Tag: Oscar Dyson

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Laura Guertin: Personal Log for Acoustic-Trawl Survey, June 22, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, to Shumagin Islands area
Location (in port, Kodiak Island): 57o 47.0200′ N, 152o 25.5543′ W

Date: June 22, 2023

Laura, wearing a heavy orange rain coat and large yellow gloves, holds a pollock (fish) up for a photo. She is also wearing a blue Teacher at Sea beanie. She's standing in the wet lab, where plastic green sorting baskets are stacked behind her on a long metal table.
TAS Laura Guertin and a pollock!

I’m wrapping up my time on NOAA Ship Oscar Dyson. There was so much that went in to getting out to sea for this expedition, and so many people that did so much work pulling for me and coordinating all the logistics before I joined Dyson (starting in 2020!), during my time at sea, and I’m sure after I leave the ship. Thank you to the wonderful people in the NOAA Teacher At Sea Office (Jennifer, Emily, Britta) and for giving me an opportunity to sail as a Teacher At Sea Alumna in 2023.

While waiting to board Oscar Dyson in 2022 during my first trip to Alaska, I prepared several blog posts that provided a background to NOAA, NOAA Fisheries, fisheries surveys, etc. With my undergraduate students in mind as my audience, I wanted to start the posts at the broadest scale and have the content easily utilized in multiple courses that I teach. As I authored these posts from Alaskan hotel rooms in 2022 and in 2023 and not while on the ship, they do not contain personal logs. Again, I thank the Teacher At Sea Program for giving me this flexibility in having one post that captures my personal log from the shortened expedition and keeping the “academic” focus for the prior content.

I’m trained as a geoscientist. During and after my studies in marine geology and geophysics, I’ve had the opportunity to participate in fieldwork in expeditions that have lasted hours to days to weeks to months. Although I think I know what it takes to live/work at sea, I’m reminded of new challenges on new ships in new ocean basins. It is so important as an educator that I take advantage of opportunities to get out to sea for my own professional development and to remind myself of what to share with students and community members when I present the story of what we did during our time at sea. I know I sound like a broken record – I’ve written these same words before. But that doesn’t mean these points are less important!

First topic of reflection – the people

This expedition had 32 people on board, which included the science party, bridge crew, stewards, engineering, deck, electronics technicians, and survey. The people on Oscar Dyson were born/raised and live in parts across the United States. Some people were sailing on a NOAA ship for the first time, and a few people were working for their first time on the ocean! We all have different backgrounds and training and personalities. In a way, I feel like stepping on to Oscar Dyson was like joining a game of Yahtzee – put all of these people together, shake us up (by sending us out to sea), and see what rolls out. Fortunately, during this “game”, everybody was a winner. On this 208.6-foot long ship, everyone has a purpose and function, and we must all work together to accomplish our research goals and the mission of the expedition. And to be successful, this group was supportive, understanding, respectful, took the time to listen, and made sure to laugh and smile through everything we faced.

Person standing on a ship on the ocean with clouds and an island in the background
Departing Kodiak aboard NOAA Ship Oscar Dyson

Next topic – the work

The schedule is very different than one I keep as an instructor. At home, I know the days/times I’m teaching, and I have a calendar to organize meetings and personal appointments. I’m pretty much in charge and in control of my own schedule. At sea, it’s not “me” but “we” when it comes to all day, each and every day. There are no weekends or holidays off. We work 12-hour shifts (mine was 4AM to 4PM) during the entire expedition. Once you leave your room at the start of your shift, you can’t go back to your room until your shift is over (you are sharing a room with someone that works a different shift than you, so the room is theirs during your work time).

But you are plenty busy during your 12 hours! There can be downtime as the ship transits to a site to begin data collection, and the weather can cause a change of plans for where you are headed and what work you can do. High winds, rainstorms, cold air temperatures, the ship rolling and heaving… we faced it all during our 13 days at sea.

And this work is hard! It is a balance of the physical demands faced by the deck crew setting the trawl net, and those working in the fish lab to furiously and accurately process the catch brought on board, and everyone ensuring that safety is a top priority at all times. The Chief Scientist working in the ship’s acoustics laboratory and all the NOAA Corps Officers working on the bridge must balance the scientific mission with the realities of our present situation – is there too much ship traffic to “go fishing” and set out the trawl net? Are there whales or other marine mammals in the vicinity? Is the wind speed too high for us to operate safely?

Everything on Oscar Dyson operates at a different pace and schedule from back home. Fortunately, we are able to balance out our time in the laboratories with taking short breaks to view beautiful sunrises and do some whale watching. Again, it is the amazing group of people on this ship, from the seasoned sailors to those doing fisheries work for the first time, that come together to mentor and support one another. They all make the work not seem like “work” but instead a really enjoyable and exciting time, knowing our efforts are making a difference for sustainable fisheries.

person standing on a ship with a volcanic mountain in the background
TAS Laura Guertin in the Gulf of Alaska

Final topic – what comes next

My time on Oscar Dyson has provided me an amazing opportunity and wealth of information about a field where I have had no training. Now that Leg 1 of the 2023 Summer Survey has wrapped up, I’m reminded of a popular saying from one of my graduate school faculty members – “so what?”

“So what?” stands for a family of questions or an attitude that leads to consideration of the broader significance of specific studies. These kinds of questions are particularly useful in descriptive research because, often, one can get so absorbed in collecting, organizing, and analyzing observations one forgets to consider the implications of the results.  —  Ginsburg (1982), Seeking Answers; suggestions for students

This “so what” piece is something I will spend even more time in the future thinking about. The “so what” of the survey is clear – NOAA does an excellent job explaining what sustainable fisheries are and why it matters (see my previous blog posts). But I still need to do a better job of figuring out how to connect the dots – the endpoints being what we do on the water (and the data we collect) to the production of the annual Status of Stocks and other products NOAA uses to inform the ecosystem management. The Magnuson-Stevens Fishery Conservation and Management Act, the primary law that governs marine fisheries management in federal waters, is also something I want to get up to speed on.

In addition, I need to think about defining the “so what” for the various audiences I will be sharing my at-sea experience. I have more NOAA resources to explore, such as The NOAA Fisheries Distribution Mapping and Analysis Portal (DisMAP) and The Fisheries One Stop Shop (FOSS) Public Data Portal. I will certainly be looking for other resources to pull in to my materials for students and presentations to the public, ranging from the Food and Agriculture Organization of the United Nations (FAO) to episodes of The Fisheries Podcast. I also look forward to exploring more resources on diversity and representation in fisheries science, with articles catching my eye: Women Leaders Are Essential for Tackling Ocean Sustainability Challenges (Fisheries Magazine, 2023) and Examining Diversity Inequities in Fisheries Science: A Call to Action (BioScience, 2016).

