Gregory Cook, The Dance, August 7, 2014

NOAA Teacher at Sea

Gregory Cook

Aboard NOAA Ship Oscar Dyson

July 26 – August 13, 2014

Mission: Annual Walleye Pollock Survey

Geographical Area: Bering Sea

Date: August 7, 2014

Science and Technology Log: Abiotic Factors in the Bering Sea

Ecosystems are made up of biotic and abiotic factors. Biotic is just another word for “stuff that is, or was, alive.” In a forest, that would include everything from Owl to Oak Tree, from bear to bacteria, and from fish to fungi. It includes anything alive, or, for that matter, dead. Keep in mind that “dead” is not the same as “non-living.”

Salmon and Black-Legged Kittiwake

The salmon and the black-legged kittiwake are both biotic members of the sub-arctic ecosystem.

“Non-living” describes things that are not, cannot, and never will be “alive.” These things are referred to as “abiotic.” (The prefix a- basically means the same as non-). Rocks, water, wind, sunlight and temperature are all considered abiotic factors. And while the most obvious threat to a salmon swimming up river might be the slash of a bear’s mighty claw, warm water could be even more deadly. Warm water carries less dissolved oxygen for the fish to absorb through their gills. This means that a power plant or factory that releases warm water into a river could actually cause fish to suffocate and, well, drown.

Bering Panorama

A 90 degree panorama of the Bering Sea from atop the Oscar Dyson. I’d show you the other 270°, but it’s pretty much the same. The sea and sky are abiotic parts of the sub-arctic ecosystem.

Fish in the Bering Sea have the same kind of challenges. Like Goldilocks, Pollock are always looking for sea water that is just right. The Oscar Dyson has the tools for testing all sorts of Abiotic factors. This is the Conductivity Temperature Depth sensor (Also known as the CTD).

CTD Deployment

Survey Technicians Allen and Bill teach me how to launch The Conductivity Temperature Depth Probe (or CTD).

The CTD sends signals up to computers in the cave to explain all sorts of abiotic conditions in the water column. It can measure how salty the water is by testing how well the water conducts electricity. It can tell you how cloudy, or turbid, the water is with a turbidity sensor. It can even tell you things like the amount of oxygen dissolved in the ocean.

To see how abiotic factors drive biotic factors, take a look at this.

Thermocline

The graph above is depth-oriented. The further down you go on the graph, the deeper in the water column you are. The blue line represents temperature. Does the temperature stay constant? Where does it change?

I know, you may want to turn the graph above on its side… but don’t. You’ll notice that depth is on the y-axis (left). That means that the further down you are on the graph, the deeper in the sea you are. The blue line represents the water temperature at that depth. Where do you see the temperature drop?


Right… The temperature drops rapidly between about 20 and 35 meters. This part of the water column is called the Thermocline, and you’ll find it in much of the world’s oceans. It’s essentially where the temperature between surface waters (which are heated by the sun) and the deeper waters (typically dark and cold) mix together.

OK, so you’re like “great. So what? Water gets colder. Big deal… let’s throw a parade for science.”

Well, look at the graph to the right. It was made from another kind of data recorded by the CTD.

Fluoresence

Fluoresence: Another depth-oriented graph from the CTD… the green line effectively shows us the amount of phytoplankton in the water column, based on depth.

The green line represents the amount of fluorescence. Fluorescence is a marker of phytoplankton. Phytoplankton are plant-like protists… the great producers of the sea! The more fluorescence, the more phytoplankton you have. Phytoplankton love to live right at the bottom of the thermocline. It gives them the best of both worlds: sunlight from above and nutrients from the bottom of the sea, which so many animals call home.

Now, if you’re a fish… especially a vegetarian fish, you just said: “Dinner? I’m listening…” But there’s an added bonus.

Look at this:

CTD Oxygen

Oxygen data from the CTD! This shows where the most dissolved oxygen is in the water column, based on depth. Notice any connections to the other graphs?

That orange line represents the amount of oxygen dissolved in the water. How does that compare to the other graphs?

Yup! The phytoplankton is hanging down there at the bottom of the thermocline cranking out oxygen! What a fine place to be a fish! Dinner and plenty of fresh air to breathe! So here, the abiotic (the temperature) drives the biotic (phytoplankton) which then drives the abiotic again (oxygen). This dance between biotic and abiotic plays out throughout earth’s ecosystems.

