Phil Moorhouse: Look What the Net Dragged In! September 12, 2019

NOAA Teacher at Sea

Phil Moorhouse

Aboard NOAA Ship Oscar Dyson

August 27 – September 15, 2019


Mission: Fisheries-Oceanography Coordinated Investigations.

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

Date: September 12, 2019

Weather Data from the Bridge

Latitude: 57 35.35 N
Longitude: 153 57.71 W
Sea wave height: 1 ft
Wind Speed: 14 knots
Wind Direction: 208 degrees
Visibility: 8 nautical miles
Air Temperature: 15.4 C
Barometric Pressure: 1002.58 mBar
Sky:  Overcast


Science and Technology Log

Well, we only have a few days left on this trip and it looks like mother nature is going to force us to head for Dutch Harbor a little early.  I thought this might be a good time to spend some time sharing some information on some of the species we have been pulling out of the ocean.  This is far from a complete list, but just the ones that made “the cut”.

At the top of the list has to be the Pollock.  After all, this is the primary objective of this study.  On the left is an adult three-year-old pollock and on the right is an age-0 pollock.  The sampling of age-0 pollocks is a good indicator of the abundance of the future population.

There were several species of salmon caught on our trawls.  On the left is a Coho Salmon and on the right is a Pink Salmon.  These fish are very similar, but are classified as separately Coho Salmon are larger and have larger scales.  Coho also has a richer, fuller flavor with darker red meat while the Pink Salmon has a milder flavor and a softer texture.

zooplankton
Another important part of this survey is the collection and measurement of zooplankton as this is a primary food source and the amount and health of the zooplankton will have a lasting impact on the ecology of the fish population in the area.
capelin
Capelin is another common fish caught in our trawls. This fish eats krill and other crustaceans and in turn is preyed upon by whales, seals, cod, squid, and seabirds.
Pacific Saury
The Pacific Saury was a fish that wasn’t expected to be found in our trawls. Also called the knifefish, this species always seemed to be found in substantial quantities when they were collected – as if the trawl net came across a school of them. They are found in the top one meter of the water column.
Prowfish
The Prowfish was another interesting find. This fish is very malleable and slimy. Adults tend to stay close to the ocean floor while young prowfish can be found higher up in the water column where they feed on jellyfish. As with the saury, the prowfish was not kept for future study. It was weighed, recorded, and returned to the water.

Jellyfish were abundant on our hauls.  Here are the five most common species that we found. 

bubble jellyfish
The Bubble Jellyfish, Aequorea sp., is clear with a rim around it. This jellyfish is fragile and most of them are broken into pieces by the time we get them from the trawl net and onto the sorting table.
moon jellyfish
The Moon Jellyfish, Aurelia labiata, is translucent and when the sun or moon shines on them, they look like the moon all lit up.
white cross jellyfish
The White Cross Jellyfish, Staurophora mertensi, was another mostly clear jelly that was very fragile. Very few made it to the sorting table in one piece. You have to look close it is so clear, but they can be identified by their clear bell with a distinctive X across the top of the bell.
Lion's mane jellyfish
The Lion’s Mane Jellyfish, Cyanea capillata, are the largest known species of jellyfish. These guys can become giants. They are typically a crimson red but could appear faded to a light brown.
sunrise jellyfish
The Sunrise Jellyfish, Chrysaora melanaster, was the most common jelly that we found. It is also arguably the least fragile. Almost all made it to the sorting table intact where they were counted, weighed, recorded, and returned to the water. It lives at depths of up to 100 meters, where it feeds on copepods, larvaceans, small fish, zooplankton, and other jellyfish.
arrowtooth flounder
Arrowtooth flounder are a relatively large, brownish colored flatfish with a large mouth. Just one look at its mouth and you can tell how it got its name. Their eyes migrate so that they are both on the right side and lie on the ocean floor on their left side.
Eulachon
Eulachons, sometimes called candlefish, were another common find on the sorting table. Throughout recent history, eulachons have been harvested for their rich oil. Their name, candlefish, was derived from it being so fat during spawning that if caught, dried, and strung on a wick, it can be burned as a candle. They are also an important food source for many ocean and shore predators.
vermilion rockfish
The Vermilion Rockfish – This guy was the only non-larval rockfish that we caught. Most can be found between the Bering Sea and Washington State.

While the Smooth Lumpsucker is significantly larger than the Spiny Lumpsucker, both have unique faces.  The Smooth Lumpsucker is also found in deeper water than the smaller Spiny Lumpsucker.

