NOAA Teacher at Sea
Aboard NOAA Ship Oscar Dyson
June 8-26, 2013
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: June 22, 2013
Weather Data from the Bridge: as of 2000
Wind Speed 20.02 kts
Air Temperature 8.4°C
Relative Humidity 96.00%
Barometric Pressure 995.9 mb
Latitude: 55.86N Longitude: 159.17W
Science and Technology Log
Cam Trawl, Critter Cam, Drop Cam, Trigger Cam (dubbed “the contraption”), and a camera that will be used on Acoustic Vessel of Opportunity (AVO) project, are different camera systems scientists are testing and using on this leg of the pollock survey to help monitor the biology in the region. Each camera is designed for a specific application.
Cam Trawl is attached immediately before the codend of a survey midwater trawl net, and takes pictures of the fish swimming by. Cam Trawl allows scientists to look at what depth the fish were captured, and use this information to help identify specific fish echoes on the sonar graphs. In one of our trawls, we were able to see pictures of a female Salmon Shark entering the net. She was quickly measured and released.
Critter Cam is attached to the survey net on the Oscar Dyson and takes pictures of little critters, like krill and different types of plankton, that are too small to be captured in a trawl net.
The Drop Cam is a tethered stereo camera that is lowered to take pictures of the sea floor. This instrument is going through a series of sea trials on this cruise, where the lights, exposure, and battery life are all being tested and fine tuning adjustments are being completed. Battery life is a concern, as both the cameras and the lights require energy to operate, and the scientists want to maximize the amount of time data is being collected . In order to conserve energy a depth sensor trip switch was added that turns the system on at 15 m depth. This addition allows the camera to continually take 10 pictures a second for a longer time on the sea floor. After this cruise the Drop Cam heads west to help survey the coral reefs west of the Islands of Four Mountains were we started our pollock survey heading east. Yes, there is coral in the cold waters of the Gulf of Alaska and the Berring Sea.
Trigger Cam, which the Dyson’s crew has dubbed “the contraption”, is attached to an anchor and lowered to the sea floor. The anchor we are using is a sablefish pot (a trap that is normally used to catch fish on the bottom), which has a buoy line attached, and the buoy marks the location of the camera on the surface. There are six Trigger Cams in development; the concept is that the cameras are deployed in a series a few nautical miles apart and left for 3 to 4 hours before retrieving. To conserve energy, this piece of equipment is designed with a motion sensor. An infared camera (fish cannot see infared light) runs at very low resolution (produces a blurry picture, as the water is in constant motion). When something, such as a school of Pacific cod, swims by, the motion is detected, camera flashes are triggered and a high resolution (clear) picture is taken. When the Trigger Cam system is fully operational, scientists hope to collect more in-depth evidence about the fish population in the deployment areas.
The AVO Cam is designed to attach to a survey bottom trawl net and take picture of the fish passing through, without being caught. There are two cameras (stereo) mounted so that field of vision intersects at a specific distance. The two cameras and the point of intersection can be used in a process similar to triangulation that allows the length of the fish swimming through to be measured. The stereo photography process is the same technology that is used in the making of 3D movies. The AVO Cam will be used in a survey that is carried out onboard chartered commercial fishing vessels (“vessels of opportunity”).
I enjoy listening to the various conversations that the scientists have about what they are seeing on the sonar displays and in the pictures, how the equipment is being used, when data are inconclusive the hypothesizing about the phenomena, and the time need to complete the different science studies. There is only so much time. Today’s conversation revolved around the need to hide from the weather!
An area of low air pressure is forecasted to kick up a gale force storm, and the safety of the ship, crew and science team is an important consideration in our travels. With this in mind, the Commanding Officer of the Oscar Dyson and the science team are looking for areas of safe harbor where we are sheltered from the worst of the storm and can still do science work. I wonder will we be on the lee side of an island, in a bay or fjord? Time will tell.
Did You Know?
To date we have traveled 2670.50 nmi since leaving Dutch harbor.