We’re going to be posting on news, stories, discussions and all things relevant to the 85 currently recognised species of cetacean! I say “currently” as cetacean genetics are still at an early stage for many taxa, meaning that we may not know where one species begins or ends. Some genera appear, in fact, to be in the process of speciation; for example the two distinct populations of the tucuxi (known as the “other dolphin” of the Amazon) are likely to be reclassified as two distinct species very soon - Sotalia fluviatilis, the “tucuxi” being the river population and Sotalia guianensis, the “costero”, the coastal marine.
To kick us off I’d like to congratulate the Government of India for their recent declaration of the Ganges River dolphin as India’s national aquatic animal… !!
Found in the Ganges-Brahmaputra-Meghna and the Karnaphuli-Sangu river systems and their tributaries, the Ganges River dolphin is one of the most endangered cetaceans with an estimated 2,000 individuals remaining in India. This estimate however is not reliable and a comprehensive population assessment is of paramount importance. In addition to being classified as “Endangered” by the IUCN, the Ganges River dolphin is listed under the United Nations Convention for Migratory Species (CMS) as an Appendix I species (migratory species that have been categorised as being in danger of extinction throughout all or a significant proportion of their range) and as an Appendix II species (migratory species that have an unfavourable conservation status or would benefit significantly from international co-operation). It is also listed as an Appendix I species by the Convention of International Trade in Endangered Species (CITES), prohibiting international trade in the species.
Due to their riverine habitats and subsequent proximity to humans, they face more threats than other species of cetacean, and all in an extremely restricted habitat. Although now greatly reduced, there is some deliberate, illegal killing of Ganges River dolphins. They are taken due to the perceived fisheries competition, the value of their oil in traditional medicines, as bait, and for food. More significant however is habitat degradation due to declining flow, heavy siltation, increased growth of aquatic plants, chemical pollution and the construction of barrages, causing a physical barrier to these animals, isolating populations. Accidental capture in fishing operations, especially gill nets is also a major concern.
Let us just hope that this declaration of “national aquatic animal” for the remaining dolphins actually means proper conservation measures will be implemented and the drastic decline in population numbers can be reversed. Like it’s terrestrial counterpart, the tiger, only immediate and dedicated action can prevent this iconic species from enduring the same fate as the baiji, which was classified as “functionally extinct” not so long ago.
Interestingly, the Ganges River dolphin (or as it is otherwise referred to, the South Asian river dolphin) is another example of a genera in the process of speciation, as the classification continues to be hotly debated in scientific circles. Originally thought to be the same species, the Indus ‘bhulan’ and Ganges ‘susu’ were listed as separate species in 1971 due to apparent differences in skull structure and blood proteins. This speciation however, has never been fully accepted and currently the two populations are recognised as sub-species of the species Platanista gangetica; those found in Nepal, India and Bangladesh are classified as P.g. gangetica while those found in the Indus River in Pakistan are known as P. g. minor. WDCS has been funding research to help resolve this dispute (http://www.wdcs.org/protect/species/story_details.php?select=385 ... scrolling down to Pakistan) … so stay tuned for further updates!
Check out the following links if you want to learn more about river dolphins - http://www.wdcs.org/protect/river_dolphins/index.php - and/or the projects that WDCS supports - http://www.wdcs.org/protect/species/story_details.php?select=46