The long-term variation of the catches on the prey fish of Chinese white dolphins ¡]Sousa chinensis¡^at western Taiwan

Whales and dolphins, especially small cetaceans which inhabit rivers and coastal waters, are under the threats from environmental change, habitat destruction, and pollution. Since previous studies haven¡¦t deeply explored the relationship between marine mammal conservation and fishery catches, in this study, we focused on the objective is on the correlation between fishery catches and feeding sources of Chinese white dolphin. About 17 years (1993-2009) of fish catch data from fishery annual reports in the six counties (from Miaoli to Tainan) along the western coast of Taiwan, was used as the data source of the meta-analysis, which set four major prey categories of Chinese white dolphin, i.e., primary prey fish, secondary prey fish, potential prey fish and other prey fish.The study showed the following nine results. First of all, the change of total amount of fish production in six counties was changing irregularly¡Fin recent years, the amount of potential prey fish and other prey fish catches were increasing. Secondly, the decline of primary prey fish was due to the reduced production of Mugilidae . Thirdly, the secondary prey fish catch formed the major catches during 1999-2004 while Sparidae species was the dominated species. The potential prey fish amount was consistent, except in 1994 when Chanidae production was extremely high, making it the major components species. In accordance with Chinese white dolphin distribution hot spot, north hot spot primary prey fish families were Sciaenidae and Trichiuridae. In addition, the amount of south hot spot was irregularly distributing during 1999-2004. For the non-hot spot in the Changhua¡¦s coast, the prey fish production of Mugilidae was decreasing year by year and the non-hot spot in the Tainan¡¦s coast, the prey fish was mainly composed of other prey fish after 2002. However, in these 17 years, the number of fishing vessels increased, yet the total catch decreased. This may imply that the coastal fishery resources is depleted.The discussion on improvement about the fishery annual report and prey resources investigation were also made. At the last, we proposed two suggestions on the issues about hot spot management and enhancing fishery resources restoration.