Acoustic Trawl Survey – Page 3 – NOAA Teacher at Sea Blog

August 4, 2015August 21, 2021

Cristina Veresan, Nets and the Wet Lab, August 3, 2015

NOAA Teacher at Sea
Cristina Veresan
Aboard NOAA Ship Oscar Dyson
July 28 – August 16, 2015

Mission: Walleye Pollock Acoustic-Trawl survey
Geographical area of cruise: Gulf of Alaska
Date: Monday, August 3, 2015

Data from the Bridge:
Latitude: 58° 51.5 N
Longitude: 149° 30.8 W
Sky: Scattered Clouds
Visibility: 10 miles
Wind Direction: SSE
Wind speed: 8 knots
Sea Wave Height: <1 feet
Swell Wave: 0 feet
Sea Water Temperature: 16.3° C
Dry Temperature: 17.2 ° C

Science and Technology Log

Once it is determined where to fish, the scientists also have to decide which trawl to deploy and tow behind the ship in order to catch the targeted fish. The most common trawl we use to catch mid-water pollock is the Aleutian wing trawl (AWT). Our AWT is 140 meters long, and it can be fished anywhere from 30-1,000 meters underwater. A net echosounder is mounted at the top of the net opening and transmits acoustic images of fish going in the mouth of the net in real time to a display on a computer on the bridge that is monitored by the scientist and the Lead Fisherman. Additionally, at the entrance of the codend (the end of the net where the fish are collected), a stereo camera called the CamTrawl takes pictures of anything entering the codend. CamTrawl pictures are later analyzed to determine species and lengths of the fish that were caught. Sometimes the net is fished with the codend opened and the catch is only evaluated based on what is seen in the CamTrawl images. As this technology gets perfected less fish will need to be brought onboard.

A view of the stern as the deck crew prepares to deploy the AWT. Note the net reel at the bottom of the frame. — A view of the stern as the deck crew prepares to deploy the AWT. Note the AWT on the net reel at the bottom of the frame.

Cooperation among many different people is necessary during a trawl. The wet lab team prepares the CamTrawl to collect data. The deck crew physically handles all the gear on deck, including attaching the CamTrawl camera, net echosounders, and physical oceanography instruments to the net and deploying and recovering the net. From the bridge, the Lead Fisherman controls the winches that move the trawl net in and out of the water. Once the trawl net is in the water, the scientists work closely with the Lead Fisherman and the officers to ensure a safe, effective trawl. Sometimes the trawl net will be down for a few minutes, and other times it will be closer to an hour. Once the net is back on the ship and emptied out, the catch and CamTrawl images are ready to be analyzed by the scientist and wet lab team.

CamTrawl images were filmed by two cameras in stereo and so scientists can run a program that calculates length. — Fish are filmed in stereo so scientists can run a program that calculates their length.

Two other nets, more seldom used, are the bottom trawl net, known as the Poly Nor’easter (PNE) and the Methot net, used to catch krill and zooplankton. The PNE is deployed if there is a large concentration of fish close to the ocean floor. It is smaller than the AWT and it is usually lowered to just above the ocean floor. The Methot net was named after Dr. Richard Methot, a famous fisheries modeler who designed the net. This net has an opening of 5 square meters, and it has a finer mesh than the AWT or the PNE. At the end of the net is a small PVC codend where the sample is taken from.

Shipmate Spotlight: Interview with Kirk Perry

Kirk Smith, Lead Fisherman and Chief Boatswain — Kirk Perry, Lead Fisherman and Chief Boatswain

What is your position on the Oscar Dyson?
I am the Lead Fisherman and also sailing as active Chief Boatswain.

What training or education do you need for your position?
I went to Cal Poly San Luis Obispo and got a BS in Natural Resource Management. I have certifications from the Coast Guard like an AB (Able-Bodied Seaman) unlimited, which means I have over 1070 days sailing as an AB. I also have a Masters license to operate a 100-ton vessel. You need a lot of fishing experience.

What do you enjoy the most about your work?
Fishing! Obviously. You just never know what you are going to get, and it’s always exciting.

