Whitlow Au

Publications (2)3.1 Total impact

• Article: Estimating the biosonar detection range of mesopelagic patches by spinner dolphins.

  Whitlow Au, Marc Lammers, Jokob Jung
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  ABSTRACT: Spinner dolphins (Stenella longirostris) in the near-shore waters of the Hawaiian islands forage on the mesopelagic boundary community (mbc) of organisms consisting of myctophids, mid-water shrimp and small squids. They forage at night and supposedly in a coordinated fashion and in groups between 16 and 24 animals that are divided into pairs. In the search phase of the foraging process, the dolphins are thought to be spaced in a V-shape formation with the tip of the "V" at the deepest depth, and swim parallel to shore hunting for patches of prey that they can encircle and herd into a tight three-dimensional patch. A profiler housing a broadband echo-ranger that projected dolphin-like biosonar signals was used to measure the target strength of the mbc based on a dolphin's integration window of 264 μs. The bottlenose dolphin, Tursiops truncatus, was used as a proxy to estimate the biosonar detection ranges of Stenella longirostris searching for mbc patches because only limited acoustic research has been performed with spinner dolphins. Using the sonar equation, the biosonar threshold detection range of spinner dolphins was estimated to be approximately 50 to 64 m, more than sufficient range for the animals to formulate their prey herding behavior.
  The Journal of the Acoustical Society of America 04/2012; 131(4):3359. · 1.55 Impact Factor
• Article: Variation in the songs of humpback whales (Megaptera novaeangliae) wintering in the Northwestern and Main Hawaiian Islands.

  Jessica Chen, Marc Lammers, Whitlow Au
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  ABSTRACT: A study of the humpback whale song in the Northwestern Hawaiian Islands (NWHI) and the Main Hawaiian Islands (MHI) during the 2009 season suggests that humpback whale song may be more variable than previously suggested. Data from five autonomous acoustic recorders deployed at locations in the NWHI and MHI were analyzed to compare the frequency of occurrence of song units by whales in the island chain. There appears to be a gradient of differences in song units throughout the Hawaiian Island chain, rather than the previously assumed, more discrete differences between breeding populations. Recordings from each site were randomly selected. Song units were classified as one of 23 units and counted to compare between sites. Changes in the frequency of occurrence in a few of the most abundant units suggest a gradual change throughout the island chain. However, this may be confounded by changes that occur throughout the season throughout the ocean basin. Further work examining the amount of variation both between and within humpback whale breeding populations should be conducted.
  The Journal of the Acoustical Society of America 04/2012; 131(4):3457. · 1.55 Impact Factor