So my learning is not done! The sharing of my adventure and new knowledge is only beginning, and I look forward to sharing my pollock survey stories to not only positively impact the ocean literacy of my audiences, but to show how NOAA’s fishery work helps us address the Ocean Decade Challenges (part of the United Nations Decade of Ocean Science for Sustainable Development).

ship on the sea during sunrise
Sunrise view from Oscar Dyson (June 2023)
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Laura Guertin: Ending with a Sea Shanty for Acoustic-Trawling for Walleye Pollock, June 22, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, to Shumagin Islands area
Location (in port, Kodiak Island): 57o 47.0200′ N, 152o 25.5543′ W

Date: June 22, 2023

Person wearing blue hat on the back of a ship on the ocean
TAS Laura Guertin shows off her Teacher at Sea beanie aboard NOAA Ship Oscar Dyson

As we return to Kodiak, Alaska, for Leg 1 to wrap up and Leg 2 to begin of the 2023 Summer Survey, it’s exciting to know that even during our shortened expedition time at sea, we’ve collected data that is going to inform Alaska walleye pollock stock assessment models and catch allocation. Any/all data are good data to have! I have thoroughly enjoyed my time on Oscar Dyson and met some incredibly smart, passionate, kind, creative, and innovative people. The NOAA community is filled with amazing individuals that are not only dedicated to the NOAA science mission but then sharing that new knowledge with others. I’ve played a small part in this NOAA community during the expedition (while wearing my NOAA hat!), but I hope my future teaching and outreach efforts will shine an even brighter spotlight on the essential work carried out by NOAA Fisheries and the agency as a whole.

Prior to joining the ship, this past academic year was filled with some highs and lows in teaching and student learning. There’s one topic that I’m not quite sure how to classify – and that’s the emergence of Chat GPT, and how AI is being used in higher education. I was joking with the Instructional Designer at my campus (Penn State Brandywine) that I was going to write a sea shanty about this expedition. Turns out, he was able to get AI (Bing, specifically) to write one for me! So as I wrap up my time as a Teacher At Sea Alumna, I leave you with these versus to sing to your favorite shanty rhythm.

A Song of Pollock and Trawls

Oh we are the surveyors of the Gulf so vast and wide
We sail the seas with acoustic gear to find the pollock hide
We use sound waves to scan the depths and mark what we have found
We measure their abundance and their biomass by the pound

(Chorus)

Yo ho ho as we sing this song
On Leg 2 we’ll bring the DriX along
Yo ho ho as we sing this song
We love our job and we love our fish
We love our job and we love our fish

We work in shifts around the clock to cover all the grounds
We set the course and speed and time to trawl a certain length
We haul the net and sort the catch and check their age and health
We record all the data and we share it with the world

(Chorus)

We do this work for science and for management as well
We help to keep the fishery sustainable and well
We study the pollock’s life history, ecology, and stock
We are proud to be part of this crew and this important work

(Chorus)

Oh we are the surveyors of the Gulf so vast and wide
We sail the seas with acoustic gear to find the pollock hide
We love our job and we love our fish
We love our job and we love our fish

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Laura Guertin: Collecting data: Trawl Sonar and CamTrawl, June 20, 2023

rectangular frame with four orange round balls on top and two eyes on a metal cylinder in the middle

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, to Shumagin Islands area
Location (2PM (Alaska Time), June 19): 55o 30.9384′ N, 159o 47.6478′ W

Data from 2PM (Alaska Time), June 19, 2023
Air Temperature: 8.2 oC
Water Temperature (mid-hull): 6.8oC
Wind Speed: 18 knots
Wind Direction: 62 degrees
Course Over Ground (COG): 30 degrees
Speed Over Ground (SOG): 11 knots

Date: June 20, 2023

To conduct a fisheries survey or any oceanographic research expedition, there’s an enormous checklist of items you need on a ship. Jokingly, those on board will tell you that food and internet access are at the top of the list. But there’s no doubt that technology and its function, application, durability, etc., are critical during the time at sea. For example, see NOAA’s explainers for Ocean Exploration Technology: How Robots Are Uncovering the Mysteries of the Deep and Collecting and Visualizing Deep-Sea Data. For a broader look at the technologies NOAA uses to explore the ocean (vessels and submersibles, observing systems and sensors, communication technologies, and diving technologies), see Exploration Tools.

Leg 2 of this Summer Survey will be bringing on board the DriX, an uncrewed surface vehicle (USV), to see if this technology can improve the efficiency of collecting acoustic and biological data to estimate pollock abundance when working alongside Oscar Dyson. To read more/see a video, check out NOAA’s article, Uncrewed Surface Vehicles Complement NOAA Vessels for More Efficient Fisheries Surveys.

Trawl Sonar

A sonar device (housed in a yellow hard plastic casing marked SIMRAD) sits on deck on a pile of coiled ropes
The Simrad FS70 on the back deck of Oscar Dyson (June 2023)

Trawl sonar units are used to provide a rough estimate of how many fish are going into the trawl net. The device (which we’ve been using on our expedition, a Simrad FS70 nicknamed “the turtle”) is a third wire system that in real time establishes communication between the submerged sonar head and the bridge. On this cruise, the trawl sonar unit is placed on the headrope of the trawl net (i.e., on the top of the mouth of the net). It communicates its depth back to the ship. It also scans the mouth of the net and relays any acoustic images of things going into the net back to the ship. These data allow the scientists and crew to adjust the depth of the net and length of time the trawl net remains in the water to collect samples. Our goal is to collect enough fish (approximately one ton) to have a representative sample of the various species and lengths of fishes in the water column.

Screenshot of the display returned by the FS70 during a trawl. The display is broken into three columns. The rightmost column is a list of settings.
Screenshot of the display returned by the FS70 during a trawl. The pink/yellow/blue line in the left column is where you see the bottom of the net. This is also represented in the middle column by the multi-colored horizontal line you see in the third circle from the center. (Screenshot from Leg 1 provided by Rick Towler).

The Simrad FS70 makes an appearance in the NOAA video Alaska’s Pollock Fishery: A Model of Sustainability. NOAA Ship Bell M. Shimada uses this FS70 trawl sonar unit for Pacific hake acoustic trawl surveys (see article).

CamTrawl

CamTrawl sits on the deck of NOAA Ship Oscar Dyson next to a blue trawl net that hangs down from a huge suspended spool. The CamTrawl consists of a metal frame housing cameras (not very visible) and buoys (more visible).

One fascinating piece of technology we’re using on this pollock survey is the CamTrawl. This article I found will give you everything you would want to know about CamTrawl in a non-technical summary:

–> Developing 3D Stereo Camera Technology to Support Sustainable Fisheries (from NOAA)

Introduced in 2012, the CamTrawl is a stereo camera system when attached to a trawl net, can provide data about fish without ever touching a fish. This 3D imagery records fish passing by the camera towards the codend (the closed end of the trawl net), which provides species and size composition data as well as how fish behave in the trawl net to be collected from within a midwater survey trawl. CamTrawl is used to verify the trawl catch and specimen data, and in some cases, can be used to determine where in the water column the species entered the net. These data help inform ecosystem-based fisheries management.

  • rectangular frame with four orange round balls on top and two eyes on a metal cylinder in the middle
    The CamTrawl on Oscar Dyson for 2023 Summer Survey. The orange balls are flotation devices, the two “eyes” in the middle are the stereo camera and computer system, with the battery power across/under the eyes. The four round devices in the corner are lights used during the image recording.
  • trapezoid frame with four orange balls across the top
    Top-down view of the CamTrawl. The front of the camera set-up is the wider side of the trapezoidal frame (top of image) which is then attached to the trawl net.
  • two sketches and a photo of the CamTrawl setup
    Figure 1 from Williams et al. (2016). CamTrawl system description.
  • CamTrawl device attached to a trawl net on the deck of a ship
    CamTrawl attached to trawl net about to be set off the back of Oscar Dyson.

