Whales and waves: Humpback whale foraging response and the shoaling of internal waves at Stellwagen Bank

• Type: Article in International Scientific Journal
• Date: 2015

Authors

Jesus Pineda (Author) Other; Victoria Starczak (Author) Other; Jose C B da Silva (Author) FCUP; Karl Helfrich (Author) Other; Michael Thompson (Author) Other; David Wiley (Author) Other

Journal

Title: JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS

Vol. 120

Pages: 2555-2570

ISSN: 2169-9275

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 9 Citations

Scopus - 9 Citations

Scientific classification

FOS: Natural sciences > Earth and related Environmental sciences

Other information

Authenticus ID: P-00G-4NS

DOI: 10.1002/2014jc010564

Abstract (EN): We tested the hypothesis that humpback whales aggregate at the southern flank of Stellwagen Bank (SB) in response to internal waves (IWs) generated semidiurnally at Race Point (RP) channel because of the presence of their preferred prey, planktivorous fish, which in turn respond to zooplankton concentrated by the predictable IWs. Analysis of synthetic aperture radar (SAR) images indicates that RP IWs approach the southern flank of SB frequently (approximate to 62% of the images). Published reports of whale sighting data and archived SAR images point to a coarse spatial coincidence between whales and Race Point IWs at SB's southern flank. The responses of whales to IWs were evaluated via sightings and behavior of humpback whales, and IWs were observed in situ by acoustic backscatter and temperature measurements. Modeling of IWs complemented the observations, and results indicate a change of approximate to 0.4 m/s in current velocity, and approximate to 1.5 Pa in dynamic pressure near the bottom, which may be sufficient for bottom fish to detect the IWs. However, fish were rare in our acoustic observations, and fish response to the IWs could not be evaluated. RP IWs do not represent the leading edge of the internal tide, and they may have less mass-transport potential than typical coastal IWs. There was large interannual variability in whale sightings at SB's southern flank, with decreases in both numbers of sightings and proportion of sightings where feeding was observed from 2008 to 2013. Coincidence of whales and IWs was inconsistent, and results do not support the hypothesis.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 16