Most of the squid caught and recorded were larval.  Here are a couple of the larger ones caught in a trawl.

There were a variety of seabirds following us around looking for an easy meal.  The Black-footed Albatross on the right was one of several that joined the group one day.

Pavlof Volcano
And of course, I couldn’t leave out the great view we got of Pavlof Volcano! Standing snow capped above the clouds at 8,251 feet above sea level, it is flanked on the right by Pavlof’s Sister. Pavlof last erupted in March of 2016 and remains with a threat of future eruptions considered high. Pavlof’s Sister last erupted in 1786. This picture was taken from 50 miles away.


Personal Log

In keeping with the admiration I have for the scientists and crew I am working with, I will continue here with my interview with Rob Suryan. 

Robert Suryan is a National Oceanic and Atmospheric Administration Scientist. He is currently a Research Ecologist and Auke Bay Laboratories, Science Coordinator, working on the Gulf Watch Alaska Long-term Ecosystem Monitoring Program.

How long have you been working with NOAA?  What did you do before joining NOAA?

One and a half years.  Prior to that, I was a professor at Oregon State University

Where do you do most of your work?

In the Gulf of Alaska

What do you enjoy about your work?

I really enjoy giving presentations to the general public, where we have to describe why we are conducting studies and results to an audience with a non-science background. It teaches you a lot about messaging! I also like working with writers, reporters, and journalists in conducting press releases for our scientific publications. I also use Twitter for science communication.

Why is your work important?

Having detailed knowledge about our surroundings, especially the natural environment and the ocean. Finding patterns in what sometimes seems like chaos in natural systems. Being able to provide answers to questions about the marine environment.

How do you help wider audiences understand and appreciate NOAA science?

I provide information and expertise to make well informed resource management decisions, I inform the general public about how our changing climate if affecting marine life, and I train (and hopefully inspire) future generations of marine scientists

When did you know you wanted to pursue a career in science an ocean career?

During middle school

What tool do you use in your work that you could not live without?

Computer! So much of our instrumentation and sampling equipment are controlled by software interfaces. Also, much of my research involves data assimilation, analysis, creating graphs, and writing scientific papers. Although, at the very beginning of my career, most of our data collection was hand written, as were our scientific papers before typing the final version with a typewriter. So glad those days are gone!

If you could invent one tool to make your work easier, what would it be?

For in the office: a computer program that would scan all of my emails, extract the important info that I need to know and respond to, and populate my calendar with meetings/events. For the field: a nano-power source that provided unlimited continuous power for instruments AND global cell phone or wireless connectivity.

What part of your job with NOAA did you least expect to be doing?

I joined NOAA later in my career and had collaborated with NOAA scientists for many years, so everything was what I expected for the most part.

What classes would you recommend for a student interested in a career in Marine Science?

Biology, math, chemistry, and physics are good foundation courses. If you have an opportunity to take a class in marine biology at your school or during a summer program, that would be ideal. But keep in mind that almost any field of study can be involved in marine science; including engineering, economics, computer science, business, geology, microbiology, genetics, literature, etc.

What’s at the top of your recommended reading list for a student exploring ocean or science as a career option?

I originally studied wildlife biology before marine science and one of my favorite books initially was A Sand County Almanac, by Aldo Leopold. For marine biology, I would recommend The Log from the Sea of Cortez, by John Steinbeck.

What do you think you would be doing if you were not working for NOAA?

I would probably work at a university again – I was a professor at Oregon State University before working for NOAA.

Do you have any outside hobbies?

Pretty much any type of outdoor adventure, most frequently kayaking, mountain biking, hiking, camping, and beachcombing with my family and our dogs.

Callie Harris: Jellyfish Landslide, August 15, 2019

NOAA Teacher at Sea

Callie Harris

Aboard NOAA Ship Oscar Dyson

August 13 – 26, 2019


Mission: Fisheries-Oceanography Coordinated Investigations

Geographic Area of Cruise: Gulf of Alaska

Date: 8/15/19

Weather Data from the Bridge

Latitude: 57° 16.15 N
Longitude: 152 ° 30.38 W
Wind Speed: 6.53 knots
Wind Direction: 182°
Air Temperature: 17.1°C
Sea Temperature: 15°C
Barometric Pressure: 1026 mbar


Science and Technology Log

Now that we have been out to sea for 3 days, I can better describe what my 12 hour ‘work shift’ is like. We average about three stations (i.e. research locations) per shift. Each ‘station’ site is predetermined along a set transect.

transect map of stations
Transect Map of all of our tentative stations to survey (red dots). Image credit: Matt Wilson

Before we can put any scientific equipment in the water, we have to get the all clear that there are no marine mammals sighted within 100 yards of the boat. I was thrilled yesterday and today that we had to temporarily halt our survey because of Humpback Whales and Harbor Porpoises in the area. I rushed from the scientific deck up to the bridge to get a better look. Today, we saw a total of 6 Humpback Whales, one of which was a newborn calf. Chief Electronics Technician Rodney Terry explained to me that you can identify the calf because the mother often times pushes the calf up to help it breach the surface to breathe. We observed one tall and one short breathe ‘spout’ almost simultaneously from the mother and calf respectively.

humpback whale spout
Humpback Whale breath spout off of bow.