The CamTrawl has uses and applications beyond our walleye pollock survey. It can go to depths of the ocean where it is not possible to lower a trawl net and capture data on other fish species like the bottom-dwelling rockfish. CamTrawl can explore and map deep-sea corals, and there is potential for collaborative research with the fishing industry.

Some CamTrawl footage from Leg 1 of 2023 Summer Survey.

The CamTrawl was developed by NOAA scientists  Kresimir Williams and Rick Towler (both of whom I’m sailing with on Oscar Dyson for Leg 1). I feel incredibly fortunate to have sailed with these two scientists and to hear how NOAA encourages their researchers to be creative and experiment with developing technologies to advance NOAA’s overall mission and expedition objectives.

people around a net removing equipment, while standing on the back of a ship at sea
CamTrawl being detached from a trawl net after a mid-water trawl (June 16, 2023, on Oscar Dyson)

Curious to see more? Check out this Salmon shark caught on CamTrawl underwater camera. Below is a picture of a salmon shark from the Shumagin Islands, Alaska area in February 2017 (photo provided by Sarah Stienessen).

shark seen by an underwater camera

Additional sources for exploration:

Using AI and 3D stereo cameras to support fisheries (National Fisherman, March 12, 2023)

Boldt et al. (2018). Development of stereo camera methodologies to improve pelagic fish biomass estimates and inform ecosystem management in marine waters. Fisheries Research, 198. https://doi.org/10.1016/j.fishres.2017.10.013

Williams et al. (2018). A method for computing volumetric fish density using stereo cameras. Journal of Experimental Marine Biology and Ecology, 508. https://doi.org/10.1016/j.jembe.2018.08.001

Williams et al. (2016). Automated measurements of fish within a trawl using stereo images from a Camera-Trawl device (CamTrawl). Methods in Oceanography, 17. https://doi.org/10.1016/j.mio.2016.09.008

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Laura Guertin: Collecting Data: Acoustic Survey, June 19, 2023

What looks like a long fishing rod attached to a ship's rail on the ocean

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, to Shumagin Islands area
Location (2PM (Alaska Time), June 18): 55o 15.3391′ N, 160o 17.8682′ W

Data from 2PM (Alaska Time), June 18, 2023
Air Temperature: 8.9 oC
Water Temperature (mid-hull): 7.7oC
Wind Speed: 4 knots
Wind Direction: 182 degrees
Course Over Ground (COG): 356 degrees
Speed Over Ground (SOG): 12 knots

Date: June 19, 2023

Acoustic fisheries surveys seek to estimate the abundance and distribution of fish in a particular area of the ocean. In my case, this Summer Survey is looking at walleye pollock in the Gulf of Alaska. How is this accomplished? Well, it’s not through this method:

The Alaska walleye pollock is widely distributed in the North Pacific Ocean with the largest concentrations in the eastern Bering Sea. For this expedition, Oscar Dyson is traveling to specific regions in the Gulf of Alaska and running transects perpendicular to the bathymetry/contours (which are not always perpendicular to the shore) to take measurements using acoustics and targeted trawling to determine the abundance and distribution of walleye pollock which informs stock assessment and management models. For this blog post, let’s focus on how and why we can use acoustics to locate fish.

A map of the distribution of walleye pollock in the waters around Alaska. Alaska is centered in this map, but not disconnected from adjacent portions of Canada, and portions of Russia are visible to the east. Colors representing topography are visible, emphasized on the land of Alaska and depicted faintly on Canada and Russia. The ocean is depicted as a solid blue. We see latitude and longitude lines at ten degree intervals. We can see labels for the Beaufort Sea (north of Alaska), Chukchi Sea (northwest), Bering Sea (west), Bristol Bay (southwest), Gulf of Alaska (south and southeast.) The polygon representing the distribution of pollock is shaded with diagonal red lines. It starts in the Chukchi Sea, extends southwest out to the Bering Sea, and curves around the Aleutian Islands, hugging the coastline around the Gulf of Alaska.
Walleye pollock (Gadus chalcogrammus) are distributed broadly in the North Pacific Ocean and eastern and western Bering Sea. In the Gulf of Alaska, pollock are considered as a single stock separate from those in the Bering Sea and Aleutian Islands.  Image from Alaska Department of Fish and Game.
A screenshot of an electronic nautical chart of the area around the Alaska Peninsula. Overlain on the chart are straight blue lines connecting blue points in a boxy meandering path in and out from the coastline, west to east. A few segments are red instead of blue.
An snapshot of a nautical chart with transects plotted. The first transect was run during Leg 1 on June 14 at the furthest location to the west, then the ship worked its way back east with approximately 40 nautical miles between transects. Once Oscar Dyson reached the Shumagin Islands, survey work shifted into this area..

Our story starts with the fish itself. Alaska walleye pollock have a swim bladder. The swim bladder is an internal organ filled with gas that allows a fish to maintain its buoyancy and stability at depth.

One interesting effect of the swim bladder is that it also functions as a resonating chamber that can produce and receive sound through sonar technology. This connection was first discovered in the 1970s, when low-frequency sound waves in the ocean come in contact with swim bladders and they resonated much like a tuning fork and return a strong echo (see WHOI’s Listening for Telltale Echoes from Fish).

illlustrated diagram of the internal anatomy of a boney fish. The swim bladder is located in the middle of the fish, beneath the long, skinny kidney and behind the stomach.
Internal anatomy of a boney fish. From Wikipedia (CC BY-SA 3.0).
Illustration of a survey ship on the ocean surface, with the ocean cutaway so that we can see a cone of sound pulses extending out from the ship's hull to the ocean floor. A school of fish is depicted in the middle of the water column, in the cone of sound.
The sound pulses travel down into the water column, illustrated by the white cones here, and bounce back when encountering resistance. (from NOAA Fisheries)

NOAA Fisheries uses echo sounding, which works by emitting vertical pulses of sound (often referred to as pings), and measuring the return strength and recording the time for the signal to leave and then return. Anything having a different density from the surrounding water (in our case – fish, plankton, air bubbles, the seafloor) can return a signal, or “echo”.

The strength or loudness of the echo is affected by how strongly different ocean elements reflect sound and how far away the source of the element is. The seafloor usually makes the strongest echo because it is composed of rock which has a density different than the density of water. In fish, the swim bladder provides a contrast from the water. In addition, each fish species has a unique target strength or amount of sound reflected to the receiver. The size and shape of the swim bladder influence the target strength. There is a different target strength to length relationship for each species of fish – the larger the fish, the greater the strength of the returning echo.

It’s important to note that echo sounders cannot identify fish species, directly or indirectly. The only way we know which fish species is causing a signal is based on trawl catch composition. There is nothing within the acoustic data that lets us identify fish species, even with the catch data. This is a subtle, but important, distinction. Acoustic data, particularly calibrated acoustic data, in tandem with the information from the trawl, definitely allows us to count fish.

