Marla Crouch

July 15, 2013August 11, 2021

Marla Crouch: I Bid You Adieu, July 14, 2013

NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8-26, 2013

Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: July 14, 2013

Weather Data from the Bridge: as of 1700
Wind Speed 6.02 kts
Air Temperature 52.10°C
Relative Humidity 100.00%
Barometric Pressure 1,024.60 mb

Latitude: 57.16N Longitude: 151.78W

Science and Technology Log

The 2013 Walleye Pollock Survey extends from the Isles of Four Mountains to Yakutat, Alaska. As the crow flies that is a distance of 2371 statute miles. By the time the Oscar Dyson reaches Yakutat the distance traveled will be over three times that distance. The survey is completed in three segments, called legs; during the first leg of the survey we traveled 3448 nmi. A nautical mile is longer than a statute mile, 1 nmi is equivalent to 1.15 statute mile.

When we were surveying the waters around the Shumigan Islands we frequently encountered large schools of juvenile pollock, identified as age 1. I asked Patrick Ressler, the lead scientist on this leg, if this was a nursery area. Patrick indicated that the science team would need to go back and review the data collected on previous surveys to determine if there was sufficient evidence to make that determination. The high number of age 1 pollock is a good sign that the fish stocks are healthy.

In my “Gumbi Marla” blog I talked about NOAA’s Ship Tracker and the transects, or the course, the ship navigates during the survey. Surveys are completed during daylight hours, as the pollock behave differently at night, by changing the depth at which they swim. When the acoustics data show a school of pollock that the science team wants to fish the position is recorded and the science team communicates with the Dyson’s bridge officer about when they can safely return to the specific position to trawl the area. When the bridge crew is ready to leave the current transect they contact the science team, the science team then records the time and the exact position where the Dyson left transect. After the trawl is completed the Dyson returns to the exact position they left transect to continue the survey. During night time hours one of the scheduled tasks was to use the camera to review areas of the sea floor that had previously been deemed “untrawlable” as the seafloor was to rocky and would snag or tear the nets.

One type of gas that is trapped in Earth’s lithosphere is methane. Methane escapes the lithosphere under the seafloor through vents and along fault lines. The screen shot of the acoustics monitor shows vertical columns believed to be methane. One theory about the Bermuda Triangle is a massive release of methane that creates a massive bubble. When the bubble bursts objects in the immediate area are sucked into the momentary void created by the bubble, and swallowed by the sea.

Acoustic image of probable methane seepage.

Personal Log

Trees, there are trees on Kodiak! I saw trees for the first time in 18 days, and I realize that I have missed seeing trees. It’s interesting that the first three people I talk to as we approach the island of Kodiak all ask if I saw the trees. I guess I’m not the only one that has missed seeing trees. Sometimes the simplest observation makes the biggest impression.

Thank you to the crew of the Oscar Dyson and Science Team and to NOAA for giving me a phenomenal experience with the Teacher at Sea Program. Many students will benefit from my experiences. Pictured is the Science Team from Leg 1 of the Pacific Walleye Pollock Survey, from left to right: Lead Scientist Patrick Ressler, Taina Honkelehto, Kresimir Williams, Rick Towler, Abigail McCarthy, Marla Crouch (that’s me), behind me is Charles Andersen and Mike Gallagher.

There were so many great experiences; I hope you enjoy the video giving you glimpses into the science, technology, sights and the Oscar Dyson.

Thanks to everyone that made my experience possible!

June 25, 2013August 11, 2021

Marla Crouch: Pitch and Roll, June 24, 2013

NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8-26, 2013

Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: June 23, 2013

Weather Data from the Bridge: as of 2100
Wind Speed 6.30 kts
Air Temperature 11.7°C
Relative Humidity 73.00%
Barometric Pressure 1,004.20 mb

Latitude: 56.42N Longitude: 158.20W

Science and Technology Log

Who can tell me the direction longitudinal and transverse waves move? Think about the electromagnetic spectrum; what is the relationship between wavelength and frequency? The physics of these wave actions are experienced in fields other than earthquakes (seismic), and light (optics) and sound (audio).

Picture provided by NOAA NWS Prediction Center

There are two different types of water waves that mariners regularly encounter, wind waves and swell waves. An analogy for wind waves and swell is a wind wave is to weather as swell is to climate. In other words, wind waves are local and swell occurs over a great distance.

Waves are formed when repeated disturbances move through a medium, such as, air, earth and water. As the wind moves or blows across the open waters, energy is transferred from the friction of the moving air particles to the waters’ surface creating wind waves. The speed, and fetch (unchanged direction) of the wind, and the distance the wind has traveled unimpeded; influence the amplitude and frequency of the waves. As wind speed picks up so does the amplitude of the waves. Wind waves can be identified by their white caps. Wind waves have short wave lengths.

