Britta Culbertson, Big Fish Little Fish, Sept 15, 2013

NOAA Teacher at Sea
Britta Culbertson
Aboard NOAA Ship Oscar Dyson
September 4-19, 2013

Mission: Juvenile Walleye Pollock and Forage Fish Survey
Geographical Area of Cruise: Gulf of Alaska
Date: Saturday, September 15th, 2013

Weather Data from the Bridge 
Wind Speed: 11kts
Air Temperature: 12.2 degrees C
Relative Humidity: 87%
Barometric Pressure: 1010.7 mb
Latitude: 59 degrees 26.51″ N              Longitude: 149 degrees 47.53″ W

Science and Technology Log

Finally, as we near the end of the cruise, I’m ready to write about one of the major parts of the survey we are doing.  Until now, I’ve been trying to take it all in and learn about the science behind our surveys and observe the variety of organisms that we have been catching. In my last few entries, I explained the bongo net tow that we do at each station.  Immediately after we finish pulling in the bongo nets and preparing the samples, the boat repositions on the station and we begin a tow using an anchovy net.  It gets its name from the size of fish it is intended to capture, but it is not limited to catching anchovies and as you will see in the entry below, we catch much more than fish.

 Why are we collecting juvenile pollock?

We are interested in measuring the abundance of juvenile pollock off of East Kodiak Island and in the Semidi Bank vicinity.  We are not only focusing on the walleye pollock, we are also interested in the community structure and biomass of organisms that live with the pollock.  Other species that we are measuring include: capelin, eulachon, Pacific cod, arrowtooth flounder, sablefish, and rockfish.  As I described in the bongo entries, we catch zooplankton because those are prey for the juvenile pollock.

Pollock trio
On the top is an age 2+ pollock, below that an age 1 pollock, and then below that is an age zero pollock. (Photo credit: John Eiler)

The Gulf of Alaska juvenile walleye pollock study used to be conducted every year, using the same survey grid.  Now the Gulf of Alaska survey is conducted every other year with the Bering Sea surveyed in alternating years.  That way, scientists can understand how abundant the fish are and where they are located within the grid or study area.  With the data being collected every year (or every other year), scientists can establish a time series and are able to track changes in the population from year to year. The number of age 0 pollock that survive the winter ( to become age 1) are a good indicator of how many fish will be available for commercial fisheries. NOAA’s National Marine Fisheries Service (NMFS) will provide this data to the fisheries industry so that fishermen can predict how many fish will be available in years to come.  The abundance of age one pollock is a good estimate of fish that will survive and be available to be caught by fishermen later, when they reach age 3 and beyond, and can be legally fished.

The other part of our study concerns how the community as a whole responds to changes in the ecosystem (from climate, fishing, etc.).  That is why we also measure and record the zooplankton, jellyfish, shrimp, squids, and other fish that we catch.

How does it work?

The anchovy net (this particular design is also called a Stauffer trawl) is pretty small compared to those that are used by commercial fishermen.  The mesh is 5 millimeters compared to the 500 micrometer mesh that we used for the bongo.  The smallest organisms we get in the anchovy net are typically krill.

Trawl net
A picture of a generic trawling net. It’s very similar to the anchovy net that we are using.

Typically, we don’t catch large fish in the net, but there have been some exceptions.  You might wonder why larger fish do not get caught in the net. It’s because the mesh is smaller and it’s towed through the water very slowly.  Fish have a lateral line system where they can feel a change in pressure in the water.  The bow wave from the boat creates a large pressure differential that the fish can detect.  Larger fish are usually fast enough to avoid the net as it moves through the water, but small fish can’t get out of the way in time.  One night we caught several Pacific Ocean Perch, which are larger fish, but very slow moving.  They are equipped with large spines on their fins and are better adapted to hunkering down and defending themselves as opposed to other fish that are fast swimmers and great at maneuvering.

Pacific Ocean Perch
This is one of the Pacific Ocean Perch (rockfish) that got caught in our net.

When we pull in the trawl net, it is emptied into buckets and then the haul is sorted by species and age class.  The catch is then measured, weighed, and recorded on a data sheet.  After that, we return most of the fish to the sea and save 25 of the juvenile pollock, capelin, and eulachon to take back to Seattle for further investigation.  We also save some of the smaller flatfish and sablefish to send back to Seattle. Check out the gallery below to see the process from beginning to end.