Have you had much experience at sea?
I have been fishing since I was 10 years old and I helped a neighbor build a boat and go salmon fishing in Monterey Bay. When I visited family in Hawai’i, we would go trolling, set net fishing, beach casting, and spearfishing. I have been sailing professionally with NOAA for 11 years on different vessels in Hawai’i, Mississippi, and here in Alaska.

Where do you do most of your work aboard the ship? What do you do?
As Lead Fisherman I operate the machinery from the bridge when we are trawling. Basically, I get the fishing gear in and out of the water safely. As Chief Boatswain, I am in charge of the Deck Department, so I schedule crew, assign daily crew duties, maintain supply inventories, oversee the ship’s survival gear, and operate deck equipment like winches, anchor, and cranes.

When did you know you wanted to pursue a marine career?
By 25 years old I knew I had to be on the water, full time, all the time, but I did not get to be here until I was 44 years old.

What are your hobbies?
When I’m not fishing, I like to hunt. Mainly ducks and geese.

What do you miss most while working at sea?
Home, my family. And my own bed!

What is your favorite marine creature?
Tuna because they are so fast powerful and so delicious! When you are fishing for them, it’s like nothing else. It can turn into a wide open frenzy.

Inside the Oscar Dyson: The Wet Lab

The wet lab is where we do most of our work, and it gets really busy in here after a trawl. It is called a “wet” lab because it is designed to get just that. When a trawl net is full of fish, it is emptied onto a table that tilts onto a conveyor belt feeding into the wet lab. We have controls to run the conveyor belt as well as tilt the tableAs the fish are brought in on the conveyor, we sort them in large and small baskets, and then collect data from the different species. The metal counters, outfitted with electronic balances and automated length readers provide us with workspace to process our samples. The work of the wet lab is messy and fun. When we process a catch, fish scales get everywhere! The shiny, sticky little discs coat every surface, especially areas that you touch like the computer screens and handles. It is fun to clean this lab because you spray everything down with the salt water from hoses that are rigged from the ceiling. You can even spray down the computer screens themselves, and then rinse them with fresh water. Water washes over everything and drips down, entering drains in troughs along the edges of the floor.

Processing pollock in the wet lab! Photo by Emily Collins

Personal Log

Whenever it’s time to process fish in the wet lab, I have to get geared up! What is the latest in fisheries fashion, you might ask? Rubber boots are a must. We take the lead of Alaskans and wear brown XtraTuf boots. Once I get my boots on, I put on my Grundens foul weather coveralls over my pants. The weather has been mild, so I have been forgoing the matching foul weather jacket and just wearing a long sleeved t-shirt or sweatshirt. I have not been wearing a hat, but I do pull my hair back. Lastly, I pull on elbow-length yellow rubber gloves over my sleeves.

Before you enter the wet lab, you get geared up here. Sometimes to make a quick entrance/exit, you leave your boots in your coveralls (bottom right)

These boots are made for fishin' — These boots are made for fishin’

I am really enjoying my time with this ship’s crew and the rest of the science party. Everyone has been very welcoming, and, though we work hard, we maintain a sense of fun. If we have down time between data collection, Emily and I play cribbage. Or we go out on deck and take in the sights, like the Holgate glacier we passed the other day. Quite a few people on board have spent time in Hawai’i, so we can ‘talk story’ about the islands from all the way up here in the North Pacific. It is amazing how we are all connected in some way through our love of the ocean.

My voyage of discovery continues…

glacier — We sailed within 4 miles of Holgate Glacier on a beautiful sunny morning

August 2, 2015August 21, 2021

Cristina Veresan, Gone Fishin’, August 1, 2015

NOAA Teacher at Sea  
Cristina Veresan
Aboard NOAA Ship Oscar Dyson
July 28 – August 16, 2015

Mission: Walleye Pollock Acoustic-Trawl survey
Geographical area of cruise: Gulf of Alaska
Date: Saturday, August 1, 2015

Data from the Bridge:
Latitude: 58° 39.0′ N
Longitude: 148° 045.8′ W
Sky: Broken clouds
Visibility: 10 miles
Wind Direction: W
Wind speed: 15 knots
Sea Wave Height: 3 feet
Swell Wave: 0 feet
Sea Water Temperature: 15.4° C
Dry Temperature: 13.8° C

