Investigations on Cetacea (1986)


(…) This document attempts to gather together as much information as is available on the extent of current killings of small cetaceans throughout the world, and also to highlight some of the particular problems affecting individual species or populations.
The three main threats to small cetacean populations come from fisheries, which often take small cetaceans incidentally in nets, from directed “fisheries” for small cetaceans, and from habitat destruction or deterioration through pollution of one form or another or through dredging, drainage, siltation or infilling.
Even presented in this simplified way, it is clear from this that those species or populations most at risk are likely to be ones in shallow coastal water or rivers where human activities, including fishing, are concentrated. River dolphins are particularly vulnerable to any or all three of the above threats as their populations tend to be relatively small and isolated, in areas where there may be little escape from human interference.
Several other species, most notably the cochito which is probably the most endangered of all cetacean species, but also some populations of all the other porpoises (Phocoena spp.), the Irrawaddy dolphin, finless porpoise, and some Lagenorhynchus and Cephalorhynchus species are relatively confined in their distribution, and these too are vulnerable to human activities. (…)