Graphic courtesy of Tammy Pelletier, WA State Dept. of Ecology http://www.vos.noaa.gov/MWL/apr_06/waves.shtml — Graphic courtesy of Tammy Pelletier, WA State Dept. of Ecology
http://www.vos.noaa.gov/MWL/apr_06/waves.shtml

Swells are a formation of long wavelength surface waves, which travel farther and faster than short wavelength wind waves. Swells can be formed by storms that occurred somewhere else in the ocean. For example, Tropical Storm Leepi formed off the China coast south of Japan, and was active June 17 – 19, 2013. The energy from Leepi’s 40 mph winds and rain radiates outward from the storm, like the ripples that form when you drop a rock in a puddle of water, creating swells. Swells can travel in a multitude of directions as they bounce off landmasses back into the open waters.

Wind waves and swells transfer energy to ships, such as the Oscar Dyson. The energy causes ships to pitch, roll and yaw.

Pitch, roll, and yaw are three dynamic ways crafts, such as airplanes and ships move in a fluid. In my “Surf your Berth” blog I used a teeter totter as an example of pitch. If you think about the way energy moves in waves, pitch is a longitudinal wave where the energy is moving front to back, so that the bow of the ship goes up and down. Roll is a transverse wave, the energy is moving side to side, rolling the ship from port to starboard (left to right). To describe yaw, think about sitting in a chair that swivels. Yaw is the swiveling action of you in the chair moving in the chair or a ship rotating around a vertical axis. Watch the horizon in the video to get an idea of what pitch looks like from the vantage point of the bridge of the Oscar Dyson.

If you turn your field of view 90°, so you are looking either port or starboard and see the same motion that is roll.

The officers of the Oscar Dyson work to navigate through both the wind and swell waves to give us the smoothest ride possible.

Personal Log

Recently we experienced sustained wind speeds between 30 and 40 kts. Needless to say, we were a pitchin and a rollin. Chiachi Island afforded us calmer seas, as we reached the lee (wind shadow) side of the island. I noticed something different in this last encounter with rough seas, instead hearing the water race past the hull, this time the water slammed into the side of the Oscar Dyson. The crashing transformed some of the wave’s kinetic energy into thunderous claps of sound…BAM!…BAM! What caused the difference, I’m not sure, maybe we were in a convergent zone, before reaching the lee, where wind and seas raced around the island creating a collision akin to clapping your hands together that buffeted the Dyson from both sides.

What do we do aboard ship to cope with the pitch and roll? We anchor ourselves. Chairs at our work stations, do not have casters and are tethered to the desk with a cord. The dressers in our berths have straps to keep the draws shut and the closet doors lock into their closed position.

On a ship the dining hall is called the Mess. Here the chairs are tethered to the floor.

June 23, 2013August 11, 2021

Marla Crouch: Cameras and the Shark, June 22, 2013

NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8-26, 2013

Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: June 22, 2013

Weather Data from the Bridge: as of 2000
Wind Speed 20.02 kts
Air Temperature 8.4°C
Relative Humidity 96.00%
Barometric Pressure 995.9 mb

Latitude: 55.86N Longitude: 159.17W

Science and Technology Log

Cam Trawl, Critter Cam, Drop Cam, Trigger Cam (dubbed “the contraption”), and a camera that will be used on Acoustic Vessel of Opportunity (AVO) project, are different camera systems scientists are testing and using on this leg of the pollock survey to help monitor the biology in the region. Each camera is designed for a specific application.

Cam Trawl is attached immediately before the codend of a survey midwater trawl net, and takes pictures of the fish swimming by. Cam Trawl allows scientists to look at what depth the fish were captured, and use this information to help identify specific fish echoes on the sonar graphs. In one of our trawls, we were able to see pictures of a female Salmon Shark entering the net. She was quickly measured and released.

Picture of a female Salmon Shark taken be the Cam Trawl camera. Picture provided by NOAA

Critter Cam is attached to the survey net on the Oscar Dyson and takes pictures of little critters, like krill and different types of plankton, that are too small to be captured in a trawl net.

Pictured from left to right. Macrozooplankton krill, ctenophores, small jellyfish, young of the year pollock, juvenile smelt — Pictured from left to right. Macrozooplankton krill, ctenophores, small jellyfish, young of the year pollock,
juvenile smelt. Pictures provided by NOAA.

