NOAA Teacher at Sea
Amie Ell
Aboard NOAA Ship Oscar Dyson (NOAA Ship Tracker)
July 7 – July 11, 2013
Mission: Alaska Walleye Pollock Survey
Geographical Area: Gulf of Alaska
Date: July 11th, 2013
Location Data from the Bridge:
Latitude: 56.56 N
Longitude: 152.74 W
Ship speed: 11.3 kn
Weather Data from the Bridge:
Air temperature: 10.7 degrees Centigrade
Surface water temperature: 8.6 degrees Centigrade
Wind speed: 18 kn
Wind direction: 250 degrees
Barometric pressure: 1016 mb
Science and Technology Log:
So now that you know what we do with the fish after they are caught, let’s go back and see how the fishermen trawl. There are two large nets at the stern of the ship. Today we used both nets for the first time. The scientists, crew, and fishermen all work together to catch the fish. In the acoustics lab Paul is reviewing and scrutinizing the data he receives from the echo locators mounted on the hull of the ship. There are many factors he must evaluate in order to have a good trawl. There are places in our area that have been marked as “untrawlable”. This is usually due to a sea floor that is rocky. Trawling in these places may ruin the nets. We have completed at least one trawl a day since we have been out to sea. Today we completed two during my watch. The first was with a larger net and was not sent all the way to the bottom. The second trawl was sent to the bottom with a smaller net. The bottom trawl brought up the largest pollock I have seen so far. The longest pollock was 75 cm. We also brought up a salmon, cod, rock fish, and a whole lot of herring.
The nets are both on large spools and are released or returned with the help of a very large winch. Before the net is released into the water the CamTrawl is attached to it. This is a camera that takes pictures that help the scientists see at what point in the trawl fish were entering the net.
The time that the net is in the water depends on the information about the amount of fish coming from the acoustics lab. Scientists watch the echo information to determine how much time the net should be in the water to catch enough fish to sample. We must have at least 300 pollock to make a complete survey.
The fishermen bring the nets back to the trawl deck and wind them back onto the spools. They then will use a crane to lift the catch and dump it into a bin. From the fish lab we can lift this bin to dump the fish onto the conveyor belt.
Personal Log
On Monday, we had our weekly fire and abandon ship drills. After the drills I practiced putting on my survival suit. This suit is designed to keep you afloat and warm in the event that you have to go into the water.
On Tuesday, we surveyed up into Deadman’s Bay. It was a beautiful sun shiny day and the scenery was amazing. We were very close to the shore on both sides. I sat out on the trawl deck and scanned the hillsides with my binoculars. I was told that it is common to see bears here, but I did not see any.
Do commercial fisherman use cameras on their nets also?
Why is the bay called, “Dead man’s “?
I was going to ask the same thing!
Thanks for the trawl blog! What happens to all of the fish after they have been weighed and measured in your CLAMS system? Do they become Filet-o-Fish?
A lot of the fish die. We have to cut them open to find otoliths and to determine whether they are male or female. The change in pressure damages many of them also. Sometimes their eyes are bulging because the pressure inside their bodies is greater than the pressure above the surface of the water. Many of them have been served for munch and dinner.
Amy, this is completely amazing! I’m so glad that you are part of such incredible project. Thank you for sharing! Hugs.
Thanks Jose! I am learning a lot. I can’t wait to hear about Tanya’s experiences as well.
Once the fish are caught in the trawling nets, do they die or are they brought on board alive? What do you do with the non-pollock catch (salmon, cod, etc.)? Glad the fog lifted!
What a beautiful day this must have been–your pictures are amazing.