Tag: fish processing

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Guy Sturdevant: The Wet Lab, July 18, 2026

NOAA Teacher at Sea

Guy Sturdevant

Aboard NOAA Ship Oscar Dyson

June 21 – July 15, 2026

Mission: Summer Pollock Acoustic Survey, Leg 2

Geographic Area of Cruise: Bering Sea, Alaska

Date: July 14, 2026

Weather Data from the Bridge

N 58.16° W 172.21 °, 0 AMSL

Conditions: Overcast, Seas at < 1’

Visibility: >3  NM

Wind: 4°/ 6 kt

Barometric Pressure 1010.3 mBar

Dry Bulb Temp: 46 ° F

Science Log

Last time we left off with a bin full of fish waiting to be processed. Today we’ll dive into the wet lab where we sort, measure, and process the fish. 

a large bin full of hundreds of pollock (fish)
A full bin of pollock awaiting immediate processing. A full haul can take between 1.5 and 3 hours to process.

Trigger Warning: In order to provide you with the most accurate understanding of the important science aboard Oscar Dyson, I will describe laboratory procedures and handling processes that require dissection of select fish. 

While no one involved enjoys this, it helps scientists understand and protect this natural resource. Fish caught are handled ethically, bycatch (catching species other than the intended target) is extremely minimal, and any sensitive species are immediately released back into the ocean.

The wet lab is just that, wet! Seawater is used to process and clean fish, so every device and surface in the lab must be waterproofed and corrosion-resistant. Before we hop into the lab, we need to don cold-weather rain gear to keep us warm and dry. Once suited up, the science team uses a conveyor belt to sort the haul.

Each haul is unique; the wet lab supervisor decides which sorting method to use. To ensure we have gathered a statistically representative sample of what we are seeing on the echosounder, we aim to process approximately 350 pollock per haul, as well as sample any other species captured. This sample lets scientists divide the acoustic backscatter they recorded on the transect into categories by fish species and size classes- without the catch, there’s no way to know exactly how to assign this backscatter. A skilled acoustic lead scientist aims to land the perfect amount of fish; no more, no less.

view of the sorting table in the wet lab. three people stand - one on each side and one at the end - each wearing orange overalls and large yellow gloves. a pile of pollock (fish) is visible extending down the right side of the sorting table.
A nice, clean haul of juvenile pollock. Night lab lead David Bryan weighs and counts the fish into baskets for further processing. It is important that no bias is introduced in which pollock to include in the sample (no keeping just the big ones, etc.). Kevin McCarty and Julia Clemons are ensuring that only pollock make it to David. Anything else is diverted into other bins and handled separately.
top down view of a sorting table covered mostly in pollock (fish). yellow gloved hands reach into the frame from both sides of the table and image. one gloved hand lifts a jellyfish out of the pile.
Day lead Mike Levine removes a Chrysaora jellyfish from the sorting table. Jellyfish are far and away the most common bycatch. Luckily, Chrysaora jellies are unlikely to cause a reaction in humans.
top-down view of a salmon on an electronic fish measuring board set up on a metal table. a yellow gloved hand places a red magnet at the base of the fish's tail to electronically record its length.
A rare bycatch, Chum Salmon (Oncorhynchus keta), is quickly measured, weighed, and returned to the ocean. The icthystick measuring board was developed in the MACE fish lab and is now a commercial product that uses a magnet placed behind the fish’s tail to automatically record its length in CLAMS. A skilled user can process about 400 fish in about 20 minutes. The icthystick is a great example of the innovations being made by the Midwater Assessment and Conservation Engineering team.

The Midwater Assessment and Conservation Engineering (MACE) group of the Alaska Fisheries Science Center is responsible for running acoustic pollock surveys representing over 2.5 million square kilometers. To achieve this herculean task, the team has designed and continues to develop novel tools, processes, and methods. This spirit of innovation makes MACE unique.

screenshot displaying output from the computer program used to track fish data inputs; currently, it displays an image of an adult pollock, the name of the scientist doing the measurement, the weight and count
The CLAMS software suite, developed by MACE, allows them to quickly gather, organize, and analyze large data streams from both the wet lab and the cave.

In my next (and last!) post, we will look at some of these innovations and how they will empower scientists in MACE and across NOAA to produce the best possible data and science.