Where is the echo sounder on Oscar Dyson? Look at the figure in the next section of this post – it’s a sketch of NOAA Ship Rainier, but the placement of the echo sounder is the same for Dyson. You can see a rectangular “board” that is extended down from the center of the ship. This is called – what else – the center board! Attached to the bottom of the center board are the echo sounders. When lowered, the echo sounders sit at 9 meters below the level of the sea (~4 meters below the bottom hull of the ship).

Did you know… Southern Resident killer whales use their own echolocation clicks to recognize the size and orientation of a Chinook’s swim bladder? Researchers report that the echo structure of the swim bladders from similar length but different species of salmon were different and probably recognizable by foraging killer whales. (reported in Au et al., 2010)

It starts with a calibration

Typical setup of the standard target and weight beneath the echo sounder. (from NOAA Fisheries)

Before we can begin collecting data, we need to calibrate the echo sounder. The calibration involves a standard target (a tungsten carbide sphere) with a known target strength. The calibration needs to be completed in waters that are calm and without significant marine life for the best results.

The sphere is suspended below the ship’s hull using monofilament lines fed through downriggers attached to ship railings. One downrigger is in line with the echo sounder on the starboard side, and the other two on the port side. This creates a triangle that suspends the sphere in the center of the echo sounder’s sound beam. By tightening and loosening the lines, the sphere can be positioned under the center of the sound beam and can also be moved throughout the beam. By doing an equipment calibration at the beginning and end of a survey, we can ensure the accuracy of our data.

  • What looks like a long fishing rod attached to a ship's rail on the ocean
    One of the port side downriggers
  • Two people holding a ball on string on a ship
    A weight that goes at the bottom of the filament to ensure the calibration sphere remains below the echo sounder
  • Shiny ball being lowered over side of ship
    The tungsten carbide sphere attached to the line, being lowered over the side

For further exploration

NOAA Ocean Service – Ocean Facts – How do scientists locate schools of fish?

Discovery of Sound in the Sea – How is sound used to locate fish?

NOAA Fisheries – Acoustic Echosounders–Essential Survey Equipment and Acoustic Hake Survey Methods on the West Coast

NOAA Ocean Service – Ocean Facts – What is sonar?

Science – Sounds like my favorite fish – killer whales differentiate salmon species by their sonar echoes

NOAA Fisheries – Sound Strategy: Hunting with the Southern Residents, Part 2

The Pew Charitable Trusts – Advanced Sonar Technology Helps NOAA Count Anchovy

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Laura Guertin: Alaska Pollock and Sustainable Fisheries 101, June 15, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, Western Gulf of Alaska
Location (2PM (Alaska Time), June 14): 52o 30.9860′ N, 169o 08.0942′ W

Data from 2PM (Alaska Time), June 14, 2023
Air Temperature: 8.11 oC
Water Temperature (mid-hull): 8.0oC
Wind Speed: 8.27 knots
Wind Direction: 243.96 degrees
Course Over Ground (COG): 239.25 degrees
Speed Over Ground (SOG): 13.05 knots

Date: June 15, 2023

I’m trained as a geologist and oceanographer. My teaching and research has focused on the physical sciences, which is why I’m so excited to have the opportunity to work with scientists in the life sciences. But before I start with the acoustic-trawl survey of walleye pollock, I had to do my homework – namely, learn something about this fish!

There is a wealth of resources on NOAA’s website that are providing me the introductory overview or “101” on pollock and the overall mission of maintaining sustainable fisheries. I started by viewing this NOAA video on Alaska’s Pollock Fishery: A Model of Sustainability.

This video shared so much but also generated so many more questions! I decided to take a step back and do a deeper dive into some of these topics, starting with the fish…

Alaska (walleye) pollock

Photo of dead Alaska pollock on a flat surface
Alaska pollock (Gadus chalcogrammus) on the sorting table, from NOAA Photo Library

NOAA Fisheries is doing an incredible volume of work in the Alaska region – including a focus on the Alaska pollock.

A member of the cod family, Alaska pollock (Gadus chalcogrammus) is also referred to as pollock, walleye pollock, and Pacific pollock. The NOAA Fisheries Species Directory for Alaska pollock states that Alaska pollock typically grow between 12 and 20 inches and weigh between 1 to 3 pounds. Their speckled coloring allows them to blend in with the seafloor to avoid predators such as Stellar sea lions, fish, seabirds – even older pollock will feed on juvenile pollock! Humans feed on pollock in products from fillets to fish sticks to surimi.

Alaska pollock are found throughout the North Pacific Ocean but are most common in the Bering Sea. Pollock migrate inshore to shallow water to breed and feed in the spring, then move back to warmer, deeper waters in the winter.

Sustainable fisheries

I always like to start by ensuring I’m using the terminology correctly. The NOAA web page for Understanding Fisheries Management in the United States defines fishery as the following:

The word “fishery” is used in many ways. It can refer to the occupation, industry, or season for catching fish. It can also refer to the area of ocean where fish are caught, or the business of catching the fish. U.S. fisheries include commercial (catching/marketing fish and shellfish for profit), recreational (fishing for sport/pleasure), and subsistence (fishing for personal/family/community consumption or sharing.

Next, what is meant by sustainable fisheries? NOAA defines this in the following video and in the quote below:

“U.S. fisheries are big business, providing jobs and recreation and keeping our coastal communities vibrant. In fact, the United States is a global leader in responsibly managed fisheries and sustainable seafood. Working closely with commercial, recreational, and small-scale tribal fishermen, we have rebuilt numerous fish stocks and managed to create some of the most sustainably managed fisheries in the world. U.S. fisheries are scientifically monitored, regionally managed, and legally enforced under 10 national standards of sustainability. Managing sustainable fisheries is a dynamic process that requires constant and routine attention to new scientific information that can guide management actions.” — from NOAA Fisheries – Sustainable Fisheries

[*Note – To help my students with ocean definitions, I also like to show video clips from the Pew/Jim Toomey (cartoonist behind “Sherman’s Lagoon”) Visual Glossary of Ocean Terminology, such as the videos for What Is U.S. Fisheries Management? and What Is Ecosystem-Based Fishery Management? ]

NOAA’s FishWatch website is a great place to find the most up-to-date information on popular seafood harvested or farmed in the United States. This helps each of us as consumers to make smart choices! Check out the page for the Alaska pollock to see the details available for this fish, currently classified as a smart seafood choice because it is “sustainably managed and responsibly harvested under U.S. regulations.” This is so important to note, as according to FishWatch, the Alaska pollock fishery is one of the most valuable in the world, with commercial landings of Alaska pollock from the Bering Sea and Gulf of Alaska in 2020 totaling more than 3.23 billion pounds and were valued at approximately $420 million.

Alaska pollock library of articles

Several articles on NOAA’s website were helpful in not only providing me more background information to prepare for my time on Oscar Dyson, but the content really showed me the context of what NOAA is doing for fisheries research/management and why it matters. My students probably recognize this as a list of articles I would give them to develop their current event literacy, as these are recent dates of publication and from a credible source (NOAA, of course!) – and of course, contribute to advancing their ocean literacy.

