Omar A Amir

Bottlenose dolphin (Tursiops sp.) populations often show small-scale genetic differentiation and have a capacity to adapt both their social strategies and structure to local environmental conditions. Here we investigate population structure and genetic diversity of Indo-Pacific ...

Marine mammal species diversity off Zanzibar and Tanzania, East Africa, has been recorded by the Marine Mammal Education and Research Group at the Institute of Marine Sciences, Zanzibar, Tanzania since 1998. The data presented in this report reflect the efforts of 10 years collection of information from marine mammals stranded and incidentally caught in Tanzanian waters. Additional information from dedicated surveys of cetaceans (whales and dolphins) and incidental sightings reported by the general public are also provided. From 1992 through 2008 a total of 235 specimens of 13 cetacean species and the dugong were recorded. 214 (90.7%) records referred to specimens from bycatch in drift and bottom-set gillnets and 22 (9.3%) referred to specimens from strandings. Based on incidental catch and sightings records, Indo-Pacific bottlenose, spinner and Indo-Pacific humpback dolphins, observed year-round, and humpback whales, observed seasonally during July to November, were the most common...

The level of incidental catches of dolphins in artisanal gillnet fisheries was investigated in a questionnaire survey of 101 gillnet vessel operators from 10 villages in Unguja island of Zanzibar, representing half of all the gillnet fishing fleet in 1999. A total of 96 dolphins were reported to have been incidentally caught between 1995 and 1999; 43 Indo-Pacific bottlenose dolphins ( Tursiops aduncus ), 29 spinner dolphins ( Stenella longirostris ), 5 IndoPacific humpback dolphins ( Sousa chinensis ) and 19 unidentified dolphins. Most of these incidental catches (46) were reported in 1999. We extrapolate that 93 animals may have been incidentally caught by the entire fishing fleet (201 vessels) during 1999. This estimate represents a serious cause for concern, suggesting that the incidental capture of dolphins in Zanzibar’s artisanal gillnet fisheries may be high enough as to have a significant negative impact on local populations. Further studies to accurately estimate the total b...

In developing regions, coastal communities are particularly dependent on small-scale fisheries for food security and income. However, information on the scale and impacts of small-scale fisheries on coastal marine ecosystems are frequently lacking. Large marine vertebrates (marine mammals, sea turtles and chondrichthyans) are often among the first species to experience declines due to fisheries. This paper reviews the interactions between small-scale fisheries and vulnerable marine megafauna in the southwestern Indian Ocean. We highlight an urgent need for proper documentation, monitoring and assessment at the regional level of small-scale fisheries and the megafauna affected by them to inform evidence-based fisheries management. Catch and landings data are generally of poor quality and resolution with compositional data, where available, mostly anecdotal or heavily biased towards easily identifiable species. There is also limited understanding of fisheries effort, most of which rel...

... Omar A. Amir a , b , Corresponding Author Contact Information , E-mail The Corresponding Author , Per Berggren c , Simon GM Ndaro d ... such as indicating what food a predator depends on, the predator's diving prowess, foraging behavior and ecology (Clarke and Kristensen ...

1 University of La Rochelle. LIENSS (Littoral, Environnement et Sociétés). UMR 6250 CNRS-Université de La Rochelle. 2 rue Olympe de Gouges, 17000 La Rochelle, France. 2 Direction de l'Environnement et du Développement Durable, Conseil Général de Mayotte, BP 101, ...

The conservation of humpback dolphins, distributed in coastal waters of the Indo-West Pacific and eastern Atlantic Oceans, has been hindered by a lack of understanding about the number of species in the genus (Sousa) and their population structure. To address this issue, we present a combined analysis of genetic and morphologic data collected from beach-cast, remote-biopsied and museum specimens from throughout the known Sousa range. We extracted genetic sequence data from 235 samples from extant populations and explored the mitochondrial control region and four nuclear introns through phylogenetic, population-level and population aggregation frameworks. In addition, 180 cranial specimens from the same geographical regions allowed comparisons of 24 morphological characters through multivariate analyses. The genetic and morphological data showed significant and concordant patterns of geographical segregation, which are typical for the kind of demographic isolation displayed by species units, across the Sousa genus distribution range. Based on our combined genetic and morphological analyses, there is convincing evidence for at least four species within the genus (S. teuszii in the Atlantic off West Africa, S. plumbea in the central and western Indian Ocean, S. chinensis in the eastern Indian and West Pacific Oceans, and a new as-yet-unnamed species off northern Australia).