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.