Once we arrive at each station, we must put on all of our safety equipment before venturing out on the deck. We are required to wear steel-toed boots, a life preserver, and hardhat at all times. On scientific vessels, one must constantly be aware that there is machinery (A frames, booms, winches, etc.) moving above you overhead to help raise and lower the equipment in the water. We survey each station using bongo nets, a midwater trawl, and sometimes a CTD device. In future posts, I will go more into detailed description of what bongo nets and a CTD device entail. This post I want to focus on my favorite survey method: the midwater trawl, aka the ‘jellyfish landslide.’

A midwater trawl (aka a pelagic trawl) is a type of net fishing at a depth that is higher in the water column than the bottom of the ocean. We are using a type of midwater trawl known as a Stauffer trawl which has a cone shaped net that is spread by trawl doors.

trawl net
Trawl net aboard NOAA Ship Oscar Dyson

One of the survey’s goals over the next two weeks is to assess the number of age-0 Walleye Pollock (aka Alaskan Pollock.) These juvenile fish hatched in April/May of this year. As NOAA Scientist Dr. Lauren Rogers, my fellow shift mate, explains, this population of fish species tends to naturally ebb and flow over the years. Fisheries management groups like NOAA study each ‘year class’ of the species (i.e. how many fish are hatched each year).

Typically, pollock year classes stay consistent for four to five years at a time. However, every so often management notes an ‘explosion year’ with a really large year class. 2012 was one of these such years. Hence in 2013, scientists noted an abundance of age-1 pollock in comparison to previous years. Based on the data collected so far this season (2019), scientists are hypothesizing that 2018 was also one of these ‘explosive’ years based on the number of age-1 pollock we are observing in our trawl net samples. It is extremely important scientists monitor these ebbs and flows in the population closely to help set commercial limits. Just because there is a rapid increase in the population size one year doesn’t mean commercial quotas should automatically increase since the population tends to level itself back out the next year.

If you have ever gone fishing before, you probably quickly realized just because you want to catch a certain species doesn’t mean you are going to get it. That is why I have nicknamed our midwater trawl samples, “The jellyfish landslide.” After the trawl net is brought back onto the deck, the catch is dumped into a large metal bin that empties onto a processing table. I learned the hard way on our late night trawl that you must raise the bin door slowly or else you will have a slimy gooey landslide of jellies that overflows all over everywhere. At least we all got a good laugh at 11:15 at night (3:15AM Florida time).

Jellyfish Landslide
Jellyfish landslide! (I’m desperately trying to stop them from falling over the edge.) Photo credit: Lauren Rogers.
jellyfish landslide thumbs up
Jellyfish landslide, managed. Photo credit: Lauren Rogers

Once on the processing table, we sort each species (fish, jelly, invertebrate, etc.) into separate bins to be counted and weighed. Each fish specimen’s fork length is also measured on the Ichthystick.

Measuring fork length
Measuring fork length of pollock.

We then label, bag, and freeze some of the fish specimens to bring back for further study by NOAA scientists in the future. There is a very short time window that scientists have the ability to survey species in this area due to weather, so each sample collected is imperative.

Callie and salmon
Our first salmon catch in the trawl. Photo credit: Lauren Rogers.


Personal Log

This experience is nothing short of amazing. Upon arriving in Kodiak on Sunday, I got to spend the next two days on land with my fellow NOAA scientists setting up the boat and getting to know these inspiring humans. Everyone on the boat, scientists and the Oscar Dyson crew, are assigned a 12 hour shift. Therefore, you may not ever see half of your other ship mates unless it is at the changing of a shift or a safety drill. I did thoroughly enjoy the abandon ship safety drill yesterday where we had to put on our survival (nicknamed the orange Gumby) suits as quickly as possible.

