echosounders – NOAA Teacher at Sea Blog

NOAA Teacher at Sea

Germaine Thomas (she/her)

Aboard NOAA Ship Oscar Dyson

August 7 – August 21, 2023

Mission: Acoustic Trawl Survey (Leg 3 of 3)
Geographic Area of Cruise: Pacific Ocean/ Gulf of Alaska
Date: Wednesday, August 16, 2023

Weather Data
Lat 59.47 N, Lon 144.1 W
Sky condition: Cloudy with Rain
Wind Speed: 22.62 knots
Wind Direction: 125.44°
Air Temp: 14 °C

Science and Technology Lab

While on the third leg of our cruise we have had a lot of weather delays, so when the going gets rough the Oscar Dyson science team calibrates! Plus they do not hesitate to work on a couple special projects. No time is wasted. In a secluded bay, waiting for the storm to pass, lots of work can be done to further science.

As I mentioned, this summer has been cold, dark, rainy, and windy. As a fisher person who works in this environment, I cannot overstate how important the internet has become with weather apps like Windy. They accumulate data from oceanic buoys, local weather stations, and satellite images to create a picture like the one you see below.

a screenshot showing simple political map of the Gulf of Alaska coastline. it has been colored with a scale to indicate wind speed. small white dashes are scattered through the image, showing the wind blowing up from the southwest, into the center of the coastline, curving counterclockwise toward Anchorage. A few major locations are labeled with air temperatures: Anchorage: 59 degrees, Homer: 57 degrees, Kodiak: 55 degrees, Juneau: 55 degrees, Whitehorse: 59 degrees. — This image is from the weather app Windy. The white lines indicate the wind direction and the warmer colors are higher wind speeds.

The crew and scientists were able to be proactive in their decision to find a safe place to harbor and then could set up a work plan through the weather day.

Calibration of the Ships Echosounders

The Oscar Dyson’s echo sounders get calibrated about four times a year, at the start and end of the winter and summer field seasons. Because this is the last leg of the cruise, and we are nearing the end of the summer, a weather day is a good day to make sure they are working well

The first step in calibration is to set up down riggers on the starboard, port and aft decks.

Abigail, Robert, and Matthew pose for a photo in the wet lab, each holding a downrigger. The downriggers look like heavy-duty black fishing poles that can be secured onto the deck railings. Abigail is wearing a red light headlamp. — From left to right Abigail McCarthy, Robert Levine and Matthew Phillips, part of the night crew, head outside to place the down riggers.

Once placed, the downrigger lines are very cleverly connected underneath the boat, so all three lines meet.

a downrigger, which looks like a heavy-duty black fishing pole, attached to a railing of the ship. a fishing line extends down from the end into the water, angled back toward the ship to meet up with the other lines. The water is a calm, gray-blue, with fog-shrouded mountains not far in the distance. — Downrigger mounted on a railing

Where all three lines meet, a single line is suspended directly down underneath the keel of the boat where the echo sounders are located. The down line has a tungsten carbide sphere suspended above a lead weight. The scientists use the known target of the sphere and the known properties of the water column to figure out the difference between expectations and reality in their calibration. The tungsten carbide sphere works extremely well for calibration because it is extremely dense when compared to water, has a known sound reflection, and allows calibration at multiple frequencies.

photo of a computer screen; on the left, many circles (most blue, some white, one red) within a larger circle; on the right, a table full of numbers. — Pictured above is a screen scientists see as they are moving the sphere around for calibration.

The picture is showing a black circle representing the transducer face as observed from above. The blue dots represent individual measurements of the reflected echo of the calibration sphere as it is moved around in the transducer beam. Using this calibration software the scientists can evaluate the measurement sensitivity and the beam characteristics of the echo sounders.

Calibrating the acoustics was not the only event that happened while weathered deep in a fjord arm of Nuka Bay.