Another major abiotic factor is the depth of the ocean floor. Deep areas, also known as abyss, or abyssal plains, have food sources that are so far below the surface that phytoplankton can’t take advantage of the ground nutrients. Bad for phytoplankton is, of course, bad for fish. Look at this:

The Cliff and the Cod

The blue cloud represents a last grouping of fish as the continental shelf drops into the deep. Dr. Mikhail examines a cod.

That sloping red line is the profile (side view of the shape of the land) of the ocean floor. Those blue dots on the slope are fish. As Dr. Mikhail Stepanenko, a visiting Pollock specialist from Vladivostok, Russia, puts it, “after this… no more Pollock. It’s too deep.”

He goes on to show me how Pollock in the Bering Sea are only found on the continental shelf between the Aleutian Islands and Northeastern Russia. Young Pollock start their lives down near the Aleutians to the southeast, then migrate Northwest towards Russia, where lots of food is waiting for them.

Pollock Distribution

Alaskan Pollock avoid the deep! Purple line represents the ocean floor right before it drops off into the Aleutian Basin… a very deep place!

The purple line drawn in represents the drop-off you saw above… right before the deep zone. Pollock tend to stay in the shallow areas above it… where the eating is good!

Once again, the dance between the abiotic and the biotic create an ecosystem. Over the abyss, Phytoplankton can’t take advantage of nutrients from the deep, and fish can’t take advantage of the phytoplankton. Nonliving aspects have a MASSIVE impact on all the organisms in an ecosystem.

Next time we explore the Biotic side of things… the Sub-arctic food web!

Personal Log: The Order of the Monkey’s Fist.

Sweet William, a retired police officer turned ship’s engineer, tells the story of the order of the monkey’s fist.

William and the Monkey's Fist

Sweet William the Engineer shows off a monkey’s fist

The story goes that some island came up with a clever way to catch monkeys. They’d place a piece of fruit in a jar just barely big enough for the fruit to fit through and then leave the jar out for the monkeys. When a monkey saw it, they’d reach their hand in to grab the fruit, but couldn’t pull it out because their hands were too big now that they had the fruit in it. The monkey, so attached to the idea of an “easy” meal wouldn’t let go, making them easy pickings for the islanders. The Monkey’s Fist became a symbol for how clinging to our desires for some things can, in the end, do more harm than good. That sometimes letting go of something we want so badly is, in the end, what can grant us relief.

Another story of the origin of the monkey’s fist goes like this: A sea captain saw a sailor on the beach sharing his meal with a monkey. Without skipping a beat, the monkey went into the jungle and brought the sailor some of HIS meal… a piece of fruit.

No man is an Island. Mt. Ballyhoo, Unalaska, AK

No man is an Island. Mt. Ballyhoo, Unalaska, AK

Whatever the true origin of the Order is, the message is the same. Generosity beats selfishness at sea. It’s often better to let go of your own interests, sometimes, and think of someone else’s. Onboard the Oscar Dyson, when we see someone committing an act of kindness, we put their name in a box. Every now and then they pull a name from the box, and that person wins something at the ship store… a hat or a t-shirt or what have you. Of course, that’s not the point. The point is that NOAA sailors… scientists, corps, and crew… have each other’s backs. They look out for each other in a place where all they really have IS each other.

And that’s a beautiful thing.

Frank Hubacz: ADCP Deployment, May 2, 2013

NOAA Teacher at Sea
Frank Hubacz
Aboard NOAA ship Oscar Dyson
April 29 – May 10, 2013

 

Mission: Pacific Marine Environmental Laboratory Mooring Deployment and Recovery
Geographical Area of Cruise: Gulf of Alaska and the Bering Sea
Date: May 2, 2013

Weather Data from the Bridge:

Partly sunny, WindsN 5-10 knots
Air Temperature 1.3C

Relative Humidity 60%

Barometer 1008.2 mb

Surface Water Temperature 2.8C

Surface Water Salinity 31.37 PSU

Science and Technology Log

As I described previously, one of the instruments being deployed on this cruise is an Acoustic Doppler Current Profiler (ADCP), which measures speed and direction of ocean currents across an entire water column using the principle of Doppler shift (effect).  The Doppler Effect is best illustrated when you stop and listen to the whistle of an oncoming train.  When the train is traveling towards you, the whistle’s pitch is higher. When it is moving away from you, the pitch is lower. The change in pitch is proportional to the speed of the train.  The diagrams below illustrates the effect.