This slideshow requires JavaScript.

Where are the pollock in the food web?

Eulachon and capelin are zooplanktivores and compete with the juvenile pollock for food. Larger eulachon and capelin are not competitors (those over 150 mm).  Arrowtooth flounder and Pacific Cod are predators of the juvenile walleye pollock.  Cyanea and Chrysaora jellyfish are also zooplanktivores and could potentially compete with juvenile walleye pollock, so that is why we focus on these particular jellyfish in our study.

 What’s in that net?

When we pull in the trawl, we sort it into piles of different species and different age classes.  If we get a lot of juvenile pollock (age 0), we measure and weigh 100 and freeze 25 to take back to the lab so their stomach contents can be examined.  We do the same procedure for young capelin, eulachon, and flatfish.  Other organisms like jellyfish are counted and weighed and put back in the ocean.

Below is a list of different organisms we have found in the anchovy net during this cruise:

  • Walleye Pollock
  • Eulachon
  • Capelin
  • Shrimp
  • Larger zooplankton
  • Pink and Coho Salmon
  • Pacific Ocean Perch
  • Lanternfish
  • Prowfish
  • Arrowtooth Flounder
  • Cyanea Jellyfish
  • Chrysaora Jellyfish
  • Miscellaneous clear jellyfish (some moon jellyfish)
  • Ctenophores (comb jellyfish)
  • Spiny Lumpsucker
  • Toad Lumpsucker
  • Grenadier
  • Flathead sole
  • Pacific cod
  • Herring
  • Sablefish
  • Sand Fish
  • Octopus
  • Snail fish

Personal Log

As we wind down the cruise, I’m feeling a little sad that it’s ending.  I’m looking forward to going home and seeing my husband and our dog, but I’ll miss the friends I’ve made on the ship and I’ll certainly miss collecting data.  Even though it can be quite repetitive after awhile, I can’t think of a more beautiful place to do this work than the Gulf of Alaska.  The last few days we have had a couple of stations near the coastline around Seward, Alaska and we have ventured into both Harris Bay and Resurrection Bay.  There we caught sight of some amazing glaciers and small islands.  There was even an island that had bunkers from WWII on it.  Yesterday, 3 Dall’s Porpoises played in our bow wake as I stood on the bridge and watched.  It’s moments like this that all of the discomforts of being at sea fall away and I can reflect on what an incredible experience this has been!

Beautiful scenery from Resurrection Bay.
Dall's Porpoise
Three Dall’s porpoises that were playing in our bow wake.


Did You Know?

Spiny lumpsuckers are tiny, cute, almost spherical fish that have a suction disk on their ventral (bottom) side.  The suction disk is actually a modified pelvic fin.  They use the suction disk to stick to kelp or rocks on the bottom of the ocean.

Their family name is Cyclopteridae (like the word Cyclops!).  It is Greek in origin.  “Kyklos” in Greek mean circle and “pteryx” means wing or fin.  This name is in reference to the circle-shaped pectoral fins that are possessed by fish in this family.

These lumpsuckers are well camouflaged from their predators and their suction disk helps them overcome their lack of an air bladder (this helps fish move up and down in the water).  Because lumpsuckers don’t have an air bladder, they are not great swimmers.

Spiny lumpsuckers are on average about 3 cm in length, but there are larger lumpsuckers that we have found, like the toad lumpsucker that you can see in the photo below.

You can read more about the spiny lumpsucker on the Aquarium of the Pacific’s website.

Amanda Peretich: Theragra chalcogramma, July 6, 2012

NOAA Teacher at Sea
Amanda Peretich
Aboard Oscar Dyson
June 30 – July 18, 2012

Mission: Pollock Survey
Geographical area of cruise:
Bering Sea
July 6, 2012

Location Data
Latitude: 58ºN
Longitude: 172ºW
Ship speed: 11.4 knots (13.1 mph)

Weather Data from the Bridge
Air temperature: 4.6ºC (40.3ºF)
Surface water temperature: 6.3ºC (43.3ºF)
Wind speed: 5.7 knots (6.6 mph)
Wind direction: 108ºT
Barometric pressure: 1016.5 millibar (1.00 atm, 762 mmHg)

Science and Technology Log
Today’s lesson is all about the lovely object of FRV (fisheries research vessel) Oscar Dyson’s affection on the summer survey: Theragra chalcogramma, also known as pollock, walleye pollock, Pacific pollock, or Alaska pollock. However, the word pollock could actually refer to the Pollachius genus, which includes Atlantic pollock, but this blog is about the Pacific variety.

