English abstract
Data from underwater surveys conducted between 2009 and 2021 were analyzed to determine the effect of closed fishing seasons on the density and size composition of Omani abalone, in the main fishing areas (Mirbat, Sadah, Hadbin, and Hasik). The average density of abalones, the abundance of mature and legal size abalone, and the average abalone size increased significantly after a 3-year closure (2008-2010). From 2012 to 2021, abalone density and size decreased despite four 1-2 years of closed fishing seasons. The density of mature abalone after 2011 was below the minimum spawning density of Haliotidae. Abalone densities were found to be relatively high in Sadah and Hadbin but very low in Mirbat and critical conditions in Hasik. Lack in regulations' enforcement, overlap between fishing and reproduction season, and the uncontrolled number of divers are probably the main reasons for the decline in abalone abundance and size. Future fishing closure must be extended for at least three years, and abalone harvest in Mirbat and Hasik should be banned for at least five years. The number of divers must be regulated, and changing the fishing season must be evaluated. It is necessary to identify if the population is sustainable, threatened, or recovering, by studying more biological aspects of the Omani abalone, including minimum spawning density, abalone aggregation, and recruitment levels at each fishing ground. These studies will help the authorities to decide when fishing must stop to avoid any further reduction in the abalone densities. It is important to understand the socioeconomic status of abalone diver's communities in Oman for better management and development.
