Document Type

Internship Report

Publication Date

Fall 2014

Abstract

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.

Comments

Department: MBF

MPS Track: MMS

Location: NOAA Cruise GU-0906 (054), Gulf of Mexico

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