Science and Technology Log

So, you might be wondering how our scientists know when it’s time to “go fishin’”? That is, how do they determine if there might be a significant concentration of pollock to deploy a trawl? The answer is acoustics! The ship is equipped with a multitude of acoustic transducers on the bottom of the ship, five of which are primarily used in the pollock population assessment. These transducers both send and receive energy waves; they transmit sound waves down to the ocean floor, which reflect back to the ship. However, if there are obstacles of a different density in the water (like fish), the signal bounces back from that obstacle. The amount of energy that pollock individuals of different lengths return is known to our scientists.

Chief Scientist Darin Jones studies the echogram and talks to the bridge

The real-time data from transducers is automatically graphed in what is called an echogram. When we are on our predetermined transect line, the scientist on watch analyzes the echograms to make the determination of when to trawl. The transducers are different frequencies. In general, the higher the frequency, the smaller the object it can detect. To make a final decision on fishing, the scientist must also coordinate with the officers on the bridge who take into account wind speed, wind direction, water currents, and ship traffic. Once we collect the trawl data, scientists use the catch information to assign a species and length designation to the echogram data in order to produce a pollock biomass or abundance estimate. In addition to the pollock we are targeting, we have caught salmon, cod, jellyfish, and a few different types of rockfish.

We often catch one type of rockfish, the Pacific Ocean perch (Sebastes alutus), which has a similar acoustic signature as pollock. On the ship, we call this fish POP, and they are difficult to handle because of the sharp spines on their dorsal fin, anal fin, head, and gill covers (operculum). You have to watch out for spine pricks when handling them! Their eyes usually bulge when they come up from depth quickly and gases escape, which is a form of barotrauma. One interesting fact about Pacific Ocean perch is that they are viviparous (give birth to live young); the male fish inserts sperm into the female fish and her egg is fertilized inside her body. These fish can also be incredibly long-lived, with individuals in Alaska reaching almost 100 years old. The Pacific Ocean perch fishery declined in the 1960’s-1970’s due to overfishing, but has since recovered due to increased regulation.

Shipmate Spotlight: Interview with Allen Smith

What is your position on the Oscar Dyson?
I am the Senior Survey Technician. It’s my second season in this role.

Where did you go to school?
There is no formal training for this position, but you do need a scientific/technical background. I have a BS in geology, and right after college, I worked in technical support for Apple.

What do you enjoy the most about your work?
My favorite part is meeting people and re-connecting with ones I already know. Different scientists rotate in and out and they are my contact with the outside world.

Have you had much experience at sea?
I have worked on ships since 2011. I worked on cruise ship as a cook then I joined NOAA and sailed on the NOAA ship Oscar Elton Sette in Hawai’i as a cook and then later joined the NOAA ship Oscar Dyson as a survey tech. I really wanted to get back into science so I made the switch.

Where do you do most of your work aboard the ship? What do you do?
The domain of the survey technician is the laboratory. We have wet, dry, chemical, and computer/electronics labs aboard the Oscar Dyson. I am responsible for the meteorological, oceanographic, and navigation data that the ship collects full-time. We also help visiting scientists to accomplish their missions using the ship’s resources, like deploying fishing gear, CTD, cameras, or other equipment. Sometimes we do special missions like last year when we went to the Bering Sea for an ice-associated seal survey and our ship had to break through sea ice. During scientific operations, I work a 12-hour shift everyday.

When did you know you wanted to pursue a marine career?
I grew up in Dallas, Texas, which is totally land-locked, so you could say I wanted a change.

What are your hobbies?
No time for hobbies at sea! Just kidding, I like photography and playing guitar and ukulele. When I am not at sea, I enjoy hiking and biking.

What do you miss most while working at sea?
Probably what I miss the most is being able to cook vegetarian meals for myself.

What is your favorite marine creature?
The red-footed booby because they have so much personality and are very entertaining.

