Maelezo ya mafunzo : hifadhi ya kasa na nguva

Sharks and their relatives, the rays and chimaeras, are the diverse group of cartilaginous fishes that have evolved over 400 million years. Historically considered of low economic value to large-scale fisheries, today many of these fishes have become the target of directed commercial and recreational fisheries around the world, and they are increasingly taken in the by-catch of fisheries targeting other species.
Consistent evaluation and new recommendations for action are required of protective measures to address threats that were unrecognised or non-existent until recently. Global warming, noise pollution and reduced availability of prey are now of great concern. The all too familiar threats of accidental killing in fishing gear and exposure to toxic chemicals remain almost intractable. This Action Plan reviews threats and offers possible solutions.
These proceedings provide an overview of the ongoing research and management activities on polar bears in the circumpolar arctic. Together with the previous 12 proceedings, they provide an historic record of international efforts in protecting polar bears from over-harvest and document more recent concerns of threats arising from increased human activities in both the Arctic and in regions far beyond the realm of polar bears.
The fourth part in a series of action plan, this publication covers less than one-quarter of the world's antelope species that are found in North Africa, the Middle East and Asia. Herds numbering in the tens of thousands formerly occurred across the steppes and semi-deserts of Eurasia and India, but these have nearly all been reduced to fractions of their earlier size. Populations are fragmented across the region and several species have disappeared altogether during recent decades.
Although most antelope species still exist in large numbers in sub-Saharan Africa (some in hundreds of thousands), up to three-quarters of the species are in decline. Threats to their survival arise from the rapid growth of human and livestock populations, with consequent degradation and destruction of natural habitats, and excessive offtake by meat hunters.