The MiniCam

While waiting out the weather, other members of the science team had a chance to work with a new piece of equipment called a minicam.

small underwater camera apparatus sitting on deck — The MiniCam, pictured above, has two stereo cameras which can film marine organisms.

The purpose of this camera is to connect the images it records to the backscatter shown with the Oscar Dyson‘s echo sounders. Again, backscatter, as I mentioned in the previous blog, are images that are produced when the echosounders’ different frequencies are reflected back to the ship. The images created by sound are shown on a computer screen and can be used to identify different species of fish or other marine organisms. The images need to be verified by either the minicam or trawl sampling. Scientists want to make sure that the length and species of what they see in the camera can relate to the scaling of the backscatter. The minicam was deployed by scientists and the crew several times to look at the fish and euphausiids in the water column, while we waited out the bad weather.

Germaine and another crewmember, wearing life vests, hard hats, and boots, stand on deck in the evening. the minicam, attached to cables extending beyond the top of the image, sits on deck near the railing, awaiting deployment. In the background, we can just barely see dark blue water, and a darker blue mountain, hidden in fog. — Getting ready to suspend the MiniCam before it is lifted over the side of the boat from the Hero deck.

Recreational Fish Finders “Little Pingers” Project

This is a project by NOAA oceanographer Robert Levine. The echosounders that are suspended below the Oscar Dyson are extremely precise and expensive. Robert and a colleague want to compare the echosounder’s data/readout for recreational fish finders to the echosounders on the Oscar Dyson. There are situations where scientists would love to monitor fish and marine organisms’ populations, but may not need the accuracy and precision of the scientific Simrad echosounders.

Robert, wearing a life vest, works on a laptop inside a storage area with one door open to an outer deck. he appears to be sitting on an overturned bucket. in front of him, another overturned bucket props up equipment (probably fish finders). Behind Robert, we see other equipment, hoses, life preservers, a fire extinguisher, a ladder. — Robert Levine working with the ” Little Pingers.” Environments on board a ship can be challenging to work in, as seen here.

They also might not be able to recover the fish finders, so having them less expensive is very important.

At this point they are just collecting data and monitoring performance with the recreational fish finders, affectionately called “little pingers.” Later in the project they will do more of a data comparison to the Oscar Dyson‘s echo sounders.

Personal Log

On board a ship, one way to keep the crew’s spirits up in bad weather is excellent food. According to the people I have worked with so far on the cruise, the meals on this leg of the acoustic-trawl survey have been amazing.

Meet The Dream Galley Team

Rodney and Angelo pose for a photo against a wall in the mess. They are standing in front of a coffee machine. Rodney wears an Oscar Dyson trucker cap. Angelo is wearing a black chef's uniform. — From left to right, Rodney Bynum and Angelo Santos

Meet the Dream Galley Team. From left to right, Rodney Bynum and Angelo Santos. These men share a passion for food and see how it brings smiles to the faces of their customers, friends, and family. Both have fathers who worked on ships in the Steward Department. Rodney fondly remembers his father bringing home exotic food from all over the world. His father inspired him to open a Soul Food restaurant in Norfolk, Virginia. Years later, Rodney decided to take his culinary career in a different direction: cooking on a ship. The Oscar Dyson was his first time working on a ship and he has really enjoyed it thus far. The crew loves his congenial personality, mad cooking skills, and awe-inspiring work ethic.

Angelo started cooking at the age of 11, often helping his mom roll lumpia (Filipino egg rolls) and make other traditional Filipino food while religiously watching Giada de Laurentis, Emeril Lagasse, and Ina Garten on Food Network. Angelo grew up in San Francisco and rural Oregon, spent 3 years in San Diego, and is now based in Oregon once again while traveling the world for work. In Oregon, he decided to major in Culinary Arts and graduated with his associate’s degree after going through Linn-Benton Community College’s Culinary program. Angelo mentioned, “culinary school isn’t required, but it helps you gain a fundamental understanding of cooking to prepare you for the real world.” He recommends trying out a restaurant job before spending money on tuition for culinary school.

