Pollock – Page 18 – NOAA Teacher at Sea Blog

June 18, 2010March 12, 2021

Richard Chewning, June 18th, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 18, 2010

Weather Data from the Bridge

Position: Bering Sea, north of Dutch Harbor
Time: 1600 hours
Latitude: N 55 06.120
Longitude: W 166 33.450
Cloud Cover: Mostly cloudy
Wind: 10 knots from the west
Temperature: 7.1 C
Barometric Pressure: 1010.8

Science and Technology Log

In order to manage a public resource such as pollock, fisheries managers must develop a stock assessment. A stock assessment is a big picture overview of a certain population of fish. Fisheries managers use stock assessments to determine opening and closing dates for fishing seasons, catch limits (the number of fish that can be caught by a particular fisherman or boat), and the total allowable catch for the season. Stock assessments are developed from a combination of fishery dependant and independent data. Fishery dependant data includes catch records from commercial fishing boats and reports from processors dockside that prepare and package the fish for market. Combined with this information is fishery independent data. This information is gathered from sources not involved with commercial fishing.

chewning_log8_img_1 — Cod end filled with pollock

chewning_log8_img_3 — Unsorted catch entering wet lab

The Dyson’s acoustic trawl survey is one of the primary sources of fishery independent data for the pollock stock assessment. The Dyson’s transducers provide a wealth of acoustic data from each transect. These acoustic returns must first be identified or deciphered before being used in the stock assessment. Just like you need a key to decode the symbols on a road map or need a scale to interpret the colors on a weather map, the acoustic returns also need to be referenced with actual pollock specimens collected by trawling. By matching up the characteristics of the fish caught in the trawl with their acoustic returns, researchers can interpret all the acoustic data from the entire survey area.

chewning_log8_img_4 — My what sharp teeth you have! Arrowtooth flounder

Pollock specimens are collected with Aleutian wing trawls, or AWTs for short. An Aleutian wing trawl is a single large net deployed off the stern of the Dyson. Large metal fishbuster doors are used to open the mouth of the net in the water. The catch is collected in a bag located at the end of the net called the cod end. The cod end’s mesh size prevents anything larger than 0.5 inches from escaping. Once the net is hauled back on deck, the cod end is emptied in the wet lab, and the entire catch is sorted. Fish are identified, counted, weighed, and measured. The gender and maturity of a subsample of pollock are also recorded. Stomachs are collected to determine what the pollock are eating. Finally, otoliths, the ear bones of fish, are collected. Just like counting the rings of a tree, researchers will count the number of rings in the otolith to determine the age of the pollock. Notable bycatch (fish that were not targeted) include eulachon, arrowtooth flounder, Pacific cod, sturgeon poacher, and yellowfin sole. Misha told me Russians used to dry out eulachon whole and use them as candles because of their high oil content. In fact I learned that one of common names in the US for eulachon is candlefish!

Why gather so much information on a single species of fish like pollock? Fisheries managers are responsible for the sustainable use of public resources. Without careful monitoring, fishing pressure, natural predation, and disease might remove pollock from the population faster than they can replace themselves. There is great demand for pollock both commercially and in the Bering Sea ecosystem. Walleye pollock is the largest US fishery by volume and third largest by value. Annual US catches can average 2.5 billion pounds. Pollock is also an important food source for Stellar sea lion, other marine mammals, birds, and other fish.

chewning_log8_img_8 — The Dyson in Dutch Harbor

Personal Log

On Thursday, I had the pleasure of joining two members of the deck crew, Joel Kellogg and Glen Whitney, to pick up a new addition of the science party in Dutch Harbor. Mike Sigler, a fish biologist with NOAA, is a project leader and principal investigator with the North Pacific Research Board’s Bering Sea Integrated Ecosystem Research Program (BSIERP). He is joining the Dyson for the last week of our survey. BSIERP is a six year long collaborative study with the National Science Foundation’s Bering Ecosystem Study (BEST). More than a hundred scientists from these two groups are investigating the organisms and physical forces that make up and influence life in the Bering Sea ecosystem.

chewning_log8_img_9 — Recovering the Peggy D.

