NOAA Teacher at Sea
Jo Slavitz
Aboard NOAA Ship Oscar Dyson
July 19th – August 10th
Mission: Summer Pollock Acoustic-Trawl Survey, Leg 3
Geographic Area of Cruise: Bering Sea, Alaska
Date: July 30, 2026
Weather Data from Bering Sea
Latitude: 58° 38.303’ N
Longitude: 176° 17.674’ W
Winds: SW at 9 mph
Air Temperature: 46.94° F (8.3° C)
“It is that range of biodiversity that we must care for – the whole thing – rather than just one or two stars.” – David Attenborough
Science and Technology Log
NOAA scientists conducting the Acoustic-Trawl survey are skilled at finding pollock, but even, so tiny amounts of other species also sometimes slip into the net. These unexpected creatures are called “bycatch.” Although not targeted, it doesn’t mean that these species are not important. A healthy pollock population depends on a complete and healthy ecosystem, so the science team also measures and takes data on these creatures before releasing most of them back to the water. Sometimes, the science team also gathers information about these species for other scientists on land conducting special projects for other programs. Here are some of the interesting fish that came in with trawls aboard Oscar Dyson on Leg 3.
Jellyfish
Outside of pollock, jellyfish have been the most frequent visitor to the trawl. Existing before dinosaurs, jellyfish trace their origin back over 500 million years, their closest relatives being corals and anemones. They are invertebrates (meaning they do not have a backbone) in the phylum Cnidaria, subphylum Medusozoa. Jellyfish are found around the planet in the world’s oceans and even in some fresh water ponds/lakes. Not a fish at all, jellies contain no brain, bones, gills or hearts. They are considered a keystone organism, one that holds the ecosystem together because it interacts with so many other species within the food web. Jellyfish’s main diet consists of tiny animals and plankton. They serve as food for sea turtles, fish, crabs, birds and even humans. Even though they can often sting, small animals will swim among jellies to hide from predators. So far we have seen 3 species of jellyfish in the trawls in the Bering Sea:
Chrysaora: The most common jellyfish found in the trawls this trip are by far Chrysaora. These stunning animals get their name from mythology. Chrysaor was the warrior child of Poseidon the sea god and Medusa, and his name means “adorned in gold” or “golden warrior.” It’s the perfect name for this golden beauty. Chrysaora are in the family commonly referred to as sea nettles. They can grow to reach up to 2’- 3’ in diameter. Chrysaora is typically found at depths up to 100 meters in the Bering and Arctic Seas. Since the 1990’s the total biomass of this species has been increasing. Biomass is the total amount of mass of an animal population in a specific area.
Aequorea: Less showy and bright than Chrysaora, Aequorea jellies are predominantly clear with a flat smooth disk-shaped bell. Its name is taken from the Latin words aequor “from the sea” and aequus “even, flat or level.” Their family is commonly known as crystal jellies. This family of jellyfish fascinates scientists because they contain photoproteins that allow them to fluoresce with bioluminescence. Bioluminescence is the ability for animals to create their own light. Animals such as backyard lightning bugs and deep-sea fish are also capable of this unique adaptation.
Aurelia: Aurelia or moon jellyfish are one of the most widely distributed family of jellies. A. limbata, or brown moon jellies are native to the Bering Sea and coastal Alaska. They range in size from about 9 to 12 inches in diameter. They have a clear cup-shaped bell with brown to orange organs arranged in a circle around the center.
Fish
Pacific Cod: A relative of the Alaskan pollock, Pacific cod are also a cold water whitefish. Also similar to pollock, many people like to cook and eat cod, so this fish ended up as our guest in the mess later that night for dinner.
A Pacific cod in sample basket; later, plated for dinner in the mess hall
Flathead Sole: As a bottom dweller, the flathead sole has both eyes on a single side of its head. His topside is a splotchy brown color, while his underside is a translucent white.
Chum Salmon: Though this one is not so big. Chum salmon are the second largest pacific salmon after chinook. Males of this species develop large canine-like fangs
Smooth Lumpsucker: A deep-sea fish, the smooth lumpsucker has a slippery, scaleless skin. Look closely to see the circle on its underside. The pelvic fins in this species are modified to form a disk used to help secure the fish to ocean surfaces in fast moving waters.
Try It on Dry Land
Although you may not be able to hitch a ride out to the Bering Sea for the pollock acoustic survey, you can create your own trawling simulation with a box of Trix cereal and a few kitchen materials.
Trix Trawl
Materials:
- 1 box Trix Cereal
- 1 cookie sheet or shallow baking pan
- A ruler
- Tape
- 1 Tbs measuring spoon or scoop
- Data chart (downloadable pdf)
* Optional small kitchen scale
Instructions
- Use ruler to measure and mark with tape both long sides of the cookie sheet in 2” segments. These are your transects lines that you will sample from.
- Drag the tablespoon from the mark on one side to the corresponding mark on the opposite side. This is your trawl net. You may not touch the cereal with anything but the spoon.
- Sort the cereal into groups of the same shape/color type and record on data sheet.
- Repeat until all steps until transects are complete.
- Did you get the same number for each shape/color?
- Do you feel like it was an accurate representation for all the cereal in the box?
- Did you find anything unexpected in the cereal box?
- NOAA scientists also gather the weight for each species group. If you have a small kitchen scale you can weigh each shape/color group and record. Is the set with the most individual pieces also the heaviest?
Happy Sampling!