Survival Suit Practice.
Survival Suit Practice. Photo credit: Lauren Rogers

Everyone has been commenting that I brought Key West here to Alaska. The last three days at sea have been absolutely beautiful — sunny, warm, and calm seas. I am sure I am going to regret saying that out loud, haha. At the end of my work shift, I am beat so I am beyond thrilled to curl up in my bunk for some much needed rest. Yes, it does finally get dark here around 10:30PM. I was told we might be lucky enough to see the Northern Lights toward the final days of our survey. I am also getting very spoiled by having three delicious homemade meals (and dessert J) cooked a day by Chief Steward Judy. That is all for now, we have another trawl net full of fun that is about to be pulled back onto the deck.


Did You Know?

NOAA CORPS Officer LT Laura Dwyer informed me of the ‘marine mammal’ protocol aboard the NOAA Ship Oscar Dyson. Scientists must temporary halt research collection if any marine mammal (i.e. a Humpback Whale, porpoise, orca, seal, etc.) is within 100 yards or less of the vessel; if a North Pacific Right Whale is within 500 yards; or if a polar bear (yes you read that correctly) is within half a mile on land or ice.


Challenge Yourself

Do you know how to convert Celsius to Fahrenheit? You take the temperature in Celsius and multiply it by 1.8, then add 32 degrees. So today’s air temperature was 17°C and the sea temperature 15°C. Therefore, what were today’s temperatures in Fahrenheit? Answers will be posted in my next blog.

Jessica Cobley: Not Just Fishing, August 1, 2019

NOAA Teacher at Sea

Jessica Cobley

Aboard NOAA Ship Oscar Dyson

July 19 – August 8, 2019


Mission: Midwater Trawl Acoustic Survey

Geographic Area of Cruise: Gulf of Alaska (Kodiak to Yakutat Bay)

Date: 8/1/2019

Weather Data from the Gulf of Alaska: Lat: 59º 18.59’ N Long: 146º 06.18W 

Air Temp:  14.8º C

Personal Log

We made it to Prince William Sound the other day, but I was asleep by the time we got all the way up. The part I did see, near the entrance, was pretty, but fog and clouds blocked the majority of the view. One of the beaches we attempted to fish by had what looked like an old red train car washed up on it. We wondered where it came from and how it got there!

Sunrise over Gulf of Alaska
Sunrise the day before we headed into Prince William Sound.

We are sailing the last few transects of the trip now and headed towards a small bay, called Broken Oar Bay, near Yakutat. Once we arrive, we need to calibrate the instruments used for collecting data and compare the results to the start of the trip. This will let the scientists know that their instruments are stable and making consistent measurements.

While calibrating we may have an opportunity to get a glimpse of the Hubbard Glacier at the head Yakutat Bay. The Hubbard Glacier is approximately 6 miles wide and when it calves, makes icebergs 3-4 stories tall. Fingers crossed we get to see it! 

On a side note, I have been drawing while on the boat. Here are some photos!

Jessica's sketch of a squid
One of the squids we caught… it was just a tiny little guy, about 2 cm.
Diagram of commercial fishing methods
Gus Beck, lead night fisherman, sat down with me yesterday and explained the main types of commercial fishing methods. Now I won’t get them mixed up.
Abigail's prowfish sketch
This is my favorite one! Abigail’s drawing of a prowl fish. They have the best facial expressions.


Science and Technology Log

The majority of my time has been spent above deck with the science and deck crews. Yesterday, I took the opportunity to head down below and learn some of the ways Oscar Dyson is kept running smoothly. 

Danielle and deck crew
Some of the deck crew that are responsible for putting the nets out. Danielle, one of our senior survey techs, is up top and controls the movement of the net.

There are several areas/rooms that hold different types of equipment below deck. One of the largest rooms is the engine room, where not 2 or 3, but 4 engines are located. At night, 2 of the engines are needed since the ship sails slowly for camera drops. During the day, when traveling along the transects and fishing, 3 engines are used. Engines 1 and 2 are larger with 12 cylinders and 3 and 4 are smaller with 8 cylinders. These engines are attached to generators. The engines give moving force to the generators, which they then convert into kilowatts/power and as a result, power everything on board. Also, I learned that the boat has at least 2 of every major piece of equipment, just in case!

Engineers Kyle and Evan
Two of the engineers, Kyle Mulkerin and Evan Brooks, who gave me a tour below deck. They are standing in front of engine #1.

The engine room also stores the water purification system, which Darin had mentioned to me the other day. He knew the ship converted seawater into potable water, but wasn’t exactly sure how the process worked. Here is a brief summary. 