Inside the Oscar Dyson: The Galley

The galley is ship-speak for the kitchen and dining area. Our ship stewards (chefs) work really hard to prepare buffet-style meals three times a day. Breakfast is served from 7-8am, lunch from 11am-noon, and dinner from 5-6pm. There is also a salad bar and a soup available for lunch and dinner. One night we even had food popular in Hawai’i: Kalua Pork, ramen stir fry, and chicken katsu! You can also come in the galley 24 hours a day to get coffee, espresso, tea, water, and various snacks. There is even an ice cream freezer! You might notice the chairs in the galley have tennis balls on the ends of the legs, as well as tie downs attached to them; this is to prevent sliding during rough seas.

Personal Log

One of the challenges of working on a moving platform is seasickness. Nausea can be really debilitating, and it prevents many people from enjoying time on the water. I am not prone to it, but I am aware it could still afflict me at any time. Luckily, we have had very calm seas, and I have felt great, even when typing on the computer or slicing up fish! I brought some anti-seasickness medication with me but I have not needed it yet. I also have some candied ginger with me that I have been enjoying, though not for medicinal purposes.

Good morning from the Oscar Dyson! — Feeling happy, not seasick!

The scenery this week has been incredible as we weave our way through the bays and fjords of the Kenai Peninsula. McCarty fjord, carved 23 miles into the coast, was very impressive. The fjord is flanked by massive green mountains and towering cliffs. This majestic landscape was carved by ancient glaciers. I have spotted a few bald eagles, and, with binoculars, one of the deck crew members saw a brown bear mama and two cubs. As much as I love the open ocean, it’s exciting to be close to shore, so we can enjoy Alaska’s dramatic vistas and wildlife.

I am loving life at sea!

July 30, 2015August 21, 2021

Cristina Veresan, Welcome Aboard the Oscar Dyson, July 29, 2015

NOAA Teacher at Sea
Cristina Veresan
Aboard NOAA Ship Oscar Dyson
July 28 – August 16, 2015

Mission: Walleye Pollock Acoustic-Trawl survey
Geographical area of cruise: Gulf of Alaska
Date: Wednesday, July 29, 2015

Data from the Bridge
Latitude: 58° 27.7′ N
Longitude: 149° 31.0′ W
Sky: Clear
Visibility: 10 miles
Wind Direction: S
Wind speed: 2 knots
Sea Wave Height: 1 ft.
Swell Wave: 0 ft.
Sea Water Temperature: 14.4° C
Dry Temperature: 14.8° C

Science and Technology Log

We steamed out of the port of Kodiak, sailing northeast into the Gulf of Alaska. From the bow, I looked back and saw the busy harbor, full of fishing boats of all sizes, slowly fade away. Scanning the water, I saw two sea otters floating on their backs with their arms in the air. I spotted a few puffins dotting the surface of the water, with their characteristic black and white plumage and orange beaks. In the distance, a spout rose from the ocean’s surface, evidence of a whale below. The sea was calm and the sun was shining. I breathed in the salty air. I was feeling grateful to be a NOAA Teacher at Sea and ready for this mission.

So what exactly is our mission here aboard the Oscar Dyson? We are conducting fisheries research, primarily a Walleye Pollock Acoustic-Trawl survey. A fish survey is like a scientific fishing trip! The surveys, when conducted consistently and repeatedly over time, allows scientists to monitor trends in fish abundance and changes in the marine ecosystem. The data from these surveys are used, along with data collected from fishermen and other sources, to set sustainable catch limits, ensuring a healthy supply of pollock in the future..

The science team is from the Midwater Assessment and Conservation Engineering (MACE) group of the Alaska Fisheries Science Center in Seattle, Washington. This is the third and final leg of their summer assessment of the walleye pollock population in the Gulf of Alaska. We will be traveling along predetermined, randomized transect lines, and scientists will use acoustic technology, along with catch data from nets towed behind the boat, to assess the pollock population. Walleye pollock is the targeted species, though everything we catch will be identified and measured.

