Estimating abundance of sperm whales (Physeter macrocephalus) in the Gulf of Mexico from acoustic data collected during the NOAA Cruise GU-09-06 (054)

• Main Author: Kirkpatrick, Aaron
• Format: Other/Unknown Material
• Language: unknown
• Published: Scholarly Repository 2014
• Subjects: sperm whale; Physeter macrocephalus; NOAA; Gordon Gunter; research cruise; Environmental Sciences; Gunter; Sperm whale
• Online Access: https://scholarlyrepository.miami.edu/rsmas_intern_reports/143; https://scholarlyrepository.miami.edu/cgi/viewcontent.cgi?article=1142&context=rsmas_intern_reports

Sperm whale (Physeter macrocephalus) abundance was estimated for the northern Gulf of Mexico from data collected during a line-transect abundance cruise carried out onboard the NOAA ship Gordon Gunter in 2009. Acoustic and visual data were collected between 16th June and 13th August 2009. Initially, a 5-element array was used to collect data,but the instrumentation failed early in the cruise and was replaced with a backup 2-element array. Click detections, click train associations, localization and perpendicular distance measurements were analyzed with PAMGUARD (ver.1.12.04), and the program DISTANCE was used for estimating abundance. A total distance of 8950.82 km was surveyed for acoustic data (6051.98 during day surveys, 2898.84 during night surveys). Acoustic surveys detected 74 groups of sperm whales (day = 52, night = 22),and a total of 271 acoustic detections were identified in PAMGUARD (187-day, 84 night). Comparatively, visual assessments identified only 43 groups of sperm whales. Estimated abundance from acoustic data was 2346 (CV=28.96) individuals, while visual abundance estimates were 763 (CV=0.38) individuals. Acoustic surveying identified more individuals, allowed for night sampling, and provided a more precise abundance estimate.