  1. Seawater is pumped onto the boat and is boiled using heat from the engine.
  2. Seawater is evaporated and leaves behind brine, which gets pumped off of the ship.
  3. Water vapor moves through cooling lines and condenses into another tank producing fresh water. 
  4. The water is then run through a chemical bromide solution to filter out any left over unwanted particles.
  5. The finely filtered water is stored in potable water holding tanks.
  6. The last step before consumption is for the water to pass through a UV system that kills any remaining bacteria or harmful chemicals in the water.
Evan's notes
Notes from Evan Brooks on how to convert seawater into potable water. I wish all my student’s notes were this neat and organized!

After the engine room, Kyle and Evan took me one level deeper into the lower engine room. There are a few other lower areas but, being a bit claustrophobic, I was happy we didn’t explore those. The lower engine room (or shaft alley) holds the large rotating shaft which connects directly to the propeller and moves the ship. It was neat to see! 

Jessica descends to lower engine room
Heading down into the lower engine area.

We rounded out the tour in a workshop that holds most of the tools on board. The engineers help fix things from engines to air conditioners to plumbing. This week I may even be able to see them do some welding work. 

Did you know? 

If a large piece of equipment needs to be replaced, they do not take it apart and lug it to the upper deck and off the boat. Instead, they cut a giant hole in the side of the ship and get the parts in and out that way. I had no idea!

Cheers, Jess 

Erica Marlaine: Oh, the Places You’ll Go! July 6, 2019

NOAA Teacher at Sea

Erica Marlaine

Aboard NOAA Ship Oscar Dyson

June 22 – July 15, 2019


Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Gulf of Alaska

Date: July 6, 2019

Weather Data from the Bridge:

Latitude: 55º 4.07N
Longitude: 156º 42 W
Wind Speed: 3.2knots
Wind Direction: 96º
Air Temperature:  10.3º Celsius
Barometric Pressure: 1025.7. mb
Surface Water temperature: 11.05º Celsius
Depth of water column: 1,057.6 meters


If you love science and exploring, consider a career in the NOAA Corps!

NOAA Corps

The NOAA Corps is one of our nation’s seven uniformed services (along with the Army, Marine Corps, Navy, Air Force, Coast Guard, and Public Health Service Commissioned Officer Corps). NOAA Corps officers are an integral part of the National Oceanic and Atmospheric Administration (NOAA), an agency of the U.S. Department of Commerce. NOAA and the NOAA Corps can trace their lineage to 1807 when President Thomas Jefferson signed a bill for the “Survey of the Coast.” The survey work was done by Army and Naval officers along with civilian men and women. The Coast Survey was actually the first federal agency to hire female professionals! Their duties included charting our nation’s waterways and creating topographic maps of our shorelines, which made our marine highways among the best charted in the world.

Today, the NOAA Corps is an elite group of men and women trained in engineering, earth sciences, oceanography, meteorology, and fisheries science. NOAA is comprised of the National Weather Service, National Marine Fisheries Service (NOAA Fisheries), Office of Oceanic and Atmospheric Research (NOAA Research), National Environmental Satellite, Data and Information Service, National Ocean Service, and the Office of Marine and Aviation Operations. NOAA Corps officers operate NOAA’s ships, fly aircraft, manage research projects, conduct diving operations, and serve in staff positions throughout NOAA.

NOAA Officer Spotlight

ENS Lexee Andonian
ENS Lexee Andonian

I had the opportunity to speak with Ensign (ENS) Lexee Andonian (although by the time this is published Ms. Andonian will have been selected for LTJG (Lieutenant junior grade)! ENS Andonian has been a member of NOAA Corps for almost 2 years, and loves her job, but it was not something she originally considered as a career (or even knew about). She first learned about NOAA while working at a rock climbing gym. A patron mentioned it to her, and offered to show her around a NOAA ship. She went home and googled NOAA. With her interest piqued, she decided to accept the patron’s offer, and went to Newport, Oregon to tour the NOAA Ship Bell M. Shimada (which is actually the sister ship of the NOAA Ship Oscar Dyson. A sister ship means they were based off the same blueprint and can serve similar projects.)

ENS Andonian applied for the NOAA Corps, but was waitlisted. NOAA is highly selective and accepts a very limited number of applicants (approximately 15-25 twice a year.) Undeterred, she applied for the next NOAA class, and was once again waitlisted, but this time she was accepted off the waitlist. After 5 months of training at the Coast Guard Academy, she was ready to begin her assignment onboard a NOAA ship, where additional hands-on training occurs non-stop. Each NOAA Corps member wears a multitude of “hats” while onboard. ENS Andonian is currently the Acting Operations Officer, the Navigation Officer, the Environmental Compliance Officer, and the Dive Officer. ENS Andonian loves that her job allows her to see unique places that many people never get to explore since they are not accessible by plane or car. Asked what she misses the most from home, she said, “Bettee Anne” (her dog).