Doppler Effect

Doppler Effect

Another view of the Doppler Effect
Another view of the Doppler Effect

The ADCP exploits the Doppler Effect by emitting a sequence of high frequency pulses of sound (“pings”) that scatter off of moving particles in the water. Depending on whether the particles are moving toward or away from the sound source, the frequency of the return signal bounced back to the ADCP is either higher or lower. Since the particles move at the same speed as the water that carries them, the frequency shift is proportional to the speed of the water, or current.

The ADCP has 4 acoustic transducers that emit and receive acoustical pulses from 4 different directions. Current direction is computed by using trigonometric relations to convert the return signal from the 4 transducers to ‘earth’ coordinates (north-south, east-west and up-down. (http://oceanexplorer.noaa.gov/technology/tools/acoust_doppler/acoust_doppler.html).  The most common frequencies used on these units are 600 KHz, 300 KHz, and 75 KHz.  The lower the frequency the greater the distance that the wave can propagate through the ocean waters.

Determining current flow helps scientist to understand how nutrients and other chemical species are transported throughout the ocean.

Typical 4 beam ADCP sensor head. The red circles denote the 4 transducer faces.

Typical 4 beam ADCP sensor head. The red circles denote the 4 transducer faces.

Prior to sailing, ADCP mooring locations are selected by various research scientists from within NOAA.  Next, engineers develop a construction plan to secure the unit onto the ocean floor.  Once designed, the hardware needed to construct the mooring is sent to the ship that will be sailing in the selected mooring locations.  Prior to arriving at the designated location it is the responsibility of the science team to construct the mooring setup following the engineering diagram shipped with each ADCP unit. ADCP moorings can be constructed to hold a wide variety of measuring instruments depending upon the ocean parameters under study by the research scientist.

ADCP Construction Diagram

ADCP Construction Diagram

The moorings are built on the ship’s deck starting with an anchor.  The anchor weight is determined based upon known current strength in the area where the mooring will be located.  Anchors are simply scrap iron railroad train car wheels which bury themselves into the sediment and eventually rust away after use.  The first mooring unit that we assembled had an anchor composed of two train wheels with a total weight of 1,600lbs.  Although this mooring was built from the anchor up this is not always the case.  When setting very deep moorings the build is in the reverse order.

Selecting the anchor

Selecting the anchor

Anchor on the back deck

Anchor on the back deck below the gantry

Next, an acoustic release mechanism is attached to the anchor by way of heavy chains.  This mechanism allows for recovery of the ADCP unit as well as the release mechanism itself when it is time to recover the ADCP.  The units that we are deploying will remain submerged and collect data for approximately 6 months.

Acostic Release Mechanism
Acoustic Release Mechanism
Bill attaching the acoustic release mechanism

Bill attaching the acoustic release mechanism

Finally, an orange closed-cell foam and stainless steel frame containing the actual instrumentation is connected to the assembly and then craned over the back deck.  The stainless steel frame has a block of zinc attached to it which acts as a sacrificial anode.  Sacrificial anodes are highly active metals (such as zinc) that are used to prevent a less active metal surface from rusting or corroding away.  In fact, our ship has many such anodes located on its hull. Once the entire unit is in position, a pin connected to a long chord is pulled from a release mechanism and the unit is dropped to the ocean floor.  Date, time, and location for each unit are then recorded. 

Hoisting ADCP

Hoisting ADCP

ADCP unit assembly

ADCP unit assembly

Assembling mooring unit

Assembling mooring unit

Ready for launch

Ready for launch

To recover the unit, an acoustic signal (9-12 Khz) is sent to the ship from the sunken mooring unit to aid in its location.  Once located, a signal is used to activate a remote sensor which powers the release mechanism to open.  The float unit then rises to the surface bringing all of its attached instruments along with it.  The stored data within the units are then secured and eventually sent along to the research scientist requesting that specific mooring location for ocean current analysis.

