VU

Vulnerable

A4cd

3.1

The species was listed as Data Deficient in 1996, but a great deal of new information has become available and five subpopulations have been listed as Critically Endangered since that time. Where the species has been studied: (1) subpopulation sizes are generally low (10s to low 100s) with the single exception of Bangladesh (approximately 5800), (2) there have been significant range declines, and (3) threats, especially bycatch and habitat degradation, have been well documented and remain severe and pervasive. Even within the largest known population of the species in Bangladesh (see above), opportunistic observations of deaths in drifting gillnets and reports from local fishermen suggest that bycatch rates are not sustainable (Smith et al. 2005).

At least a 30% reduction in the range-wide population size is suspected over a period of three generations (45-48 years), including the past and future, based on increasing levels of bycatch and habitat degradation in recent years. Generation length (15-16 years) was assumed to be similar to that of Sotalia fluviatilis – a species that lives in similar habitat and has similar, but better known, life history characteristics (Taylor et al. 2007 estimated generation length for S. fluviatilis as 15.6 years). The species therefore qualifies as Vulnerable A4cd. Given the vast area and complexity of coastline inhabited by this species, it is unlikely that a more quantitative assessment of the global population will be feasible in the near future.