The Drop Cam is a tethered stereo camera that is lowered to take pictures of the sea floor. This instrument is going through a series of sea trials on this cruise, where the lights, exposure, and battery life are all being tested and fine tuning adjustments are being completed. Battery life is a concern, as both the cameras and the lights require energy to operate, and the scientists want to maximize the amount of time data is being collected . In order to conserve energy a depth sensor trip switch was added that turns the system on at 15 m depth. This addition allows the camera to continually take 10 pictures a second for a longer time on the sea floor. After this cruise the Drop Cam heads west to help survey the coral reefs west of the Islands of Four Mountains were we started our pollock survey heading east. Yes, there is coral in the cold waters of the Gulf of Alaska and the Berring Sea.

Brittle stars. Picture provided by NOAA.

Trigger Cam, which the Dyson’s crew has dubbed “the contraption”, is attached to an anchor and lowered to the sea floor. The anchor we are using is a sablefish pot (a trap that is normally used to catch fish on the bottom), which has a buoy line attached, and the buoy marks the location of the camera on the surface. There are six Trigger Cams in development; the concept is that the cameras are deployed in a series a few nautical miles apart and left for 3 to 4 hours before retrieving. To conserve energy, this piece of equipment is designed with a motion sensor. An infared camera (fish cannot see infared light) runs at very low resolution (produces a blurry picture, as the water is in constant motion). When something, such as a school of Pacific cod, swims by, the motion is detected, camera flashes are triggered and a high resolution (clear) picture is taken. When the Trigger Cam system is fully operational, scientists hope to collect more in-depth evidence about the fish population in the deployment areas.

Deployment of the Trigger Cam. AKA The Contraption. Picture provided by NOAA.

School of Pacific Cod taken by Trigger Cam. Picture provided by NOAA.

The AVO Cam is designed to attach to a survey bottom trawl net and take picture of the fish passing through, without being caught. There are two cameras (stereo) mounted so that field of vision intersects at a specific distance. The two cameras and the point of intersection can be used in a process similar to triangulation that allows the length of the fish swimming through to be measured. The stereo photography process is the same technology that is used in the making of 3D movies. The AVO Cam will be used in a survey that is carried out onboard chartered commercial fishing vessels (“vessels of opportunity”).

Readying the AVO camera for sea testing.

The stereo camera data is input into measuring software, which calculates the length of the fish in cm. Screen shot provided by NOAA.

Personal Log

I enjoy listening to the various conversations that the scientists have about what they are seeing on the sonar displays and in the pictures, how the equipment is being used, when data are inconclusive the hypothesizing about the phenomena, and the time need to complete the different science studies. There is only so much time. Today’s conversation revolved around the need to hide from the weather!

An area of low air pressure is forecasted to kick up a gale force storm, and the safety of the ship, crew and science team is an important consideration in our travels. With this in mind, the Commanding Officer of the Oscar Dyson and the science team are looking for areas of safe harbor where we are sheltered from the worst of the storm and can still do science work. I wonder will we be on the lee side of an island, in a bay or fjord? Time will tell.

Did You Know?

To date we have traveled 2670.50 nmi since leaving Dutch harbor.

June 20, 2013August 11, 2021

Marla Crouch: Gumbi Marla and Setting Course, June 18, 2013

NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8-26, 2013

Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: June 18, 2013

Weather Data from the Bridge: as of 1900
Wind Speed 13.48 kts
Air Temperature 7.0°C
Relative Humidity 99.00%
Barometric Pressure 1,010.00.5 mb

Latitude: 54.31N Longitude: 159.80W

Science and Technology Log

Another fashion statement – Gumbi Marla

Here I am, all zipped up in my immersion suit.

I’ve donned an immersion suit, also known as a survival suit. One of the first things I did when I came aboard was to locate this suit and my life vest, two pieces of equipment that save lives. In the event we had to abandon ship, the survival suit would keep me both warm and afloat until rescue. During our evacuation drill we needed to unpack and get into the suit, and be completely zipped up in 60 seconds or less. Getting into the suit was much easier after I took my shoes off, as the soles caught on the fabric of the suit. The suit is made of neoprene, which was invented in 1930. SCUBA wetsuits are also made of neoprene, and even some laptop and tablet cases.

In an earlier blog I talked about the CTD being used to calibrate the sonar aboard the Oscar Dyson, but not all technologies on the Dyson are as high tech as the CTD and sonar equipment. In fact you can build a weather station at home that is similar to some of the equipment used by the Dyson’s crew. Below is a picture of a hygrometer. There are actually two hygrometers aboard, one is located on each side of the bridge. Hygrometers are used to measure relative humidity (how much moisture is in the air). Also pictured is the wind bird which shows the direction the wind is moving. The propeller was actually turning rapidly when the picture was taken. The camera was able to “stop” the action. The wind bird is mounted atop the jack staff, high above the bow.