East Coast meets West Coast aboard the Oscar Dyson. Both men have solid fundamentals in cooking from their years of experience as restaurant chefs. Angelo is the Chief Steward while Rodney is the 2nd Cook. The Chief Steward is in charge of galley operations while the 2nd cook provides breakfast and assists as needed. Chief Steward is like an Executive Chef position on land while 2nd cook is like a breakfast cook/prep cook/dishwasher. Rodney and Angelo often collaborate for menu ideas and feed off each other’s passion for delicious food.

Both of them enjoyed high school and had lots of advice for students looking into a career in Culinary Arts. As I interviewed them, they’d often finish each others’ sentences in agreement.

Rodney: “If you’re looking to become a good chef, don’t be afraid to taste everything, including food that may not be familiar to you. Every job in the kitchen matters, whether it’s the prep cook, dishwasher, or executive chef. Learn every position and never stop learning.”

Angelo attended culinary school shortly after graduating high school, so he found it to be stressful and chaotic, but very rewarding. He mentioned, “Focus as much as possible on having a good work-life balance. Find the joy in simple pleasures, take care of your mental health, and make friends outside of work. Work on networking with peers who share your passion for food as well as people outside of your cohort. Connections can help a lot.” Angelo enjoys cooking on ships because the compensation was very good. The only chef jobs on land that compare to this salary are executive chefs at very high end venues and private/personal chefs. Being able to travel around the world on business was a cool perk of being a chef at sea.

Overall, both men agreed that some of the best moments of pursuing a career in the food industry have been about seeing the joy that good food brings to people. Life is too short to not eat well and this is especially appreciated when one works on a ship. It makes all the difference for the morale of a ship to know that while you’re away from your loved ones, you can still eat well.

Finally, I have to give Angel credit for helping me write the sections about the “Dream Galley Team,” not only is he a great cook but also a fantastic writer.

top down view of a purple mug on a red table containing a latte with foam designs — This beautiful latte was made by Angelo Santos on the *Oscar Dyson*

NOAA Teacher at Sea
Caitlin Thompson
Aboard NOAA Ship Bell M. Shimada
August 1 — 14, 2011

Mission: Pacific Hake Survey
Geographical Area: Pacific Ocean off the Oregon and Washington Coasts
Date: August 4, 2011

Weather Data from the Bridge
Lat. 46 degrees 22.4 N
Long. 124 degrees 41.1
Present weather: cloudy
Visibility: 10 n.m.
Wind direction: 330
Speed 11 kts
Sea wave height: 2-3 feet
Swell waves – direction: 310
Swell waves – height: 3-4 feet
Sea level pressure: 197.3 mb
Temperature – dry bulb: 17.0 degrees C
Temperature – wet bulb: 15.0 degrees C

Science and Technology Log

Yesterday, I saw, sexed, and measured my first hake. And my second hake, and hundredth hake, and two hundredth hake. Most of the time, the scientists on the acoustics team watch computer monitors that show acoustic data as colors to represent life under the ship. Twice today, however, they identified large populations of hake and decided to fish for them in order to get more accurate data.

Pressure Housing — The pressure housing, held together by electrical tape and sponges, holds the battery and data storage for the light, lasers, and camera attached to the net.

Both times, the ship went into immediate action. Upstairs in the bridge, or command room, the NOAA officers slowed and repositioned the ship. Two scientists watched for marine mammals. If mammals were too close, we would have to abort the operation entirely. On the fish deck, John Pohl, on the acoustics team, taught me to assemble the pressure housing and attach it to the net. Objects attached to the net include the video camera, which will film anything passing by the mouth of the net, a four-beam laser to judge the length of the images that are filmed, a light to illuminate the water, batteries for power, and another camera for storing the data. The crew began lowering the net.

