NOAA Teacher at Sea
Onboard NOAA Ship Oscar Dyson
July 1 – 18, 2009
Mission: Bering Sea Acoustic Trawl Survey
Geographical Area: Bering Sea/Dutch Harbor
Date: Tuesday, July 10, 2009
Position: N 56.30.202; W 172.34.37
Air Temp: 7.4 (deg C)
Water Temp: 7.4 (deg C)
Wind Speed: 19 knots
Science and Technology
Once the fish are onboard a rigorous data collection process begins. All of the data collected are recorded via instruments linked to a computer network in the fish lab. Below is a series of photos showing the process used in the fish lab to collect valuable data.
Once the fish are on the table, we carefully look through the fish for any species other than pollock caught in the trawl. These non-pollock species are sorted into bins and accounted for. The fish are weighed one basket full at a time as they reach the end of the conveyor belt. Initially, we take a count of how many fish fill one basket. There is a scale connected to a computer program that records the basket’s weight.
After weighing the pollock, we move on to sorting a sample of approximately 300 fish by sex. To find the sex of a fish we cut open its belly and look for either male or female reproductive organs. The sexed fish are then placed in the appropriate bin. Next, each pollock from the male/female sort is measured in centimeters. We use a measuring board linked to a computer that records the size of each fish. There is a small tool in my hand that gets placed at the “v” of the fish tail. Sensors on the board detect the placement of the measuring wand, and send a length measurement to the computer so it can be recorded. This program also keeps track of how many fish we measure, so we get an accurate sample count.
Several scientists have asked us to collect pollock for various research projects. One project, designed to study the diet of pollock, requires us to sex, measure, weigh and take the stomach of 20 pollock from each haul. A label with all of the information is placed in a bag with the stomach. They are placed in a freezer for preservation purposes.
We also use a similar process for scientists examining one-year-old pollock. This study asks for the entire fish to be preserved, not a specific organ. In one 12-hour shift there is a maximum of 3 trawls if fish sign is identified in the acoustics lab. Each trawl takes 2 to 3 hours to process. It’s possible another trawl could happen while finishing up the data collection from the previous haul. This makes for a very busy, fish filled shift.
Working in the fish lab has provided for a tremendous amount of new learning to take place. I’ve learned to identify species of fish that mix in with pollock (capelin, flatfish, skate and cod), and have seen several crustaceans and jellyfish, too. All of the measuring technology has been straight forward and user friendly. Sexing the fish has been the most difficult job, but has become easier with practice. Examining the innards to identify male or female reproductive organs seems nearly impossible in the young fish, and it’s not always clear in the older fish.
Today I was in charge of weighing the fish as they came down the conveyor belt. I was certainly mistaken when I thought it would be a simple task. First off, I had to count the fish as they dropped into the basket at a speed faster than I could count. At the same time I had to control the speed of the belt and open the gate so more fish would move down the line. When the basket was full, I stopped the belt and placed the full (semi-accurately counted) basket on the scale and waited for the scale’s “steady” signal to come on. Since the boat is constantly in motion the steady light rapidly blinks on and off. It took me three tries before I managed to get the basket weighed. Meanwhile the rest of the team patiently waited. Maybe I’ll give it another try tomorrow.
- Minke Whale
- Pacific Cod
- Tanner Crab
- Snow Crab
- Sturgeon Poacher
- Hermit Crabs
- Arrow Tooth Flounder