NOAA Teacher at Sea: Linda Tatreau
Onboard NOAA Ship Oscar Elton Sette
Mission: Fisheries Surveys
Geographical Area of Cruise: Equatorial Pacific
Date: February 22, 2010
Guppies
Sunset
Yesterday was a picture perfect day at sea. The sunrise was accompanied by 6 dolphins frolicking in front of the bow. The day was sunny, the sea was calm and we could see the bottom in 100 feet of water. It doesn’t get better. Steve and Sparky are preparing video clips from the BRUVs. New footage shows a feeding frenzy of snappers and at one point, a stingray parks itself on top of the bait bag. I am anxious to post these clips, but I must be patient. The BRUV boys and the BotCam girl have 85 hours of video to watch. Analyzing it will take much longer.The preliminary bathymetric map of Galvez Bank is completed and shown below.
Bathymetric Map of Galvez Bank
There is a new page on the blog. Click on the page titled, “Mutibeam Sonar.” Joyce Miller gives the basic information on how the multibeam works and how they generate these great bathymetric maps.
We have said good-bye to Galvez Banks and, after a bit of multibeam work west of Guam in the middle of the night, we are cruising towards Rota.
Steve swinging in the long-line pit. This is the area that is used for recovery of the BotCams, BRUVs and the AUV. On other expedtions the area is actually used for long-line fishing as a survey method.
Pet guppies getting some sun and enjoying the view on the ship’s deck.
NOAA Teacher at Sea: Linda Tatreau
Onboard NOAA Ship Oscar Elton Sette
Mission: Fisheries Surveys
Geographical Area of Cruise: Equatorial Pacific
Date: February 22, 2010
Daily Routine
Sparky cutting bait
The days are settling into a routine. As the sun rises, the multibean sonar is lifted and secured or Eric turns off the echo sounder he uses for locating schools of fish. By 7:30 A.M., the camera teams are ready with the 2 BotCams and 8 BRUVs. The deployment depths have been determined so each rig is set with the appropriate length of line. The camera batteries have been charged over night (10 rigs make for a total of 20 cameras). The bait has been cut and stuffed into the bait bags. Deployment of all 10 sets takes about 1.5 hours. Each set of cameras runs for just over an hour so as soon as the last cameras are deployed, the first are ready to be retrieved. Retrieval is more time consuming. Each camera set is marked by 2 orange buoys. The ship must approach with the buoys on the lee side (sheltered from the wind ). A crew member then throws a line with a big 4-pronged hook to snag the line between the buoys. If the ship is too close, it runs over the buoys―too far away and they have to come around for another try which can take up to 30 minutes. Generally, the morning cameras are back on board in time for lunch. Afternoons are a repeat of the morning and the cameras are back on board just in time for dinner.
Mills with a mahi mahi
We have a couple of fishing enthusiasts on board. They put out troll lines whenever they get the chance, usually at sunrise or sunset when the captain kicks up the speed to about 10 knots to reach the next study location. There has not been much time for fishing but we have eaten a few mahi mahi. This makes everyone happy―the fishermen of course, and the rest of us for the fillets.
Night time operations with the AUV
After dinner, the AUV team prepares the vehicle for deployment. The AUV is the most time consuming project. They spend hours with the electronics and hours more getting it ready to go underwater. When the communications work, the AUV follows a pre-programmed path about 4 hours in duration. When communications cannot be established, they have to bring it back on board and try again the next night. They have been so busy that we have not yet been able to see their pictures. Soon, I hope. It will be interesting to see the differences between daylight and night time activities on the sea floor.
NOAA Teacher at Sea: Linda Tatreau
Onboard NOAA Ship Oscar Elton Sette
Mission: Fisheries Surveys
Geographical Area of Cruise: Equatorial Pacific
Date: February 15, 2010
Autonomous Underwater Vehicle
Deployment
Autonomous Underwater Vehicle
The past two days have been spent working with the Autonomous Underwater Vehicle. On Sunday, the AUV was put in the water but never set free because it was having communications problems. On Wednesday, it was communicating perfectly, but just as it was to be released, the last line holding it to the ship became entangled and The AUV had to be brought back aboard. The afternoon deployment went perfectly. The AUV stayed on track for about two hours. It brought back pictures and video but I haven’t seen them yet.
The AUV without its protective housing.
There are many different kinds of AUVs. The AUV being used on this trip is called the SeaBed from Woods Hole Oceanographic Institute (WHOI). It can be programmed to fly slowly or hover over the seafloor to depths of 6,000 feet. It is used to gather detailed sonar images and pictures of the seafloor. http://www.whoi.edu/page.do?pid=10078Retrieval
WHOI’s newest vehicle is the Nereus. Nereus is actually a Hybrid Remotely Operated Vehicle (HROV). It can operate autonomously or by remote control. In May of 2009 it explored the depths of the Marina Trench at a depth of almost 7 miles. This was only the third time man has been able to see the deepest spot on Earth. http://www.whoi.edu/page.do?pid=10076
AUVs are an excellent tool to explore depths not easily accessible to divers. Although they are expensive and sensitive high tech machines, they are not as expensive as Remotely Operated Vehicles (ROVs) and manned submersibles.
NOAA Teacher at Sea: Linda Tatreau
Onboard NOAA Ship Oscar Elton Sette
Mission: Fisheries Surveys
Geographical Area of Cruise: Equatorial Pacific
Date: February 22, 2010
Sonar and CTD
Jeff & Jonathan prepare the CTDRetrieving the CTD (check the feet)
All day Friday, all night, and into Saturday has been spent with the multibeam sonar collecting data and mapping the area of study. The “fish people” need an idea of the bottom contours to decide where to put the cameras. Yesterday afternoon, the scientists used a CTD tool to measure conductivity, temperature and density. The results of this test were used by the map makers to most effectively use the sonar data for accurate maps. Currently the camera crew is preparing to launch 5 sets of cameras. The BotCam (bottom camera bait station) has an anchor and floatation that will keep it a few feet above the bottom. The BRUVs (Baited Remote Underwater Video) will sit directly on the bottom. We should have fish data later tonight but, 10 cameras will make a lot of video to watch.
With great anticipation (at least on my part) we departed Guam at 11:30 A.M. Thursday. The scientists have great expectations and most of them matched my excitement. The ship’s crew is mellow – they sail all the time. We went about a mile off shore and spent a few hours while scientists calibrated their equipment. We then went back into Apra Harbor so the multibeam sonar could be calibrated. During the night we actually set sail and are now at Galvez Banks, our first study site. The scientists are continuing their work with the sonar. This will probably take all day today and maybe part of tomorrow. We need the sonar to get good maps of the seafloor so the fish experts can place their gear in the best spots to find fish. We have at least four ways to survey the fish: acoustically, with an AUV (autonomous underwater vehicle), with a towed camera and several rigs that have 2 cameras each and use bait to attract fish. I will share more when the equipment is being used.
