codend – NOAA Teacher at Sea Blog

July 2, 2019July 5, 2019

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.

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.

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.

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.

July 27, 2017July 27, 2017

Jenny Hartigan: Tucker Trawl: Collecting Sea Life! July 24, 2017

NOAA Teacher at Sea

Jenny Hartigan

Aboard NOAA Ship R/V Fulmar

July 21 – July 28, 2017

Mission: Applied California Current Ecosystem Studies: Bird, mammal, zooplankton, and water column survey

Geographic Area: North-central California

Date: July 24

Weather Data from the Bridge:

Latitude: 37.8591° N,

Longitude: 122.4853° W

Time: 0700

Sky: overcast, foggy

Visibility: less than 1 nautical mile

Wind Direction: NW

Wind speed: 10-20 knots

Sea wave height: 2-4 feet

NW Swell 7-9 feet at 8 seconds

Air Temperature: 52 degrees F

Wind Chill: 34 degrees F

Rainfall: 0mm

Scientific Log:

On Sunday we encountered heavy fog as soon as we headed out to sea, so the captain sounded the foghorn every 2 minutes. The scientists Jaime, Ryan and Kirsten deployed the Tucker Trawl. It consists of a large net with 3 codends. A codend looks like a small cup that attaches to the end of the net. Each codend collects sea life at a different depth. The Tucker Trawl is always deployed at the edge of the continental shelf. The shelf is about 200 meters below sea level. The goal is to take organism samples from the pelagic (non-coastal or open) ocean. 400 meters of cable are deployed along with the net, so you can see that it goes deep in the ocean!

The scientists deploying the Tucker Trawl.

Using the Tucker Trawl requires a whole team of people. 3 scientists deploy the net, and the captain operates the winch and A Frame so the net doesn’t hit the deck during the process. The NOAA Corpsman drives the boat so as to maintain alignment and speed. One scientist keeps an eve on the angle of the cable, and communicates with the driver to maintain the proper angle by adjusting speed. After recovering the net, all three samples must be rinsed into a bottle. Too much water pressure can mangle the specimens, so we use a gentle rinse. The bottle is then labeled and treated with fixative to preserve the samples. Then it is stored to later be sent to a lab for identification. I have learned that taking these samples requires a lot of communication, to maintain fidelity to a testable process, utilize equipment wisely, and to ensure safety of all personnel.

2017-07-26 09.16.36

A view from above as the Tucker Trawl goes out to sea.

Each offshore transect has one Tucker Trawl site. After that we move to another site and take Hoop net, CTD, Niskin, water, phytoplankton samples. I will explain these later. Sampling all of these sites provides data for the scientists to investigate the entire ecosystem. They collect plankton (producers) from shallow and deep water, observe marine mammals and birds (predators) on the surface, and sample the environmental conditions such as ocean temperature, salinity, nutrients, and ocean acidification indicators. These studies inform decisions for managing a sustainable environment for both sea life and humans.

2017-07-25 11.39.15

Two scientists collecting sea life from the Tucker Trawl.

Personal

I want to tell you about the galley. This is the kitchen where we store and prepare our food. We have an oven, stove, microwave, sink and two refrigerators, but everything is compact due to limited space. All of the cabinets and the fridge have latches on them to keep food from flying around when the seas are rough. I have to remind myself to latch the fridge each time I open it. I don’t want to be the person who created a giant smoothie in the kitchen!

We eat our meals at the table, which then converts to a bed for sleeping. Every little bit of space is used efficiently here.

Did you know?

An albatross is part of the tube-nose family of birds. One of its features is having a tube nose above the nares. Nares are the openings to the nostrils. The birds also have openings at the end of the tubes. This adaptation gives it a keen sense of smell. We saw black-footed albatross, which nests in the Hawaiian Islands, and flies long distances across the ocean to find food in the productive waters of Cordell Bank and Greater Farallones National Marine Sanctuaries. So this albatross has been traveling at sea for a long distance!

Animals Seen Today

We spotted a CA sea lion cavorting in the wake of the ship. It looked like it was having so much fun as it leaped and twisted above the waves.

I love hearing from you. Keep those comments coming!