Personal Log

As my time at sea draws to a close, I am so grateful for this amazing opportunity and the very special crew of people that make this research happen. In my next and final post, we will look at the career pathways across the different departments and meet some of the new friends I’ve made aboard Oscar Dyson.

four NOAA Corps officers stand in a line at the controls on the bridge of NOAA Ship Oscar Dyson. they each face out the windows, away from the camera. through the bridge windows, we can see green land and other docked vessels.
The junior officers on the bridge during docking at Dutch Harbor. Left to right: LT Jesse Pierce, LTJG Robert Sobelsohn, ENS Miles Litzmann, and ENS Alex Banh. Each operates a single control as ENS Banh practices what might be the toughest parallel parking job in the world.

Emergencies At Sea

During safety drills, we practice mustering to life rafts and donning survival dry suits. As we wait on the back deck, the lead for each lifeboat practices recording key information, such as our current location and the bearing and distance to the nearest land. As I sat on the back deck, flopping like a fish while I squeezed into my survival suit, it struck me that the nearest hospital could well be over 500 kilometers away.

Aboard NOAA vessels, medical emergencies are the responsibility of the medical person in charge (MPIC). MPICs are typically junior officers trained in basic life support who have access to a small medical bay, basic life support equipment, and a limited cabinet of medications. A fair comparison might be to think of the medical bay like the back of an ambulance. Unlike an ambulance, however, the medical bay could be tasked with keeping a person alive for days awaiting evacuation. The MPIC is not alone; they are supported by a team of medical professionals ashore, with access to live feeds of patients’ vitals, who will help guide the MPIC in providing care.

Aboard Oscar Dyson, we were incredibly lucky to have LCDR LeeAnn Keener, a nurse practitioner serving in the US Public Health Service. Were we to have an emergency, LCDR Keener’s training and practice as a licensed medical professional would be a great asset. Currently, only a handful of vessels sail with a licensed medical professional.

orange, white, and navy rescue helicopter in flight over water; the door is open, and one person leans out to help lower another person
A USCG MH-60 rescue helicopter prepares to lower a rescue swimmer to respond to an emergency. Photo credit: Wikimedia Commons

Were an emergency to occur, the US Coast Guard would respond from their base in Kodiak, the largest USCG base in the world. First,  an MH-60 Jayhawk rescue helicopter would scramble and begin moving towards the vessel in distress; this could take as long as 8 hours to arrive on scene. While underway, the flight surgeon aboard would contact the MPIC and begin preparing to receive the patient or patients. If necessary, Kodiak would begin marshaling additional resources to aid in the evacuation. In some cases, aircraft such as an HC-130 will be dispatched to a remote airfield to serve as the second leg of the emergency relay. Even with this incredible effort, it may take well over a day for a patient to reach the nearest level II trauma center in Anchorage. The total cost of such a remote rescue may well exceed $100,000. 

a U.S. Coast Guard rescue plane in flight past large icebergs in an ocean
The USCG operates the HC-130H, sister to the famous AC-130, a highly specialized aircraft designed to respond to nautical emergencies. The C-130 class of aircraft has astonishing range and endurance and can be equipped with specialized electronics, including radar and radio systems, that allow it to serve as a mobile command center at sea. NOAA Hurricane Hunters operate a similar airframe in their mission to predict and study the tropical systems that produce hurricanes. (photo credit: U.S. Coast Guard Visual Information Gallery)

Stay tuned for my final post where we put all the pieces together and profile career opportunities at NOAA!

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Kathryn Lanouette, July 25, 2009

NOAA Teacher at Sea
Kathryn Lanouette
Onboard NOAA Ship Oscar Dyson
July 21-August 7, 2009 

Mission: Summer Pollock Survey
Geographical area of cruise: Bering Sea, Alaska
Date: July 25, 2009

Walleye pollock (Theragra chalcogramma)
Walleye pollock (Theragra chalcogramma)

Weather Data from the Ship’s Bridge 
Visibility: 10+ miles (to the horizon)
Wind direction: 030 degrees (NE)
Wind speed: 15 knots
Sea wave height: 4-6 feet
Air temperature: 6˚C
Seawater temperature: 6.4˚C
Sea level pressure: 29.85 inches Hg and rising
Cloud cover: 8/ 8, stratus

