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Andy Y. Kwarteng

Sultan Qaboos University, Oman

Title: Barr Al Hikman as an Important Nursery Ground for Blue Swimming Crabs Portunus segnis

Biography

Andy Kwarteng obtained his PhD degree in remote sensing and economic geology at the University of Texas at El Paso, USA, in 1988 and MSc in mineral exploration at McGill University, Montreal Canada in 1984. He has worked as a geologist and research scientist in USA, Saudi Arabia and Kuwait. He is currently the director of the Remote Sensing and GIS Center, Sultan Qaboos University, Muscat Oman. His research interests include remote sensing applications to urban, marine, and desert environments. He is the author and co-author of 170 scientific, technical and company reports.

Abstract

Barr Al Hikman is a vast pristine coastal wetland in the Sultanate of Oman that belongs to one of the world’s most undisturbed tropical intertidal ecosystems. The area supports large numbers of shorebirds and benthic invertebrates, offers safe foraging place for turtles and serves as a nursery ground for fishes. In this study, we investigated the significance of the nursery ground for the commercially important blue swimming crab Portunus segnis. The density of the blue swimming crabs was appraised during six sampling campaigns from 2012–2015 on a spatial grid with 200 m sampling interval during high and low tides. The crab densities differed substantially between the years from virtually absent to densities up to 2 individuals per m2. The blue swimming crabs sampled on the mudflats during low tide had carapax widths that were smaller than 25 mm. For the crabs that were sampled during high tide, approximately 25% had carapax widths smaller than 25 mm, 50% had carapax widths between 25 and 50 mm, and the other 25% had carapax widths between 50 and 100 mm. All crabs were identified as males without eggs. A carapax size of greater than 100 mm is usually acceptable for commercial fisheries. The Barr Al Hikman area is therefore an importance nursery grounds as the study shows that relatively small crabs that are below the commercial size spend about 2.5 months in the intertidal mudflat to attain the sizes of greater 100 mm.