If you wish to learn more about the current state of Alaska pollock research with NOAA, I highly recommend these recent articles from NOAA Fisheries News & Announcements:

For podcast fans, this 2013 NOAA Fisheries podcast episode titled Keeping an Eye on Pollock is an excellent overview of how “scientists and fishermen work together to understand how walleye pollock respond to a changing environment” (transcript available online).

NOAA Fisheries podcast, Keeping an Eye on Pollock

In reviewing these articles and the podcast, it is clear that NOAA is focused on advancing the technology to survey Alaska pollock with new tools such as saildrones. There is also an interest in closely monitoring the impact climate change is having on the juvenile and adult populations of pollock (see the NOAA Fisheries site on Climate Change). This video, released January 2022, is a great snapshot of how NOAA Fisheries is preparing and responding to the impacts of climate change (link to web page that supports the video).

OK, I’m feeling good about my background on the “what” and “why” of Alaska pollock, and I hope you are, too! Next, it’s time to share the activities of the science team that is applying science knowledge and technology tools to studying pollock on Oscar Dyson!

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Laura Guertin: A shout-out to Oscar Dyson, the person and the ship, June 13, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska
Geographic Area of Cruise: Islands of Four Mountains area, Western Gulf of Alaska
Location (in transit, location recorded on June 12 at 2PM (Alaska Time)): 56o 45.1227′ N, 155o 38.3353′ W

Data from 2PM (Alaska Time), June 12, 2023
Air Temperature: 7.72 oC
Water Temperature (mid-hull): 6.8oC
Wind Speed: 18.71 knots
Wind Direction: 201.27 degrees
Course Over Ground (COG): 207.53 degrees
Speed Over Ground (SOG): 11.46 knots

Date: June 13, 2023

Photo facing the front of the NOAA Ship Oscar Dyson while it was in dock in Kodiak, Alaska
NOAA Ship Oscar Dyson as it docked in Kodiak, Alaska, on February 6, 2022

The journey of NOAA Ship Oscar Dyson begins as we are underway from Kodiak Island and head out along the Aleutian Islands.

Every NOAA ship has a name – but who is behind the name? I dedicate this blog post to Oscar Dyson (both Oscar Dysons, actually!)

Here’s a short summary from the NOAA Office of Marine & Aviation Operations on NOAA Ship Oscar Dyson:

Launched in 2003 and commissioned in 2005, the ship is named after Alaskan fisherman Oscar Dyson, a pioneer in Alaska’s fishing industry for half a century before his death in 1995. A well-known fishing activist and an industry advisor to government, Dyson was dedicated to improving the industry for the many Alaskans who make their living at sea. The ship is homeported in Kodiak, Alaska.

Peggy Dyson, wife of Oscar, christened the ship at its launch on October 17, 2003, in the VT Halter Marine shipyard in Moss Point, Mississippi. The first commanding officer was Commander Frank Wood.

Oscar Dyson (and Peggy!)

Oscar Dyson made an impact in Kodiak and across Alaska. I found a transcript of a Congressional Record read in 1995 less than two weeks after his passing with a detailed biography. There is a scholarship named for Oscar and his wife Peggy managed by the University of Alaska Fairbanks with a description I found online in 2022 that reads:

Oscar Dyson was a dedicated fisherman who turned his hobby into a business and his life’s work for 50 years. A Kodiak resident, Oscar had ample opportunity to partake in Alaska’s expansive fishing opportunities, but he also pioneered the crab fishing industry in Alaska. Oscar co-founded All Alaskan Seafoods (one of the largest seafood processing companies in the state) and built military bases during World War II …. The Oscar Dyson Memorial Scholarship was created in his honor and funded by numerous fishing and seafood companies within Alaska — a fitting homage to a man who did so much to develop Alaska’s marine economy. Oscar thought of himself — first, last and always — as a fisherman.

There is a dock in Kodiak named after Oscar Dyson with a marker to note his contributions and achievements (*photos taken by me as I spent some time exploring Kodiak in 2022)

  • A photo of a blue sign with orange lettering that reads: Oscar's Dock. All vessels much schedule dock use with Harbormaster. 486-8080 or 12 VHF Dock fees apply to all vessels. The sign is mounted in front of a chain link fence. We can see a snowy hill in the background,.
    Entrance sign for Oscar’s Dock
  • a large parking lot at Oscar's Dock; a pile of old snow in the middle of the parking lot; snowy hills and mountains in the background; a bright blue sky with many clouds
    View of the dock
  • Oscar's Dock, Dedicated to the memory of a pioneer Kodiak fisherman. Oscar Dyson 1913-1995. Oscar Dyson's vision resulted in the construction of this dock. His civic leadership and insight also contributed to many other public harbor facilities including Fishermen's Terminal, the Container Cargo Facility, and Saint Herman Harbor with its breakwater. Each facility helped Kodiak become the State of Alaska's largest commercial fishing port.National Fisheries Institute Person of the Year - 1995.
    Memorial plaque for Oscar Dyson
  • another view of the parking lot with
    View beyond Oscar’s Dock

And I’d like to give a shout-out to his wife Peggy, who made significant contributions of her own to the fishing community. Between 1965 and 2000, Peggy Dyson broadcast the marine weather from her house in Kodiak, twice a day over single sideband radio. She also reported sports scores and election results! The Kodiak Maritime Museum has a wonderful description of Peggy, including an audio clip of her voice, on their webpage, Peggy Dyson, Voice of the North Pacific. And NOAA Ship Oscar Dyson has a launch named Peggy D!

Photo of small boat Peggy D secured in its cradle on the NOAA Ship Oscar Dyson
The launch Peggy D on NOAA Ship Oscar Dyson

NOAA Ship Oscar Dyson

NOAA Ship Oscar Dyson plays a major role in collecting data used in the management of Alaska pollock, one of the world’s largest commercial fisheries. At 208-feet in length with a cruising speed of 12 knots and an endurance of 40 days at sea, Oscar Dyson can support 24 crew and 15 scientists (*see additional Specifications). The six onboard laboratory spaces include: a wet lab, dry lab, electronics/computer lab, bio lab, acoustics lab and hydrographics lab. Oscar Dyson sails primarily in the Gulf of Alaska and Bering Sea.

In 2016, NOAA put together a Photo story: Virtually cruise aboard a NOAA ship for a fish trawl survey to show how scientists collect fish science data at sea, with all photos from Oscar Dyson.

I look forward to sharing more information about the ship and stories from my time at sea. But I don’t want to repeat the incredible work done by educators that sailed before me. Here are some excellent recent blog posts by other educators that have sailed on Oscar Dyson that describes everything from the facilities to the work involved on a fisheries survey:

Looking at the back of the NOAA Ship Oscar Dyson
View of NOAA Ship Oscar Dyson just as she docked in Kodiak, Alaska, on February 6, 2022

Old Ships, New Ships

The first NOAA ship I sailed on, Thomas Jefferson, started its life as US Naval Ship Littlehales. From January 1992 to January 2003, Littlehales recorded 85,018 hydrographic survey miles along the coast of Africa and in the Red Sea and Mediterranean Sea. Littlehales ended its time with the Navy and then renamed Thomas Jefferson and officially entered the NOAA fleet on July 8, 2003 (*see About Thomas Jefferson which also explains why the ship was named after the former U.S. president).  