July 20, 2016August 21, 2021

Cathrine Prenot: A Fish Tale, Too Big to Fail. July 18, 2016

NOAA Teacher at Sea
Cathrine Prenot
Aboard the Bell M. Shimada
July 17-July 30, 2016

Mission: 2016 California Current Ecosystem: Investigations of hake survey methods, life history, and associated ecosystem

Geographical area of cruise: Pacific Coast from Newport, OR to Seattle, WA

Date: July 18, 2016

Weather Data from the Bridge:
Lat: 45º19.7 N
Lon: 124º21.6 W
COG: 11.2
Speed: 17.1 knots
Air Temp: 16.4 degrees Celsius
Barometer (mBars): 1019.54
Relative Humidity: 84%

Science and Technology Log

It is exciting to be out to sea on “Leg 2” of this cruise! The official title of our research is “2016 California Current Ecosystem: Investigations of hake survey methods, life history, and associated ecosystem.” One of the key portions of this leg of the trip is to collect data on whether or not a piece of equipment called the “Marine Mammal Excluder Device” (MMED) makes any difference in the fish lengths or the species we catch. Here is how it works (all images from Evaluation of a marine mammal excluder device (MMED) for a Nordic 264 midwater rope trawl):

The catch swims towards the codend of the net and encounters the MMED — The catch swim towards the codend of the net and encounter the MMED

The catch encounters the grate; some go through the grate while others escape the net through the hatch (shown by the orange buoy). — Some of the catch go through the grate (to the codend) while others escape the net through the hatch (shown by the orange buoy).

Why is this important? For example, if all of one type of fish in a trawl escape through this MMED, we would be getting a different type of sample than we would if the equipment was off the nets. Our lead scientist, Dr. Sandy Parker-Stetter explained: “If all the rockfish go out the top escape panel, how will we know they were there?” To collect data on this, we will be doing a lot of trawls—or fishing, for those non-sea faring folk—some with the MMED and others without it. These will be small catches, we need about 300-400 fish, but enough to be able to make a determination if the equipment effect the data in any way.

We have done a few trawls already, and here are some of the photos from them:

'Young of the Year' Hake — ‘Young of the Year’ Hake

All of this reminds me of why we are so concerned with accurately estimating the population of a little fish. To illustrate, let me tell you a story—a story of a fishery thought too big to fail—the Great Banks Atlantic Cod fishery. Why don’t you click on Issue 2 of Adventures in a Blue World: A Fish Tale, Too Big to Fail.

Adventures in a Blue World, CNP. A Fish Tale: Too Big to Fail

Cod populations decreased to such a degree (1% of previous numbers), that the Canadian Government issued a moratorium on Cod fishing in 1992. Our mission—to investigate of hake survey methods, life history, and associated ecosystem—is designed to prevent such a devastating result. We don’t want Hake or other species to go the same route.

Personal Log

We left the left the dock on Sunday at 1145, and made our way under the Newport Bridge and out to sea. It was really wonderful to watch the ship leave the harbor from way up on the Flying Bridge—the top-most deck of the ship. There are four tall chairs (bolted to the deck) at the forward end of the deck, an awning, and someone even rigged a hammock between two iron poles. It is rather festive, although again, there were no drinks with umbrellas being brought to us.

View of Newport, OR from the flying bridge of the Shimada — View of Newport, OR from the flying bridge of the *Shimada*

I didn’t have any problems with seasickness on my last voyage, but I did take some meds just in case. One of the researchers said that he doesn’t take any meds any more, he just gets sick once or twice and then feels much better. If you are interested, here is a link to my previous cartoon about why we are sea-sick, and how and why ginger actually works just as well as other OTC drugs. All I can say now is that I’m typing this blog in the acoustics lab, and the ship does seem to be moving rather alarmingly from fore to aft–called pitching. Maybe I should find a nice porthole. In the meanwhile, you can read “Why are we seasick.”

Did You Know?

The end of the fishing net is called the codend. Who knew? This and many more things can be learned about fishing from reading this handy reference guide.

