Red List Category Year Assessed
Critically Endangered Red List Criteria
Reeves, R.R., Dalebout, M.L., Jefferson, T.A., Karczmarski, L., Laidre, K., O’Corry-Crowe, G., Rojas-Bracho, L., Secchi, E.R., Slooten, E., Smith, B.D., Wang, J.Y. & Zhou, K. Reviewer/s
Brownell Jr., R.L. & Cooke, J. (Cetacean Red List Authority) Contributor/s Justification
The total population (all ages) was estimated at about 100 individuals in the mid-2000s and the extent of occurrence is only a small stretch of coastal waters off western Taiwan
(estimated to be ca. 515 km2
). Given the number of development projects that are underway or proposed, and the fact that only minimal or no conservation measures are in place to reduce the probable impacts of the various threats (e.g., bycatch in net fisheries, severe reduction of freshwater flow to estuaries, land reclamation), a continuing decline in the subpopulation is projected. Although there is no prospect of obtaining a long enough time series of data to show a decline over the last three generations (about 60 years; see Taylor et al.
2007), a decline almost certainly has occurred (at least since the beginning of Taiwan’s rapid industrialization about 30 years ago) and there is no reason to believe that the causes have stopped, or even slowed. Therefore, it is reasonable to project a continuing decline and this subpopulation meets criterion C2a(ii) for Critically Endangered (total of fewer than 250 mature individuals, projected continuing decline, and at least 90% of mature individuals in a single subpopulation). This subpopulation also may meet criterion D for CR because the total number of mature individuals may be close to (or fewer than) 50 (depending partly on the value used to estimate percent mature – 60% from Jefferson (2000) or 50% from Taylor et al