DYK? (Did You Know?): biological organisms are classified using a system created by Carolus Linnaeus. Theragra chalcogramma refers to the genus and species classification for Pacific Pollock, just as Homo sapiens is used to classify humans. This is known as binomial nomenclature. You will see this naming throughout the blog. One mnemonic device to remember the order of classification (Kingdom –> Phylum –> Class –> Order –> Family –> Genus –> Species)? King Phillip Called Out For Greasy Spaghetti!

What do they look like?

Alaska Pollock
Alaska Pollock

All pollock are part of the cod family Gadidae. They can grow to a maximum of over 3 feet (91 cm) but will be about 12-20 inches (30.5-50.8 cm) in length on average. Their speckled color pattern allows them to blend in with their surroundings to avoid predators.

This is the main area where pollock can be found.

Where do we find them?
Alaska pollock are a semipelagic schooling fish closely related to Atlantic cod, which means they mainly swim together in the middle of the water column. Alaska pollock are found throughout the northern part of the Pacific Ocean, most notably in the Bering Sea, but also can be found in the Gulf of Alaska.

What do they eat?
Juvenile (younger) pollock eat zooplankton and small fish whereas older pollock eat other fish including juvenile pollock. We have seen some very full stomachs when sexing the pollock this week!

Who studies them?
Scientists are constantly conducting various pollock surveys in the Arctic area. The Alaska Fisheries Science Center (AFSC) as well as the Alaska Department of Fish and Game are two places that will use both acoustics and midwater and bottom trawls to determine the relative abundance and more during a pollock survey. You can read more about the AFSC walleye pollock research here. This type of research allows for decisions to be made with respect to how much pollock can be harvested each year.

How are they harvested?

Westward Seafoods
The seafood processor Westward Seafoods in Captains Bay, Dutch Harbor, Alaska

Pollock are harvested by trawlers. This means that the ship has a large net (see my previous blog on trawling) that is towed behind the vessel in midwater. Some vessels (not the scientific ones like the Oscar Dyson) are “catcher-processors”, which means that they will both catch pollock and process them at sea. Other ships are just “catchers” and will then transfer their loot to a shore-based processor or a “tramper” vessel. In Dutch Harbor and Unalaska, there are multiple seafood plants: UniSea, Westward, Alyeska, Icicle, Trident, and Royal Aleutian Seafoods. The “trampers” are most often foreign vessels that are not able to dock in the United States but will instead anchor in a place such as Captains Bay in Dutch Harbor and await a commercial fishing vessel to unload their catch. The tramper can then return back home to somewhere like South Korea with the seafood.

DYK? The two-tone color on the trampers is helpful to know how “full” the ship is – the less red you can see above the water, the more fish that are onboard!

This is a foreign “tramper” vessel, sitting in Captains Bay in Dutch Harbor, Alaska

In the United States, there is a 12-mile boundary from the shore that is marked on nautical charts to allow individual states to determine the fishing rules. They will dictate how many of each species can be kept, what months fishing can occur, and what size fish must be thrown back. Foreign ships can pass through these areas, but are not allowed to fish or look for resources (hence the “trampers”). Outside of this exists the exclusive economic zone, or EEZ, 200 nautical miles off shore. Permits are required to travel or fish through a foreign EEZ. For example, on Leg 3 of the Pollock survey, the Oscar Dyson is set to cross the International Date Line into Russian waters, which requires a permit.

Fun Fishy Facts
* You’ve actually probably eaten Alaska pollock and not even known it! It is used to make imitation crab meat (surimi) and fish sticks, amongst other things.
* Compared to Atlantic pollock, Alaska pollock has a milder taste, whiter color, and lower oil content.
* Alaska pollock is considered to be an eco- and ocean-friendly choice due to abundance and the fact that trawling does not cause significant habitat destruction.
* Alaska pollock is the largest fishery in the U.S. by volume and one of the best managed fisheries in the world.