May 11, 2015August 21, 2021

June Teisan, Science at Sea! May 9, 2014

NOAA Teacher at Sea
June Teisan
Aboard NOAA Ship Oregon II
May 1 – 15, 2015

Mission: SEAMAP Plankton Study
Geographical area of cruise: Gulf of Mexico
Date: Sunday, May 10, 2015

Weather Data from the Bridge:
1600 hours ; Partly Cloudy; wind 6 knots; air temp 27.5C; water temp 28.4C; wave height 3 ft

Science and Technology Log:

It’s been fascinating to work beside the fisheries science staff here on the Oregon II. Moving through the station protocols – deploying nets and sampling devices, processing, preserving, and cataloging the ichthyoplankton samples, analyzing the chemistry of water samples – I have learned so much and enjoyed every minute.

transferring water samples from CTD to lab bottles

waiting to deploy the CTD with science team member Jonathan Jackson

Personal Log:

I am always curious about why people choose the careers they do. At what point did a door open, who pointed the way, when did the proverbial light bulb go on? So I asked a few members of our science team the when, how, and why behind their chosen career.

Alonzo Hamilton

Path to a STEM Career: When his asthma closed the door to a career in the Air Force, Alonzo reluctantly headed to community college instead. From his stellar work at Prentiss Normal and Industrial Institute in Prentiss, Mississippi, he earned a full ride to Jackson State University.

When Alonzo showed up for registration at JSU the first day, the attendant at registration told Alonzo that he had not just one, but two academic scholarships! He needed to make a choice between the scholarship he knew he had and an additional biomedical research assistant scholarship. He rushed over to speak with the director of the biomed program, only to be told that the scholarship had been given away without consulting Alonzo. Angry and disappointed, Alonzo stormed out down the hall and literally ‘turned a corner’ into the first door he saw: The Office of Marine Sciences. He asked the director of that division to explain her program to him, which she did and encouraged him to join. As they say, the rest is history. Alonzo finished his bachelors degree in biology, and went on to Master in Marine and Environmental Sciences. Since 1984, Alonzo has worked with NOAA in the Trawl Survey Unit of NOAA Fisheries in Pascagoula.

Best Part of His Job: He enjoys the new discoveries he sees out on the water.

Favorite Teacher: 6^th grade Ms. MaeDora Frelix – “Because she was pretty, and smart, and she said I was smart, so that topped it off”

Taniya Wallace

Path to a STEM Career: Taniya always liked science and in high school took the medical program vocational classes which involved clinicals in the hospital and shadowing doctors. However, after she passed out during rounds one day, Taniya decided she didn’t want to be a nurse. She did, however, find a new science interest; she job-shadowed her aunt who was working at Gulf Coast Research Lab in Ocean Springs, Mississippi and loved it. She attended Mississippi Valley State University in Ittabena, MS with a biology major and a minor in chemistry. She completed her bachelors in May 2010 and is now working in marine sciences, with part of her work assisting with research on NOAA vessels.

Best Part of Her Job: Being out on the water, the fact that it is always something different.

Favorite Teacher: Mrs. S. Williams, 7^th grade science “because she opened my eyes to a new world, it wasn’t regular textbook material. She did nature walks, integrating arts – keeping science exciting and interesting.”

Denice Drass

Path to a STEM Career: Denice always liked science, and on vacation trips to the beach as a kid she decided she wanted to do marine biology. She selected a university that had marine bio as undergraduate major. Millersville University in Pennsylvania was part of the Wallops Island Marine Science Consortium of Virginia so Denice could take summer marine science classes in Virginia, graduating with a Bachelor’s degree in Marine Biology. She then earned her Masters’ in Marine Biology from the Florida Institute of Technology. Denice spent 7.5 months working for the state of Florida on their Red Drum Stock Enhancement Program (red drum fish Sciaenops ocellatus) then moved to NOAA’s National Marine Fisheries Mississippi Laboratories in 1993.

Best Part of Her Job: “Variety! It’s never the same thing twice, and I can go between field work and lab work so that keeps everything interesting.”

Favorite Teacher: Denice had so many wonderful teachers she can’t pick just one.

BOB Trio — Alex Beels, Craig Trebesh, and June Teisan with BOB (basic observation buoy) in the background

The classroom shout out for this blog goes to students with Ms. Alexandra Beels, Grosse Pointe South High School in Grosse Pointe, Michigan, and Mr. Craig Trebesh, SOAR Academy in Sheridan, Colorado.