Recovering a mooring with a rope lasso

Recovering a mooring with a rope lasso

Personal Log

On my first day of “work” I was able to watch the science teams deploy three different ADCP moorings as well as conduct several CTD runs.  I will discuss CTD’s in more detail in future blogs.  I was impressed by the camaraderie among all of the science team members regardless of the institution that they represented as well as with members of the deck crew.  They all work as a very cohesive and efficient group and certainly understand the importance of teamwork!

Adjusting to my new work schedule is a bit of a challenge. After my work day ended today at 1200 hours, I fell asleep around 1500 hours for about 4 hours.  After trying to fall back asleep again, but to no avail, I decided to have a “midnight” snack at 2000 hours (8pm).  I finally fell asleep for about 2 more hours before showering for my next shift.  I think I now have more empathy for students who come to my 8am chemistry class and occasionally “nap”!

A wide selection of food is always available in the ship’s galley. I have discovered that I am not the only one taking advantage of this “benefit”!  I will definitely need to reestablish an exercise routine when I return home.  We are currently heading for Unimak Pass which is a wide strait between the Bering Sea and the North Pacific Ocean southwest of Unimak Island in the Aleutian Islands of Alaska.

Did you know that since the island chain crosses longitude 180°, the Aleutian Islands contain both the westernmost and easternmost points in the United States. (172° E and 163° W)!

180 longitude

Tammy Orilio, My First Pollock Trawl, June 20, 2011

NOAA Teacher at Sea: Tammy Orilio
NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: 20 June 2011
Weather Data from the Bridge:
Latitude: 54.29 N
Longitude: -165.13 W
Wind Speed: 12.31 knots
Surface Water Temp: 5.5 degrees C
Water Depth: 140.99 m
Air Temp: 6.1 degrees C
Relative Humidity: 97%

Science & Technology Log: walleye pollock, which is an important fish species here in Alaska. Walleye pollock make up 56.3% of the groundfish catch in Alaska (http://www.afsc.noaa.gov/species/pollock.php), and chances are you’ve eaten it before.  It’s a commonly used fish in all of the fast food restaurants, in fish sticks, and it’s also used to make imitation crab meat.

Our first catch had a little over 300 walleye pollock, and we processed all of them. Three hundred is an ideal sample size for this species. If, for example, we had caught 2,000 pollock, we would only have processed 300 of the fish, and we would have released the rest of them back into the ocean.  Check out the photos/captions below to see how we process the catch.

Conveyer belt

Gender Box

Length Station

After sexing, we then measured the length of each fish. There’s a ruler embedded in the lab table, and we laid each fish down on the ruler. Then we put a hand-held sensor at the caudal (tail) fin of the fish, and the total length was recorded on a computer.

At the sexing station, cutting open pollack.

At the sexing station, cutting open pollack.

We also removed and preserved 20 stomachs from randomly selected fish in order to (later) analyze what they had been eating prior to them being caught. One of the last things we do is collect otoliths from each of those 20 fish. Otoliths are ear bones, and they are used to determine the age of a fish- they have rings, similar to what you see in trees.

Here’s a look at some of the bycatch in our nets:

Basket Star.  Marine 1: What phylum are sea stars in?

Basket Star. Marine 1: What phylum are sea stars in?

Arrowtooth flounder.

Arrowtooth flounder.

The reason(s) WHY they're called ARROWTOOTH flounder.

The reason(s) WHY they’re called ARROWTOOTH flounder.

Animals Spotted:
walleye pollock
chum salmon
rockfish
arrowtooth flounder
squid
basket star
Northern Fulmars
Gulls
Albatross (couldn’t tell what kind)
* I did spot some kind of pinniped yesterday, but have no idea what exactly it was!

Personal Log:
I was very excited that we finally got to fish today!!  As an added bonus, we caught 2 salmon in the trawl, which means we’re having salmon for dinner tonight!  We we supposed the have teriyaki steak, but the cook has changed it to teriyaki salmon instead 🙂  I didn’t get any pics of them because my gloves were covered in fish scales, blood, and guts by that point and I didn’t want to get any of that funk on my camera 🙂
We passed by Dutch Harbor yesterday- it should sound familiar if you watch Deadliest Catch.  We didn’t go into the Harbor, so no, I didn’t see any of the crab boats or any of the guys from the show!  Below are some pics of the Aleutian Islands that I’ve see thus far…many more to come, since we still have another 13 days (give or take) of sailing left!