To pick up Mike, the Dyson launched the Peggy D. Named for wife of Oscar Dyson, the Peggy D. is a small power boat used to ferry people to and from shore. Peggy Dyson is a famous Alaskan in her own right, serving as a National Weather Service ship to shore weather broadcaster. Her voice brought vital information and reassurance to Alaskan fisherman. She diligently performed these duties twice a day, seven days a week for 25 years. I really enjoyed having the opportunity to see the Dyson from the water as my only vantage point for the last two weeks has been from the Dyson looking out. I was surprised how quickly the Dyson shrunk on the horizon as we sped away and traveled into Dutch Harbor. Dutch Harbor felt like a true frontier town. The vehicles seemed to reflect the character of the town. While looking rough and weathered on the outside, the beat-up cars and trucks of Dutch Harbor revealed a resilience and gritty determination to keep moving forward and press on against an unforgiving environment. I loved hearing the cry of the bald eagles that were spotted everywhere you looked. While I enjoyed having solid ground under my feet for a few short minutes, I appreciated the sense of familiarity and belonging I felt upon returning to the Dyson.

chewning_log8_img_7 — Scute visits the Bering Sea

Scute, the Georgia Sea Turtle Center Mascot, was spotted visiting the Bering Sea today! Scute, a loggerhead sea turtle, travels the world promoting awareness of sea turtles. We know Scute was only visiting the Bering Sea as these waters are too cold for loggerhead sea turtles. Loggerhead sea turtles are the most abundant sea turtles in US coastal waters. Scute’s home is the Georgia Sea Turtle Center (GSTC) located on Jekyll Island, Georgia. The GSTC is a research, rehabilitation, and education center dedicated to helping sea turtles along the GA coast and around the world. Sea turtles released from the GSTC will often have a satellite transmitter attached to their shell just like Scute. The transmitters allow researchers to track their movements at sea. Only one of the seven species of sea turtles found worldwide can survive this far north – the leatherback sea turtle. The leatherback sea turtle is the largest species of sea turtle reaching six and a half feet in length and weighing as much as 2000 pounds! Leatherbacks have several adaptations such as high oil content in their large bodies that help them tolerate the cold waters of the southern Bering Sea. Leatherback sea turtles feed on jellyfish and can dive to great depths because the protection provided by their leathery shell (a hard shell would crack under the high pressure of the water). For more information about Scute and sea turtles, check out the GSTC website at http://www.georgiaseaturtlecenter.org !

June 10, 2010March 12, 2021

Richard Chewning, June 10, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 10, 2010

Weather Data from the Bridge

Position: Bering Sea
Time: 2147 hours
Latitude: N 56 48.280
Longitude: W 161 48.549
Cloud Cover: Overcast with fog
Wind: 9.2 knots from NE
Temperature: 4.6 C
Barometric Pressure: 1010.8 mbar

Science and Technology Log

In addition to hosting fish biologists studying walleye pollock, the NOAA ship Oscar Dyson also has groups of researchers studying birds and marine mammals aboard. Both the birders and marine mammal observers are conducting supplementary projects taking advantage of the Dyson’s cruise track. As the Dyson sails back and forth across the Bearing Sea along equally spaced parallel transects, these researchers are able to survey a wide area of habitat, investigating not only what animals are present and absent in these waters, but also how many are present (called abundance). These surveys are considered passive since these researchers are not actively directing the ship’s movements but are surveying along the cruise track laid out by the fish biologists.

Our migratory bird observers are Liz Labunsky and Paula Olson from the United States Fish and Wildlife Service (USFWS). They are members of the North Pacific Pelagic Seabird Observer Program and are providing data for the Bering Sea Integrated Ecosystem Research Project. Pelagic seabirds are birds found away from the shore on the open ocean. Liz is from Anchorage, Alaska and has been involved with this project since 2006. Calling Gloucester, Massachusetts home, Paula is new to these waters but has spent years studying the birds of Prince William Sound as part of the ecosystem monitoring efforts resulting from Exxon Valdez oil spill.

