Spatial and temporal distribution pattern and biomass trend of flathead slipper lobster, Thenus orientalis (Lund, 1793) from Gulf of Oman

Abstract

The aim of the present study was to investigate the amount of biomass and Catch Per Unit Area (CPUA) as well as to determine the distribution pattern of flathead slipper lobster, Thenus orientalis as one of the most important and commercial aquatic species in the north coast of the Gulf of Oman. There was an annual monitoring survey during 2009-2019 by using R/V ʻ Ferdows-1 ʼ covering the depths10-100 m which equipped with bottom trawl net. The highest CPUA was recorded in eastern and western region of the study area (45.54 kg/nm 2 and 25.40 kg/nm 2 ), although density of species was lower in the central area (Stratum B, C, D). The highest biomass (22.7 tons) and CPUA (52.13 kg/nm 2 ) was found in 10-20 m and 20–30 m depth layer, respectively. The comparison of mean CPUA and biomass in different depth-layers and stratum revealed that the mean CPUA and biomass have a descending trend with increasing of depth. Results of this study showed that the abundance of this species dramatically decreased over past decade to about 13.3 kg/nm 2 in 2019. Therefore, it is necessary to implement a regulatory mechanism to manage the stocks of this commercially valuable species, such as closed fishing season during the breeding and reproduction period, only permitted to use traps for harvesting of lobster, prohibited to take egg-bearing females or juvenile lobsters.