The Oscar Dyson in the Port Of Kodiak, Alaska

Young Pollock caught in the pocket net of a trawl — Young walleye pollock

You might not have seen walleye pollock on a menu, but you probably have eaten it. Pollock is the “Fish” in McDonald’s “Filet-o-Fish” sandwiches. Pollock are also masters of disguise and can sometimes be found imitating crab meat. Yes, that imitation crab (surimi) in your California roll is usually ground up and re-formed pollock. In fact, the pollock fishery is one of the largest and most valuable in the world. Walleye pollock are a schooling, semi-demersal (bottom) fish that is found at depths up to 1000 feet and widely distributed throughout the North Pacific Ocean. They can grow up to 3.5 feet and live up to about 20 years old. Pollock feed mainly on krill when they are young; when they mature, they eat young pollock and other teleosts (bony fish). That’s right, they are cannibalistic! Recently, after extensive genetic studies, the scientific name of this fish changed from Theragra chalcogramma to Gadus chalcogrammus. This change placed the walleye pollock in an evolutionary lineage that includes the Pacific, Atlantic, and Greenland Cods. In Alaska, about 1.5 million tons of this fish are caught each year. With each fish weighing an average of 3 pounds, that’s about 1 billion fish annually!

Shipmate Spotlight: Emily Collins

What is your position on the Oscar Dyson?

I am on the science team, and for all three legs of the survey this summer, I have been the Lab Lead.

Where did you go to school?
I earned a BS in Biology (marine science concentration) from Boston University. I am attending Southern Oregon University in the fall for graduate work in Environmental Education.

What do you enjoy most about your work?
I certainly like playing with fish, but I enjoy the people the most. This is an awesome group of scientists and I really like meeting new people each cruise, too. I enjoy learning new things from different scientists.

Have you had much experience at sea?
Yes, after college, I worked as a fisheries observer for 2 ½ years on various east coast boats from Maine to Virginia and 1 ½ years on boats in Alaska. As an observer, I boarded commercial fishing vessels and kept fishing data on the catch and discarded species and collected biological samples for the National Marine Fisheries Service. I have been on trawlers (pollock, ground fish), gillnet vessels (cod), scallop dredgers, pair trawls (herring), pot vessels (cod) and longliners (halibut, sablefish). Observer data is used to conduct stock assessments, which are used in managing the fisheries.

Where do you do most of your work aboard the ship?
You can usually find me in the wet lab. I am in charge of the wet lab and sampling all the fish that we catch: identifying, weighing, measuring fish and collecting otoliths and other biological samples. I also help with camera operations and data management, so I am often in the Chem Lab or Acoustics Lab on a computer.

When did you know you wanted to pursue a career in science?
I always liked biology and knew it was a career goal. I took a Lindblad Expeditions/National Geographic voyage in the Galapagos my senior year of high school and Sylvia Earle was onboard as an expert naturalist. The snorkeling was unbelievable. I saw so many fish, sea turtles, penguins, and sea lions. That was my inspiration for studying marine biology

What are your hobbies?
I love to travel, hike and snowboard. And I do arts and crafts, like paper arts and beadwork.

What do you miss most while working at sea?
I miss my friends and family the most (Hi Mom!). And being able to eat out at different restaurants.

What is your favorite marine creature?
Bluefin Tuna because they are huge, fast, and they live in the open ocean.

Inside the Oscar Dyson: Staterooms

So once our work is finished, where do we finally get some rest? Staterooms are what you call the sleeping quarters aboard the ship. Emily Collins and I share a stateroom. There are bunk beds, and I am on the top and Emily is on the bottom. We each have a locker to store our clothes, and there is a desk and shelving to stow odds and ends. You have to latch the locker doors closed, or they will slam when the ship moves. There is a head (bathroom) with a toilet, sink and shower attached to our stateroom. It is important to keep voices down in your stateroom and moving through the corridors, as people are sleeping at different times of the day! We have a porthole in our room, but since it is summer in the high latitudes, it is dark for only about 4-5 hours a day. The quarters are cozy but comfortable. I enjoy getting lulled to sleep by the rolling motion of the ship.

Personal Log

As Teacher at Sea, I am an active member of the science team and I have been assigned the day shift, which means that I work from 4am-4pm. I think this shift will be great because it is a little more of a regular schedule, just getting up really early and going to bed really early. I come on shift when it is actually dark and then, after about an hour, I enjoy the sunrise over the water. During the shift, as our work allows, we can break for breakfast and lunch. And we can get coffee as needed…which is a lot!

