Indo-Pacific Humpback Dolphin Occurrence North of Lantau Island, Hong Kong, Based on Year-Round Passive Acoustic Monitoring
Indo-Pacific humpback dolphin occurrence north of Lantau Island, Hong Kong, based on year-round passive acoustic monitoring Lisa Munger,1,a) Marc O. Lammers,1,2 Mattie Cifuentes,1 Bernd Wursig,€ 3 Thomas A. Jefferson,4 and Samuel K. Hung5 1Oceanwide Science Institute, P.O. Box 61692, Honolulu, Hawaii 96839, USA 2Hawaii Institute of Marine Biology, P.O. Box 1346, Kaneohe, Hawaii 96744, USA 3Department of Marine Biology, Texas A&M University, 200 Seawolf Parkway, OCSB #243, Galveston, Texas 77553, USA 4Clymene Enterprises, Lakeside, California 92040, USA 5Hong Kong Cetacean Research Project, Lam Tin, Kowloon, Hong Kong (Received 4 February 2016; revised 24 August 2016; accepted 9 September 2016; published online 18 October 2016) Long-term passive acoustic monitoring (PAM) was conducted to study Indo-Pacific humpback dol- phins, Sousa chinensis, as part of environmental impact assessments for several major coastal development projects in Hong Kong waters north of Lantau Island. Ecological acoustic recorders obtained 2711 days of recording at 13 sites from December 2012 to December 2014. Humpback dolphin sounds were manually detected on more than half of days with recordings at 12 sites, 8 of which were within proposed reclamation areas. Dolphin detection rates were greatest at Lung Kwu Chau, with other high-occurrence locations northeast of the Hong Kong International Airport and within the Lung Kwu Tan and Siu Ho Wan regions. Dolphin detection rates were greatest in sum- mer and autumn (June–November) and were significantly reduced in spring (March–May) com- pared to other times of year. Click detection rates were significantly higher at night than during daylight hours.
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