March 23, 2015August 21, 2021

Julia West: Bongos! March 22, 2015

NOAA Teacher at Sea
Julia West
Aboard NOAA ship Gordon Gunter
March 17 – April 2, 2015

Mission: Winter Plankton Survey
Geographic area of cruise: Gulf of Mexico
Date: March 22, 2015

Weather Data from the Bridge

Time 1700; clouds 100%, stratus; wind 325° (NNW), 9 knots; air temperature 22°C, sea temperature 25°C

Science and Technology Log

Here’s what we have covered as of Sunday evening, 3/22. I’m getting quite the tour of the Gulf! Notice we are going back and forth across the shelf break (the edge of the continental shelf), as that is our area of interest.

Stations covered 3/22 — This is what we’ve covered so far. We’re doing well!

Again, thanks to all of you who are reading and asking questions. One recent question had to do with whether we are bringing specimens back. So let me explain what we do with them. Most plankton are so small that you see them best through a microscope. So the “specimens” that we are bringing back are all in jars – thousands of organisms per jar! Every time we collect samples, we get at least three jars – two from the bongo nets and one (or more) from the neuston net. That’s not including the CUFES samples described earlier, which are only big enough for a tiny bottle. Here are some pictures:

Kim labeling a sample — Kim Johnson (scientist) in the wet lab, labeling a sample. Notice the cardboard boxes – they are all full of sample jars, both empty and full.

Bongo sample — This is a nice sample from one of the bongo nets. Lots of little guys in there!

These samples get brought back to shore for analysis in the NOAA lab. Oddly, many of the samples get sent to Poland to be analyzed! Why Poland, you ask? Well, for a few decades we have had a cooperative agreement with the Polish sorting and identification center. They remove the fish and eggs from all samples, as well as select invertebrates. These specimens and the data get sent back to US for analysis. We double check some of the IDs, and plug the data into models. (If you are a biology student, this is an example of how models get used!) The information then goes to fisheries managers to use to help form fishing regulations. This division of NOAA is called the National Marine Fisheries Service (NMFS), which manages stocks of fish populations.

NOAA has been doing spring and fall plankton sampling for 30 years now. Winter sampling is newer; it started in 2007. SEAMAP (SouthEast Area Monitoring and Assessment Program) is cooperative agreement between the Gulf states, federal (NOAA), and university programs. The samples from the states and universities get sent to Poland with our samples. The the timing of the surveys is to target specific species when they are spawning. This winter survey is targeting grouper, tilefish, and other winter spawning species. The other surveys target bluefin tuna, red drum, red snapper, and mackerels, which spawn at other times of the year. The invertebrate data is used to build an understanding of invertebrate community structure throughout the Gulf.

In science, research is cumulative. We know, from past research, what the mortality rate of some fish species is. So if we get a fish larva or fry that is a certain size, we can estimate the percentage of that size larvae that will reach adulthood, and back calculate to see how much mortality has already happened to get fish of that size. All this allows us to get a peek into the size of adult population.

The first piece of equipment that we use when we get to each station is the bongo nets. You can see how they got their name!

Here are the bongos ready to be deployed:

Bongos ready to deploy — These bongos are ready to go as soon as we get the OK.

Flow meter for bongos — This little whirlybird is the flow meter.

The flow meter is inside each bongo net, near the top. We read the numbers on it before the net goes out, and after it comes back. Using this information – the rate of flow, together with the area of the opening, we can calculate the volume of water filtered. The SeaCAT is a nifty unit that measures conductivity (salinity), temperature, and depth. Since we have a much fancier unit to measure these factors, we use this primarily for depth, so we know when we are getting to 200 meters (or the bottom, whichever comes first). We go to 200 meters because that is the lowest effective light penetration. Phytoplankton need light, and zooplankton need phytoplankton! What’s more, larval fish have not yet developed their lateral line (the organ that many fish use to sense vibrations in the water around them), so they feed visually. Even if they want to eat something below the photic zone, they wouldn’t be able to “see” it yet.

I, of course, am full of questions, and knowing that I’m supposed to identify every acronym I write, I asked what SeaCAT stands for. The unit is made by a company called SBE (Sea Bird Enterprises), so is the CAT just a fun name that they came up with? Nobody knew the answer! But everyone was curious, and Tony and Steve (both electronics technicians) did some emailing and got the answer straight from SBE. CAT stands for “Conductivity And Temperature” (seems we could have figured that out). And the Sea? Could be for Seabird, Seattle, or just the plain ol’ sea!

