NOAA Teacher at Sea Anne Mortimer Onboard NOAA Ship Oscar Dyson July 4 — 22, 2011
Mission: Pollock Survey Geographical area of cruise: Gulf of Alaska Date: July 7, 2011
Weather Data from the Bridge Air temperature: 9.53 C, Foggy
Sea temperature: 8.19 C
Wind direction: 145
Wind Speed: 18.73 knots
Barometric pressure: 1013.22 mbar
Science and Technology Log
Last night, we attempted a bottom trawl for walleye pollock. The way scientists know that fish are present is by using acoustic sampling. The centerboard of the ship is set-up with sound emitting and recording devices. When a sound wave is emitted toward the bottom, it will eventually be returned when it hits a fish or the ocean bottom. This is called echo-sounding and has been used by sport & commercial fisherman and researchers for many decades. The sound waves are sent down in pulses every 1.35 seconds and each returned wave is recorded. Each data point shows up in one pixel of color that is dependent on the density of the object hit. So a tightly packed group of fish will show as a red or red & yellow blob on the screen. When scientists see this, they fish!
The scientists use this acoustic technology to identify when to put the net in the water, so they can collect data from the fish that are caught. The researchers that I am working with are specifically looking at pollock, a mid-water fish. The entire catch will be weighed, and then each species will be weighed separately. The pollock will all be individually weighed, measured, sexed, and the otolith removed to determine the age of the fish. Similar to the rings on a tree, the otolith can show the age of a fish, as well as the species.
These scientists aren’t the only ones that rely on technology, the ships navigation systems is computerized and always monitored by the ship’s crew. For scientific survey’s like these, there are designated routes the ship must follow called transects.
I think that I must have good sea legs. So far, I haven’t felt sick at all, although it is very challenging to walk straight most times! I’ve enjoyed talking with lots of different folks working on the ship, of all ages and from all different places. Without all of the crew on board, the scientists couldn’t do their research. I’ve been working the night shift and although we’ve completed a bottom trawl and Methot trawl, we haven’t had a lot of fish to sort through. My biggest challenge is staying awake until 3 or 4 am!
Did you know?
That nautical charts show depths in fathoms. A fathom is a unit of measurement that originated from the distance from tip to tip of a man’s outstretched arms. A fathom is 2 yards, or 6 feet.
Species list for today:
In the Methotnet:
Multiple crab species including tanner crabs
Multiple sea star species, including rose star
Multiple shrimp species including candy striped shrimp
NOAA Teacher at Sea: Sue Zupko NOAA Ship: Pisces Mission: Extreme Corals 2011; Study deep water coral and its habitat off the east coast of FL Geographical Area of Cruise: SE United States from off Mayport, FL to St. Lucie, FL Date: June 7, 2011 Time: 10:00 EDT
Weather Data from the Bridge Position: 27.3°N 79.6°W Present weather: 4/8 Alto cumulus Visibility: 10 n.m. Wind Direction: 082° Wind Speed: 4 kts Surfacel Wave Height: 2-3 ft Swell Wave Direction: 100° true Swell Wave Height: 2-3 ft Surface Water Temperature: 27.1° Barometric Pressure: 1014.5mb Water Depth: 80m Salinity: 36.56 PSU Wet/Dry Bulb: 27.2/24
This blog runs in chronological order. If you haven’t been following, scroll down to “1 Introduction to my Voyage on the Pisces” and work your way back.
The first ROV we used on the Pisces for our Extreme Corals 2011 expedition is a custom designed craft called The Arc. The crew, led by Dr. John Butler at the Southwest Fisheries Science Center, has been developing The Arc since 2007 and launched it in January of 2011. The Arc is ideal for monitoring fisheries, improving species identification, and developing new methods of studying fisheries. It can withstand pressures and dive to 1000 meters (actually it dives to 600 meters since that is how long the tether is). When on land, it weights 264 kg (580 pounds). It has a rectangular prism shape with a length of 190 cm (75 in), width of 117 cm (46 in), and a height of 84 cm (33 in). Just for fun, do this math quiz.
The pilot sits on the ship and tells The Arc what to do. It’s like playing a video game. The pilot and his navigator coordinate movements, watching the computer screen with the ship’s and The Arc’s positions clearly showing. The navigator is in constant communication with the officers on the bridge of the Pisces using a walkie-talkie to relay messages and information between the ship’s pilot and the ROV’s pilot. The bridge also has a navigation screen to monitor the position of the ship relative to the ROV. The fishermen on the deck running the winch also have walkie-talkies so they can be told when to adjust the length of the cable to the ROV. Communication is very important.
