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Small boat surveys were conducted between 2000 and 2003 in three main regions of Oman’s coastal waters: Muscat, the Gulf of Masirah and Dhofar. Survey data were analysed to calculate relative abundances of the seven most frequently encountered species in these areas. These include (in order of frequency) bottlenose dolphins (Tursiops sp.), long-beaked common dolphins (Delphinus capensis), humpback whales (Megaptera novaeangliae), spinner dolphins (Stenella longirostris), Indo-Pacific humpback dolphins (Sousa chinensis), Bryde’s whales (Balaenoptera sp.) and Risso’s dolphins (Grampus griseus). Other species observed include false killer whales (Pseudorca crassidens), blue whales (Balaenoptera musculus), rough-toothed dolphins (Steno bredanensis) and unidentified beaked whales. Encounter rates per distance searched were plotted by 0.1 x 0.1 degree grid cell, giving an indication of relative abundances and key areas of habitat used by each of the seven most frequently encountered species. These plots demonstrate that the nearshore areas of the Gulf of Masirah, as well as the coastal waters of Dhofar, are areas of concentration for the Arabian Sea’s recently designated Endangered subpopulation of humpback whales, as well as Indo-Pacific humpback dolphins, which are considered Near Threatened on the IUCN Red List of Threatened Species.1 The results presented here provide valuable baseline data for future research and help to inform conservation management efforts that are required to address the highly vulnerable status of the humpback whale and Indo-Pacific humpback dolphin populations in question.

Private industry, the Government of Gabon and two international NGOs collaborated to conduct marine surveys off the coast of Gabon, Central Africa. Surveys addressed multiple objectives of surveillance and monitoring, the documentation of the distribution of and threats to the marine megafauna, and capacity-building among government agents and local early-career scientists. During 22 days of survey effort over a two-year period, observers documented humpback whales Megaptera novaeangliae, bottlenose dolphins Tursiops truncatus, Atlantic humpback dolphins Sousa teuszii and common dolphins Delphinus delphis. Humpback whale presence was limited to the months of July to November. Bottlenose dolphins were present year-round and photo-identification of individuals indicated a closed, resident population, with an abundance estimate of 118 (CV = 21.6%, 95% CI 78–180). Small open-decked fishing vessels with gillnets were observed concentrated around river mouths within 2 km of shore, while commercial trawlers were at least 10 km offshore; all were confirmed to be registered and legal. Observations of marine turtles, flocks of marine birds, and floating logs and other debris were sparse. This multi-stakeholder collaboration to conduct a marine survey can serve as an effective model by which funding and logistic support from private industry paired with technical expertise from NGOs and academic institutions can benefit marine and coastal conservation.Keywords: fishing pressure, marine survey, Megaptera novaeangliae, photo-identification, relative abundance, Sousa teuszii, stakeholder engagement, Tursiops truncatus

The presence of tattoo-like skin disease is reported in an endangered, non-migratory subpopulation of Humpback Whales (Megaptera novaeangliae) from Oman. We examined 522 images taken during small-boat surveys in the Gulf of Masirah and in Dhofar in 2000-2006 and in 2010-2011. Tattoo-like lesions were detected in regular, good and outstanding images. They appeared as irregular or rounded, light grey marks often showing a whitish outline, and were located on the flanks, dorsum, dorsal fin and caudal peduncle. They could be relatively small to very large and cover up to an estimated 40% of the visible body surface. Over the whole study period disease prevalence reached 21.7% in 60 whales and 16.7% in 36 adults. In this category, prevalence was higher in males (26.7%, N=15) than in females (9.1%, N=11), but the difference was not significant. Lesions appeared larger in males than in the positive female and progressed in two males. Disease prevalence increased significantly from 2000 through 2011 (r2 =0.998). Advanced tattoo skin disease, with lesions extending over more than 10% of the visible body surface seemed to occur more frequently in 2010-2011 than in 2000-2006, but samples were small. This is the first confirmed report of tattoo-like disease in the Balaenopteridae family and the first time it is documented in the Arabian Sea. The disease high prevalence, its increase over time and its progression in some individuals are of concern.

Humpback whales in the Southern Hemisphere are separated by the International Whaling Commission (IWC) into seven wintering Regions (A-G) based on tropical distribution. To better evaluate the significance of these stock subdivisions, an analysis of mtDNA was conducted for the eastern and western South Atlantic (Regions A and B), the southwestern Indian Ocean (Region C) and the northern Indian Ocean (Region X). A total of 1,416 individual whales representing eleven sampling sites within the four wintering Regions were sequenced for a portion of the mtDNA control region. A hierarchical analysis of molecular variance (AMOVA) using FST and FST supported the division of wintering Regions based on IWC designated boundaries of A, B, C, and X. Pairwise comparisons further confirmed the A, B and C divisions, although varying degrees of heterogeneity (particularly molecular distances) were detected for proposed sub-divisions within Regions B and C. Overall, this large-scale mtDNA analysis for humpback whales in the Indian and South Atlantic Oceans supports wintering Region designations by the IWC. However, additional analyses and consideration of biological parameters such as gene flow are needed so that ‘within-region’ genetic analyses can help evaluate population structure and recovery in a management context.

Data are presented on beach cast cetaceans recorded in central and southern Oman between January 1999 and February 2000 during systematic beach surveys. Crude encounter rates of cetacean specimens are comparable with previous published data and indicate relatively high levels of mortality of Tursiops sp. and Sousa plumbea. Over two-thirds of specimens are recorded as stranding state V with cause of mortality unknown. Of the remaining specimens, empirical and circumstantial evidence for cause of death is suggestive of interactions with fisheries activities in the majority of cases. Direct evidence of interactions between cetaceans and fisheries, including information on incidental catch, is also presented. Other possible causes of mortality are hypothesised. Two mass strandings of small cetaceans are also discussed. Given the high numbers (725 records) and diversity (18 spp.) of beach cast cetaceans recorded in Oman, and the value of specimens to scientific study and conservation and fisheries management, recommendations are made to expand the scope of research and application of data.

The photo-identification catalogue of humpback whale tail flukes from Oman was compared with those from Antongil Bay, Madagascar and study sites in South Africa and Mozambique collectively termed the ‘East African Mainland’. No matches were found, supporting other lines of evidence that the humpback whales studied off the coast of Oman form part of a discrete Arabian Sea population, which adheres to a Northern Hemisphere breeding cycle, and has little or no ongoing exchange with the nearest neighbouring populations in the southern Indian Ocean. While the sample size from Oman is small, and low levels of ongoing exchange might not be detected in this type of catalogue comparison, the study nonetheless emphasises the need to pursue research and conservation efforts in the known and suspected range of the Endangered Arabian Sea humpback whale population.