Oscar Dyson was new construction, the first of four planned 208-foot NOAA fisheries survey vessels.

In my first post, I mentioned how I’m reflecting upon this year being the 150+-year celebration of H.M.S. Challenger expedition. Launched in 1858, Challenger was a small warship with cannons assigned to coastal patrols and to support larger ships in the British naval fleet, not built for a science expedition. Modifications to Challenger were funded by the British government through the navy to include laboratories and accommodations for six civilian scientists to join the 250 British Royal Navy sailors and officers for the 3+ year journey at sea. I could not find information on why the navy chose “Challenger” as the name of the ship – but this ship’s name was the inspiration for the NASA space shuttle, the lunar module on the Apollo 17 mission, the scientific ocean drilling vessel Glomar Challenger, and even Sir Author Conan Doyle is said to have named his recurring character Professor Challenger after this ship. (*information from Macdougall, 2019)

Sketch of ship H.M.S. Challenger from Challenger Expedition Report, published in 1800's
Sketch of H.M.S. Challenger. Image in public domain, from Freshwater and Marine Image Bank
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Laura Guertin: NOAA and NOAA Fisheries, June 12, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, Western Gulf of Alaska
Location (site of calibration, June 11): 57o 32.6154′ N, 153o 55.8318′ W

Data from 2PM (Alaska Time), June 11, 2023
Air Temperature: 8.29 oC
Water Temperature (mid-hull): 6.3oC
Wind Speed: 10.35 knots
Wind Direction: 166.14 degrees
Course Over Ground (COG): 222.34 degrees
Speed Over Ground (SOG): 0.13 knots

COG = The direction the ship is heading relative to land. Over Ground means in relation to the Earth, so COG means the true direction free from the effects of sea currents.
SOG = Speed, real progress with respect to Earth. SOG means the true speed free from the effects of sea currents.

Date: June 12, 2023

I am pretty sure that, on a daily basis, I mention NOAA in my classroom, during public outreach events, and in conversations with colleagues and neighbors. But too often, individuals are not aware of this government agency and the critical role NOAA plays in our lives, even for those that are not scientists. So this blog post is for everyone not familiar with the services NOAA provides us all, along with a focus on NOAA’s National Marine Fisheries Service (aka “NOAA Fisheries”).

NOAA is an agency that enriches life through science. Our reach goes from the surface of the sun to the depths of the ocean floor as we work to keep the public informed of the changing environment around them. — from About our agency

The letters N-O-A-A stand for National Oceanic and Atmospheric Administration, an agency in the U.S. Department of Commerce. NOAA has a fascinating history, going back to 1807 and President Thomas Jefferson founding America’s first physical science agency, the Survey of the Coast. Fast-forward to 1870, when the Weather Bureau was establshed as the first agency dedicated to the atmospheric sciences. In 1871, the first conservation agency, the U.S. Commission of Fish and Fisheries, was in place. All three of these agencies were brought together in 1970 with the formation of NOAA. (*yes, NOAA recently celebrated its 50th anniversary! See this playlist of videos to learn even more about its history and the people of NOAA from over the years. There is an additional video that goes back to the original agency and mission of 1807.)

NOAA mission: To understand and predict changes in climate, weather, ocean, and coasts, to share that knowledge and information with others, and to conserve and manage coastal and marine ecosystems and resources. — from Our mission and vision

View this video for an overview of NOAA “meeting the moment.”

When I think of and hear “NOAA”, there are several terms/phrases that pop into my mind – science research, atmosphere, hydrosphere, weather and climate, health and safety, economy, conservation, sustainability, and so many more. The educational resources provided by NOAA are also valuable for additional background reading, citizen science opportunities, and multimedia materials (including podcasts!).

Quilt hanging on a wall with NOAA across the top and images that represent NOAA's areas of work

A STEAM Moment

I mentioned in my first blog post how I have a passion for and explore the integration of science and creative arts, specifically crafting via crocheting and quilting. To help others learn about the mission of NOAA and its key focus areas, I created a quilt to showcase NOAA’s work in research, weather, climate,  ocean & coasts, fisheries, charting, satellites,  marine & aviation, sanctuaries, and education. This quilt is just another tool in my education/outreach toolkit! To learn more about this quilt and to view a video, see this post.

NOAA Fisheries

NOAA Fisheries provides science-based conservation and management for sustainable fisheries and aquaculture, marine mammals, endangered species and their habitats. — from Fisheries

NOAA Fisheries, also known as the National Marine Fisheries Service, is a NOAA office composed of five regional offices, six science centers, and more than 20 laboratories around the United States and U.S. territories. Working with additional partners, NOAA Fisheries achieves its two core mandates: (1) to ensure the productivity and sustainability of fisheries and fishing communities through science-based decision-making and compliance with regulations; and (2) to recover and conserve protected resources including whales, turtles, and salmon.

There are several NOAA websites and videos that showcase the history and work of this office. I recommend the NOAA Fisheries About Us page, History page, YouTube playlist of NOAA Fisheries videos, and especially this overview video:

The main Fisheries page on NOAA’s website has fascinating facts you can scroll through. For example, I did not know that the total area NOAA Fisheries is responsible for monitoring and enforcing regulations for marine fisheries is 4.4 million square miles! This area is the largest Exclusive Economic Zone (EEZ) in the world! And the Fisheries News & Announcements page is a wealth of articles, press releases, multimedia material and more that will soon become required reading for students in my courses, adding to the materials I already tap into on NOAA’s Climate.gov and NOAA’s Ocean Facts!

#TheMoreYouNOAA

NOAA has an incredible range of resources and materials that are constantly being updated and expanded upon. There is something for everyone! (*including on Twitter, where you will find individuals and organizations highlighting NOAA’s work with the hashtag #TheMoreYouNOAA)

I’ll end this post with one of the fun audio narratives from the NOAA Ocean podcast series, which details phrases we use today that came from the Age of Sail (the period of time between the 16th and 19th centuries, transcript available).

NOAA Ocean Podcast: Episode 29 – The Nautical Origins of 10 Popular Phrases

The Challenger mission – so much more than fish

The mission of H.M.S. Challenger 150+ years ago was not as developed as the statements for NOAA and NOAA Fisheries – terms such as ‘conservation’, ‘management’, and ‘sustainability’ were not part of the expedition. Challenger was all about collecting samples, whether those samples be seafloor mud, manganese modules, corals, crabs, and plant and animal life from the islands they visited over their 3-year journey. The six Challenger scientists were not concerned about aquatic systems or human/environment interactions – this really was a journey of discovery and documenting what exists in these unexplored areas. It took 50 volumes of the Challenger Report to describe what was seen and collected – including roughly 4,700 new plant and animal species!

For the fish samples collected at that time, the “Challenger fishes” were incorporated into the British Museum (of Natural History) collection. There were 688 specimens of shallow water, shore and miscellaneous estuarine and freshwater fishes; 261 deep-sea fishes; and 125 pelagic fishes. Some of the fish were then sent over to the National Museum of Ireland in 1899, including type specimens of sixteen species (*data on the Challenger fishes from Wheeler and O’Riordan, 1969).