Liz and Paula work for two-hour alternating shifts from the bridge. They continuously survey an area of water 300 meters by 300 meters in size. They are looking for birds both on the water’s surface and flying through the air. Liz and Paula must have quick eyes and be very familiar with a wide variety of birds. Identifying birds on the move can be very challenging. Often you only have only a few seconds to train your binoculars on your target before your query becomes a spot on the horizon. In addition, the same species of bird can vary greatly in appearance. Liz and Patti may only see a handful of birds over an entire morning but can also witness hundreds at any given moment!

One constant challenge for observers aboard moving vessels is counting the same bird multiple times. For example, you will often spot northern fulmars flying laps around the Dyson when underway. To avoid introducing this bias (or error) in their survey, flying birds are only counted at certain time intervals called scan intervals. The frequency of these scan intervals are determined by the speed at which the Dyson is traveling. For example, when the Dyson is traveling 12 knots, birds flying are counted every 49 seconds. If the Dyson is traveling slower, the time is reduced.

While very familiar with the coastal birds of Georgia, I have been introduced to several new species of birds found in the Bering Sea. I have become a big fan of the tufted puffin. Easily identified by their reddish orange bills, tufted puffins resemble little black footballs when flying. These birds dive in the frigid waters to catch fish, their favorite prey. The black-footed albatross is another bird new to me identified by the white markings around the base of the beak and below the eye along with its large black feet. One of my favorite observations with Liz and Patti was identifying a group of northern fulmars so tightly packed on a piece of driftwood that it showed up on the ship’s radar!

Personal Log

Just before my shift ended around 1545 hours, a call came over the radio from Yin, one of the Dyson’s three marine mammal observers. She reported that a large number of humpback whale blows had been spotted on the horizon. A blow refers to the spray of water observed when a whale surfaces for a breath of air. Like all mammals, whales have lungs and must surface to breath. The humpback whale is a baleen whale that feeds on krill (small marine invertebrates that are similar to shrimp) and small fish in the summer. Krill is a major link in the marine food web, providing food for birds, marine mammals, and fish such as pollock. Baleen whales have plates made of baleen instead of teeth that are used to separate food from the water. Baleen resembles a comb with thick stringy teeth. Think of the movie Finding Neo when Marlin and Dory are caught in the whale’s mouth.

Not sure how many whales constitute a large group, I eagerly headed to the bridge to see if I could catch a glimpse of this well-known marine mammal. I quickly climbed four companionways (a stair or ladder on a ship) up to the flying bridge from the main deck where the acoustics lab is located. Upon reaching the highest point on the vessel, I was told that I was in for a treat as we were approaching a massive aggregation (a group consisting of many distinct individuals or groups) of humpback whales. Whales often travel in small social groups called pods, but this gathering was much larger than usual. This gathering was more than a single pod of whales as there were so many blows you didn’t know which way to look!

The Dyson’s CO (Commanding Officer), Commander Michael Hoshlyk, carefully maneuvered through the whales affording the growing gathering of onlookers a great view. Observations from the Dyson’s fish biologists and birders supported the hypothesis from marine mammal observers that these whales were almost certainly gathered together to feed. Evidence to support this conclusion included acoustic data and the presence of large numbers of seabirds. The Dyson’s transducers showed large acoustic returns that were most likely from plankton (organisms that drift in the water) such as krill. There were also countless numbers of shearwaters (medium-sized long winged sea birds) gathered where the whales were swimming. Estimating the number of whales and shearwaters proved difficult because of their large numbers. The first group of whales numbered at least 50, and we later encountered a second group of humpbacks that numbered around 30. The shearwaters numbered in the thousands! I was able to capture some great pictures of the flukes (the horizontal tail of the whale used for propulsion) and blows of the humpbacks by holding my camera up to the powerful BIG EYES binoculars. Looking through the BIG EYES gave me the sensation being so close that I almost expected to feel the spray of water every time the whales surfaced for a breath. I counted myself fortunate to see this inspiring and unforgettable sight. Along with the beautiful weather, the opportunity to see these amazing creatures of the deep made for a very enjoyable cruise to the beginning of the pollock survey.

