Whales, Dolphins, and Beautiful Skies—Oh, My!

Day Eight

We spent the morning moving away from inclement weather building in the southeastern Gulf of Mexico. The winds were slightly higher with an average sea state near Beaufort 3. It was a slow day for the visual team who only encountered one sighting of unidentified dolphins.

Transiting through deeper waters normally results in acoustic detection of one of the deep diving species, but our trackline was quiet today with zero detections. We are hoping for some action tomorrow as we steam northeast towards the shelf edge.

Even quiet days are important for refining our understanding of the abundance and distribution of marine mammals in the Gulf.

We are hoping for more sightings and detections, it is simply more exciting that way!

Steamin' and dreamin' - The Survey Crew

Day Nine

We spent the day cruising northeast along our next trackline and made it up the slope onto the continental shelf in the late afternoon.

The visual team had a flurry of sightings from around dinner time until sunset, making an exciting end to an otherwise slow day. Species identified include pantropical spotted dolphins, Risso's dolphins, and common bottlenose dolphins.

Acoustics finally broke the silence with an afternoon of detections, including two sperm whales and many unidentified dolphins. We also saw a sneaky toothed whale who vocalized while the team was deploying the array early this morning.

Keep on keepin` on - The Survey Crew

Day 10

Today, we completed another trackline and turned onto the next shortly after lunchtime, heading west-southwest with calm conditions. It seemed like Groundhog Day for the visual team, who saw similar species the day before. They had 10 sightings (again) featuring Risso's dolphins and common bottlenose dolphins, the latter of which ran to the ship to ride the bow wave on the Gordon Gunter.

This is one time where a photo really fails to capture the true excitement of a large dolphin running to the bow.

The acoustics team spent the morning conducting maintenance as we surveyed in shallow waters. After lunch, in deeper waters, we dropped in the acoustics array. With the influx of detections we got late last night, we were hoping for more of the same. However, it was quiet. There was one acoustic detection of dolphins that came to sing some karaoke into the hydrophone and then a last-minute toothed whale detection at the end of the day's effort.

Day 11

Sightings today were slightly slower for the visual team. As we surveyed the remainder of the trackline we were on and began rolling along the next, highlights included a Cuvier's beaked whale-sometimes called goose-beaked whales-and some pantropical spotted dolphins. We have been experiencing relatively nice weather all week, although the average sea state has been slightly higher (more than 3-foot seas) compared to before we made the jump to the current trackline (where we had less than 2-foot seas).

Our acoustics team was busy today with nine detections-mostly unidentified toothed whales or dolphins. However, one confirmed whale of the genus Kogia(either a dwarf sperm whaleor pygmy sperm whale) made an appearance. These sightings are always exciting because these whales spend very little time at the water's surface, almost never approach vessels, and have a very low profile so are difficult to see. Surprisingly, this deepwater day has been dominated by unidentified biological clicking, likely from patches of sargassum which are home to surprisingly loud communities of marine life!

There is Saharan dust blowing into the Gulf this week making some spectacular skies! If you haven't heard of it, dry, dusty air that forms over the Sahara in Africa travels across the Atlantic Ocean in the atmosphere. NOAA's Atlantic Oceanographic & Meteorological Laboratory continuously monitors the Saharan Air Layeras it "has been shown to suppress tropical cyclone formation and intensification." NOAA scientists use satellites to detect and monitor this air layer. We can also see it with our own eyes in the form of colorful orange-tinged skies.

Day 12

The acoustics team heard dolphin whistles as soon as they started recording, which was a promising start to the day. This was followed by four sperm whale detections, one of which was localized to an individual 5,000 meters away. The day ended in the shallow waters where they had to retrieve the hydrophone to protect the equipment (and our sanity) from the endless sound of snapping shrimp!

The visual team had several sperm whale sightings, which they had not seen since the first few days of Leg 1. There were also unidentified dolphins and pantropical spotted dolphins. We finished up another trackline today in the northeastern Gulf. The sea state was higher for most of the day, but settled nicely after dinner at 4 p.m.

Stay tuned!

- The Survey Crew

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