Deploying the bongos — Here I am holding the “codends,” ready to drop them over the side. The crane does all the heavy lifting. Photo by Andy Millett

Once we get the nets in the water, the crane operator monitors the speed that it is lowered. Our job is to communicate the “wire angle” constantly to the bridge and the lab. Here’s how this is done:

Measuring wire angle — Measuring the wire angle (angle of the cable) with the inclinometer. Photo by Madalyn Meaker.

The angle of the cable is important because it allows the nets to sweep the desired amount of water as they are pulled up. If the wire angle is too high (above 55°), the crew on the bridge slows the ship down just a bit. The perfect angle is 45°. Many other factors can mess this up, most notably current. The ship has to be facing the right direction, for example, so the current isn’t coming toward the ship (have you ever been fishing and had your line swept under the boat?). It’s tricky business, requiring constant communication between bridge, lab, and deck! Oh, and by the way, the cable is a “smart wire,” meaning it has electrical flow through it, which is how the depth gets communicated to the computers. Fascinating technology, both on the micro and macro scale!

Once we pull in the bongos, we hose them off very thoroughly, to get any of the little plankton that are stuck to the net. They are all funneled into the codend, which is a PVC cylinder. From there, we dump the sample into a sieve, and transfer it into a jar, and get read to do it again in 3 hours or so.

Bongo cod end — This is a close-up of the “cod end” of the bongo, where the plankton get funneled into.

Plankton from the bongo — This is the sample from one of the bongo nets. Can you see why it’s hard to come up with pictures of individual organisms? There are thousands in here!

Did I tell you that sampling goes on 24/7? Perhaps you figured that out when you heard the shift times. It costs a lot to run a ship; operations continue whether it’s night or day.

Personal Log

Now, to keep people happy when they are living in close quarters, far from home, and working strange shifts, what’s the most important thing of all? FOOD! The Gunter is well known among NOAA circles for having fantastic food for people of all diet types and adding ethnic flavor to her meals. The person responsible for our good and abundant food is Margaret, our Chief Steward. She has worked for NOAA for ten years, and says it’s the best job she has ever had. Her husband is now retired from the Coast Guard, so they moved around a lot. Margaret worked for the Coast Guard for four years, then went back to cooking school, and had various other jobs before signing on with NOAA. She has a few years left before she retires, and when she does, what will she do? She wants to do subsistence farming! This is right up my alley – Margaret and I have a lot to talk about! Not to mention the fact that Margaret makes her own juices, some amazing homemade hummus, AND dries her own fruit (dried cherries -yum!).

Margaret, chief steward — Margaret, assembling some spinach lasagna rolls while talking about her life.

Margaret also has a helper, Mike, who was reluctant to have his picture taken. He’s not the usual assistant steward, but sure seems highly capable! It always sounds like a lot of fun is being had in the galley.

Gunter dining room — The dining room, or “mess deck.”

condiment selection — World’s largest selection of condiments, including anchovy sauce and REAL maple syrup!

That’s it for this post – I’m getting hungry. Time to eat!

Challenge Yourself

What executive branch of the U.S. government does NOAA belong to? Is it the same branch that oversees our national parks? How about our national forests?

Did You Know?

There are nearly 4000 active oil and gas platforms in the U.S. Gulf of Mexico (NOAA), and more than 27,000 abandoned oil and gas wells (Assoc. Press, 2010)

Oil and gas platforms in the Gulf — Locations of the active oil and gas platforms in the Gulf of Mexico. From http://oceanexplorer.noaa.gov/

August 6, 2012August 11, 2021

Johanna Mendillo: Nets, Northern Sea Nettles and More…, August 5, 2012

NOAA Teacher at Sea
Johanna Mendillo
Aboard NOAA ship Oscar Dyson
July 23 – August 10

Mission: Pollock research cruise
Geographical area of the cruise: Bering Sea
Date: Sunday, August 5, 2012

Location Data
Latitude: 61º 10′ N
Longitude: 179º 28’W
Ship speed: 4.3 knots ( 4.9 mph)

Weather Data from the Bridge
Air temperature: 11.1ºC (52ºF)
Surface water temperature: 8.1ºC (46.6ºF)
Wind speed: 5.4 knots ( 6.2 mph)
Wind direction: 270ºT
Barometric pressure: 1013 millibar ( 1.0 atm)

Science and Technology Log:

So far, you have learned a lot about the pollock research we conduct on board. You have learned:

How to age fish (with otoliths)
How to measure fish (with the Ichthystick)

and

How to identify fish gender (with your eyes!)

