Fiordland bottlenose dolphin population redlisted as Critically Endangered

The Fiordland subpopulation of common bottlenose dolphins (Tursiops truncatus) inhabits the fiords and bays of Fiordland, a mountainous, rainforest-covered World Heritage Area in the southwest of New Zealand’s South Island.  These dolphins are at the southern limit of the species’ global range and recent studies have shown them to be genetically and geographically isolated from bottlenose dolphins elsewhere in New Zealand.

The subpopulation was estimated to consist of only205 individuals in 2008, of which 123 were mature. In a Population Viability Analysis, more than two thirds of the model runs predicted a decline of > 25% over one generation and more than a third predicted a decline of > 80% over three generations.  As a result, the Fiordland Bottlenose Dolphin subpopulation was assessed as Critically Endangered (A3bcd;C1).  For the full assessment, which was completed in 2010, see http://www.iucnredlist.org/apps/redlist/details/194300/0

New Red List Assessments for Two Species of Finless Porpoises

CSG member John Wang and collaborators recently presented strong morphological and molecular evidence for reproductive isolation of two main forms of finless porpoises in sympatry, leading to the conclusion that there are at least two biological species: the Indo-Pacific finless porpoise (Neophocaena phocaenoides) and the narrow-ridged finless porpoise (Neophocaena asiaeorientalis). The latter has two recognized subspecies: the Yangtze finless porpoise (N. a. asiaeorientalis) and the East Asian finless porpoise (N. a. sunameri). View the list of marine mammal species and subspecies recognized by the Society for Marine Mammalogy’s Committee of Taxonomy

One consequence of the revised taxonomy of finless porpoises was the need for separate IUCN Red List assessments.  New assessments of the two species were included in the Red List in 2011. Both species were assessed as Vulnerable (A2cde) based on the fact that they are experiencing high and likely unsustainable levels of mortality in fisheries over much of their range, with essentially no mitigation of this threat anywhere finless porpoises exist. The evidence of large declines in several regions led assessors to infer species-wide declines of at least 30% over the past three generations.

Although the primary immediate threat to finless porpoises comes from fisheries, they are also at risk from habitat degradation or destruction, pollution, and noise, especially given that they live in coastal waters adjacent to some of the densest concentrations of humans in the world.  Difficulties of studying finless porpoises, which are small, lack a dorsal fin and avoid vessels, have meant that we lack even some of the most basic biological information about them (e.g., number of species/subspecies, population structure and abundance).  For all of these reasons, there is great concern about the future of these animals.

Solomon Islands dolphin project: Progress report

As a follow-up to the Solomon Islands dolphin workshop held in Samoa in 2008 (see Special Projects, Solomon Islands), Marc Oremus and colleagues have been conducting field research in the Solomons to obtain abundance estimates of Indo-Pacific bottlenose dolphins in the area where the recent live-capture for export operations have been centered. In the course of this work, they have also obtained interesting new data and information on other cetaceans in the region and on the traditional drive hunt for small cetaceans at Malaita.

To view or download a June 2011 progress report on this work by Oremus et al., click here:

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