QUESTION(S) OF THE DAY:

  • The Aleutian Islands were formed at the boundary where the North American and Pacific Plates are coming together.  The Pacific Plate is denser than the North American Plate, so it slides underneath the North American Plate.  What is this type of plate boundary called (where plates move towards each other), and what is it called when one plate slides underneath another?
  • One thing we’re doing on this trip is trawling for fish.  We are conducting both mid-water and bottom trawls.  Describe one advantage and one disadvantage to trawling in order to gather scientific data.

Richard Chewning, June 10, 2010

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

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

Weather Data from the Bridge

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

Science and Technology Log

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

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

Liz and Paula: an office with a view

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

Black-footed albatross

Northern fulmar

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

Shearwaters

Shearwaters

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

Personal Log

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

There be whales here!

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

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

Viewing humpback whales equals a Kodak moment!

New Word of the Day – Bearing

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

Blue sky and blue water

Sunrise over the Aleutians

Katie Turner, July 18, 2008

NOAA Teacher at Sea
Katie Turner
Onboard NOAA Ship Miller Freeman
July 10 – 31, 2008

Mission: Pollock Survey
Geographical Area: Eastern Bering Sea
Date: July 18, 2008

The ship

The ship

Science and Technology Log 

Where is the Bering Sea?

Where is the Bering Sea?

The Vessel 

NOAA Ship MILLER FREEMAN is a 215 foot fishery and oceanographic research vessel, and one of the largest research trawlers in the United States.  She carries up to 34 officers and crew members and 11 scientists.  The ship is designed to work in extreme environmental conditions, and is considered the hardest working ship in the fleet.

She was launched in 1967 and her home port is Seattle, Washington. MILLER FREEMAN has traditionally been used to survey walleye pollock (Theragra chalcogramma) in the Bering Sea.  These surveys are used to determine catch limits for commercial fisherman.  In 2003 NOAA acquired a new fisheries research vessel, the NOAA Ship OSCAR DYSON. OSCAR DYSON is to eventually take over MILLER FREEMAN’s research in Alaskan working grounds, allowing MILLER FREEMAN to shift her focus to the west coast. OSCAR DYSON was built under a new set of standards set by the International Council for the Exploration of the Sea (ICES), which reduces the amount of noise generated into the water below, while MILLER FREEMAN is a more conventionally-built vessel which does not meet the ICES standards.  The assumption is that marine organisms, including pollock, may avoid large ships because of the noise they make, thus altering population estimates.  It is therefore important for scientists to know the difference between population estimates of the two ships. This is done through vessel comparison experiments, in which the two ships sample fish populations side by side and compare their data.  The primary purpose of this July 2008 cruise is to complete a final comparison study of the two ships and measure the difference in the pollock population data they collect.  

Image of the eruption of Okmok, taken Sunday, July 13, 2008, by flight attendant Kelly Reeves during Alaska Airlines flights 160 and 161.

Image of the eruption of Okmok, taken Sunday, July 13, 2008,
by flight attendant Kelly Reeves during Alaska Airlines
flights 160 and 161.

The Location 

The Bering Sea covers an area of 2.6 million square kilometers, about the size of the United States west of the Mississippi.  The maximum distance north to south is about 1,500 kilometers (900 miles), and east to west is about 2,000 kilometers (1,500 miles).  The International Date Line splits the sea in two, with one half in today and the other in tomorrow. The area is also bisected by a border separating the Exclusive Economic Zones (EEZ) of Russia and the United States. The EEZ is the area within a 200 mile limit from a nation’s shoreline; where that nation has control over the resources, economic activity, and environmental protection. More than 50% of the U.S. and Russian fish catch comes from the Bering Sea. It is one of the most productive ecosystems in the world.  The broad continental shelf, extensive ice cover during the winter, and the convergence of nutrient-rich currents all contribute to its high productivity. It is a seasonal or year round home to some of the largest populations of marine mammals, fish, birds, and invertebrates found in any of the world’s oceans.  Commercial harvests of seafood include pollock, other groundfish, salmon and crab.  The Bering Sea has provided subsistence resources such as food and clothing to coastal communities for centuries.