Now, we are going to backtrack a bit to the two big-picture topics that remain:

How do we CATCH the pollock (hint hint, that is today’s topics… NETS!)

and

How do we even find pollock in the Bering Sea (that is the next blog’s focus: acoustics!)

So, to begin, there are several types of nets we are carrying on board. Remember, when a net is dragged behind a ship in the water it is called trawling, and the net can be considered a trawl. The most-used is the Aleutian Wing Trawl, or AWT, which we use to sample the mid-water column (called a midwater trawl). We are also using a net called the 83-112, which is designed to be dragged along the ocean floor as a bottom trawl, but we are testing it for midwater fishing instead. In fact, sometimes during my shift we do one AWT trawl, and immediately turn around and go over the same area again with the 83-112 to see differences in the fish sizes we catch!

If the 83-112, which is a smaller net, proves to be adequate for midwater sampling, NOAA hopes it can be used off of smaller vessels for more frequent sampling, especially in the years the NOAA does not conduct the AWT (NOAA currently does AWT surveys biennially).

Now, for each type of net, there is some new vocabulary you should know:

The codend is the bottom of the net. A closed codend keeps the fish inside the net and an open cod end allows them to swim through. It may seem odd, but yes, sometimes scientists do keep the codend open on purpose! They do this with a camera attached to the net, and they simply record the numbers of fish traveling through a certain area in a certain time period, without actually collecting them! Here on the Dyson, the NOAA team is testing that exact type of technology with a new underwater camera called the Cam-Trawl, and you will learn about it in a later post.

The headrope is the top of the opening of the net.

The footrope is the bottom of the opening of the net.

(The 83-112 is called such because it has an 83 ft headrope and an 112 ft footrope.)

The trawl doors are in front of the headrope and help keep the net open. Water pressure against the trawl doors pushes them apart in the water column during both setting of the net and while trawling, and this helps spread out the net so it maintains a wide mouth opening to catch fish.

There are floats on the top of the net and there can be weights on the bottom of the net to also help keep it open.

Lastly, the mesh size of the net changes: the size at the mouth of the net is 3 meters (128in.), and it decreases to 64in., 32in., 16in.., 8in., etc. until it is only ½ inch by the time you are holding the codend!

Here is a diagram to put it all together:

awt-model-commented1 — Courtesy of Kresimir Williams, NOAA

If you think about the opening of the net in terms of school buses, it will help! It turns out that the AWT’s opening height, from footrope to headrope, is 25m, which is 2 school buses high! The AWT’s opening width, is 40m across, about 3.5 school buses across! Now, you can see why positioning and maneuvering the net takes so much care– and how we can catch a lot of pollock!

Here is a trawl returning back to the ship's deck! — Here is a trawl returning back to the ship’s deck!

Now, when the scientists decide it is “time to go fishing” (from acoustic data, which will be the topic of the next blog) they call the officers up on the Bridge, who orient the ship into its optimal position and slow it down for the upcoming trawl. Meanwhile, the deck crew is preparing the net. The scientists then move from their lab up to the Bridge to join the officers– and they work together to monitor the location and size of the nearby pollock population and oversee the release and retrieval of the net.

Along the headrope, there are sensors to relay information to the Bridge, such as:

The depth of the net
The shape of the net
If the net is tangled or not
How far the net is off the bottom and
If fish are actually swimming into the net!

The fish and the net are tracked on this array of computer screens. As the officers and scientists view them, adjustments to the net and its depth can be made:

The start of the trawl is called “EQ” – Equilibrium and the end of the trawl is called “HB” – haul back. The net can be in the water anywhere from 5-60 minutes, depending on how many fish are in the area.

The AWT will get would up on this new reel — The AWT will get wound up on this reel

Now, sometimes an AWT catches so many fish that there are simply too many for us to measure and process in a timely fashion, so it is deemed a “splitter”! In a splitter, there’s an extra step between hauling in the net from the ocean and emptying it to be sorted and processed. The codend of the AWT is opened over a splitting crate, and half of the pollock go into a new net (that we will keep and sort through) and the rest of the pollock are returned to the water.

The net is back on board! Time to open up the codend and see what we have caught!

