NOAA Teacher at Sea
Lacee Sherman
Aboard NOAA Ship Oscar Dyson
June 6, 2018 – June 28, 2018
Mission: Eastern Bering Sea Pollock Acoustic Trawl Survey
Geographic Area of Cruise: Eastern Bering Sea
Date: June 27, 2018
Weather Data from the Bridge at 15:00 on 6/27/18
Latitude: 56° 32.03 N
Longitude: 168° 08.15 W
Sea Wave Height: 2 ft
Wind Speed: 9 knots
Wind Direction: 229° (SW)
Visibility: 8 nautical miles
Air Temperature: 9.8° C
Water Temperature: 8.5° C
Sky: Broken cloud cover
Science and Technology Log
Sometimes the pursuit of scientific knowledge requires very precise scientific instruments, and sometimes it just requires a bucket, funnel, and a coffee filter. During the CTD casts, a special bottle collects water samples from a specific depth. The CTD can hold multiple water sample bottles, so a few days ago I was able to choose the location for an extra water sample to be taken. The required water sample was taken near the ocean floor, and I requested one at about 15 meters below the surface.
On the EK60 we had noticed a lot of “munge” in the water near the surface and we wanted to know exactly what was in the water that was reflecting an acoustic signal back up to the transducers since it did not appear to be fish. The upper part of the water column that had the munge was expected to have more small and microscopic organisms than the sample taken at a lower depth because of what had been seen on the EK60.
The CTD water bottles have flaps on the ends that can be triggered at specific depths. When the two CTD bottles were brought back on the ship, they were opened to pour out the water samples. Once the required 1 liter sample from the bottle taken near the ocean floor was put aside for another scientific study, the rest of the water was put into large white buckets to be sampled and inspected as we saw fit. We had one large bucket filled with water from near the bottom which we labeled “deep” and the water from only 15 meters down, which we labeled “shallow”.
We used coffee filters placed in funnels to strain out any microscopic organisms from the water. We had one set up for the “shallow” water sample, and another for the “deep” water sample. When there was a tiny bit of water left in the filter, we used a pipette to suck up the slurry of microscopic organisms and a bit of water and place them in a glass dish. From there, we took a few drops from each dish and put them under a dissecting microscope.
Using the dissecting microscope we were able to identify a few things that we were seeing, and even take photos of them through a special part of the microscope where a camera could be attached. We did not individually identify everything that we saw, but we did notice that there were diatoms, rotifers, crab larvae, and some type of egg. There was a noticeable difference though between the quantity of organisms in the shallow and deep samples. As predicted, the shallow water sample had many more microscopic organisms than the deep water sample.
Personal Log
Yesterday we did two trawls and one Methot sample. I understand so much more now about exactly how all of the instruments work and how to operate some of them. I finally feel like I was getting the hang of everything and able to be more helpful. Each trawl takes about 3 hours plus processing time, so the days pass much quicker when we are fishing often.
In our second trawl of the day we ended up catching a really neat kind of snailfish that isn’t very common. It’s always exciting to get something other than pollock in the nets, and it was really neat this time since no one else had ever seen one before either! After spending a lot of time taking photos, looking at identifying features and using books and the internet to help, we finally were able to identify it as an Okhotsk Snailfish.
Today we are steaming back to Dutch Harbor, AK and I have to admit that I have mixed feelings about leaving life on the ship behind. I will miss being a part of research and working with the MACE team. I love being able to do research, and work closely with scientists and learn more about something that I really enjoy. I will also definitely miss seeing the ocean every day. I think it will probably be strange to walk on land now. Since the ground won’t be moving anymore, hopefully that means that I can stop walking into walls!
All operations stopped on the ship last night so that we can have enough time to make it back to land before 09:00 on June 28, 2018. Today I will be packing up my things, cleaning up my room for the next person, and then helping to clean and scrub the fish lab. Tomorrow I will return to life as a land dweller, although hopefully not forever.
Did You Know?
According to the Encyclopaedia Britannica, “The Bering Sea has more than 300 species of fish, including 50 deep-sea species, of which 25 are caught commercially. The most important among them are salmon, herring, cod, flounder, halibut, and pollock.”