Midwater Pollock Cam Trawl
This photo showing Alaska pollock is from a midwater trawl on the Oscar Dyson on July 6, 2012 using the AWT (Aleutian Wing Trawl) at about 100 meter depth.

NOAA Fishwatch: Alaska Pollock
Wikipedia: Alaska Pollock
New England Aquarium: Alaska Pollock
Assessment of the walleye pollock stock in the Eastern Bering Sea
– Scientists on board the Oscar Dyson 🙂

Personal Log

Pyrotechnics Demonstration
Pyrotechnics demonstration (aka shooting off expired flares after getting permission from a bunch of people) for the Fourth of July off starboard on the Oscar Dyson

I last posted on the Fourth of July, before our big “pyrotechnics demonstration” to celebrate the holiday. What a great ending to a beautiful day filled with blue skies!

I’ve finally gotten my “sea legs”, which I’ve been told isn’t how well you can walk in a straight line on board, but how well you can maintain standing position and move with the rolling, pitching, and yawing of the ship. I may not have mastered the treadmill yet, but I’m quickly learning to enjoy the elliptical again.

During the night shift on the Fourth of July, my wonderful roommate Carwyn came to tell me they were doing a bottom trawl if I wanted to come check it out. The lost hours of sleep were well worth the vast array of new critters and creatures that came up in the net! I plan to do a future blog on what we found, so be sure to look for that.

In adding to the awesome experience I’m having on board, I’ve gotten some great news online in the past few days. First, my amazing AP chemistry class earned all 3s, 4s, and 5s on the AP chemistry exam they took back in May (scores were just posted online for teacher access). Then I received an e-mail with a job offer to teach chemistry and honors biology at La Plata High School in La Plata, Maryland, after having a phone interview from the Anchorage airport the day I was flying out to Dutch Harbor. This helped relieve a little bit of stress from not having a full-time job offer after my big move to Maryland from Tennessee and helped to confirm that teaching high school is what I should be doing with my life!

Animal Love
I have been spending plenty of time on the bridge, up above that on the flying bridge, and looking out my stateroom window for something in the water other than birds. Today was the day I finally saw something (although this was thanks to ENS Kevin Michael coming to get me and show me)!

Introducing a Dall’s porpoise (Phocoenoides dalli):Dall's porpoise

A Dall’s porpoise swimming next to the Oscar Dyson around 6am on July 6, 2012

They resemble a killer whale in coloring and have a very thick body and smaller head, ranging through much of the northern Pacific Ocean and nearby seas (like the Bering Sea). Lucky for me!

Richard Chewning, June 15th, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 15th, 2010

Weather Data from the Bridge

Position: eastern Bering Sea
Time: 1530
Latitude: N 55 47.020
Longitude: W 165 24.970
Cloud Cover: overcast
Wind: 14 knots
Temperature: 6.4 C
Barometric Pressure: 1003.7 mbar

Science and Technology Log

In addition to researchers on the lookout for seabirds, the Oscar Dyson is also hosting researchers hoping to catch a glimpse of some the world’s largest animals: marine mammals. Either ocean dwelling or relying on the ocean for food, marine mammals include cetaceans (whales, porpoises, and dolphins), manatees, sea lions, sea otters, walrus, and polar bears. Although marine mammals can be enormous in size (the largest blue whale ever recorded by National Marine Mammal Laboratory scientists was 98 feet long or almost the length of a ten story building laid on its side!), studying marine mammals at sea can be challenging as they spend only a short time at the surface. Joining the Dyson from the NMML on this cruise are Suzanne Yin, Paula Olson, and Ernesto Vazquez. As a full time observer, Yin spends most of the year on assignment on various vessels sailing on one body of water or another and only occasionally is to be found transitioning through her home of San Francisco, California. Paula calls San Diego, California home and spends most of her time when not observing at sea working on a photo identification database of blue and killer whales. Ernesto is a contract biologist from La Paz, Mexico and has been working on and off with NOAA for several years. Ernesto has worked with several projects for the Mexican government including ecological management of the Gulf of California Islands.