Aleutian Island volcaneos

Aleutian Island volcaneos

Repairs and Delays 

Anchorage high school teacher, Katie Turner, arrives at the pier in Dutch Harbor, Alaska

Anchorage high school teacher, Katie Turner,
arrives at the pier in Dutch Harbor, Alaska

While all aboard were anxious to begin this Bering Sea Cruise, the ship could not sail until crucial repairs could be made.  During the previous cruise a leak was discovered in the engine cooling system that brought the ship in from that cruise early.  The location of the leak was the big mystery.  After days of testing and a hull inspection by divers the leak was located.  It was in a section of pipe that runs hot water from the engine through the ship’s ballast tanks and into a keel cooler on the outside of the ship’s hull, where it is cooled before circulating back to the engine. This turned out to be a very labor intensive job and workers spent days draining and cleaning the tanks before the leak could be repaired.

In the meantime, a repair to one of the engine’s cylinders required a part that had to be shipped from Seattle via Anchorage (about 800 miles northeast of Dutch Harbor). To complicate the arrival of this part, a nearby volcano erupted, spewing ash 50,000 feet into the path of flights to and from Dutch Harbor.   Alaska has many active volcanoes. The Aleutian Island arc, which forms the southern margin of the Bering sea, comprises one of the most active parts of the Pacific’s “ring of fire”. This tectonically active area has formed due to the subduction of the Pacific plate beneath the North American plate. So far we do not have a definite departure schedule.  Each day spent at the dock is one day less for the scientific team to complete the goals of the cruise.  Meanwhile, OSCAR DYSON is completing its survey in the Bering Sea, and anticipates the arrival of MILLER FREEMAN to complete the comparison study.

NOAA Teacher at Sea, Katie Turner, gets a tour of the bridge and quick navigation lesson from Ensign Otto Brown

NOAA TAS, Katie Turner, gets a tour of the bridge and quick navigation lesson from Ensign Otto Brown

Personal Log 

I arrived in Dutch Harbor on July 9th with a forewarning that repairs to the ship would be necessary before heading out to the Bering Sea, and that I would have some time to explore the area. I have managed to keep busy and take advantage of opportunities to interview the crew, hike, and find my way around town. The weather in Dutch Harbor has been exceptional with many sunny days. It’s uncommon for a NOAA research ship to spend so much time at the dock, and we attracted the attention of a newsperson from the local public radio station. Commanding Officer Mike Hopkins and Chief Scientist Patrick Ressler were interviewed by KIAL newsperson Anne Hillman while MILLER FREEMAN was delayed for repairs in Dutch Harbor. Unalaska Island has few trees and along with other islands on the Aleutian chain is known for its cool and windy weather. There are no large mammals such as bear on the islands but small mammals, such as this marmot, are common along with many species of birds and a wide variety of wildflowers, which are in bloom this time of year.

Chief Scientist Patrick Ressler explains how he uses acoustic equipment to study pollock in the Bering Sea.

Chief Scientist Patrick Ressler explains how he uses acoustic equipment to study pollock in the Bering Sea.

A marmot spotted on a ridge alongside the road up Mt. Ballyhoo on Amaknak Island

A marmot spotted on a ridge alongside the road up Mt. Ballyhoo on Amaknak Island

A Bald Eagle guards the crab pots stored near the pier

A Bald Eagle guards the crab pots stored near the pier

The view from Mt. Ballyhoo on Amaknak Island. Lupine, a common plant found on the island, is in bloom in the foreground

The view from Mt. Ballyhoo on Amaknak Island. Lupine, a common plant found on the island, is in bloom in
the foreground

Black Oystercatchers take flight over the harbor

Black Oystercatchers take flight over the harbor

Learn more about the Bering Sea ecosystem at these Web sites: 

http://www.avo.alaska.edu/volcanoes/aleutians.php http://www.worldwildlife.org/what/wherewework/beringsea/index.html http://www.nature.org/wherewework/northamerica/states/alaska/preserves/art19556.html http://www.panda.org/about_wwf/where_we_work/europe/what_we_do/arctic/what_we_do/marine/bering/index.cfm

