gyotaku – NOAA Teacher at Sea Blog

NOAA Teacher at Sea

Cheyanne Vanderdonckt

Aboard NOAA Ship Oregon II

July 27 – August 12, 2026

Mission: Shark/Red Snapper Bottom Longline Survey, Leg 1

Geographic Area of Cruise: Western North Atlantic Ocean

Date: August 4, 2026

Latitude: 34° 20.659’ N

Longitude: 76° 35.444’ W

Weather Data from the Bridge: Southwest winds 5 to 10 knots becoming 10 to 15 knots in the afternoon. Seas 3 to 4 feet. Showers with a chance of thunderstorms in the morning, then a slight change of showers and thunderstorms in the afternoon.

Science and Technology Log

The survey is in full swing. Every day during our 12-hour shift we will arrive at 2-3 stations, and the night shift will do the same. The exact number depends on how far apart the day’s stations are, as well as weather conditions and how long haulbacks take. We work in the rain, but not if there is lightning. The distance between stations varies from about 10 to 50 nautical miles. (A nautical mile is approximately 1.15 miles on land.) Our exact speed varies with current and wind, but we generally travel at about 11 knots, which means 11 nautical miles per hour. We begin to bait the hooks for the next station about 15-20 minutes before we arrive. Then it takes about 20 minutes to deploy the line off the ship’s stern. As soon as we are done with that, a few members of the science team will go to the bow with the deck crew to deploy a device that collects data about the water column (more on that below). An hour after the line was set, we will begin to haul in the line.

What are we hauling in? In this part of the Atlantic Ocean, we are mostly catching sandbar sharks (Carcharhinus plumbeus). Other species include tiger sharks (Galeocerdo cuvier), nurse sharks (Ginglymostoma cirratum), and Atlantic sharpnose sharks (Rhizoprionodon terraenovae). As explained in my previous post, most sharks are hauled up using the cradle. In the cradle, length measurements are taken.

Why more than one measurement? Before this trip, I always heard about, say, a “six foot shark.” I knew that scientists use the metric system so we wouldn’t be measuring in feet and inches, but we are also taking 3-4 length measurements for each fish. These measurements have been standardized using parts of the shark’s anatomy as endpoints. This allows scientists to make comparisons across different specimens and field studies, but it also helps them check for accuracy. It can be challenging to get accurate measurements on a living, moving shark. In addition, some species do not have a fork in the tail or a pre-caudal pit. The measurements generally taken are the pre-caudal length (from the tip of the snout to the point where the caudal fin meets the body), the fork length (from the snout to the fork in the tail), and the total length. You can see these lengths on this helpful diagram from the Florida Museum of Natural History. As a scientist takes the measurements, a recorder stands by with a data sheet to write them down.

simple diagram of a shark (possibly a sandbar shark) with 10 different length measurements denoted by horizontal blue lines extending from the left side (length = 0) to specific body features. they are: pre caudal length, pre second dorsal length, pre first dorsal length, head length, pre orbital length, pre pectoral length, pre pelvic length, pre anal length, fork length, total length (tip of caudal fin) — A diagram showing how to take different length measurements of a shark (Image credit: Florida Museum of Natural History)

When we catch a small shark, we can measure and weigh it on the deck. However, there isn’t a practical or safe method for weighing a large shark in Oregon II’s cradle. Instead, weights can be estimated based on length. If you are interested in how much a shark of a specific length might weigh, you can use this handy calculator from NOAA: https://apps-nefsc.fisheries.noaa.gov/shark/ This could be a great activity for having a little fun with measurement for students! After using good measurement practices to get your height, type your height in inches or centimeters into the calculator to see how much you would weigh if you were a shark. (If I were a sandbar shark, I would weigh about 95 pounds.)