Science and Technology Log

Today I was introduced to a few new species in the fish lab. Until now, most of the jellyfish have been Chrysaora melanasta, which are beautiful and can be quite large, but today I saw 2 egg yolk jellyfish, aptly named as they look like egg yolks.

Egg yolk jellyfish
Egg yolk jellyfish

I also saw a lumpsucker, which is the cutest fish I have ever seen. Lumpsuckers look like little balls of grey goo. He (or she) seemed to look right at me and kept opening and closing its mouth as if trying to say something. Lumpsuckers have a suction cup on their bottom which allows then to adhere to rocks or other surfaces.

Lumpsucker
Lumpsucker


Personal Log

As a teacher, I create experiences for my students that will take them out of their comfort zone so that they can realize just how much they are truly capable of. On the NOAA Ship Oscar Dyson, it is my turn to step outside my own comfort zone. If you would have told me a few months ago that I would feel comfortable being elbow-deep in live fish and jellyfish, or dissecting fish to see whether they are male or female, or slicing into a fish’s head to collect otoliths (ear bones), I would not have believed you, but that is how I spend every day onboard the Oscar Dyson, and after 2 weeks, it feels like something I have done all my life.  It is an experience I highly recommend to everyone!

Erica Marlaine: One Fish, Two Fish, June 26, 2019

NOAA Teacher at Sea

Erica Marlaine

Aboard NOAA Ship Oscar Dyson

June 22 – July 15, 2019


Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Kodiak Island, Alaska

Date: June 26, 2019


Weather Data from the Bridge:

Latitude: 58º 33.15 N
Longitude: 152º 58.87 W
Wind Speed: 17.5 knots
Wind Direction: 229º
Air Temperature:  13º Celsius
Barometric Pressure: 1020.2 mb


Science Log

Today we did our first two trawls of the trip. According to Webster’s dictionary, trawl is defined as the act of fishing with a trawl net, which is a large conical net dragged along the sea bottom in order to gather fish or other marine life. It can also mean the act of sifting through something as part of a search.  Both definitions are accurate for what is done on the NOAA Ship Oscar Dyson.

The Oscar Dyson uses a variety of nets to catch the fish being studied. One net that has been used for many years is called an Aleutian Wing Trawl (or an AWT). The mesh size of the AWT is ½ inch.  Attached to the AWT net are smaller nets (called pocket nets) which also have a ½ inch mesh size.  The new net being used this year is an LFS 1421, which has a 1/8 inch mesh size. It has 9 pocket nets, also with 1/8 inch mesh size. It is thought that fewer fish will escape the LFS net because the mesh size is smaller, in turn allowing the scientists to get a more accurate picture of the fish and other creatures living in the areas they are trawling.  Trawls are being conducted using both nets (back-to-back) to determine the extent to which the new net is more efficient and provides a more accurate measure.

AWT and LFS nets
The older AWT net is on the left. The newer LFS 1421 net is on the right.

Once the nets are pulled in, the processing begins. The main net (i.e., codend) is emptied onto the large processing table in the fish lab.

catch on the processing table
One catch on the processing table.

Each pocket net is emptied into a separate plastic bin.  The fish are then identified, weighed, measured, and sometimes dissected in order for us to accurately determine the age and sex of each fish.

Evan with plastic bin
Volunteer Biologist Evan Reeve with a pocket net bin.

Otoliths (ear bones) and ovaries are collected from a sample of the walleye pollock caught in the codend of the net. Otoliths allow scientists to determine the age of the fish.  Over time, ridges form on the otoliths, and are indicative of age in much the same way a tree’s age can be determined by counting the rings of its trunk. 

Ovaries are collected to be sent back to the lab as part of a long-term histology study which hopes to determine whether walleye pollock experience multi-batch spawning events (i.e., do pollock spawn more than one time) within or between seasons. Histology, also known as microscopic anatomy or microanatomy, uses a microscope to study the anatomy of biological tissues. In contrast, gross anatomy looks at structures without a microscope.

After a trawl, scientists onboard the NOAA Ship Oscar Dyson examine the ovaries with the naked eye to determine the reproductive stage of the walleye pollock that has been caught. There are 5 stages: Immature (not yet capable of spawning, typically age 0-2); Developing (beginning to develop the ability to spawn) Pre-spawning, Spawning, and Spent (completed spawning).  Once a pollock spawns, it begins the cycle again beginning at step 3 (pre-spawning). Additionally, the histology study also hopes to determine whether the spawning stages being designated by scientists during the cruise are in fact accurate.

