Weedlines: A Sargassum Blog

PS-19-05 Daily Log

June 2, 2019 (Day 6)*

*Note: these will be posted on a one-day delay, i.e., this report is for yesterday’s activities.

We hope you enjoyed yesterday’s blog entry. Remember we also post throughout the day on the @larvalfishlabTwitter account, so follow us there as well!


Photo: Sandra Huynh

Welcome back to the offshore waters of the Gulf of Mexico, where the price you pay for calm seas and light winds is blazing sun and stifling heat. We are going through sunscreen and Gatorade like crazy, but having fun and getting lots of great data on this, the last cruise for our NOAA RESTORE Sargassum project.

Last night we steamed west, having earlier followed the southward flow of the Loop Current to within 100 miles of the Cuban EEZ! Our sampling permits don’t work down there, so we needed a new direction. Our westward track had us crossing the ‘loop’ over night, and by breakfast we had arrived near the northerly flow of the Loop Current. Finding ourselves in relatively open water, we decided to do our open water station first. Following our CTD cast and water sample collections, we towed the neuston, deuceton, and frame trawl nets, and in each instance we collected relatively few larvae or juvenile fishes. So pretty much a ‘desert’ in the open water area inside the ‘loop’ today, at least in our location.


April Hugi records data which is one of the most important jobs on a research cruise. (Photo: Sandra Huynh)

After completing the open water ops, we steamed further west to get closer to the northerly flow of the Loop Current. We decided to sample in a region where there were numerous, small-to-medium Sargassum patches. After collecting our CTD and water samples, we towed our neuston net along a small weedline and had one of our largest fish hauls of the trip, with juvenile Bermuda Chubs, Sergeant Majors, jacks, Orangespotted Filefishes, and Sargassum fish, among others. This sample was processed while the small boat team collected reflectance measures from Sargassum and open water habitats. While floating among the Sargassum patches, we did not notice many larger juvenile fishes, and we did not see many during a quick scan of our camera rig video. Because of this, and the lack of any larger patches in the area, and the fact that it was getting late in the day, we decided to forgo our Sabiki fishing set. We tried fishing the baited Sabiki rigs for 10-15 minutes to see if we could collect anything at all, and we did manage to get a Rough Triggerfish and a Blue Runner for diet analyses, so not a total loss. But in general, the larger juveniles were lacking in this area, or at least unavailable using our samplers.


IMG_2161Having had a long day, we relaxed for a few minutes before dinner, and afterwards we collected to deuceton net samples along the eastern edge of the north-flowing portion of the Loop Current. These worked well as we collected several more billfish larvae and their zooplankton prey field. The early evening was spent cleaning up, refreshing the ethanol preservative in collected samples, and other routine chores to ensure our data are secure and that we are ready to do it all again tomorrow.



The science team launches the ‘dueceton’ net at sunset.  (Photo: Sandra Huynh) 

And speaking of tomorrow, we’re setting a course north to a region just south of the Louisiana birdsfoot, where our remote sensing imagery suggests relatively high Sargassum biomass. It’s a long transit, but we’ll have a little assistance from the Loop Current!



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