Day Five
The visual team is happy to report having their most exciting day so far. The winds were fair, the waters calm, and the sightings of dolphins and whales were abundant. Today’s lineup of 17 sightings included two mixed species groups: one a group of Risso’s dolphins and an unidentified toothed whale or dolphin, and one group of bottlenose dolphins and Atlantic spotted dolphins. The latter is the most commonly encountered mixed species grouping in the Gulf of Mexico.
The acoustics team spent the morning troubleshooting and preparing their equipment for data collection. After 4 hours of surveying with two detections, they retrieved the array to traverse shallower waters. They took advantage of this time to do some maintenance on the tow cable before redeploying in deeper waters to continue the survey.
The bird team reported more than 100 sightings today! Highlights included bridled terns, sooty terns and a white-tailed tropicbird. We are on day 5 of booby sightings … will we see one every day of the survey? Stay tuned!
Shout out to Jonny Reid for capturing some amazing photographs today! We are lucky to have his skills on this survey!
Moving on…
Days Six and Seven
We hope everyone had a relaxing weekend ashore. Aboard NOAA Ship Gordon Gunter, it was business as usual for survey operations. As we approached the southern end of our eastern track lines, the visual team was spoiled with excellent, albeit warming, conditions.
On Saturday, there were 11 sightings but only one of them was close enough to the ship to be identified to species. Sunday ended with nine sightings, four of which were identified to species. Highlights included spinner dolphins, pygmy killer whales, and pilot whales.
Sometimes animals cannot be identified to species due to sea state, weather conditions, or distance from the ship. Rather than guessing what species an animal might be, visual observers aggregate identifications to a broader taxonomic category. For example, using skills they have gathered from years of experience observing animals, they know they are looking at a group of small dolphins as opposed to beaked whales, but not necessarily the genus or species of the dolphins.
This weekend started out quiet for the acoustics team, both figuratively and literally, with zero acoustic detections on Saturday despite 13.5 hours of effort. Sunday had some excitement with the detection of a sperm whale, an unidentified dolphin species, and a species of the genus Kogia—either a pygmy or dwarf sperm whale—before retrieving the array for the afternoon due to shallow waters. Similar to the visual team, the acousticians only identify separate species when they are extremely confident in the acoustic signals.t The two species in the Kogia genus, pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales, both produce narrow-band high-frequency echolocation clicks. These clicks differentiate them from other toothed-whale species that occur in the Gulf, but not from each other.
The weekend update for the bird team consisted of two red-billed tropicbirds followed by a brown phase red-footed booby. As the ship approached the waters off of the Dry Tortugas National Park, Florida, large feeding flocks of sooty terns appeared. At the close of observations on Sunday they observed a steady stream of sooty terns flying back to their nesting area in the Dry Tortugas. With the first week of the survey coming to an end, the bird team has sighted a total of 18 different bird species!
That’s the news! Good night, and have a pleasant tomorrow – The Survey Crew
Answer to the “guess this species” photo: spinner dolphins!