Viewing humpback whales equals a Kodak moment!

New Word of the Day – Bearing

You will often hear the word ‘bearing’ used on the bridge of the Dyson. A bearing is a term for direction that relates the position of one object to another. For example, the Dyson’s lookout might call out, “Fishing vessel, bearing three one five degrees (315°)”. This means the fishing vessel is in front of and to the left of the ship when facing toward the bow. A bearing does not relate distance, only direction. The area around the Dyson is divided into 360 equal parts called degrees. One degree is equal to 1/360th of a circle. When calling out a bearing, degrees allow for precise communication of an object’s relative position to that of the Dyson. The Dyson always has a member of the deck crew stationed on the bridge serving as lookout when underway. The lookout’s responsibility is to monitor the water around the Dyson for boat traffic, hazards in the water, or any other object important to the safe navigation of the ship.

June 8, 2010March 12, 2021

Richard Chewning, June 8, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 7 – 8, 2010

Weather Data from the Bridge

Position: Just southwest of the Semidi Islands, Alaska
Time: 1400 hrs
Latitude: N 55 54.331
Longitude: W 156 54.606
Cloud Cover: mostly cloudy
Wind: 9.2 knots from E
Temperature: 7.2 C
Barometric Pressure: 1019.6 mbar

Science and Technology Log

Calming seas greeted our arrival at Snake Head Bank around 1800 hours on Sunday. Snake Head Bank is an area of the Gulf of Alaska that has been designated as untrawlable habitat. Trawling is a fishing technique where a net is towed behind one or more boats. The Dyson will be using this technique later in our cruise to catch pollock. Fishermen trawl on the bottom or somewhere in the water column depending on what fish is being targeted. Previous NOAA surveys using both acoustic and ROV (remotely operated vehicle) data have indicated that the ocean bottom in this area contains terrain such as large rocks that could snag a trawl net skimming along the bottom.

Our mission was to further study select areas of Snakehead Bank to better understand the seafloor where acoustic research had been conducted but the bottom composition had not been verified. NOAA scientists call this ground-truthing. To accomplish this task, the Dyson deployed a self-contained camera to the seafloor to collect video footage. This operation requires both a specially designed rig to film on the ocean floor and the coordinated efforts from crew members from various departments throughout the ship.

chewning_log3_img_7 — Success! Video footage from the bottom of the Gulf of Alaska

You might be surprised to learn that an over-the-shelf handheld camcorder and lens were used to record the footage of Snake Head Bank. Both the camera and lens are mounted to and protected by a heavy metal frame. Similar to a roll cage of a car, this cage protects the video camera from the weights used to send the rig to the bottom and from any hazards on the seafloor such as large rocks. Since we are sampling areas beyond the depth sunlight penetrates, a light must also be included to reveal the bottom. This means our camera operations can be conducted both during the day and night! The camera and the battery for the light are protected in a waterproof case that can easily be opened to change tapes and batteries.

In addition to darkness and unknown obstacles, filming at depth is also complicated by water pressure. Water pressure refers to the weight of the water pressing down (think about the pressure in your ears build as you dive to the bottom of a swimming pool). A tight seal must be maintained as water will force its way through the smallest opening. Water pressure can be enlisted to serve a useful purpose. Water pressure activates a switch once the rig reaches a certain depth turning the camera and light on and off. This conserves the batteries and ensures only the video at the bottom is recorded.

chewning_log3_img_3 — Richard waiting on the hero deck for camera recovery

The entire rig is deployed using one of the Dyson’s powerful winches using a long wire cable. The wire cable is threaded through a block attached to a metal support structure called the A-frame that can be extended over the side of the ship. The entire rig was constructed to be neutrally buoyant so the rig would hover just off the bottom. Plastic floats tied on top and metal chains hanging down from the rig ensured the camera was angled correctly towards bottom.

In order for a successful deployment, crew members from throughout the ship must work together. Just like any successful workplace or athletic team, these deployments require coordinated efforts, communication, and clearly defined job responsibilities.

