Abstract:

This dataset contains a listing of the acquisition times for a subset of Littoral Acoustic Demonstration Center (LADC) passive acoustic Environmental Acoustic Recording System (EARS) buoys data collected from 2015-06-27 to 2015-07-24. Data from Buoy 3 (28.65173°N, 88.52617°W) and Buoy 4 (28.65091°N, 88.51998°W) are used to estimate the length of sperm whales in the northern Gulf of Mexico. Wavelet techniques were applied to determine the inter-pulse intervals (IPIs) of echolocation clicks. The equations of Gordon (1991) and Growcott (2011) were used to calculate the lengths of the whales from the IPIs.

Suggested Citation:

George Drouant, Juliette Ioup. 2020. Sperm whale lengths determined using interpulse intervals of echolocation clicks recorded in the northern Gulf of Mexico from 2015-06-27 to 2015-07-24. Distributed by: GRIIDC, Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7319THR

Purpose:

Passive acoustics are filtered for sperm whale echolocation clicks to determine the body size of sperm whales. Body size comparisons between sites and years may highlight trends in age, as well as the distribution and trends in sex difference.

Data Parameters and Units:

day, hour, minutes, seconds, seconds from new year, fraction of day (converted hours, minutes, seconds from the file timestamps into a fraction of 24 hours), day+fraction of day, fileindex, p0 (first pulse of a sperm whale's echolocation click), p1 (second pulse of a sperm whale's echolocation click), p0_p1 interval (interval between the p0 and p1 pulses given in both sample intervals and milliseconds), length (calculated length of sperm whale using p0_p1 interval).

Methods:

Two equations were used to estimate the length of the whales, depending on size class. If the whale was less than 11 m long, Gordon’s equation (1991) was used: Length [meters] = 4.833 + (1.453*IPI_) -_ (0.001_*_ IPI^2) If the whale was longer than 11 m, the equation of Growcott (2011) was used: Length [m] = 5.736 + (IPI * 1.258) In both cases IPI, the interpulse interval, is expressed in milliseconds, eg IPI = 5 is 0.005 seconds.

Provenance and Historical References:

Gordon, J. C. D. (1991). Evaluation of a method for determining the length of sperm whales (Physeter catodon) from their vocalizations. Journal of Zoology, 224(2), 301–314. doi:10.1111/j.1469-7998.1991.tb04807.x Growcott, A., Miller, B., Sirguey, P., Slooten, E., & Dawson, S. (2011). Measuring body length of male sperm whales from their clicks: The relationship between inter-pulse intervals and photogrammetrically measured lengths. The Journal of the Acoustical Society of America, 130(1), 568–573. doi:10.1121/1.3578455

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