Elementary Math Fun

Let’s say 200 total fish were caught in the new LFS 1421 net, including the nine pocket nets attached.

Pocket nets 1, 2 and 3 each had 20 age-0 pollock in them.

Pocket nets 4, 5 and 6 each had 13 lantern fish in them.

Pocket net 7 had 3 small herrings  in it.

Pocket nets 8 and 9 each had 2 age-1 pollock in them.

How many fish were in the codend or main part of the net?


Personal Log

As a Southern Californian, I imagined Alaska to be cold even in the summer, and packed sweaters and a big puffy winter coat.  Apparently shorts and t-shirts would have been more appropriate! The weather in Kodiak has been warm and beautiful, with the sun shining until midnight.

Barometer Mountain
Barometer Mountain, Kodiak, Alaska

My first day in Kodiak was a free day, so I joined the science team on a hike up Barometer Mountain, which many say is the most difficult hike in Kodiak.  It is 2100 feet straight up a very steep, rocky, brush-filled path, and then 2100 feet down that same, steep path.  It was quite the challenge, but the view from the top was magnificent.

NOAA Ship Oscar Dyson
My home for the next three weeks!

At present, there are 31 people onboard the NOAA Ship Oscar Dyson, including NOAA corps officers, engineers, deck personnel, cooks, scientists, interns, and me, the NOAA Teacher at Sea. The ship, which was originally launched in 2003, and commissioned into service as a NOAA ship in 2005, is named for Alaskan fisherman and fishing industry leader Oscar E. Dyson. It is one of the most advanced fisheries research vessels in the world, due in part to its acoustic quieting technology.  This allows scientists to monitor fish populations without concern that the ship’s noise will affect the behavior of the fish.

Erica Marlaine: Introduction

NOAA Teacher at Sea

Erica Marlaine

Aboard NOAA Ship Oscar Dyson

June 24 -July 15, 2019


Mission: Gulf of Alaska Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: South Bering Sea, Alaska

Date: June 14, 2019

Hello! My name is Erica Marlaine, and in one week I will be flying to Alaska for the first time ever to spend three weeks aboard NOAA Ship Oscar Dyson as a NOAA Teacher at Sea.  I am a Special Education Preschool Teacher at Nevada Avenue Elementary School in West Hills, California.

Erica holding a stuffed lamb
Me at the Noah’s Ark Exhibit at the Skirball Cultural Center in Los Angeles

My students are 3-5 year olds who have a variety of special needs, such as autism, Down syndrome, and speech delays. They are fascinated by science experiments and nature, love to explore their surroundings with binoculars and magnifying glasses, and often notice the details in life that the rest of us walk right by. 

little scientist
One of my little scientists
magnifying glasses
Checking the growth of our tadpoles.

Like most 3-5 years olds, they are obsessed with whales, octopi, and of course, sharks. (If you don’t yet know the baby shark song, ask any preschooler you know to teach it to you.)

When I tell people (with much excitement) that I have been selected to be a NOAA Teacher at Sea, they ask “who will you be teaching?” thinking that there will be students onboard the ship.  I explain that in many ways, I will actually be both a Student at Sea and a Teacher at Sea. I will be learning from the scientists onboard the ship how to use acoustics as well as more traditional, hands-on methods to count Alaskan pollock in the Bering Sea, and exploring the issues oceanographers are most concerned or excited about.  Then, through blogging while onboard, and upon my return to the classroom, I will use this first-hand knowledge to create STEM projects involving oceanography that will help students see their connection to the ocean world, and instill in them a sense of stewardship and responsibility for the world around them. I am hopeful that these experiences will inspire more students at my school to choose a career in science, perhaps even with NOAA.

When I am not teaching, or taking classes for my administrative credential through the University of Southern California, or being involved with education policy through a fellowship with Teach Plus, I enjoy spending time with my husband and daughter, and apparently EATING Alaskan pollock. It turns out that the imitation crabmeat in the California rolls and crab salad that I eat quite often is actually Alaskan pollock.  We will see if catching them, looking them in the eye, and studying them, will make me more or less interested in eating them.