The Officer of the Deck and Navigation officer positions the ship at each station and must keep the ship as stationary as possible when the camera is deployed so the camera is not dragged along the bottom. A member of the deck crew operates the winch and raises and lowers the A-frame. Another member of the deck crew assists a survey technician casting and retrieving the camera rig over the side. Two scientists change out the tapes and batteries, transfer and log the video, and adapt the rig as necessary.

chewning_log3_img_4 — Deployments require teamwork and coordination

chewning_log3_img_5 — Recovering remote camera rig at Snakehead

Finally, the unsung hero of this camera deployments was the science team’s IT (Information and Technology) Specialist. The IT specialist on th is cruise is Rick Towler. If you like to solve problems and develop a wide range of skills, then this is the job for you. Rick saved the day on more than one occasion during the camera operations. Using some creative engineering, Rick overcame some technical difficulties with the pressure switch and wiring on the control circuit board for the camera and light. Rick is an indispensible member of the science team and is responsible for maintaining the equipment brought onboard by the scientists. When you are miles from the nearest hardware store or electronics shop, you have to be able to make do with what you have and be able to think outside the box. I think of Rick as the science team’s MacGyver! By the end of the survey’s 42 stations, the crew of the Dyson was a well-oiled machine and had overcome every challenge.

chewning_log3_img_8 — Rick, the Dyson’s MacGyver, is on the job!

Personal Log

The weather continues to improve by the hour. I am starting to find my rhythm after recovering from my drowsiness resulting from the combined effects of jet lag and the seasickness medication from the beginning of the cruise. I was surprised and pleased to learn that the Dyson has a large roll stabilization tank located just in front of and below the bridge. Tall buildings built near earthquake prone areas also use large containers of water to counter the swaying motion that damages buildings during earthquakes.

Meals aboard the Dyson are a key part of any ship routine. Meals are served for one hour starting at 0700, 1100, and 1200 hours. Meals are an interesting time to visit with people. Some crew members at meals are tired as they are just coming off watch, others are wide awake and in a hurry as they are grabbing a quick bite between deployments or projects, and others are still trying to wake up as they have just left their rack even though the meal might be dinner! Dinner Monwas very satisfying: roast beef and game hen with broccoli, steamed rice, and noodles.

You might also see someone headed for their morning workout. I discovered that the little physical exercise. I haven’t tried the treadmill yet as I hear running can be a littletricky on the rolling seas!

After completing our deployments around 0545, we turned southwest for Unimak Pass. We are leaving the Gulf of Alaska behind and now heading for the Bering Sea. I am looking forward to seeing the Aleutian Islands up close as we will be sailing among the islands rather than the open sea. This will give us the benefit of smoother sailing and the added bonus of beautiful scenery along the way!

chewning_log3_img_9 — Headed to the Bering Sea!

Animals Observed from Snake Head Bank Seafloor
Rock Fish
Brittle stars
Skate (similar to a sting ray minus the barb)
Euphausiids (commonly called krill)

June 5, 2010March 12, 2021

Richard Chewning, June 5th, 2010

NOAA Teacher at Sea
Richard Chewning
Onboard NOAA Ship Oscar Dyson
June 4 – 24, 2010

NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor)
Date: June 5th, 2010

Weather Data from the Bridge

Position: Three Saints Bay, Kodiak Island, Alaska
Time: 1000 hrs
Latitude: N 57 10.480
Longitude: W 153 30.610
Cloud Cover: overcast with light rain
Wind: 12 knots from NE
Temperature: 10.3 C
Barometric Pressure: 1001.1

Science and Technology Log

While taking on supplies and preparing for our cruise, the NOAA ship Oscar Dyson had the pleasure of welcoming six kids from the United States Coast Guard (USCG) 2010 Summer Program for a visit. These kindergarten through second graders were visiting from the USCG Integrated Support Command Kodiak, the largest Coast Guard base in the US. The Oscar Dyson’s medical officer ENS Amber Payne and I gave the students a firsthand tour of the Dyson.

chewning_log1_img_1 — NOAA Ship Oscar Dyson tied up in Kodiak, AK.

