Humpback whale study off Cabo San Lucas, Mexico

 

Since 2013 our group (with support from the non-profit Ocean Foundation) has been collaborating with the Universidad Autonoma Baja California Sur (UABCS) to study the acoustic environment off Cabo San Lucas during the winter humpback whale breeding season.  Punta Gorda and Cerros Colorados are locations with relatively little vessel traffic; Punta Ballena is near the mouth of Cabo San Lucas harbor.

Deployment locations of the three bottom-mounted hydrophones for the 2014 Cabo project. (Figure courtesy of Esther Jimenez).
Deployment locations of the three bottom-mounted hydrophones for the 2014 Cabo project. (Figure courtesy of Esther Jimenez).

A preliminary analysis of the 2013 deployments from Punta Gorda  indicates that there is a 24 hour cycle in the background noise levels between 50 and 500 Hz, which is dominated by humpback song:

 

10th, 50th, and 90th percentiles of integrated sound intensity between 50 and 500 Hz at Punta Gorda.  Note a diel (24 hour) cycle in the song; a minimum is reached between 8 and 10 AM each day.
10th, 50th, and 90th percentiles of integrated sound intensity between 50 and 500 Hz at Punta Gorda. Note a diel (24 hour) cycle in the song; a minimum is reached between 8 and 10 AM each day.

 

Close up view of several days at Punta Gorda.
Close up view of several days at Punta Gorda.

 

Near the harbor, however, humpback song no longer dominates the band, and the 24 hour cycle vanishes:

 

Humpback whale song no longer dominates the ambient noise near Cabo San Lucas harbor.
Humpback whale song no longer dominates the ambient noise near Cabo San Lucas harbor.

 

In 2013 our colleagues at UABCS began tagging animals with the Acousonde bioacoustic tag.  A summary of taggings to date:

Successful tag deployments during Year 2.  “Group type” refers to whether the tagged individual was part of a mating/competitive group or a mother/calf pair.  “Auxiliary Data” refers to whether additional accelerometer and depth data were logged.  The last four deployments turned off this feature in order to determine the source of electrical interference on the tag acoustic data.
Successful tag deployments during Year 2. “Group type” refers to whether the tagged individual was part of a mating/competitive group or a mother/calf pair. “Auxiliary Data” refers to whether additional accelerometer and depth data were logged. The last four deployments turned off this feature in order to determine the source of electrical interference on the tag acoustic data.

Here is a picture of what the tag looks like on a mother/calf pair on Feb. 21:

An Acousonde deployed on a humpback whale in Feb. 2013.  The red portion is a float that allows the device to send a radio signal once the package detaches from its non-invasive suction cups.
An Acousonde deployed on a humpback whale in Feb. 2013. The red portion is a float that allows the device to send a radio signal once the package detaches from its non-invasive suction cups.

 

Here are some samples of sounds recorded on the tags.

The escort of a mother/calf/escort group was tagged on March 13th. At 13:06, two whups follow a short exhalation.:

Three social calls from February 14th are shown here from a recording on a tag attached to a mother whale alone with her calf. It is likely that this call did not come from the mother, but rather from the calf alongside her as visual observations would indicate that no other whales were at the surface within a mile. The mother and calf stayed very close to the shore near Punta Palmilla for the first few hours of this recording:

Song can be captured on the acoustic tags from animals up to a few miles away. Two small competitive groups were on the surface at least a mile away from this tagged mother whale and her calf on February 14th at 11:52 when a song snippet was recorded:

On Feb 10 at 13:49, the escort of a 14-whale competitive group had been tagged. While the tag data overall would indicate that the group was rather acoustically inactive, the few recorded calls showed up clearly on the tag. This sample may be from an animal nearby the escort and not the escort itself.

One thought on “Humpback whale study off Cabo San Lucas, Mexico”

  1. We have had 5 successful tags to date (March 21st), insomuch that acoustic data was actually recorded during the deployment. Three of these tags have auxiliary data that could provide additional information about the diving behavior of the tagged whale itself.
    The successful tags include 9.75 hours of acoustic data from competitive groups and 13 hours from mother/calf pairs.
    A sixth tag is currently deployed on a competitive group.

Leave a Reply

Your email address will not be published. Required fields are marked *

We listen.

scripps oceanography uc san diego