Rebecca Himschoot, July 8, 2007

NOAA Teacher at Sea
Rebecca Himschoot
Onboard NOAA Ship Oscar Dyson
June 21 – July 10, 2007

Mission: Summer Pollock Survey
Geographical Area: North Pacific Ocean, Unalaska
Date: July 8, 2007

Weather Data from Bridge 
Visibility: 10 nm (nautical miles)
Wind direction: 346° (NNW)
Wind speed:  light
Sea wave height: less than 1foot
Swell wave height: less than 1 foot
Seawater temperature: 8.8°C
Sea level pressure: 1019.4 mb (millibars)
Cloud cover: stratus

NOAA ship OSCAR DYSON

NOAA ship OSCAR DYSON

Science and Technology Log: Who was Oscar Dyson? 

The 206-foot OSCAR DYSON is one of the newest ships in NOAA’s fleet, and was commissioned in 2005.  The OSCAR DYSON is home ported in Kodiak, Alaska, and sails primarily in the Gulf of Alaska, the Aleutian Islands, and the Bering Sea, researching fish stocks, marine mammals, and seabirds, observing weather, sea and environmental conditions, and conducting habitat assessments.

The ship is a stern trawler, and is outfitted with two trawl nets, among others, to support the annual fish surveys and biological assessments that are conducted in support of commercial fisheries, primarily pollock.  The OSCAR DYSON is outfitted with a Scientific Sonar System, which can accurately measure the biomass of fish in the survey area. Trawling is used to collect specific biological data, such as length, weight, and gender of the sample.  Weather, sea and environmental data are also collected continuously using hundreds of sensors on board, such as the Acoustic Doppler Current Profiler (ADCP), which measures ocean currents. The OSCAR DYSON can also assist in maintaining and deploying stationary buoys to collect similar information for a specific area at depth over time.  

In support of the science mission of the OSCAR DYSON, the ship has been built to minimize sound.  By decreasing the hull noise, scientists are better able to observe fish without disturbing their natural behavior.  Another special feature of the OSCAR DYSON is a retractable centerboard that carries many of the sensors used in scientific studies. By lowering the sensors over 10 feet below the hull, the acoustic data collected by the scientists is less affected by the ship’s noise.  When retracted, the scientists and crew aboard the OSCAR DYSON are able to access the sensors for maintenance and replacement as needed.

Oscar Dyson

Oscar Dyson

The ship’s namesake, Oscar Dyson, was an innovative leader in fisheries in Kodiak. He came to Alaska in 1940, where he worked for the Army Corps of Engineers to build infrastructure in Southwest Alaska.  Immediately after the war he began fishing out of Kodiak. He fished crab and shrimp, and was a leader in the development of the pollock fishery. Dyson also was a founding partner in All Alaskan Seafoods, the first company controlled by fishermen who owned both the vessels and the processing plants. Oscar Dyson served on the North Pacific Fisheries Management Council for nine years, and fished until his untimely death in 1995. In an interview with the Kodiak Daily Mirror in 1981, Dyson commented, “You’ve got to love the water first, or you’ll never make it.”

Personal Log 

My leg of the summer Pollock survey is drawing to a close, and we have ended with some different kinds of trawls.  We’ve collected jellyfish and plankton, and we’re still hoping to trawl using a special net that opens and closes, enabling the scientists to target multiple sets of fish at multiple depths in one cast.  We’re ending with much improved weather, which has been a welcome change for everyone.

The crew of the OSCAR DYSON has made this experience particularly memorable, with scientists explaining their work in detail and crewmembers sharing their knowledge willingly. I’ve toured the engine room, spent time on the bridge, eaten once-in-a-lifetime meals, talked commercial fishing with the deckhands and even learned to tie some knots and splice lines with their help. It has been an amazing learning experience!

