No quantitative estimates of population trends are available, but significant range declines in Tonle Sap (Great Lake) and the Mekong mainstem below Kratie imply that the number of dolphins in the Mekong River has declined substantially over the past several decades. Also, for small cetaceans generally, it is recommended that yearly removals should not exceed 1?2% of the population size (Wade 1998) ? the lower bound being more applicable to very small populations that are already vulnerable because of demographic and genetic factors. Four deaths per year (the mean number of carcasses recovered and determined to have died from gillnet entanglement in 2001?2003; Beasley et al. [2002] and Beasley [unpublished]) would represent 5.8% of the population, assuming a best estimate of abundance of 69, based on pool count surveys. Considering that the small size of the Mekong population already makes it vulnerable from demographic stochasticity, inbreeding depression and catastrophic environmental and epizootic events, the current rate of incidental mortality in gillnets will almost certainly lead to extirpation.

Decreasing