Behaviour and habitat selection of Yangtze finless porpoises in Dongting Lake, China, and the adjacent waters: Impact of human activity

Seven ecological surveys on the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) were carried out in Dongting Lake, China, and the adjacent waters between September 2006 and January 2010 using the line transect sampling method. The surveys covered a total of 2135.1 km, and 954 individuals were observed in 419 sightings. Among these sightings, traveling behaviour was predominant (52.5%), followed by infant care (19.3%), foraging (14.8%), socializing (1.0%) and resting (1.0%). A total of 68.0% of sightings (285 sightings) belongs to the situation that these behaviours occurred within or near the classified habitats (soil bank, river and lake confluences, riffles, islets, open water, sand bars, rock banks, water channels within the sand bar, eddies and areas with mixed currents, and river bends). Among these 285 sightings, traveling, infant care and foraging behaviours predominantly occurred near soil banks (35.1%, 12.6% and 4.9%, respectively). A total of 73.7% of sightings (309 sightings) belonged to the situation in which five behaviours were associated with at least one human activity (shipping, fishing, pollution, dredging and hydroprojects). Among these 309 sightings, traveling was predominantly associated with shipping (22.7%), followed by fishing (8.7%), pollution (6.8%) and dredging (1.6%). For infant care, it was shipping (5.5%), fishing (3.6%), pollution (1.9%) and hydro-projects (0.3%). For foraging, it was fishing (7.4%), shipping (3.2%), pollution (1.0%) and dredging (0.6%). To protect Yangtze finless porpoises in Dongting Lake and the adjacent waters, over-fishing and illegal fishing operations should be banned, and boat traffic should be urgently managed, particularly close to soil banks.