The most exciting part of a shark catch is getting to tag the shark. Shark tagging helps scientists study shark behavior, populations and migration. If somebody catches a tagged shark, they can provide updated information on its location using a phone call or a website with a form. The tags we are using look like a piece of yellow coated electrical wire rather than a big plastic tag. They are inserted into the body right alongside the shark’s dorsal fin. After making a short (less than an inch) incision in the skin, the tagger inserts the tip of the tag with a device that resembles a large metal hypodermic needle. It’s important for everyone to work carefully but quickly to reduce stress on the animal and the chances of anyone being injured. After tagging, the hook is cut from the shark’s mouth and it is lowered back down to the water to be released. I have been allowed to tag three sandbar sharks so far and it is awe-inspiring to be so close to these amazing creatures.

top-down view of three people wearing hard hats and gloves leaning over a shark in a cradle. Most of the shark is obscured by the crewmembers. Cheyanne, in the center with a yellow hard hat, rests on hand on the shark's back. another crewmembers stands off to the side partially out of frame. — Cheyanne Vanderdonckt (in yellow hardhat) tags a sandbar shark in the cradle while science party chief William Driggers and lead fisherman Sean Gronquist control the head and tail (Photo credit: Masyn Douglas)

This is the first leg (of four) of the Shark/Red Snapper Bottom Longline Survey. On this leg, we are fishing off the east coast of Florida, Georgia, South Carolina, and North Carolina. On the next legs, they will be in the Gulf and will likely catch much more red snapper. Red snapper has been fished commercially in the Gulf since the 1840’s and by the 1920’s there were already signs of overfishing that led to regulation. Today, it is considered a sustainable seafood choice because it is responsibly managed in the United States. The annual survey conducted by NOAA Fisheries helps inform the process of establishing catch limits.

Gretchen, wearing a life vest and fish gloves, squats next to a wooden fish measuring board on the deck floor. She uses two hands to line a large orange-red snapper along the board and read its length. — Survey technician Gretchen Arndt measures the length of a red snapper (*Lutjanus campechanus*)

When a red snapper is caught, length and weight measurements are taken. Then the otoliths (ear stones) are retrieved. Otoliths are structures made of calcium carbonate that help the fish with balance and determining their position in the water. Otoliths of different species develop new layers at different rates. Marine scientists use the layers of the otolith to determine the age of a fish — much like counting the rings of a tree’s trunk. The fish is also examined to determine its sex and other tissue samples may be taken.

Maritime Career Focus: Survey Technician

Senior Survey Technician Gretchen Arndt is responsible for the scientific survey equipment on Oregon II. She has a bachelor’s degree in biological sciences with a marine focus from Florida Atlantic University. She worked as a field biologist and a field operations manager in the Florida Everglades. Marine biology is a competitive field that attracts many talented individuals. Gretchen says that driving and maintaining airboats and other equipment in the field helped give her the technical experience that led to her being hired by NOAA.

One of the pieces of survey equipment that Gretchen is responsible for is known as the CTD (for conductivity, temperature and depth). CTDs come in various designs and they are integral to the science of oceanography. The CTD can be used to retrieve samples of water for further analysis, as well. This device is deployed off the bow deck after each line is set. Getting the CTD into and out of the water is a coordinated effort between the bridge, the science team, and the deck crew. Gretchen also equips Oregon II’s CTD with a light and camera so that the science team can visually evaluate the seabed.

Gretchen, wearing a hard hat, life vest, and rubber boots, poses for a photo with one hand on a large scientific instrument. a round metal cage houses an array of narrow vertical gray water sample bottles. beneath that array is the conductivity, temperature, and depth probe. Gretchen and the CTD apparatus and photographed in front of a railing on NOAA Ship Oregon II and we can see blue water and blue sky behind them. — Gretchen Arndt with the “CTD”

Personal Log

sunset seen over the ocean. the water is dark blue and choppy. at the horizon, thin bands of yellow, orange, and pink peak out behind low gray clouds. — Another beautiful sunset, viewed from the stern deck.

I feel like I could just look at the sea and the sky all day and night. Fortunately, we do have transit time between stations so I am able to spend some time gazing. At first I just see blue everywhere, but the longer and closer I look, the more colors I can pick out. In the reading curriculum we use in my school district we have lessons in which students spend time silently observing a work of art. They aren’t allowed to speak for at least a minute because it’s important to let everyone form their own impressions before they hear others’ ideas. I will definitely share some of my sea and sky photos with my class to have them look for as many colors as they can see.

view of the horizon over the ocean. the water is blue-gray with some chop. the sky is light blue, with hints of pink toward the horizon, obscured by wispy white and gray clouds at different heights. — A view of the Atlantic Ocean from *Oregon II*. How many colors can you see?

