NOAA Teacher at Sea
Julia Harvey
Aboard NOAA Ship Oscar Dyson (NOAA Ship Tracker)
July 22 – August 10, 2013
Mission: Walleye Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: July 22, 2013
Weather Data from the Bridge: (7/23/13 at 11 pm)
Wind Speed = 13 knots
Air Temperature = 12.7 C
Humidity = 93%
Barometric Pressure = 1017 mb
Science and Technology Log:
There is a great deal of hope to complete the survey, which is supposed to end near Yakutat in the southeast of Alaska. It began near the islands of Four Mountains during leg 1. We are on leg 3, the final leg this summer. Leg 3 began in Kodiak. Three Legs of the Survey
The purpose of this cruise is to survey the walleye pollock (Theragra chalcogramma) in the Gulf of Alaska. Pollock is a significant fishery in the United States as well as the world. Pollock is processed into fish sticks, fish patties and imitation crab. Last year, about 3 million tons of pollock were caught in North Pacific. The scientists on board will collect data to determine the pollock biomass and age structure. These data are used with results from other independent surveys to establish the total allowable pollock catch.
According to the Alaska Fisheries Science Center, pollock can grow to about 3 ½ feet and weigh about 13 lbs. More typically the pollock are approximately 50 cm (20 in) and weigh .75 kg (1.7 lbs). They live in the water column and feed on krill, zooplankton and other crustaceans. As they age they will eat juvenile pollock and other small fishes such as capelin, eulachon and herring as well. Sexual maturity is reached around age 4. Spawning and fertilization occurs in the water column in early spring. The eggs stay in the water column and once hatched are part of the zooplankton until they are free swimming.
The general process used to catch the pollock involves multiple parts. I will break down those steps in a series of blogs. But basically, acoustics are used to locate fish in the water column. Once the scientists have located the fish along the transect (transects are the paths that the ship will travel on so the scientists can collect data), the Oscar Dyson sets out a trawl equipped with a camera. The trawl is brought in and data from the catch is documented. And then the ship continues on.
Trawling is usually completed only during daylight hours. Fortunately the sun does not set here in Alaska right now until after 10 pm. When it is dark, work aboard the Oscar Dyson continues. Jodi is documenting the sea floor with a drop camera. She is looking at life that is there as well as potential threats to the trawl nets for the bottom trawl surveys.
Questions:
- How do scientists use acoustics to locate pollock?
- How are the transects locations determined?
- How are pollock and the rest of the catch processed?
- What information is retrieved from the trawl camera?
- What is a bottom trawl and how is it different from a mid-water trawl?
Personal Log:
We left Kodiak at 1 pm on July 22 heading southwest.
We had 8 hours of travel time before we would reach our first transect. But before we got too far away from Kodiak, we needed to practice the three drills for the safety of everyone. The fire drill and man overboard drill required me to report to the conference room and meet up with the rest of the science team. Patrick, the lead scientist, then reported that we were all accounted for. The crew had more complex tasks of deploying a small boat and retrieving “the man overboard”.
The other drill was the abandon ship drill. We are assigned to a lifeboat and I reported to my muster on the portside of the trawl deck with my survival suit, long sleeve shirt, hat and life preserver. We will have drills weekly at anytime.
For the last two days I have been becoming oriented to the ship and to my responsibilities to the science team. Jodi, a post doctorate from Juneau gave us a tour of the boat on the first day we arrived in Kodiak. I then practiced finding all of the key parts of the ship I will need to access. I now am confident that I can find my stateroom, the mess, laundry room, both exercise spaces, acoustics lab, and fish lab. For other sites, I wander around for a while until I locate it.
My first shift began at 4 pm on Monday. There are two shifts for scientists. Some work 4 am to 4 pm and the others work 4 pm to 4 am. I work the night shift. I never drink coffee but today I realized that I needed it. My shift includes scientists Paul, Jodi and Darin as well as a survey tech named Vince. We all share staterooms with people who work the opposite shift.
The ocean is very calm but most of us took Bonine (a seasickness medication) anyway to acclimate to the movement. Hopefully we will be adjusted to the motion before the seas get very rough if it does. The rocking of the boat does make one very sleepy.
Did You Know?
The requirements for joining the NOAA Corps include a bachelor’s degree in science, math or engineering and a 5 month program at the US Coast Guard Academy in New London, CT. This is Abby’s second cruise with the NOAA Corps. She has a bachelor’s degree in chemistry and just completed her NOAA officer basic training.
Something to Think About:
What is a day in the life aboard the Oscar Dyson like?