Sketch of a deep-sea eel, a figure from the Challenger publication
A deep-sea eel, one of the many sketches from samples collected on the H.M.S. Challenger (image in the public domain, part of the Freshwater and Marine Image Bank)
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Laura Guertin: My Journey Begins on NOAA Ship Oscar Dyson, May 31, 2023

NOAA Teacher at Sea

Laura Guertin

Aboard NOAA Ship Oscar Dyson

June 10 – June 22, 2023


Mission: 2023 Summer Acoustic-Trawl Survey of Walleye Pollock in the Gulf of Alaska

Geographic Area of Cruise: Islands of Four Mountains area, Western Gulf of Alaska
Location (in port): 57o 47.0200′ N, 152o 25.5543′ W

Date: May 31, 2023

Not every educator has the amazing opportunity to volunteer with scientists on a NOAA ship. But in 2014, that opportunity became a reality for me when I joined NOAA Ship Thomas Jefferson for a hydrographic survey in the Atlantic Ocean. Now my journey at sea with NOAA continues in 2023 as I head out on NOAA Ship Oscar Dyson for an acoustic-trawl survey of walleye pollock populations in the Gulf of Alaska.

Ever since I was an undergraduate intern for two summers at NOAA Maine Operations Center – Atlantic in Norfolk, VA, I wanted to sail on a NOAA ship. The NOAA Teacher at Sea (TAS) program opened that door for me and has provided so much, from my own advancement of the science and technology used to map the ocean floor, to content and stories I share with students and at science outreach events for the public. Now as a TAS alumna, I can’t wait to see how much more I can learn, teach, and share from my latest ocean expedition with NOAA.

Photo of Laura Guertin on a boat on the Atlantic ocean
Offshore of Miami, Florida, where I went to graduate school (University of Miami – Rosenstiel School of Marine & Atmospheric Science)

I’m a college professor, teaching introductory-level earth science courses primarily for non-STEM majors at Penn State Brandywine in Media, Pennsylvania. I am dedicated to not only helping my students build their science literacy but also seeing the relevance of why and how science matters in their present and future lives. My research has involved using technology tools to enhance student learning of geoscience content, with my current work focusing on having students produce audio narratives (or “podcasts”).

Photo of Laura Guertin with RDML Gallaudet standing in front of flags in DC office
RDML Gallaudet and I in his office in Washington DC

I also blog for the American Geophysical Union (AGU) about educational technology, pedagogy, and science communication on my blog GeoEd Trek. I’ve dedicated several posts on NOAA and its programs and resources . But it was my blog post A New Year’s resolution: help the public learn about NOAA (December 30, 2017) that caught the attention of RDML Tim Gallaudet, Assistant Secretary of Commerce for Oceans and Atmosphere and Acting Under Secretary of Commerce for Oceans and Atmosphere at that time. He was kind enough to invite me to his office in Washington DC to thank me for the post – and, naturally, I wrote up a blog post about the visit and our conversation! That visit has been “the” highlight of all my NOAA experiences! (*see A conversation about science communication with NOAA’s RDML Tim Gallaudet, Ph.D. (March 13, 2018))

Heading back out to sea with NOAA in 2023 is special for so many reasons. Life for all of us was disrupted in March 2020 – the COVID pandemic has been long and hard. My teaching and research has had so many twists and turns, and I still don’t know how everything will be moving forward. Getting out to sea on my first-ever fisheries expedition is not just exciting for me, but it has been heartwarming to see how many of my students and colleagues are sending me messages and looking forward to frequent updates! In a way, I’m taking so many people out to sea with me, and I’m going to work so hard to make this an informative and thrilling adventure for us all!

Photo of book cover, Endless Novelties of Extraordinary Interest - The Voyage of H.M.S. Challenger and the Birth of Modern Oceanography
Cover photo of Macdougall’s book on the Challenger expedition

Last year (2022) was a notable year for the field of oceanography. It was the 150-year celebration of when the H.M.S. Challenger set sail to collect meteorological and oceanographic data ranging from deep sea soundings and temperatures to biological samples. Although there were several ships that went out on scientific expeditions prior to 1872, the Challenger expedition (from 1872-1876) is the one credited as giving rise to the field of oceanography – and it’s interesting that before 1872, the term “oceanography” didn’t even exist in any dictionaries! I read the book Endless Novelties of Extraordinary Interest: The Voyage of H.M.S. Challenger and the Birth of Modern Oceanography by Doug Macdougall, and I couldn’t help but make connections between the methods of oceanographic research back at the time of Challenger versus today. Keep a look out for many comparisons between the work and logistics of Challenger to my experiences on Oscar Dyson in my upcoming blog posts – no doubt I will be sharing some current items of “extraordinary interest!”

I’m also looking forward to continuing to explore the intersections of science and art (STEAM) can be used to engage audiences and to communicate science data. I like to crochet temperature data and use these temperature records created in yarn for teaching and outreach (it is similar to the amazing work of The Tempestry Project!). While on board Oscar Dyson, I’ll not only be exploring under the sea but looking up towards the sky as my atmospheric observations will inform my Stitch the Sky project! Stay tuned for a future blog post to follow along and/or to create your own data visualization for your location.

*If you are interested in reading about my first TAS experience on NOAA Ship Thomas Jefferson, here are direct links to those blog posts:

Photo of Laura Guertin in front of the hull of the NOAA Ship Thomas Jefferson
NOAA Ship Thomas Jefferson (at Marine Operations Center-Atlantic, 2014)
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Phil Moorhouse: The Rest of the Story, September 22, 2019

airport meal

NOAA Teacher at Sea

Phil Moorhouse

Aboard NOAA Ship Oscar Dyson

August 27, 2019 – September 15, 2019


Mission: Fisheries-Oceanography Coordinated Investigations.

Geographic Area of Cruise: Gulf of Alaska (Kodiak – Aleutian Islands)

Date: September 22, 2019


Weather Data from Richmond, Virginia

Latitude: 37 44.36 N
Longitude: 77 58.26 W
Wind Speed: 5 knots
Wind Direction: 195 degrees
Air Temperature: 31 C
Barometric Pressure: 1018 mBar
Sky:  Clear

Conclusion

Wow, it’s hard to believe that my time on the waters of Alaska aboard the Oscar Dyson are over.  It was an experience I will never forget.  I just hope that I can instill in my students the idea that all kinds of things are possible when you follow your interests. 

It has taken me several days to reacclimatize to life on land.  Standing in front of my class, I have caught myself swaying.  It also took several days to readjust my sleep schedule.  (I don’t get rocked to sleep anymore and my hours are completely different.)

There were so many things I will miss and never forget: all of the unique experiences and sights I got to see, starting with my side trip to Barrow and swimming in the Arctic Ocean before the start of the expedition, getting to explore some of Kodiak before we left port, all of the open sea and species that were part of the random samples, the little coves we snuck into when storms were approaching, getting a “close-up” of the Pavlof volcano, and getting to explore the native land around Dutch Harbor where we were able to watch Salmon spawning and Bald Eagles doing their thing. 