Yin keeping warm from the cold
Ernesto keeping sharp lookout for marine mammals

Paula keeping an eye on the horizon

Yin, Paula, and Ernesto undoubtedly have the best view on the Oscar Dyson. Working as a three member team, they search for their illusive quarry from the flying bridge. The flying bridge is the open air platform above the bridge where the ship’s radar, communication equipment, and weather sensors are located. One observer is positioned both on the front left and front right corners of the flying bridge. Each observer is responsible for scanning the water directly in front to a line perpendicular to the ship forming a right angle. Two powerful BIG EYE binoculars are used to scan this to scan this 90 degree arc. These binoculars are so powerful they can spot a ship on the horizon at over ten miles (even before the Dyson’s radar can detect the vessel!). The third person is stationed in the middle of the flying bridge and is responsible for surveying directly ahead of the ship and for scanning the blind spot just in front of the ship that is too close for the BIG EYES to see. This person is also responsible for entering sightings into a computer database via a lap top computer. The three observers rotate positions every thirty minutes and take a thirty minute break after one full rotation. One complete shift lasts two hours. Yin, Paula, and Ernesto start soon after breakfast and will continue observing until 9:30 at night if conditions allow.

Dall’s porpoise

Weather can produce many challenges for marine mammal observers as they are exposed to the elements for hours at a time. Fortunately, Yin, Paula, and Ernesto are well prepared. Covered from head to toe wearing insulated Mustang suits (the name come from the manufacturer), they are pretty well protected from light spray, wind, and cold. Although a certain amount of the face is always exposed, a shoulder high wind shield helps deflect most of the spray and wind. In addition to wind chill and wind burn, a strong wind can also produce large rolling waves called swells that make viewing through the BIG EYES next to impossible. Sometimes reducing visibility so much that the bow can barely be seen the bridge, fog is undoubtedly a marine mammal observer’s greatest adversary.

Humpback whales through the Big Eyes
Salmon fishing operation through the Big Eyes

So far during the cruise, Yin, Paula, and Ernesto have spotted many blows on the horizon and have identified several species of marine mammals. A common sighting is the Dall’s porpoise. Your eyes are easily drawn towards these fun marine mammals as they produce characteristic white splashes by repeatedly breaking the water’s surface exposing a white stripe on their side. Blows from fin whales have also been regularly observed. Other sightings include killer whales, humpback whales, Pacific white sided dolphins, and a rare sighting of a Baird’s beaked whale.

Personal Log

Life aboard a constantly moving platform can take a little getting used to! I imagine if a person doesn’t live in an area frequented by earthquakes, one will easily take for granted the fact that the ground usually remains stable and firm underfoot (I know I did!). Over the last view days, steady winds from the south have conspired to create conditions ideal for rolling seas. Large swells (waves created by winds far away) make the Dyson very animated as we push forward on our survey transects. In addition to making deployments of gear more difficult, routine personal tasks soon assume a challenging nature as well. Whether you are simply getting dressed in the morning, trying to make your way to your seat with lunch in hand, or taking a shower in the evening, a constantly pitching and rolling deck will make even a seasoned deckhand wobble and stumble from time to time.

Building seas

A piece of advice I have often heard during these conditions calls for “one hand for you and one for the ship”. Maintaining three points of contact with ship, especially when moving between decks, can save you from being tossed off balance. The crew is very considerate of these conditions and allows even more understanding than customary when you bump into shipmates. I have also learned the importance of securing any loose equipment and personal items after usage during rough seas as they might not be in the same place when you return. In addition to waking several times during the night and having a restless sleep, these conditions will also leave you feeling stiff and fatigued in the morning after a bumpy night of being tossed around in your rack. Once you muster the strength to get moving, your legs become surprisingly tired as you constantly try to keep your balance. Along with the rest of the crew, the Dyson also feels the effects of jogging through rough seas as you constantly hear the rhythmic sounds of the bow plowing though the next wave and of the ship’s superstructure groaning under the strain.

Measuring the Dyson’s roll
Passing through the fog

Did you know? Fog is essentially a cloud on the ground’s surface.