Personal Log:

Let’s continue our tour aboard the Oscar Dyson! Follow me, back to the bridge, where the OOD (Officer on Duty) is at the helm. As you already know, the first thing you notice on the bridge is the vast collection of computer screens at their disposal, ready to track information of all kinds. You will learn more about these in an upcoming blog.

Busy at work on the bridge... — Busy at work on the Bridge…

In addition to these high-tech instruments, I was very happy to see good old-fashioned plotting on a nautical chart. In class, students, you will have a special project where you get to track the changing position of the Oscar Dyson!

This chart is showing the northernmost point of three of our sampling transects- including the one closest to Russia!

Here is a sample of the hour-by-hour plotting, done by divider, triangle, and pencil:

I will end here with a sea specimen VERY different from pollock, but always a fan favorite— jellyfish! Interestingly, there are a large number of jellyfish in the Bering Sea- something I never would have assumed. The one that we catch in almost every net is the Northern Sea Nettle (Chrysaora melanaster). In one net, we collected 22 individuals!

When we collect non-pollock species such as these, we count, weigh, and record them in the computerized database and then release them back into the ocean. Here they are coming down the conveyor belt after the net has been emptied:

The so-called bell, or the medusa, can be quite large- some are the diameter of large dinner plates (45cm)! Their tentacles can extend to over 3m in length. They consume mostly zooplankton, small fish (including juvenile pollock), and other jellies. How so, exactly? Well, when the tentacles touch prey, the nematocysts (stinging cells) paralyze it. From there, the prey is moved to the mouth-arms and finally to the mouth, where it’s digested.

This same mechanism is used by sea nettle when it encounters danger like a large predator. It stings the predator with its nematocysts and injects its toxins into its flesh. In the case of smaller predators, this venom is strong enough to cause death. In larger animals, however, it usually produces a paralyzing effect, which gives the sea nettle enough time to escape.

Now in the case of me handling them… and other humans…their sting is considered moderate to severe. In most cases, it produces a rash, and in some cases, an allergic reaction. However, we wear gloves on board and none of the scientists have ever had an issue holding them. In fact, they offered to put one on my head and take a picture… but I declined! If a few students email me, begging for such a picture, maybe I will oblige…

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

July 22, 2010March 12, 2021

Story Miller, July 22, 2010

NOAA Teacher at Sea: Story Miller
NOAA Ship: Oscar Dyson

Mission: Summer Pollock III

Geographical Area: Bering Sea

Date: July 22, 2010

Time: 0754 AKST
Latitude: 58°31N
Longitude:175°45W
Wind: 13-20 knots (approx. 14.96 – 23.02 mph)
Direction: 239° (SW)
Sea Temperature: 8.28°C (approx. 46.9°F)
Air Temperature: 8.03°C (approx. 46.5°F)
Barometric Pressure (mb): 1017
Wave Height: 4 feet
Sea Swells: 6 feet
Combined Wave Height: 10 – 12 feet

Scientific Log

This afternoon, we conducted a test with a drogue which is like a large sea anchor. Sea anchors allow a boat that is simply sitting in the water to not drift so far with the waves. This drogue will stabilize the camera of an experimental trawl net device, called a Cam-Trawl, and prevent it from fluttering when it is photographing the fish. The Cam-Trawl was designed by Kresimir Williams. Currently the objective of this new device is to observe the fish we see in the backscatter which are the animals we can see in the echosounder

(See Figure 1).

Figure 1: Image of the echo sounder in the acoustics lab. The image on the top in the blue is representing a swarm of jellyfish. Jellyfish tend to be best seen using the 18 kHz transducer.

In short, the ship’s hull has transducers that send pings of sound energy down through the ocean and when they hit some object, such as the bottom of the ocean or a fish, some of the energy in the sound ping is returned to the ship and received by our echo sounding system in the acoustics lab of the ship.

