NOAA Teacher at Sea
Aboard NOAA Ship Oscar Dyson
September 4 – 16, 2011
Mission: Bering-Aleutian Salmon International Survey (BASIS)
Geographical Area: Bering Sea
Date: September 11, 2011
Weather Data from the Bridge
Latitude: 58.00 N
Longitude: -166.91 W
Wind Speed: 23.91 kts with gusts over 30 kts
Wave Height: 10 – 13ft with some bigger swells rolling through
Surface Water Temperature: 6.3 C
Air Temperature: 8.0 C
Science and Technology Log
Today Jeanette and Florence took me under their wing to teach me about the oceanographic research they are conducting onboard the Dyson. At every station there is a specific order to how we sample. First the transducer, then the CTD, then numerous types of plankton nets, and then we end with the fishing trawl. The majority of the oceanographic data that they collect comes from the CTD (Conductivity, Temperature, Depth). The CTD is lowered over the side of the ship and as it slowly descends to about 100 meters it takes conductivity, temperature, and depth readings. Those readings go to a computer inside the dry lab where Jeanette is watching to record where the pycnocline is located.
The pycnocline is a sharp boundary layer where the density of the water rapidly changes. The density changes because cold water is more dense than warm water and water with a higher salinity is more dense than water that is lower in salinity. So as the CTD travels down towards the bottom it measures warmer, less salty water near the surface, a dramatic change of temperature and salinity at the pycnocline, and then colder, saltier water below the pycnocline. Once Jeanette knows where the pycnocline is, she tells the CTD to collect water at depths below, above, and at the pycnocline boundary. The water is collected in niskin bottles and when the CTD is back on deck Florence and Jeanette take samples of the water to examine in the wet lab.
Back in the lab, Jeanette and Florence run several tests on the water that they collected. The first test that I watched them do was for chlorophyll. They used a vacuum to draw the water through two filters that filtered out the chlorophyll from the water. As the water from the CTD passed through the filters, the different sizes of chlorophyll would get stuck on the filter paper. Jeanette and Florence then collected the filter paper, placed them in labeled tubes, and stored them in a cold, dark freezer where the chlorophyll would not degrade. In the next couple of days the chlorophyll samples that they collected will be ran through a fluorometer which will quantify how much chlorophyll is actually in their samples.
Besides chlorophyll, Jeanette and Florence also tested the water for dissolved oxygen and nutrients like nitrates and phosphates. All of these tests will give the scientists a snapshot of the physical and biological characteristics of the Eastern Bering Sea at this time of year. This is very important to the fisheries research because it can help to determine the health of the ecosystem and return of the fish in the following year.
One of the high points for me so far on the cruise has been seeing and learning about all the new fish that we catch in the net. We have caught lots of salmon, pollock, and capelin. The capelin are funny because they smell exactly like cucumbers. When we get a big catch of capelin the entire fish lab smells like cucumbers…it’s so weird. We have also caught wolffish, yellow fin sole, herring, and a lot of different types of jellyfish. The jellies are fun because they come in all different shapes and sizes. We had a catch today that had some hug ones and everyone was taking their pictures with them.
Today we also caught three large Chinook or king salmon. Ellen taught me how to fillet a fish and I practiced on a smaller fish and then filleted the salmon for the cook. What is even cooler was that at dinner we had salmon and it was the fish that we had caught and I had filleted. Fresh salmon is so good and I think the crew was happy to get to enjoy our catch.
What else did we catch?