Occasionally I see other ships on the horizon and sometimes I can make out some features on shore. When we passed by the Kennedy Space Center at Cape Canaveral, I could see the massive Vehicle Assembly Building. My favorite view, however, is when dolphins swim alongside the ship. Dolphins follow boats and ships for many reasons. They can ride the bow wave to conserve energy. As the ship moves through the water, it can also disorient smaller fish, making them easier to catch. It is very hard to catch the exact moment a dolphin leaps to the surface, but I took a video one night while a spotlight was being used to illuminate the water for hauling back the longline.

One thing I enjoy about being a teacher is that people often tell me what they were like as children at school. At least a couple of people working aboard Oregon II have told me tales of having trouble at school because they didn’t like to sit still or got bored easily. Like many teachers, I always loved school. But I know this is not the case for everyone. In education circles, we talk about the “hidden curriculum.” Success in school requires a set of skills and traits that have nothing to do with the academic content being taught and which can be really challenging for neurodivergent students, students with disabilities, and many others. But this does not mean they lack the intelligence or drive to learn. In fact, many of them have the type of insight and creativity that is needed to drive innovation. If schools can’t support them, we are all losing out on the unique gifts and talents they have to share. To that end, I am always trying to find ways to make learning hands-on and connected to the real world. Although there is time for quiet and reflection, most of the day should be active and even a little loud. I try to highlight ways that my students’ character traits and interests might lend themselves to different career paths. I’m getting so many ideas from watching people work aboard Oregon II.

In my opinion, one of the coolest jobs on board is that of Fisherman. Fishermen handle lines and operate equipment, including cranes (I’m jealous!), winches, and the anchor windlass. They work with the scientists during fishing operations and maintain the fishing equipment. On this survey we are using a longline, but the ship is also equipped with trawling nets. (In fact, the ship’s design is basically that of a fishing trawler). When a shark is in the cradle, fishermen operate the crane to haul it up, handle the lines on the cradle to help guide it into place, and help control the shark.

view up at the crane used to lift shark cradles up to the level of the deck; some crewmembers stand on deck and up at the crane, wearing hard hats and life vests — Fishermen, deck crew and science team members setting longlines and operating the crane used to haul sharks up to deck level.

four crewmembers wearing hard hats and life vests stand at the back railing of NOAA Ship Oregon II as the long line extends over their heads and down into the water. we can see a large white barrel whose rim is lined with baited hooks. the sky and ocean are dark - it is near dusk. — Fishermen, deck crew and science team members setting longlines and operating the crane used to haul sharks up to deck level.

Lead Fisherman Sean Gronquist shared one of his hobbies with us after we caught a red snapper. He paints one side of the fish with a biodegradable ink and stamps it onto canvas to make a print. This preserves the size and details of the fish, and makes a beautiful piece of art. The Japanese name for this art is gyotaku. In my classroom, I use arts integration a lot in science and math. Arts integration is a method in which a lesson addresses both academic content standards and fine arts standards. It has been shown to increase student engagement and improve retention of learning. It’s also great fun. I’m really excited to share this cool art form with my students. It has a physicality to it that makes it more interesting than a photograph. It will also be a great starting point to talk about texture. If you’re interested in educational uses for fish printing, here is an article from Smithsonian Museum of Natural History: https://ocean.si.edu/conservation/get-involved/educational-uses-gyotaku-or-fish-printing

Sean stands at a table set up on deck, applying dark gray paint to a red snapper laid out on top of some cardboard. — Lead Fisherman Sean Gronquist demonstrates steps in the process of making prints from fish. After the initial printing, he will return to add details.

Sean lifts a large piece of paper over a red snapper, painted gray, lying on a table on deck — Lead Fisherman Sean Gronquist demonstrates steps in the process of making prints from fish. After the initial printing, he will return to add details.

We have about a week to go in our survey and I am still enjoying every minute of my time on board. We had a couple of windy days that tested my sea legs, as well as my ability to sleep. Ships are very noisy in the first place, but the sounds increase as things start to slide around and doors knock around in their frames. Fortunately, I’ve got old hands to teach me tricks like stuffing bits of paper towel into drawers and doors to stop them from rattling. Nothing is as simple on a ship as it is on land, but that’s all part of the adventure.

Did You Know?

Although they are fish, many sharks give live birth. This means that some sharks have “belly buttons” that remain for a few months after birth. (If we come across a shark belly button I promise to share a picture!) Sharks also have two uteri. This year, one of my students was very excited to tell me that sand tiger shark embryos eat their siblings in utero and that checks out too. Although it may seem a little gruesome as a “fun fact,” it also helped us put things into perspective one day when he shared that he was in a bad mood because he had a fight with his sister. You never know when some scientific knowledge will come in handy!