When we locate a group of fish we want to study with the echo sounder, we have two primary methods of collecting data from the fish. The device we use the most is the AWT(Aleutian Wing Trawl) net and the other is an 83-112 bottom trawl net. The AWT is used for catching fish located at midwater depths and the other, as stated in the name, trawls the sea floor. To imagine the shape of these devices in the water, imagine a large funnel with a catch sack on the end. The beginning portion of these nets, nearest to the boat, has large meshes and its primary function is to funnel the fish toward the catch sack. As fish move farther down the net, the meshes get smaller until they reach the catch sack, which we call the codend, and once in there, the fish cannot escape. We then pull them to the surface and begin collecting data, such as size and species. The largest drawback to these methods is that the fish caught in the net will most likely die. To understand why, think of a diver in the deep ocean. If the diver comes up too fast, the body cannot adjust to the pressure fast enough as air expands, potentially causing lungs to rupture. For the fish, bringing them up too quickly causes their swim bladders to rupture. Rockfish tend to have their stomachs inverted out of their mouth. While killing the fish for research is unfortunate, it is one of the few ways we can learn about their patterns of behavior, health, and diversity.

Chris Wilson in the process of attaching buoys to stabilize the Cam-Trawl

The Cam-Trawl is an innovative experimental design that may help reduce the killing of fish and allow us to collect data from endangered or nearly extinct fish species. For example, many Rockfish species off the west coasts of California, Washington and Oregon are endangered and as a result, we do not want to catch them in our nets because we would most likely kill them. The Cam-Trawl would remedy that and would allow us to receive continuous data at each depth along its path. The other trawls catch all the fish in their path which means the collection of fish is mixed and we cannot tell the depth at which they were originally swimming or which species was at what depth. To picture how the Cam-Trawl works underwater, imagine a funnel again, except this time, there is no codend attached. At the end of the funnel, the stereocamera is positioned to photograph the fish that pass through the funnel. The resolution of the fish photos is much more advanced than what we have ever had before. This sampling technique is supposed to give us a better resolution of what we are able to “see” using acoustics (echo sounder) than the traditional midwater (AWT) and bottom trawls (83-112).

Personal Log:

Sleeping at sea was a new experience for me. The seas were only four to eight feet high which are marginal compared to the conditions this ship experiences in the winter months. Overall, I enjoyed being rocked to sleep but my 0330h alarm was not as pleasant. My room is located four flights of stairs below the bridge deck and I’ve been told it is one of the better places to be because the rocking of the boat is not as intense. The rooms are pretty cozy as space is limited but there is room for a desk, two closets and a bathroom (called a head on a ship) that reminds me of the sizes found in European hotels. I have the top bunk and each has a curtain that wraps around the entire bed so that if your roommate has a different shift than you, the light to the main room won’t be a disturbance. Of course, since I have lived in Alaska for two years, I have become accustomed to sleeping in bright conditions.

Something the non-boating community may not realize is that on a ship, it is very important that there is a night crew and a day crew operating. On the bridge where the main controls of the ship are located, there must always be a NOAA Corps Officer, with qualifications to drive the ship, on watch 24/7. However, all crews, with the exception of the kitchen, on the ship are operating around the clock. For example, there are always engineers operating in case there is some type of mechanical issue and scientists operate because there are still fish in the ocean and their behavior needs to be observed at all times.

Me trying on my “Gumby” Suit during the fire drill

The entire crew participated in a fire drill and abandon ship drill yesterday so that all hands on the ship knew where to muster for a head count and to learn how to operate the life rafts in case the ship was sinking. Additionally we needed to learn how to get into our survival suits (Gumby Suits). My first experience putting on the suit was during a field trip onto this vessel with my seventh and eighth grade students in May so I was aware of the cozy fit! Fire and abandon ship drills are practiced once a week when the ship is underway, which is very important as the crew onboard are not just NOAA employees but also in charge of fighting fires and responding to any onboard emergencies. So, if you want to be a fireman and a scientist and cannot choose, perhaps serving aboard a NOAA ship would be right up your alley!
To end my day (remember bedtime for me is early as my alarm is set for 0330) I had a “late” supper of sushi, spring rolls, meatloaf, and for dessert a fabulous set of s’mores! Who says you can’t have them on the ship?

Animals Observed:
Northern Fulmar
Crested Auklets
Tufted Puffin
Black-legged Kittiwake
Orcas

Something to Ponder:
When we are asked, “What do you want to be when you grow up?” usually we say one occupation – firefighter, actor, scientist, teacher, soldier, waitress. However, most jobs require many skills. For example, the scientists on board put a variety of skills into practice and as mentioned in the Scientific Log, scientist Kresimir Williams engineered the Cam-Trawl which employed his knowledge of the biological sciences (fish/oceanography), physical science (how to deploy the device without it breaking), and photography! So for my students, what do you want to be when you grow up?

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 !