  • Arctic Ocean swimming partners
  • Spires marking the opening of Castle Bay where we hid out from the storm.
  • Pavlof Volcano and Pavlof’s Sister
  • Shelikof Strait
  • Bald Eagle fishing near Dutch Harbor
  • Bald Eagles were common site. This one perched on a Russian Orthodox Steeple.

It was also interesting talking to and learning from the ship crew.  There are some interesting stories there about how they got to NOAA and what they have experienced since then.

  • Oscar Dyson crew preparing the nets for the next trawl.
  • Survey crew, Megan Shapiro checking out a smooth lumpsucker.
  • Ensign Lexee Andonian and 1AE Alan Currie managing the trawling equipment off the ship stern.
  • Survey Chief Phil White and Megan Shapiro monitoring the trawl nets in the water.
  • Engineer crewmember Gavan Roddey showing me the water purification system.
  • Scientists and Survey Crew working together.

At the top of the list though would have to be the connections I made with the scientists I spent almost three weeks with.  Being able to go out into the field with them and talking about what they have seen and learned over years of research has really reenergized my love for science in general.  Starting my shift looking forward to seeing what each Bongo station would bring up or what each trawl would bring to the sorting table, made for an expedition that went much too quickly.  It was interesting listening to my fellow scientists comparing how the numbers and ages of pollock caught at the various stations compared to what they had found in the Spring and in previous years. 

airport meal
The science crew all had the chance for one last meal together at the Anchorage airport before parting ways. I am very thankful for being accepted so well and for everything I have learned.

Overall, this has been an experience I will never forget.  I have learned so much about Alaska, the ocean, marine species, global warming, and scientific technology.  My time as a Teacher at Sea aboard the Oscar Dyson is something I will never forget and hope I can pass the excitement and experiences on to my students.

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Emily Cilli-Turner: One Fish, Two Fish….Pollock Counting Techniques July 29, 2018

NOAA Teacher at Sea

Emily Cilli-Turner

Aboard NOAA Ship Oscar Dyson

July 24 – August 11, 2018

 

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Eastern Bering Sea

Date: July 29, 2018

 

Weather Data from the Bridge:

Latitude: 57° 10.46 N

Longitude: 171° 58.29 W

Wind Speed: 11.16 knots

Wind Direction: 77.54° (NW)

Air Temperature: 10.1° C (Manual Reading from the Bridge)

Barometric Pressure: 992.7 mb

Visibility: 6 nautical miles

Sea Wave Height: 3 feet

Sky: Overcast

 

Science Log:

How do the scientists aboard NOAA Ship Oscar Dyson estimate the number and biomass of pollock in the Eastern Bering Sea? By using the science of statistics, of course! When political strategists want to determine what percentage of voters support a specific candidate or issue, they take a sample from the population of all registered voters. Voters in this sample are then asked about their preferences and statistical techniques are employed to extrapolate the results from the sample to the entire population and measure the margin of error.  Similar statistical techniques are employed by the scientists on NOAA Ship Oscar Dyson, but as you can imagine it is more difficult to sample pollock than voters that can be called on the phone!

Before each pollock survey begins, a set of transects is created for the Eastern Bering Sea.  These transects are paths for the ship to follow along which the scientists sample the pollock.  As you can see below, the transects for this survey are a fixed distance apart and cover the entire area of interest.  Generally, the transects are straight lines created to be perpendicular to the ocean depth grade. This allows for the scientists to encounter a variety of species as well as different ages of pollock to gain a robust picture of the ocean life in the area.

transect
The transects for this survey leg can be seen as the straight lines. The other markings are places where the trawls have been done and other scientific instruments have been deployed.

The NOAA Ship Oscar Dyson follows the transects during daylight hours, continuously recording water column acoustic backscatter data using EK60 instruments mounted on the bottom of the centerboard.  Scientists monitor the backscatter images, and when they observe sufficient pollock or other fish aggregations they  use the trawling nets to take a random sample of the fish and other ocean life they observed.  The trawling net is 140 m long with a vertical mouth opening of 25 m and horizontal mouth opening of 35 m. The net is deployed from the back of the ship and dragged at a fixed depth for an amount of time determine by the lead scientist to ensure a large enough sample. Once the trawling net is hauled in, the sample of marine fish and invertebrates is processed in the wet lab and entered into a database. Later the pollock numbers and weights by length are combined with  recorded acoustic data to create a robust estimate of the pollock population in the Eastern Bering Sea.

View of trawling nets being hauled in from the bridge.
View of trawling nets being hauled in from the deck.

After the catch comes in, the first job in processing the sample is to sort the specimens from the trawling net.  The first part of the net to come in is called the pocket net. This small net, also called a recapture net,  has a fine mesh and is designed to capture small species such as krill, age 0 pollock and jellyfish which slip through the meshes of the large trawl.  After the pocket net is processed, we process the codend, the closed end of the net and the main section where larger fish enter and are captured.  The fish in the codend are sorted by species.  The scientists can choose to measure the length of all the pollock in the haul or, if it is a particularly large catch, split the haul and measure length of a subsample of pollock.  Other species are also identified and their length is measured for later estimates of the total biomass that pollock make up as compared to other species.  Smaller species such as krill are weighed in aggregate instead of individually.

codend
The codend of the trawling net.

Sample analysis consists of measuring the lengths of approximately 200-400 adult pollock in the catch using the magnetic length board.  This is just one of the numerous software and instruments created by the MACE (Midwater Assessment and Conservation Engineering) group at NOAA in Seattle to make analysis easier and more automated.  The length distribution of the adult pollock helps scientists determine the approximate age distribution of pollock in the sample and it also helps them compare this distribution to other samples taken in the Eastern Bering Sea.  A subsample of about 50 pollock from the haul is taken to get more in-depth measurements. From these pollock, we measure both the length and weight and a subsample from the 50 is taken to determine the gender, measure maturity (i.e. what stage in the life cycle the pollock is at), and collect the otolith (ear bone), which gives a more accurate measurement of the pollock’s age.

TAS Emily Cilli-Turner
measuring the length of pollock from a haul.

Personal Log:

At this point, I am getting used to life at sea and have a nice routine.  The beginning of my shift, from 4am to a little past 7am, starts at sunrise and during which we resume our path along the transect.  No trawling operations are conducted at night, but there is still excitement.  If the underwater acoustics show that the pollock are at an appropriate depth, we can go pole fishing off the boat.  NOAA scientist Mike Levine is interested in post-capture mortality of pollock and the feasibility of tagging pollock.  Thus, he would like to catch pollock using a fishing pole, which puts much less stress on the pollock and increases the chance of their survival after the catch, instead of the trawling nets.

fishing
NOAA scientist Mike Levine with a pollock caught with a fishing pole.

As an instructor of mathematics, I have little knowledge of fish biology, but the scientists are great teachers!  I have been given a crash course on fish anatomy using specimens from the catch and I have learned how to sex the fish as well as how to collect the ovaries and the otoliths (ear bones).  If you asked me a week ago if I ever thought I would know so much about pollock after just a couple days on board, I would have laughed.  It has been great being the student and being able to learn so much in such a short time with real hands-on experience!

Did You Know?

Most of the personnel that are responsible for piloting and maintaining the ship are part of NOAA Corps, which is one of the seven uniformed services of the United States.