The finding of a Bryde's whale with abnormal upper jaw and baleen near Weizhou Island in the Beibu Gulf: implication for conservation

摘要

In the early 2018, the Bryde's whales(Balaenoptera edeni) began to appear around Weizhou Island in the Beibu Gulf. A Bryde's whale with abnormal upper jaw and baleen had attracted public's wide attention, its videos went viral on the internet. The individual had been sighted for ten times by our team, mostly (90%) occurred alone. It mainly occurred in the waters between Weizhou Island and Xieyang Island, ranging 14.0 km~2 in minimum convex polygon, and 166.9 km~2 in kernel density estimator. Unfortunately, this individual was found to be dead floating on the sea in March 30, 2019. According to the carcass sighting date of March 30, and its highly decomposed status, the death date of this whale was probably between March 25 and March 27, and the cause of death was unknown. Based on analyses of photos and anatomy, the reason for its abnormal upper jaw and baleen were possibly deduced to the damage by fishing nets or cord strangle. Subspecies status of this Bryde's whale individual cannot be identified only by morphology, thus mitochondria! DNA (mtDNA) D-loop and cytochrome b (Cyt b) were used to do the moleclar identification. Two sequences of 909 bp and 395 bp were obtained, respectively. Sequence blasting and phy-logenetic reconstruction suggested that this individual belonged to the coastal Bryde's whale subspecies (Eden's whale, B. e. edeni).Because the species migrate long distance seasonlly, it was not confirmed whether this Bryde's whale got injured by the fishing net or cord strangle in Chinese waters. Even though, the local authorities are supposed to strengthen the publicity of whale protection and reduce the disposal of marine litter, such as fishing net, and create safe habitat for Bryde's whales.