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- Title
Frequent and prolonged nocturnal occupation of port areas by Yangtze finless porpoises ( Neophocaena asiaeorientalis): Forced choice for feeding?
- Authors
WANG, Zhitao; AKAMATSU, Tomonari; MEI, Zhigang; DONG, Lijun; IMAIZUMI, Tomohito; WANG, Kexiong; WANG, Ding
- Abstract
During the Yangtze Freshwater Dolphin Expedition 2012, Yangtze finless porpoises ( Neophocaena asiaeorientalis) were acoustically monitored in 9 port areas at night. During 6566 min of nocturnal monitoring, porpoise sonar was detected for 488 min (7.43% of the total time). Of all 81 encounters, the longest echolocation span obtained was 102.9 min, suggesting frequent and prolonged porpoise occupation of the port areas. A combined total of 2091 click trains were recorded, with 129 (6.2%) containing minimum inter-click intervals (ICIs) below 10 ms (termed a buzz). Buzzes with a decrease in ICIs and search and approach phases that resembled feeding echolocation signals accounted for 44.2% ( N = 52) of all buzzes. Buzzes with an increase in ICIs, suggesting a mirrored prey capture phase, accounted for 20.2% ( N = 26) and could reflect attempts to locate escaped prey because they were followed by approach-phase feeding buzzes. Anecdotal evidence of porpoises fleeing the proximity of vessels was observed. The recordings indicating clusters of porpoises feeding near the port areas suggest a forced choice for feeding due to the relatively higher prey availability in the port areas compared to other areas in the Yangtze River that are probably overfished.
- Subjects
FINLESS porpoise; NOCTURNAL animal activity; ECHOLOCATION (Physiology); MARINE mammals; PREDATION; MAMMALS; FOOD
- Publication
Integrative Zoology, 2015, Vol 10, Issue 1, p122
- ISSN
1749-4869
- Publication type
Article
- DOI
10.1111/1749-4877.12102