Hygrometers are weather instruments used to measure relative humidity.

The following link shows you how to build six instruments for monitoring the weather.

http://oceanservice.noaa.gov/education/for_fun/BuildyourownWeatherStation.pdf

If you checked out the above link, how many snow days to you think the kids in North Dakota had?

Did you check out ship tracker? If you did, the screen shot below will look familiar. The blue lines in the water display the Dyson’s course. Each segment of the course is called a transect. Transects are numbered, enabling scientists to easily reference a location.

Oscar Dyson's course as of 6 18 13 — *Oscar Dyson*‘s course as of 6 18 13

Are you wondering why we have traveled in rectangular patterns? The scientists establish this course for a several reasons:

Transects run perpendicular to the coast line, covering a wide range of bathymetry over the shortest distance.
Regularly spaced transects (as opposed to randomly spaced or scattered) are correlated with historical data, and are the best way to describe the distribution of pollock.
The combination of transects collects sufficient data to allow scientists to estimate the overall size of the pollock population with a high degree of certainty.

Does anyone have an idea about the meaning of “bathymetry” and a “leg”? No, in this case a leg is not something you stand on. Bathymetry is the shape and depth of the ocean floor, and a bathymetry contour line on a chart connects points of equal depth (like a topographic map). A leg, in this context, is a segment of the overall distance covered in the survey.

The information collected during this year’s survey helps determine the number of pollock that can be caught in next year’s fishing season.

Here is the ship tracker link, you can check out the Dyson’s course and other NOAA ships as well.

http://shiptracker.noaa.gov/shiptracker.html

Personal Log

I want to revisit the sonar of Mystery Mix One. In my last blog I talked about what was happening near the surface of the ocean. This time I want to focus beneath the sea floor.

Look beneath the red, yellow, and green bands, depicting the sea floor, at the blue color, notice how the density of color changes over time. The density of the color tells scientists about the composition of the sea bed. The denser the color, the denser or harder the seafloor is likely to be; probably, the places with the dark, dense color are rocky areas, which attract the fish schools seen in the water above.

Looking at this graph reminds me of an experiment that my husband worked on, when he worked for Charles Stark Draper Labs, in Boston, MA. He worked on a Gravity Gradiometer that was sent to the moon on Apollo 17. The gradiometer measured the changes in gravity. The changes in gravitational strength give scientists information about what lays beneath the moon surface, like the sonar provides information about the sea bed. The Gravity Gradiometer was a very specialized version of equipment that is commonly used in prospecting for oil on Earth. I am sharing this story because, in class, one of our foci is to take what we know and apply the knowledge to a new scenario. Next question: Where will what we know now, take us in the future?

Did You Know?

Some fish can see color.

June 17, 2013August 11, 2021

Marla Crouch: The Mystery and Surf Your Berth, June 14, 2013

NOAA Teacher at Sea
Marla Crouch
Aboard NOAA Ship Oscar Dyson
June 8 – 26, 2013

Mission: Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: June 14, 2013

Weather Data from the Bridge: as of 1900
Wind Speed 9.57 kts
Air Temperature 6.84°C
Relative Humidity 81.00%
Barometric Pressure 1,030.5 mb

Latitude: 53.52N Longitude: 166.34W

Science and Technology Log

The sonar on the Oscar Dyson recently created the graph below. The graph displays the sea floor, the red, yellow, and green bands toward the bottom and along the top a few meters from the surface the layer of green and red, is the mystery.

The echoes, that create the graph do not look like fish. The scientists recognize that something is there, the questions is, what? Further exploration is done, but nothing definitive is found. This creates a bit of a dilemma, which initiates a whole series of conversations about trouble shooting the equipment, using different data gathering techniques (something different than a trawl), and hypothesizing about what is creating the image since there are no apparent biology. Could the image be created by something physical in the water? Until the make-up of the image can be identified the sonar signature, is titled and recorded as Mystery Mix One.

Taina Honkalehto, one of the scientists on this cruise, tells me that they have been encountering Mystery Mix One for a number of years here, in the Gulf of Alaska, and in different parts of the ocean at different times of the year. Mystery Mixes Two and Three are floating around as well.

Investigating Mystery Mix One: Time stamp 12 June 2013, 050952 GMT (This time stamp equates to 8:09 almost 8:10 p.m. June 11, 2013 PDT.)