The ROV is pretty neat. It has headlights similar to robots from old Sci-Fi movies so it appears creature-like, but without the spindly legs. Bright lights are needed because that’s about the only light that is available at great depths. There are four LED lights with 2600 lumens each. A 100 watt incandescent light bulb in your lamp has about 1750 lumens. How many lumens total does the ROV produce? Again, doing the math it would be 2600×4=10,400 lumens for the ROV. This is roughly twice as much as your four lightbulbs at home. Looking at the pictures from the bottom of the sea where it is normally dark and the tiny amount of light reaching the bottom makes everything look dark blue or black (see my earlier post on light in the ocean) we can see the colors almost as they would appear in a tidal pool.
The ROV has many instruments to measure data and take photographs of what it “sees.” It has a CTD ( measures Conductivity, from which we calculate salinity, Temperature, and Depth) as well as an oxygen sensor. The best part is the laser beam system which measures things like a ruler. With the help of the high definition camera, we were able to see the fish and invertebrates we were studying. Using the laser beams, we could not only measure their size, but how far away they were.
Note the red dots parallel to each other. The top two red ones are always 20 cm apart and in this picture the two on the bottom are 40 cm apart. The green light helps measure the distance to the crab. Apparently this crab is about 20 cm across. The lasers are fabulous for helping to keep things in perspective.
Dave Murfin, one of the ROV crew, was commenting to me about this picture after reading my blog. He said the pink stuff was the foam jacket used for floatation cut off from an old ROV cable, and he thought it looked ugly. However, given a new perspective of it, he thinks it looks cool. The pink foam helps protect the tether on deck and if it scrapes across rocks on the ocean floor. These ROV engineers added the large floats for the last 40 meters of the tether to keep it off the bottom and avoid becoming tangled in the coral and rocky habitats we are studying.
The tether for The Arc is wrapped on a spool for easy retrieval and transport. It is 610 meters long and has three fiber optic cables in the center surrounded by insulation. Around that are copper wires to conduct power from the ship, which is why they need a cable. If it ran on a battery, like a submarine, it could be on the bottom alone and the scientists would have to wait for it to return to see what data was stored inside. By using a tether, the scientists have much more control and can move the ship to study something of interest. Although technology is rapidly advancing, it is not quite possible yet to create a vehicle which would do everything the scientists need. Therefore, we continue to use the tether with the ROVs.
So, what do belts and suspenders have to do with the ROV? Well, there is an old saying that you don’t rely on just one thing; you always have a backup. If the belt on your pants doesn’t work, you have the suspenders to hold them up. The Arc is a new system. It is the belt and the system with 700+ dives to its credit is the spare (suspenders), just in case. Technology. It can be fabulous, but very frustrating when it gives you problems. As a teacher, I have to plan for technology to be down as well. I can’t have my whole lesson plan revolving around technology. What if the internet is down that day? Well, the students could get pretty wild without a back up plan. As my mom used to say, “Don’t put all your eggs in one basket.” What if the basket dropped? You are out of luck.
As I mentioned before in my blog, these men and women are dedicated professionals. They have lots of experience with this equipment and know the unexpected can happen. If you forecast about the unexpected, you can be prepared. I have always known that duct tape is a useful tool. Bungee cords are useful. Redundant cables, nuts, bolts, and spare parts are all on board. Having the spare ROV was just good planning and good sense. We have still been able to work our mission with some modifications. Bravo to this bunch for continuing to make things happen despite the unexpected happening. Because of them, we have some wonderful video and photographs to see what is happening on the coral reefs we have been studying.
And the answer to the poll at the beginning of this post is…less than 2 knots. They really prefer currents less than 0.5 knots. This week we’ve launched in currents which were 3.5 knots. Sometimes it caused problems, sometimes not. Here are some pictures from the bottom.
Everyone keeps asking me if I have driven the ROV. I asked the ROV crew about it and they all just smiled. Although it looks like a video game, the ROV is not a toy and not to be given to a novice to control. Considering I can’t get down the stream on Wii Fit without crashing into the side of the stream, they sure don’t want me at the helm of this incredible piece of technology. With the ROV, there is no opportunity for a second chance if you crash and burn. Therefore, I’ll leave the driving to them.