Science Log 

Why study walleye pollock? Before even setting sail, I wondered why NOAA scientists were interested in studying walleye pollock. It turns out that walleye pollock is the largest fishery, by volume, in the USA. In one year, about 1 million metric tons of walleye pollock are fished, mostly from the waters of the Bering Sea. Given that walleye pollock accounts for such a large percentage of the total fish caught in the United States, I was curious why I had never seen it on restaurant menus or rarely seen it at supermarket fish counters. It is because walleye pollock is usually processed into other things – like fish sticks, imitation crabmeat, and McDonald’s fish fillet sandwiches. So it seems that walleye pollock is that mild white fish you often eat when you don’t know for sure what kind of fish you are eating.

Above is a map showing the 31 transect lines of the walleye pollock survey area. I have joined the cruise that is sailing along the 8 transect lines closest to Russia.
Above is a map showing the 31 transect lines of the walleye pollock survey area. I have joined the cruise that is sailing along the 8 transect lines closest to Russia.

In addition to supporting a major multi-billion-dollar fishing industry, walleye pollock is a fundamental species in the Bering Sea food web. It is an important food source for Steller sea lions as well a variety of other marine mammals, birds, and fish. The population size, age composition, and geographic distribution of walleye pollock significantly affect the entire Bering Sea ecosystem. What do scientists hope to learn about walleye pollock? NOAA scientists are primarily interested in calculating the total biomass of walleye pollock. To estimate how many walleye pollock are in the Bering Sea, scientists sample the fish, recording their age, length, weight, male/female ratio, and geographic location. This information is used by North Pacific Fishery Management Council (NPFMC) to set sustainable fishing quotas for the following year. The NPFMC, whose membership comprises university, commercial, and government representatives, uses NOAA’s survey data, fishery observer program data, as well as catch statistics from the commercial fishing industry, to determine how much walleye pollock can be fished in the coming year.

An illustration of the Oscar Dyson sending down sound waves (in order to “see” the animals swimming below the water’s surface.)
An illustration of the Oscar Dyson sending down sound waves (in order to “see” the animals swimming below the water’s surface.)

Where do scientists study walleye pollock? Every year or two, a NOAA research ship (usually the Oscar Dyson) travels throughout the Bering Sea, following approximately 31 transect lines. These transect lines can be anywhere from 60 to 270 miles long. These lines were selected because they include areas where either walleye pollock spawn in the winter or feed in the summer. As the ship travels along these lines, its sonar system uses sound waves to locate fish and other animals living below the water’s surface. As the sound waves return to the ship, they create different images, depending on which animals are swimming in the water below. Using these images, the scientists decide whether or not they should lower the nets and sample the walleye pollock. They also continuously store digital data from the images, later using this information to estimate the total biomass of the fish species. On this 18 day research cruise, the scientists are hoping to travel the last 8 transect lines (over 1,500 nautical miles).  Each transect line takes us into Russian waters. On Thursday, we reached our first transect line. Within hours of traveling along this first line, many schools of walleye pollock were spotted. After the fish net was brought up, I was amazed at the number of fish that came sliding down the conveyor belt into the science lab. I helped weigh and measure hundreds of fish, a quick introduction to the whole process!

Personal Log 

The mouth of a Pacific lamprey
The mouth of a Pacific lamprey

We traveled into Russian waters today, crossing the International Date Line as we went. So technically, Saturday became Sunday this afternoon! But later in the evening, we completed the transect line, turned, and headed back into Saturday just as night fell. Luckily, the time never changes here on the boat. The scientists and crew live on Alaska Daylight Time (ADT), regardless of how far we travel to the north and west. I’ve see a few whales spouting but so far, I haven’t been able to identify any. In the coming days, I am hoping to get a glimpse of their backs or flukes (tails). It has been exciting seeing so many animals – some of which I never even knew existed. A few of these animals look a bit scary, like this Pacific lamprey. Its mouth forms a suction and then all those small yellow teeth go to town, letting it feed on the blood and tissue of its prey. Even the small tongue in the back of its mouth is toothed! 