Emily Cilli-Turner: Catching Pollock with Mathematics! August 1, 2018

NOAA Teacher at Sea

Emily Cilli-Turner

Aboard NOAA Ship Oscar Dyson

July 24 – August 11, 2018

 

Mission: Pollock Acoustic-Trawl Survey

Geographic Area of Cruise: Eastern Bering Sea

Date: August 1, 2018

 

Weather Data from the Bridge:

Latitude: 61 55.41 N

Longitude: 172 48.34 W

Wind Speed: 2.24 knots

Wind Direction: 77.54 (NW)

Air Temperature: 9.7 C

Barometric Pressure: 998.8 mb

Visibility: 9 nautical miles

Sea Wave Height: 3 feet

Sky: Overcast

 

Science Log:

“When am I ever going to use this?”  This is the query of many students who are required to take mathematics courses.  However, scientists aboard the NOAA Ship Oscar Dyson use mathematics every day as part of their job.  As discussed in a previous blog post, underwater acoustic data are collected as the NOAA Ship Oscar Dyson navigates along the transects.  These backscatter data are relied upon to decide when to take trawling net samples as well as to estimate the number and biomass of pollock in the area.

How do these underwater acoustics work?  The answer can be found in mathematics and physics.  As previously discussed, echosounders affixed to a centerboard below the hull of the ship send an audible ping down into the water and measure how long it takes to bounce off of an object (like a pollock) and return to the surface. The echosounders know the transmitted signal power (denoted Pt) and measure the received signal power (denoted Pr).  Measuring the time between the signal transmission and reception and multiplying by the speed of sound (approximately 1450 m/s, given local water salinity and temperature conditions) will allow the calculation of distance of an object below the surface (or range denoted r). Using acoustics properties combined with known properties of pollock, we can get the equation for backscattering strength at a point as eqn1.png, where β is a constant and C(r) is a constant that is dependent on range.

However, since sound is measured in decibels which are arranged on a log scale, 10 times the log of both sides of the backscattering strength equation is desired.  Using logarithm rules, this becomes

eqn2

The value on the left-hand side of this equation is commonly referred to as target strength (TS) and is an important value to complete the survey.

The target strength is the amount of energy returned from a fish of a certain length.  Since the echosounders are transmitting through the water column below the ship, the TS values are converted to backscatter strength per volume unit of water, referred to in the literature as Sv.  The Sv values are graphed on the EK60 scientific echosounder, giving a picture similar to the one below.  Different colors in the output are matched to various ranges of Sv values.  An experienced fisheries scientist, like the ones aboard the NOAA Ship Oscar Dyson, can use the echosign data to determine a possible picture of the ocean life below the ship.  While the EK60 scientific echosounder can transmit at five different frequencies (18 kHz, 38 kHz, 70 kHz, 120 kHz, and 200 kHz), the 38-kilohertz transmission frequency is the best frequency to detect pollock.  Other transmission frequencies are shown to help delineate adult pollock from baby pollock and from other types of fish and smaller crustaceans called euphausiids.

EK60

Screenshot of an EK60 reading of the water column below the ship with identifying features notated.

The target strength is related to the length of the fish.  The age of pollock is strongly correlated to their length until they are about 4 years old, so length can help the scientists determine how many of each year class are in the ocean below.  Once again, logarithms come in handy, as the equation that relates the fork length in centimeters, l, of the pollock to the recorded target strength is TS = 20 log l – 66. This allows the scientists to use the echosounder data to get an approximate measure of the fish below without having to catch them.

Personal Log:

Today we will be going on a partial tour of NOAA Ship Oscar Dyson so you can see where I spend most of my time while aboard.  The first stop is my stateroom, where I sleep and relax when not on shift.  The top bunk is mine and the bottom bunk belongs to my roommate, NOAA scientist Abigail McCarthy.  Our stateroom has one window where we can check on the weather and sea conditions.  The picture below shows our view most of the time: cloudy!

 

Next stop is the mess hall where three meals a day are served.  The stewards do a great job of cooking creative meals for everyone aboard.  Before I boarded the ship, I bought a lot of snacks because I was worried about not getting enough to eat, but boy was I wrong.  There is always plenty to eat at every meal, snacks that are out if you get hungry in between, and lots of dessert!

mess

The mess hall.

Finally, we come to the fish lab where the trawling net samples referred to in my last blog post are processed.  Before processing, we go to the ready room and put on our gear.  This includes work boots as well as waterproof coveralls and jacket.  Measuring the length of the pollock can get messy so we have to have the right gear.  Once in the fish lab, we grab our gloves and get to measuring!

 

Did You Know?

Scientists aboard the NOAA Ship Oscar Dyson are part of the National Marine Fisheries Service (NMFS), which is one of the six major line offices of NOAA.