NOAA Teacher at Sea

Guy Sturdevant

Aboard Oscar Dyson

June 21 – July 15, 2026

Mission: Summer Pollock Acoustic Survey, Leg 2

Geographic Area of Cruise: Bering Sea, Alaska

Date: June 29, 2026

Weather Data from the Bridge

N 58.6° W 170.4 °, 0 AMSL

Conditions: Fog, Seas at 4’

Visibility: < 3 NM

Wind: 70°/ 9 kt

Barometric Pressure 29.9 inHg

Dry Bulb Temp: 43 ° F

Science Log

So, we’ve taken a chilly dive into the why behind the focus on the pollock. Today, I will take you into “The Cave,” where we can learn how scientists use sound to locate and count pollock. On the port side of the main deck sits a dark, windowless room lit only by the dozen or so monitors adorning its aft wall. A gentle, constant humming fills the room from racks and racks of electronics, servers, and support equipment that dominate the center of this space. While the OOD on the bridge steers this vessel, “The Cave” calls the scientific shots by determining the ship’s course as well as the timing and location of all science operations.

a man and a woman sit in computer chairs at a desk beneath an array of 8 computer monitors; the large computer stack is visible to the right. the two scientists lean far back in their chairs to look up at the screens above. — Abigail McCarthy and Mike Levine discuss plans for the day shift. Time at sea is precious; this vessel operates 24/7 in all conditions. For the past two days, a very quiet, fishless northern extension has limited opportunities. But remember, even a null result is a result!

Acoustics 101

Since the early 20th century, scientists have used the unique ability of sound waves to transmit very efficiently through water for remote sensing. “Pings” of acoustic energy are generated by a transmitter, and then the backscatter (or reflected sound) is detected by a receiver. Early pioneers used sonar to better understand the physical geography of ocean basins in a process called bathymetry.

a graphic showing a cut-out photo of a ship (USS Stewart, DD-13) at the surface of the ocean (depicted as a blue rectangle) above the seafloor (a brown rectangle.) in the animation, upside-down orange parabolas extend from the bottom of the ship toward the seafloor; then right-side up dotted parabolas, like rainbows, extend back from the seafloor up to the ship's bottom. there is a cutout image of the antique echosounder off to the right. There is a speech bubble containing the equation for seafloor depth. The graphic is titled The North Atlantic, 1922: Acoustic Bathymetry — *USS Stewart first tested an early form of echosounder in 1922 as part of preparations for the installation of the Transatlantic cable.*

Not long after the first echosounders made their way aboard ships, scientists realized that as the quality of the instrument increased, they could measure the backscatter (or reflected sound) off of other objects besides the seafloor. Large backscattering layers far above the seafloor were targeted by fishing vessels using the new technology, demonstrating the effectiveness of echosounders at locating marine organisms throughout the water column.

a static graphic showing a cut-out photo of a ship at the surface of the ocean (depicted as a blue rectangle) above the seafloor (a brown rectangle.) 3 upside-down orange parabolas, representing the wave front, extend from the bottom of the ship toward the seafloor; 3 right-side up dotted parabolas, like rainbows, extend back from the seafloor up toward the ship's bottom, representing seafloor backscatter. cutout images of individual pollock fish are pasted in a "school" in the middle of the blue ocean water, and 3 blue rainbow-oriented parabolas extended up from the fish school, representing fish backscatter. this slide is titled: Acoustic Trawling. — *Early innovators in Norway and England reported success in using echosounders to detect large schools of fish and began actively monitoring their behavior (Balls, 1948)*.

The following decades of acoustic research relied on analog, single-beam systems, which were often towed behind or below a vessel and recorded a narrow swath directly below the ship onto a paper echogram.

composite photo of a porcelain wall showing an echogram. arrows and text have been superimposed on the photo to point out the seafloor backscatter and the school of pollock backscatter. in the lower right are the words NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION. — A 3d porcelain rendering of this now-famous echogram (the recorded chart of an echosounder) from the Shelikof Straight adorns the entry to the NOAA Alaska Fisheries Science Center in Seattle. The strong red and yellow reflections that sweep gently across the bottom represent the strong backscatter from the seafloor, and the large red cloud represents a large school of pollock.