The rare short-tailed albatross
The rare short-tailed albatross

Animals Seen 
Hyperiid amphipod  Aequorea species, Chrysaora melanaster jellyfish,  Euphausiids (aka krill), Pacific lamprey, and Short-tailed albatross.

New Vocabulary:  Biomass – the total amount of a species, by weight Cruise – nautical trip, for science research or fun. Quotas – a limited or fixed number or amount of things. Sample – to study a small number of species from a bigger group. Transect Line – a straight line or narrow section of land or water, along which observations and measurements are made

Question of the Day 
Why are only some jellyfish species capable of stinging?

Here I am holding up a Chrysaora melanaster jelly fish (Luckily this species doesn’t sting!)
Holding up a Chrysaora melanaster jelly fish (Luckily this species doesn’t sting!)

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Rebecca Himschoot, June 26, 2007

NOAA Teacher at Sea
Rebecca Himschoot
Onboard NOAA Ship Oscar Dyson
June 21 – July 10, 2007

Mission: Summer Pollock Survey
Geographical Area: North Pacific Ocean, Unalaska
Date: June 26, 2007

Weather Data from Bridge 
Visibility: .5 nm (nautical miles)
Wind direction: 80° (ENE)
Wind speed: 10 knots
Sea wave height: 1 foot
Swell wave height: 1 feet
Seawater temperature: 4.4°C
Sea level pressure: 1018.8 mb (millibars)
Cloud cover: stratus

Deck crew of the OSCAR DYSON retrieving sensors from a buoy.
Deck crew of the OSCAR DYSON retrieving sensors from a buoy.

Science and Technology Log: Data buoy retrieval and replacement 

Luckily we had calm weather today to retrieve two data buoys that were deployed in 2006, and replace them.  These buoys contained an Acoustic Doppler Current Profiler, a marine mammal voice recorder, and sensors for other data such as water temperature, nitrates, and salinity.  Because the sensors are on a stationary buoy, the information is collected at depth (much of this same information is collected on board the OSCAR DYSON continuously, but at the surface), and over a long period of time.

Life Cycle of the Walleye Pollock  
(Interview with Dr. Mikhail Stepanenko, scientist from TINRO)

Dr. Mikhail Stepanenko is assisting in the summer pollock survey from his home institution, the Pacific Research Fisheries Center (TINRO), which is located in Vladivostok, Russia. Dr. Stepanenko graduated with a degree in fish biology in 1968, the year before an agreement was signed for scientists in the Soviet Union and the United States to cooperate to help manage international fisheries.  Dr. Stepanenko took some time to share what he knows about the life history of the walleye pollock. According to Dr. Stepanenko, walleye pollock are found throughout the Bering Sea, and south into the Gulf of Alaska. Their range extends as far west as Russian and Japanese waters, and east to the Eastern Aleutians.  These fish can live up to 25 years, however the average age of a walleye pollock is 10-12 years. Pollock are related to the cod family.

Scientist Bill Floering with some of the new sensors deployed today from the OSCAR DYSON.
Scientist Bill Floering with some of the new sensors deployed today

Pollock begin spawning around age 4, although the most productive spawning years for both males and females is between 5-8 years of age.  Dr. Stepanenko has observed pollock spawning in an aquarium setting.  The male will swim next to a female to show his interest.  If she is also interested in that male, the female will swim next to him with sudden, short bursts of speed for several hours before they spawn. If she is not interested, she will continue to swim normally until the male gets the message.

Mature pollock spawn annually in nearshore areas, mostly in the Bering Sea and Gulf of Alaska (98% of pollock spawn in US coastal waters). Although the females will spawn only once annually and then move to the edge of the spawning area to feed, the males will spawn 4-5 times during the annual spawning season.

The eggs will hatch about 25 days later, or longer if the water temperatures are colder.  The annual survival rate of the eggs and larvae is highly dependent on the sea conditions and salinity.  At the correct salinity, the eggs sink and then are suspended at a certain depth due to a thermocline at that depth.  Poor sea conditions or a dramatic shift in salinity can result in higher mortality for the eggs or the larvae. They must also survive predators such as jellyfish and other small fish.

