Anthropogenic Threats and Conservation Needs of Blue Whales, Balaenoptera musculus indica, around Sri Lanka

Blue whales in the Northern Indian Ocean are a morphologically and acoustically distinct population restricted to these waters. Off Sri Lanka a portion of the population concentrates near shore where they are exposed to a range of anthropogenic threats. We review available data to determine anthropogenic threats/stressors faced by this population and assign subjective rankings for the population-level severity of each threat/stressor based on severity, scope, and immediacy. With the cessation of direct illegal catches on this population in the late 1960s, we ranked ship strike as the most important population-level threat. Incidental catch, which includes entanglement and bycatch, is also important as it can result in death. Other less important stressors that may negatively impact this population include threats resulting from oil and gas development and pollution. However, some stressors can have a long-term cumulative impact that is difficult to assess. The most important research needed for the conservation of these whales is to obtain an estimate of the size of the population using photo-identification methods.