The 1990’s welcomed a new era in echosounder technology with the release of the SIMRAD EK-500. This landmark digital echosounder combined multi-frequency operation with improved data processing and integration tools, enabling much better estimates of fish population density and biomass.

a graph of target strength (low, medium, high) v. frequency (kHz, log scale). three lines graph this relationship for fish (swim bladders) at 50-600 mm length; krill at 10-60 mm length; and copepods 0.2-20 mm length. — Larger acoustic targets, such as the swim bladder of a large fish, produce strong backscatter at relatively low frequencies, whereas smaller organisms, such as krill and copepods, reflect sound only at much higher frequencies. Multi-frequency echo sounder measurements allow scientists to discriminate between acoustic targets of different sizes and target strengths and more accurately estimate the biomass of individual organisms as they scroll across the screen.

Next time, we will look at the echograms produced aboard Oscar Dyson and receive a crash course in interpretation from the Cave!

Personal Log

Work hard, play hard is an unofficial motto aboard Oscar Dyson. The officers, crew, and science team are keeping a fierce eye on the World Cup when off duty (Colombia’s goal call-back was a travesty!!).

a 16-competitor bracket drawn on an old hydrographic chart. beneath the chart is the title: The Inaugural Collin McMillan Memorial Biannual Oscar Dyson Amateur Cribbage Tournament. — *The “Inaugural Collin McMillan Memorial Biannual Oscar Dyson Amateur Cribbage Tournament” is underway; stay tuned for updates and potential video coverage of the championship match!*

Guy, wearing overalls and long yellow gloves, holds up a flatfish pointing toward his face, and makes a kissy face at a safe distance. — The future gyotaku model, Northern rock sole (*Lepidopsetta polyxystra*)*, posing for a picture before her big debut.*

fish print, in black ink, of a flatfish — Gyotaku is the traditional Japanese art of collecting fish prints. Engineer Victoria Southwick, ENS Josh Bennett, and Lt. Jesse Pierce captured the print of a Northern rock sole (Lepidopsetta polyxystra) brought up on haul 71, 06/28/26.

Wildlife sightings

highly detailed photo of an albatross floating at the ocean's surface — A Short-tailed albatross (Phoebastria albatrus) follows us during trawling operations, hoping for a fishy treat. This threatened marine bird is a tale of cautious conservation success. Their population in the 1950s dwindled to as low as 25 individuals. Today, roughly 4,200 individuals are known to exist.

Fun Fact

In the Cave, it is not uncommon for the shallow layer to be filled with a mix of non-fish backscatter. Everyone has their pet theories as to what may be the source of these shallow acoustic targets (we know they aren’t fish), but they have all agreed to call it by one name… munge. Below is my artist’s interpretation of Munge as a heavy metal album.

MUNGE album cover

Sources

Balls, R. 1948. Herring fishing with the echometer. Journal du Conseil International pour l’Exploration de la Mer, 15: 193–206.
Korneliussen, R. J. (2018). Acoustic target classification.
Benoit-Bird, K. J., & Lawson, G. L. (2016). Ecological insights from pelagic habitats acquired using active acoustic techniques. Annual review of marine science, 8, 463-490.
Mordy, C. W., Bond, N. A., Cokelet, E. D., Deary, A., Lemagie, E., Proctor, P., … & Wisegarver, E. (2023). Progress of fisheries-oceanography coordinated investigations in the Gulf of Alaska and Aleutian Passes. Oceanography, 36(2/3), 94-100.
De Robertis, A., McKelvey, D. R., & Ressler, P. H. (2010). Development and application of an empirical multifrequency method for backscatter classification. Canadian Journal of Fisheries and Aquatic Sciences, 67(9), 1459-1474.
Simmonds, J., & MacLennan, D. N. (2008). Fisheries acoustics: theory and practice. John Wiley & Sons.
Holliday, D. V., & Pieper, R. E. (1995). Bioacoustical oceanography at high frequencies. ICES Journal of marine Science, 52(3-4), 279-296.
Echoview. (2019). Acoustics Unpacked. https://acousticsunpacked.echoview.com/acoustics/AcousticsUnpacked.asp

Tag: gyotaku

Cheyanne Vanderdonckt: In Which I Learn How to Tag a Shark, August 4, 2026

Science and Technology Log

Maritime Career Focus: Survey Technician

Personal Log

Did You Know?

Guy Sturdevant: The Cave pt. 1, June 29, 2026