizes were used in the fishing operations. Moreover, the length-weight and length-girth relationships for ten fish species were described. Results indicated that the catch of trammel nets was composed of 99 species belonging to 36 families. The overall catch per unit effort was estimated to be 244 individuals (34.6 kg)/1000 m net length. Members of four families: Siganidae, Lethrinidae, Scaridae and Acanthuridae represented collectively 75.05% of the total number of fish caught, and 74.6% of the total biomass of fish caught. In these major fish families, four species: Siganus rivulatus, Acanthurus sohal, Hipposcarus harid, and Lethrinus harak were the most abundant and important species representing collectively 45.2% of the total catch, and having the highest index of relative importance: 29.2%, 15.4%, 12.7%, and 12.4%, respectively. The length-weight and length-girth relationships were described for the most abundant 10 coral reef species, two species of them: Rhinocanthus assassi and Plectorhinchus gaterinus have no previous data on length-weight relationships in the Literature.