Barney Peterson, August 21, 2006

NOAA Teacher at Sea
Barney Peterson
Onboard NOAA Ship Rainier
August 12 – September 1, 2006

Mission: Hydrographic Survey
Geographical Area: Shumagin Islands, Alaska
Date: August 21, 2006

Weather Data from Bridge 
Visibility: 10 n.m.
Wind direction:  light airs*
Wind speed:  light airs*
Seawater temperature: 11.1˚C
Sea level pressure: 1012.0
Cloud cover: cloudy

* “light airs” means there is little or no wind

Science and Technology Log 

I have now been out on the survey boats twice and am scheduled to go out again this afternoon. Each survey boat is set up a little differently and some work better in shallower depths than others. They use the same basic systems to create profiles of the ocean bottom.  The survey technicians and NOAA Corps officers have been great at explaining how their equipment works. On the hull (bottom) of each survey boat is a transducer, a device that sends and receives pulses of sound waves. As the sound waves strike the seabed they bounce back to the receiver. Those that come back soonest are those that bounce off objects closest to the sonar device.

However, as the sound waves are transmitted straight down into the water, they spread out from the transducer in a cone shape.  This means that waves on the outer edges of the cone normally travel farther before returning than do the ones that go straight down.  The waves that come back to the receiver first show the tops of objects that are closer to the boat. This works fine for objects straight down, but remember, the waves that are on the outside of the cone travel a little farther and take a little longer to reach things.  That means that they may strike against the tops of higher objects, but they will still take a little longer to return than echoes from objects of the same height that are directly under the receiver.

This is where the sophisticated software comes into translating the echoes that the transducer receives. When the survey boats begin work, and every four to six hours after that, the crew uses a device called a CTD to read the temperature and conductivity of the water all the way to the seabed under the boat.  Both temperature and chemical make-up of the water affect how fast sound waves can travel through it.  Knowing how fast the sound waves can be expected to travel helps the receiver understand whether echoes are  coming back from the tops of rocks (or fish, whales, shipwrecks, etc.), from straight down under the boat, or from the edges of the cone.

Screen shot 2013-04-08 at 4.16.45 PM

There are other considerations to analyzing the echoes too.  It is important to have information on the height of the waves and the swell of the water at the time readings are being made.  (Remember the sound waves are sent out from the bottom of the boat and the boat is floating on the top of the water.) This way the echo patterns analysis can take into account whether the boat is leaning a little to the right or left as it goes up or down with the swell of the water.  That lean affects the angle at which the beam is aimed to the seabed from the bottom of the boat.  The level of the sea surface changes with the tides, so the software also figures in the lowest level that probably will occur due to changes of tide. This is all linked to the time that surveys are made, (because tides change with the time of day, month, and year) the date and the exact geographical position for each bit of information is very important.  This depends upon satellite and GPS technology.

The transducers send out pings faster or slower (pulse rate) and with a stronger or weaker signal, depending upon how deep the water is in the main area of the survey.  The power is set higher for deeper water.  The cone of the beam spreads out wider in deeper water so the resolution, or focus, is not as great.  This is acceptable because objects that are hazards to navigation are generally sticking up from the bottom in shallower water.  (Something sticking up 2 meters from the bottom in water 50 meters deep would still be 48 meters below the surface at its highest point.  That same object in 10 meter water would only allow 8 meters of clearance for ships on the surface.)

There are many other considerations to using the sonar information for making good charts. Every day I have the opportunity to ask a few more questions and learn a little more about this technology.

Personal Log 

This evening I got to go out in a kayak with the XO.  We paddled away from the ship and followed the shoreline north around the island until we entered the next bay.  The waves were small, but sometimes there was a pretty good gust of wind so I really had to pay attention as I was getting used to the feel of the little boat.  About 100 yards from the ship a sudden gust caught my hat and took it off into the water.  We were not able to recover it. On the cliffs above the second bay we spotted Bald Eagles and gulls of several kinds.  One of the eagles was really concerned about what we were doing and either circled over us or sat on the high bluff and watched us the whole time we were in the area.  Its mate flew back and forth through the area calling to it as it watched us.

We were hoping to see a waterfall that we had heard came down the side into this bay, but we never did sight it. The shoreline was beautiful with steep rock walls or narrow rocky beaches and mountains rising right up from the edge.  The hillsides look like they would be smooth and easy to walk on, but the vegetation is actually thick, deep, brush and provides very uneven footing.

Our return to ship was much faster than the trip out because the wind was at our back and pushing us all the way.

Question of the Day 

How were most of the islands in the Aleutian Chain formed?