Spatial and seasonal patterns in acoustic detections of sperm whales Physeter macrocephalus along the continental slope in the western North Atlantic Ocean

Je Stanistreet,Lew Hodge,Dp Nowacek,Jt Bell,Sm Van Parijs,Ja Hildebrand,Dm Cholewiak,Aj Read

doi:10.3354/esr00867

Abstract

Spatial and seasonal patterns in acoustic detections of sperm whales Physeter macrocephalus along the continental slope in the western North Atlantic Ocean

Highlights

The seasonal distributions of many pelagic cetacean species are poorly known, owing to their highly mobile lifestyle and the vast extent of their oceanic habitat, which makes habitat-scale observations exceedingly difficult
Presence followed the same trend across recording sites, We analyzed more than 48 000 h of passive acoustic but was slightly lower at Georges Bank (21% of rerecordings collected across the 5 study sites, with the cording hours) than at Cape Hatteras (23% of recordhighest recording effort at the Cape Hatteras and ing hours), likely due to substantial underestimation
Sperm whale clicks were detected in all seasons of duty-cycled recording schedules employed at On- the year at each recording site, with considerable slow Bay and Georges Bank indicated that daily temporal variability in the number of hours per day presence was not substantially underestimated in the with detections (Fig. 3)

Summary

INTRODUCTION

The seasonal distributions of many pelagic cetacean species are poorly known, owing to their highly mobile lifestyle and the vast extent of their oceanic habitat, which makes habitat-scale observations exceedingly difficult. Most information on sperm whale occurrence and abundance in US waters in the past few decades has come from dedicated shipboard and aerial visual surveys conducted over the continental shelf and along the shelf break and slope regions during spring and summer months, when weather conditions are most favorable for visual observation. To overcome this seasonal bias in cetacean occurrence data, passive acoustic monitoring is increasingly being used to obtain continuous records of species presence throughout the year, especially in remote offshore regions that are difficult to access, during the winter. We analyzed passive acoustic recordings collected between Florida and New England to provide new baseline information on year-round sperm whale presence in this region, and to determine whether there is evidence of seasonal shifts in the relative occurrence of sperm whales across recording sites

MATERIALS AND METHODS

RESULTS

Findings

DISCUSSION