Safety is the first priority of everyone aboard the Oscar Dyson. The ship’s officers have briefed us about safety procedures, and we have participated in drills for different scenarios, such as Man Overboard and Abandon Ship. For the Abandon Ship drill, we grabbed our PFD (personal floatation device) and survival suit from our staterooms and mustered on the deck to find our lifeboat group.

Here’s to a productive and safe voyage aboard the Oscar Dyson!

Survival suit — Trying on my survival suit during an Abandon Ship drill. Photo by Mackenzie Wilson

July 28, 2011March 12, 2021

Cathrine Fox: Issue Six: Alaska, impossibly big and impossibly green

NOAA TEACHER AT SEA
CATHRINE PRENOT FOX
ONBOARD NOAA SHIP OSCAR DYSON
JULY 24 – AUGUST 14, 2011

Mission: Walleye Pollock Survey

Location: Kodiak, Alaska

Date: July 27, 2011

Weather Data from the Bridge

True Wind Speed: na

Air Temperature: 14° C dry/12° C wet

Air Pressure: na

Overcast

Latitude: 57.44° N, Longitude: 152.31° W

Ship heading: n/a

(Limited data, as ship is in port)

Scientific Log:

I’ve received an in-depth tour of the ship and labs, and I am starting to piece together how the “Acoustic Trawl Survey” works. Basically, NOAA is responsible for monitoring the populations of walleye pollock and accomplishes this task in several ways. The acoustic trawl survey is one part of how this is done.

The science team identifies particular transect areas in the Gulf of Alaska. The ship travels to that area, then transmits acoustic signals about once per second as it travels along each transect. The returning echo gives scientists an initial measurement of the abundance of organisms in the water below the ship. Just “listening,” however, is not enough. We also have to sample populations physically to determine the ages, sizes, and species of the organisms. The ship trawls for these additional data.

A trawl is a large net towed behind the ship to catch fish and other organisms. The individuals (of all species) in the catch are identified and counted. Cameras (three) are mounted inside the back of the trawl (codend) to collect images as they pass through the trawl. From this larger catch, a sample of the walleye pollock (about 300 individuals) are dissected to determine sex, diet, measured (length and weight) for size and aged by looking at (yes) their ear bones or otoliths. I’ll cover all of this in depth once I have been able to do it and see it in action, but that is the gist.

Personal Log:

I think first impressions are important. Alaska? Alaska is impossibly big and impossibly green. Too big, perhaps to describe with common adjectives. It took me about two days of travel from the 4-Corners to make my way up here: a Beechcraft 1900 from Cortez to Denver, then flights from Denver to Seattle and Seattle to Anchorage. I spent the night in Anchorage and wandered the city at midnight… …not that you can tell that it was so late from the pictures.

The next morning I took off from Anchorage and met up with the crew and scientific party onboard the Oscar Dyson in Kodiak, an island the size of Connecticut in the Gulf of Alaska

As for how ‘impossibly green’ Alaska is, I was thinking about the reasons Georgia O’Keeffe gave for moving from New York City to New Mexico in 1949. She said (and I paraphrase) that she wanted to use more vibrant colors in her palette of paints than just green. Ms. O’Keeffe would have it rough here in Alaska: greens, greys and blues abound. Adventures in a Blue World Issue 6 may not convince you of the colors of Alaska, but I hope it gives you a grasp of its size.

I’ve already settled in to the ship and my stateroom. My stateroom is small but comfortable, and I share it with a woman who is part of the scientific NOAA team. Interestingly, she worked for the same professor at the Rocky Mountain Biological Laboratory in Gothic, Colorado as an undergraduate that I did. Very Small World.

We are docked in Kodiak for a few more days than anticipated: we are awaiting the arrival of another deck-hand, and there are a few repairs that need to be made to the ship. Once we get started, I will be working the 4am-4pm shift, and taking part in whatever science is taking place. In the meantime, I get to ‘nose around’ Kodiak, go for hikes and runs, check out museums (see below), and eat as many salmonberries as I can stuff into my mouth.

Until our next adventure,
Cat