NOAA Teacher at Sea
Callie Harris
Aboard NOAA Ship Oscar Dyson
August 13-26, 2019
Mission: Fisheries-Oceanography Coordinated Investigations
Geographic Area of Cruise: Gulf of Alaska
Date: 8/24/19
Weather Data from the Bridge
Latitude: 57° 01.84 N
Longitude: 151 ° 35.12 W
Wind Speed: 8.45 knots
Wind Direction: 257.79°
Air Temperature: 15.3°C
Sea Temperature: 14.6°C
Barometric Pressure: 1010 mbar
Science and Technology Log
Chief Scientist Matt Wilson showed me how to collect otolith samples from pollock. Otoliths are the inner ear bones of fish that keep a record of a fish’s entire life. Similar to tree rings, scientists count the annual growth rings on the otolith to estimate the age of the fish. The size of the ring can also help scientists determine how well the fish grew within that year. To remove the otolith, a cut is made slightly behind the pollock’s eyes. Using forceps, you then remove the otoliths carefully.
NOAA Junior Unlicensed Engineer Blair Cahoon gave me a tour of the engine room yesterday. Before venturing below deck, we had to put on ear protection to protect our ears from the loud roars of engine equipment.
The Oscar Dyson has a total of four engines. The two larger engines are 12 cylinders and the two smaller engines are 8 cylinders. These engines are attached to generators. The motion of the engines gives force motion to the generators, which in turn power the entire ship. On a safety note, NOAA Junior Unlicensed Engineer Blair Cahoon also pointed out that the ship has two of every major part just in case a backup is needed.
The engine room also holds the water purification system, which converts seawater into potable water. Each of the two evaporators can distill between 600-900 gallons of water a day. The Oscar Dyson typically uses between 800-1000 gallons of water a day. The engineers shared with me how this system actually works:
1. Seawater is pumped onto the boat and is boiled using heat from the engine.
2. Seawater is evaporated and leaves behind brine, which gets pumped off of the ship.
3. Water vapor moves through cooling lines and condenses into another tank producing fresh water.
4. This water is then run through a chemical bromide solution to filter out any leftover unwanted particles.
5. The finely filtered water is stored in potable water holding tanks.
6. The last step before consumption is for the water to pass through a UV system that kills any remaining bacteria or harmful chemicals in the water.
We then got to explore the lower parts of the engine room where I got to see the large rotating shaft which connects directly to the propeller and moves the ship. I have learned from my years of working on boats to be extremely careful in this area near the rotating shaft. You must make sure you do not have any loose clothing, etc. that could get caught or hung up in it.
Personal Log
I was unsure of what life would be like for two weeks on a scientific research vessel. We are now steaming towards station number 72 on day twelve at sea. We have done 65 bongo tows and 65 trawls. So yes, there is a lot of repetition day in and day out. However, each day brings its own set of challenges and/or excitement. Weather (wind direction, wave direction, current, etc.) makes each station uniquely challenging for the NOAA Corps Officers on the bridge and the deck crew below. I stand back in awe watching it all come together on our 209 foot ship. I get excited to see what new creature might appear in our latest trawl haul besides the hundreds of kilograms of jellyfish, haha.
Did You Know?
One of the coolest things I learned on my engine tour is that when large equipment parts need to be replaced (like an engine or generator), engineers actually cut a giant hole in the side of the ship to get the old equipment out and the new parts in rather than take it apart and lug it up through the decks piece by piece.
Animals Seen Today
Juvenile wolf eel. Photo by Ali Deary. 
Juvenile wolf eel. Photo by Ali Deary.
The overnight science shift found a juvenile Wolf Eel in one of their trawl samples. It is not actually a wolf or an eel. It is in fact, a fish with the face of a ‘wolf’ and the body of an eel. Its appearance has been described as having the eyes of a snake, jaws of a wolf, and the grace of a goldfish. They can grow up to eight feet in length and weigh upwards of ninety pounds. Juveniles have a burnt orange hue and the adults are brown, grey, or green. Check out this website for more info about the super creepy wolf eel: https://www.alaskasealife.org/aslc_resident_species/44
Something to Think About
In one of our trawls, we processed 850 kilograms of jellyfish…. That’s 1,874 pounds of jellyfish!!!