Hake — Josh Gunter, survey technician, operates a hatch to let hake onto the flow cale, which will find the mass of the whole haul.

For me, the real excitement began once the fish began pouring onto a conveyor belt into the fish lab. First, we sorted the fish by species. In the first haul, the fish were mostly hake, as intended, but we also caught three yellow-tail rockfish and three eulachons, a type of smelt. In the second haul, there was largely yellow-tail rockfish and hake, with several Pacific Ocean perch and widow rockfish. The rockfish were difficult to sort: they have dangerous spines and fight hard. Alicia Billings, a fisheries biologist on the acoustics team, taught me how to pick them up with one hand over their eyes and the other firmly grasping their tails. Even so, we both had a few close calls. We threw most of the fish right back into the ocean but kept about three hundred hake to sex and scale. With another fifty hake, we put then stomachs in individual bags so that the lab on shore can determine what the hake were eating. We also stored the otolith, or ear bones, in order to determine the age of the hake. Just like the rings of a tree, otoliths show growth rings every year.

Finally, we cleaned up and settled back in the acoustics lab to watch for the next batch of fish.

The monitors use echosounders, which are exactly how they sound: Signals (sound waves) are emitted from beneath the ship and echo back once they hit something. The computer records the distance of an object by how long it takes for the signal to return. For example, suppose a fish were right at the surface. The signal would hit it and return in very little time.

On the other hand, in deep water the signal would take much longer to hit the bottom of the ocean and return. See the thick red line on the graph to the left? That’s the ocean floor. Notice how it curves down on the right at the edge of the continental shelf. The flat line at the top of the graph is the surface of the ocean. The scattered dots in between are most likely fish. The scientists can guess the kind of fish and the number of fish by the pattern and color of dots. All the color below the ocean floor is meaningless noise. Look to the upper left-hand corner of the graph to find the frequency of the signal, measured in kilohertz (KHz). The lower frequencies (20 kHz and 38 kHz) tend to measure larger objects and to go deeper in the water. These frequencies are perfect for finding hake. The higher frequencies (120 kHz and 200 kHz) measure smaller objects. For example, shortly before we started the first haul, we saw a large number of plankton, which showed up bright blue on the 120 kHz and 200 kHz frequencies but barely showed at all on the lower frequencies.

You can follow the progress of the Shimada at shiptracker. We’re headed for Port Angeles on August 14, making East-West transects along the way.

Chief Scientist Larry Hufnagle in the acoustics room

Personal Log

I am so happy to be at sea. The journey was delayed an entire day because of a problem with a valve, and we finally set sail yesterday. The skies are blue and the ocean calm, and I am constantly learning new stuff. I’ve had to learn to lift my feet when stepping through a doorway (I forgot once and went sprawling!) and to memorize the complicated series of halls and ladders to get from the fly deck to the bridge to the mess room to my stateroom. I’ve had to memorize thirty-some names. The scientists have been incredibly patient, explaining each part of their work while I take copious notes. Working in the fish lab is my favorite part so far. It’s fascinating and satisfying work.

I am impressed by the sense of camaraderie on this ship. The scientists on the acoustics team – also known as the hake people – keep up a constant, teasing banter, which only turns serious when discussing science. With science, they all have a different opinions. Before fishing today, Chief Scientist Larry Hufnagle worried that there were too few fish shown on the monitor. He said, “I don’t even know how you would fish on this stuff.” Dr. Rebecca Thomas, a research fishery biologist on the acoustics team, seemed to think there were plenty of fish, but suggested leaving the net in for a longer amount of time for a larger sample. After much more discussion, the team decided on a strategy and put in the net. I’m impressed how often they disagree and how carefully they listen to one another’s ideas.

Tag: echosounders

Germaine Thomas: Hurry up and Wait, or What to do when the Weather Sets In, August 16, 2023

Caitlin Thompson: Going Fishing! August 4, 2011