Highlights of the visit included a tour of the bridge with Executive Officer Lieutenant Jeffrey Shoup. The students were impressed to learn that the propeller of the Oscar Dyson is 14 feet across and specially tooled to be as quiet as possible so as not to scare away any fish that the scientists onboard want to study. The students also enjoyed looking through the BIG EYES, two high powered binoculars located on the flying bridge (the highest point on the vessel above the bridge) of the Oscar Dyson that will be used to survey marine mammals. Scientist Suzanne Yin of the National Marine Mammals Laboratory told the students about how she and her colleagues wbe surveying for whales during the upcoming cruise

The highlight of the tour involved a demonstration by Safety Officer Ensign Russell Pate of one of the Dyson’s Damage and Control lockers. The students also enjoyed trying on the immersion suits with help of Ensign Payne. Immersion suits are designed to protect the wearer from exposure other frigid waters that the Dyson will soon be sailing The kids had great fun donning the firefighting equipment and helping Fisherman Glen Whitney test one of the Dyson’s fire hoses off the fantail. The USCG kids also learned how to tie a square knot with Glen’s help. With a little practice, they were able to join their individual lines into one large line by tying each line end to end using the square knot they just learned. Each student was able to take their line home to practice their newly acquired knot tying skills

Another fun activity was led by Senior Survey Technician Kathy Hough. After Kathy led the students through a tour of the Dyson’s dry and wet labs, the students acted as junior scientists by sorting an array of Alaskan fish and measuring and describing each species, just like the Oscar Dyson’s scientists will do later during the upcoming Pollock survey.

After lunch, the students received a fun science lesson using the property of water’s high surface tension. The students constructed two-dimensional boats out of plastic milk jugs and used soap to propel their boats over a tray of water. This is a very fun activity for younger students that you can easily do at home. The materials required include cleaned plastic milk jugs, scissors, markers, trays of water, and soap (a bar of Ivory soap cut into small cubes). After tracing the outline of a boat (as if looking from the top down) on the flat surface of a milk jug, the kids cut out their boats and made a small notch on the back of the boat to place a small block of soap to serve as the engine. The kids then enjoyed racing their boats against each other across the trays of water! If trying at home, you will need to replace the water in the tray after each race as the water becomes contaminated by the soap. This activity works because water molecules want to strongly stick to each other creating a strong but flexible surface. By disrupting the arrangement of the water molecules and causing the water molecules to push away from each other, the soap enables the boat to ‘power’ across the surface of the water.

After all equipment and supplies were loaded and crew members were boarded, the Dyson moved a short distance to take on diesel at the fuel dock. At 1820 hours, we departed St Paul Harbor and said goodbye to the Oscar Dyson’s home port of Kodiak. The Dyson then sailed about eight hours south to Three Saints Bay, a protected harbor south on Kodiak Island. Three Saints Bay will serve as a location to anchor so the science team can calibrate their acoustic equipment and will shelter the Oscar Dyson from an approaching low pressure system producing gale-force winds.

Personal Log

Hello Everyone! My name is Richard Chewning, and I have the honor to be a part of NOAA Teacher at Sea program sailing with NOAA ship Oscar Dyson. For those who do not know, the National Oceanic and Atmospheric Administration (NOAA) is a federal government agency charged with studying all aspects of the ocean and atmosphere. As you can imagine, these are broad areas of study. While large in scope, the work of NOAA affects everyone, whether you live on a coast or not. Have you ever heard of The National Weather Service or The National Hurricane Center? Both are NOAA divisions.
Here I am holding a baby king crab.

NOAA’s Teacher at Sea Program (TAS) aims to increase the public’s awareness and knowledge of NOAA science and career opportunities by having educators work alongside NOAA offices, ship’s crew, and shipboard scientists. NOAA’s TAS program invites both formal classroom teachers and non-formal educators alike to be a part of this amazing program. I myself am an environmental educator with the Jekyll Island 4-H Center. A Georgia 4-H program, the Jekyll Island 4-H Center is part of the University of Georgia. The Jekyll Island 4-H Center’s Environmental Education program welcomes 1st-12th grade students for environmental education field studies teaching coastal ecology using Jekyll Island as an outdoor classroom. I am the Environmental Education Program Coordinator and have enjoyed working for Jekyll 4-H for five years. For more information, visit http://www.jekyll4h.org .