Dr. Mikhail Stepanenko processes walleyed Pollock
Dr. Mikhail Stepanenko processes walleye Pollock

Directly after hatching the pollock larvae have enough yolk reserve to survive a few days, but they must find food within the first three days of hatching if they are to survive. The larvae are approximately 3.5 mm long when they hatch, and with enough food will grow several centimeters in the first year of life. Only two of the 30-40 types of plankton in the Bering Sea are small enough to serve as prey for these tiny fish.  Harsh sea conditions, salinity changes, and scarce food resources in the first year contribute to a survival rate of only about .1% of pollock eggs. Adult pollock eat euphausids, as well as smaller fish such as capelin or smelt.  In times of scarcity, pollock are given to cannibalism.

The international pollock fishery targets four-year-old fish, and the total Bering Sea harvest of pollock is around two million metric tons annually.  Pollock is used in frozen seafood products, such as fish sticks, and as a central ingredient in surimi.

Personal Log 

We have been in an area where there are very few fish, so much of my time has been spent learning about pollock and the work that is done here on board.  The sea has been pretty rough at times, and I have continued to take some seasickness medication. We’re getting back into places with fish, so soon we’ll be collecting more data.

Question of the Day 

Answer to the last question about the controlled variables in the summer pollock survey: (The scientific method includes controlling the variables in an experiment.  What are some examples of variables the science team from the AFSC is controlling in the summer pollock survey?)

One example is the calibration of the acoustic equipment at the beginning of each leg of the survey. Another example is that the OSCAR DYSON cruises the same area of the Bering Sea during each summer pollock survey on transects of the same basic lengths and directions. The survey is conducted at the same time every year, as well.

Today’s question: Scientists use Latin names for each animal or plant they find, even though Latin is no longer a living language. How do scientific (Latin) names get selected and why are they important?

Walleye pollock
Walleye pollock

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Jillian Worssam, July 9, 2004

NOAA Teacher at Sea
Jillian Worssam
Aboard NOAA Ship Miller Freeman
July 5 – August 1, 2004

Day: Four
Friday July 9th, 2004 21:15

Longitude: 57° Sea Wave Height: 0-1′
Latitude: 172° 44 Swell Wave Height: 0-1′

Visibility: 25 yrds fog Sea Water Temperature: 9.3C
Wind Direction: 69.6 Barometric Pressure: 1022 strong high pressure
Wind Speed: 14.1kts Cloud Cover: complete 100%

Haul Data
Depth of haul: 89 meters
Temperature at depth: 4.1° C
Species breakdown: walleye pollock, chum salmon, smooth lumpsucker, unidentified jellyfish

Science and Technology Log:

First haul of the evening and to our surprise pulled up a smooth lumpsucker (Aptocyclus ventricosus). What an amazing fish quite large in girth, but relatively short( approximately 10 inches). A large globe shaped body with the ventral sucking disk. We placed the fish in water and released it back into the Bering.

As for the rest of the catch, quite a few chum salmon this time, so I anticipate some smoked snacks tomorrow. I am becoming more and more comfortable with the process of slicing the fish to determine gender. Tomorrow will attempt the removal of the otoliths. Amazing the data that can be removed for the preservation of an ecosystem. We are off to complete another haul right now, so I am off to don my rain gear: thick rubber pants, rubber boots, and rubber jacket. I must also wear a hard hat and life jacket when on deck while the cranes are in motion and the ramp is down. With the ramp down it is easy access to the ever cold Bering Sea.

Personal Log:

Well I did it, finally tackled the treadmill, what a treat. My body had wanted to jog for days so in thirty minutes this morning I completed three miles, and for the first time ever I was jogging below sea level as the workout room is toward the bottom of the boat. Amazing the difference between 7000 feet and sea level. The way the treadmill is situated it rocks back and forth not side to side, it is similar to walking rises, with an uphill climb every now and then.

I also spent some more time in the bridge today. I would like to learn all the equipment so tonight I was taught about the EOT (Engine Order Telegraph) The one instrument on the bridge that actually looks familiar as it has probably been in every old war sea movie ever made. You know the big round brass machine with a level and an arrow, and the person on deck moves the arrow to face the command they would like sent to the engine room. The commands vary from full ahead to slow, half even stand by. Now with modern technology this apparatus is obsolete, but still on board in case of emergency and the electronics fail.

I was also introduced to an amazing centrifugal force windshield washer, but those details will have to wait until tomorrow.