Biology and Conservation of Freshwater Cetaceans in Asia (2000)


Three finless porpoises (Neophocaena phocaenoides) from the Yangtze River were fitted with cotton cloth vests and small radio transmitters. They were tracked for 2.6, 11.0, and 14.6 days in the Swan Oxbow adjacent to the mainstem of the Yangtze River. The porpoises showed no adverse effects of the vests and appeared to feed normally. They dove for periods of 40 seconds to 4.03 minutes, interspersed with two to six surfacings of less than 40 seconds. As in captivity, the longest dives of three to four minutes, suggestive of feeding behavior, occurred during the day. Also, rapid movement (estimated at faster than 5km/hr) occurred during the day, never at night. All three tags fell off as predicted, the one with the quickest-release mechanism (lightly sewn) falling off earliest and the one with the most durable (heavily-sewn) attachments lasting the longest. Although this short-term tagging was successful in the relatively shallow (30m) oxbow, it is important to emphasize that longer-term vest attachments in deeper waters have not been demonstrated to be safe. Hence, other techniques must be investigated before re-considering vest attachments, which can lead to entanglement and cause abrasions if not applied properly.