I am very excited to be selected as a NOAA Teacher at Sea Participant and look forward to sharing my experiences with you through these logs.

Animals Seen Today

Bald Eagles (Haliaeetus leucocephalus)
Kittiwakes (Genus Rissa)
Pigeon Guillemot (Cepphus columba)
Magpie (Family Corvidae)

July 16, 2009April 5, 2021

Megan Woodward, July 16, 2009

NOAA Teacher at Sea
Megan Woodward
Onboard NOAA Ship Oscar Dyson
July 1 – 18, 2009

Mission: Bering Sea Acoustic Trawl Survey
Geographical Area: Bering Sea/Dutch Harbor
Date: Tuesday, July 16, 2009

All bony fish have otoliths (ear bones) that can be used for calculating the age of the fish.

Weather and Location
Position: N 58 13.617; W 171 25.832
Air Temp: 7.2 (deg C)
Water Temp: 6.54 (deg C)
Wind Speed: 15 knots
Weather: Overcast

Science and Technology Log

One of the most interesting things I’ve learned while participating in the pollock survey is the importance of otoliths. Otoliths are small bony structures situated in the head of all bony fish, and are often referred to as “ear stones.” For each haul we brought on board, 50 otoliths were taken from large fish (3+ years) and/or 5 from small fish (younger than 3 years old). The otolith holds the key to accurately calculating the age of a fish (scales and vertebrates can also be used, but are not as reliable). The average age of fish from the samples collected in the survey helps scientists estimate the strength of a year-class and size of the stock in the future.

Back in the lab, otolith samples are carefully catalogued.

The first step in taking an otolith is pictured above. An incision is made on the back of the pollock’s head, and an otolith is removed using tweezers. Once the otolith is removed, it is rinsed with water and placed in a glass vial containing a small amount of 50% ethanol solution for preservation purposes.

The otoliths are taken back to NOAA’s aging lab where ages are determined by reading rings similar to those on a tree trunk. A crosscut is made through each otolith revealing a pattern of rings. Scientists then count the rings to determine the age of the fish. Lightly burning or staining the otoliths makes the rings more visible.

New material is deposited on the surface of the otolith creating the rings as the fish grows. The translucent/light zones indicate the main growth that takes place in the summer months. The opaque/darker rings appear during the winter months when growth is slower. Because of the slower growth rate, new material is deposited on top of the old layers resulting in the dark ring. Each pair of light and dark zones marks one year. In fish younger than one year of age, rings can be identified for each day of life!

Personal Log

I was surprised to discover otoliths have been used for aging fish since the early 1900’s. While working in the fish lab I observed the scientist removing otoliths, however I did not remove any myself. The cracking sound heard when cutting the head open was like fingernails on a chalkboard to me. I spent most of my time in sorting and measuring fish, as well as assisting with the stomach collection project.

For the next two days we will be heading back to Dutch Harbor, and the likelihood of trawling for more fish is minimal. Our remaining work assignment is to give the fish lab a thorough cleaning. Everything in the lab is waterproof, so we’ll put on our Grunden’s (orange rubber coveralls) and boots and spray down the entire space. Working and living at sea for nearly 3 weeks has been an eye opening experience. My time aboard the Oscar Dyson has flown by. I have learned so much about fisheries research and life at sea. Dry land, however, will be warmly welcomed when we get back to Dutch Harbor. Would I do it again? Absolutely.

Animal Sightings

The whales have an incredible way of showing up when I don’t have my camera. Yesterday I spotted two orcas, but did not get a photograph. The seabirds continue to circle. I like the murres most. They look like small, flying penguins.

New Vocabulary

Otoliths- Small bony structures situated in the head of all bony fish. Often referred to as “ear stones.”

Stock- Refers to the number of fish available, supply.

*** Much of the information used for this log entry was found on the Centre for Environment, Fisheries & Aquaculture Science (Cefas) web site.