The stereo camera, which I talked about in my last blog, is a new piece of equipment that scientists are using to collect data about the ocean floor and the biology of the region. The stereo camera was launched and submerged to a depth of 50m into the middle of Mystery Mix One, and left at that depth for 30 minutes while the Oscar Dyson drifted with the mix. When the pictures were downloaded, the only identifiable objects were copepods, big copepods. Remember “big” is a relative term, big compared to what? Copepods can be smaller than 1 mm in length. These big copepods are probably 6 to 8 mm.

The light image in the upper left-hand corner is a copepod. Picture provided by NOAA

This is a clearer picture of a copepod. This is a clearer picture of a copepod. Picture courtesy of comenius.susqu.edu — This is a clearer picture of a copepod.
Picture courtesy of comenius.susqu.edu

The strong sonar image created by the copepods heighten the mystery; starting another round of questions and discussions by the scientists. Why are copepods creating such a strong sonar signature? Why are the copepods so prominent on 18 kHz? (18 kHz is a low frequency that usually captures echoes from large objects, while small things like copepods would be seen at higher frequencies, like 200 kHz.) Could something else be in Mystery Mix One, something that was not seen by the camera? The discussion goes on creating a working hypothesis; the signature is being created by a combination of the copepods themselves, whatever they are feeding on and gases, being produced. Not all the scientists are in agreement. If Mystery Mix One was to be sampled again, would you get similar results?

Pictures from the stereo camera provided one piece of possible evidence that may lead to answering the question, “What is in Mystery Mix One?”

The next day another piece of possible evidence is added. Oscar Dyson’s sea water intake filter is cleaned and what is found? Krill and big copepods. Pictures are taken and the evidence is recorded in the scientists’ journal. More evidence needs to be collected, but advances are being made to identify Mystery Mix One.

Krill are in the red ringed filter. Copepods can be seen at the bottom of the bucket.

Personal Log

The first few days out at sea the waters were really calm, 1 to 3 foot swells or seas, which feels like the soothing glide of a rocking chair. Now however, weather is moving in; wind speed is up around 15kts and the swells are about 9 ft. Friday’s forecast is for 30kt winds and 12ft. seas. Looking at the big picture, 9 to 12 foot seas are not very big. But, walking around the ship with seas of that height requires due diligent to safely navigate the passage ways and steep stairs. And you definitely need to mind the doors, make sure the door is securely latched and when opening hold on tight, as you don’t want the door to get away from you. Somebody might be standing on the other side. Another activity that can prove challenging is getting into and out of your bunk.

The berths, or rooms, aboard ship are, for the most part, designed for two people. Look at the picture of my berth. You can see a desk, chair, dresser and two draped bunk beds. Mine’s the top bunk. Our room is just about even with the water line. That is important to know, because the lower you are in the ship the less dramatic the motion. I’ll talk about the pitch and roll of the ship in a future blog

Now imagine yourself lying on a teeter totter. You are right above the fulcrum, so you are nice and level. An unbalanced force is now affecting your teeter totter, your feet go up your head goes down and you slide a little. Then there is a change and you head goes up your feet go down and you slide back. This back and forth motion is continuous, and the motion presses you into the teeter totter. I call this the sloshing phenomena, because all the while you are teeter tottering you hear the sea water rushing pass the hull. But wait, there is more. Your teeter totter only moves in two dimensions, but we live in three dimensions. Keep your teeter totter going, up and down, hear the water stream by and add a sideways roll, back and forth. Don’t fall off your teeter totter. You are not quite ready to surf your berth yet, sometimes the up and down, and side to side movements occur so quickly that you actually loose contact with your teeter totter. Now you’re surfing! I have yet to find the seat belt for my bunk.

Remember I said that my berth was low in the ship, there are only a few berths on this level, and more berths are two and three floors above me. Now think about a metronome. If you’re not sure what a metronome is think about a windshield wiper on a car. Both the metronome and the windshield wiper make small movements at the pivot point or fulcrum; the further away from the fulcrum the greater the range of motion. Think about how the motion is magnified as you move up from the water line. Those folks above me are really surfing.

Did You Know?

When Taina and I were talking about Mystery Mix One she said the 18 kHz frequency ensonifying the larger fish. I think ensonify is a cool word. I wonder if Mrs. Sunmark or Mrs. Delpez (our school’s band and orchestra teachers) have used the word ensonify in their classes? Can any of you tell me what ensonify means?

Did you know you can follow my voyage on NOAA’s ship tracker website? Here is the link.

http://shiptracker.noaa.gov/shiptracker.html

In my next blog, I have another fashion statement – Gumbi Marla! And maybe something about the moon and Apollo 17.