Melissa George: Catch Me if You Can, July 31, 2013

NOAA Teacher at Sea
Melissa George
Aboard NOAA Ship Oscar Dyson
July 22 – August 9, 2013

Mission:  Pollock Survey
Geographical Area of Cruise:  Gulf of Alaska
Date:  July 31, 2013

Current Data From Today’s Cruise

Weather Data from the Bridge (12 noon Alaska Daylight Time)
Sky Condition:  Cloudy
Temperature:  12.8 ° C
Wind Speed:  14 knots
Barometric Pressure:  1024.7 mb
Humidity:  89%

Clouds Seen from Bow of Oscar Dyson on July 31, 2013

Clouds Seen from Bow of Oscar Dyson on July 31, 2013

Sun and Moon Data 
Sunrise:  6:03 am
Sunset:  10:28 pm

Moonrise:  1:06 am
Moonset:  5:58 pm

Geographic Coordinates at 12 noon (Alaska Daylight Time)

Latitude:  59° 39.3′ N
Longitude:  157° 51.2′ W

The ship’s position now can be found by clicking:  Oscar Dyson’s Geographical Position

Science and Technology Log

The main goal of Leg 3 of this mission is to survey the mid-water portion of the pollock population using acoustics and trawls.  Pollock usually inhabit the middle of the water column down to the seafloor. This mid-water survey is typically carried out once every two years.  Another NOAA Fisheries survey observes the pollock that live close to the seafloor using bottom trawls.

Location of Fish in Water Column

Location of Fish in Water Column

Trawling 

The Oscar Dyson carries three different types of trawling nets for capturing fish as part of the mid-water survey:  the Aleutian Wing Trawl  (AWT),  a mid-water trawl net called the Poly Nor’Eastern bottom trawl, a net with special rubber bumpers so it can bounce along the ocean floor; and the Methot,  a small encased net that gathers very small ocean creatures such as krill.  I will be discussing trawling with the AWT in this blog.

leg 3

Leg 3 of the Mid-Water Survey Began East of Kodiak and Will End Near Yakutat

First, I will describe the AWT net, then I will explain how it works.  The AWT net is HUGE:  the mouth is about 25 m high and 35 m wide while the  net itself is over 150 m long (this is not counting the trawling wires that it is attached to!).  To give you an idea of how big this is, let’s think in school buses.  If we estimate a school bus to be about 10 m long, then this net would be 15 school buses long, and its mouth would be 3 school buses  wide and 2 school buses (end to end) tall.   The picture below also gives perspective in dimensions (keep in mind that the Blue Whale is only used to give relative dimensions, they are never caught in NOAA’s nets!)

Relative Dimensions of AWT Net (courtesy of Kresimir Williams)

Relative Dimensions of AWT Net (courtesy of Kresimir Williams)

I am going to describe how the net goes into the water, step by step.  Then you can watch a short sped-up video that my fellow Teacher at Sea mate, Julia Harvey, created.  She works the night shift (4 pm to 4 am) on the same cruise that I am on.

So here it goes…

Step 1:  The Codend

When the net is deployed from the ship, the first part of the net to hit  the water is called the codend (see the far right of the diagram above).  This is where most of the fish end up after the trawl.  The mesh size of the net is smallest at the codend (about 1 cm) and gets larger as it approaches the doors (about 1 m).

AWT

Labeled Scale Model of the Aleutian Wing Trawl (AWT) Net (courtesy of NOAA Scientist Kresimir Williams)

Step 2:  The Trawl Camera

A trawl camera is the next major part that hits the water.  This is a pair of cameras that help scientists identify and measure the fish that are caught in the net. This technology can also be used to help  scientists validate their biomass estimate from trawling sampling counts.    This piece of equipment has to be clipped into the side of the net each time the crew is instructed to deploy the AWT.

trawl camera

The Trawl Camera

Step 3:  The Kite

The next piece of the net to hit the water is the kite which is secured to the head rope.  Attached to the kite is  a series of sensors that help the scientists gather data about the condition of the net including depth, size, and shape underwater.   The major acoustic sensor, affectionately termed the turtle, can tell the scientists if the fish are actually going into the net.

Close-up view of the AWT scale model to highlight the kite and the turtle that ride at the top of the net.  The third wire holds the electrical wires that send data from the turtle to the bridge.

Close-up view of the AWT scale model to highlight the kite and the turtle that ride at the top of the net. The third wire holds the electrical wires that send data from the turtle to the bridge.

Step 4:  Deployment from A-Frame

Once the kite is deployed, a pair of tom weights (each weighing 250 lbs), are attached to the bridal cables to help separate the head rope from the foot rope and ensure the mouth of the net will open.  Then, after a good length of cable is let out, the crew transfers the net from the net reel to the two tuna towers and attaches the doors.  The doors act as hydrofoils and create drag to ensure the net mouth opens wide.

The scientists use acoustic data to determine at what depth they should fish, then the OOD (Officer on Deck) uses a scope table to determine how much cable to let out in order to reach our target depth.  Adjustments to the depth of the head rope can be made by adjusting speed and/or adjusting the length of cable released.

The scientists use more acoustic data sent from the turtle to determine when enough fish are caught to have a scientifically viable sample size, then the entire net is hauled in.  Once on board, the crew uses a crane to lift the codend over to the lift-table.  The lift-table then dumps the catch into the fish lab where the fish get sorted on a conveyor belt.  Click on Julia’s video below to see the entire process (sped up to retain the your interest!)

 Personal Log: 

Belongingness

Continuing with Maslow’s hierarchy of needs, I will discuss some of the ways that the need of belongingness is  met on the Oscar Dyson.  There are several different ways that comaraderie is fostered on the ship:   teamwork, common areas, meal time, and celebrations.

A Version of Maslow's Hierarchy of Needs

A Version of Maslow’s Hierarchy of Needs

Teamwork
Remember the main goal of Leg 3 of this mission is to survey by acoustic-trawl the mid-water portion of the pollock population.  To ensure that the goal of the mission is accomplished, several crews are necessary:  engineering, officer, deck, and science crews.   People assigned to a crew work together, and there is cross-talk between crews.  For example,  on the bridge where the officers work, there are two to four  people navigating the ship and instructing the deck crew.  The deck crew works together to put out and pull in the trawling nets, and the engineering crew works together to make sure the ship is operating properly. Similarly, the scientist crew members consult with each other while:  reading the acoustics on the computer screens;  deciding when, where, and how long to trawl; determining the best way to process the trawl; and reconciling the “catch” with the acoustical data.  The collaboration within and between the four crews mimics a sports team that has offensive and  defensive strings working together to maintain their positions to accomplish a common goal.
Oscar Dyson Crews

Oscar Dyson Crews

Common Areas
The ship is like a house with many rooms.  Most of the staterooms (bedroom/bath) are shared.  In terms of “living space” there is one dining area (called the galley), a conference room with books where people meet for drills or quiet work, a movie room, a laundry room, and an extra rest room.  Because all these areas are shared,  “ship etiquette” is followed, meaning that every individual keeps his or her space neat and also keeps the other common areas clean and organized.  Sometimes, reminders are placed in areas where ship etiquette needs polishing.
Reminder of Ship Etiquette in Common Restroom

Reminder of Ship Etiquette in Common Restroom

Meal Times
Meals on the Oscar Dyson are during one hour windows three times a day.  Breakfast is served from 7 to 8 am, lunch 11am to noon, and dinner 5 to 6 pm.  Unless people are sleeping or actively involved in trawling or processing, they eat at these times.  Therefore, mealtime is a time to chat, joke, ask questions, and tell stories.  
Galley Reminder

Galley Reminder

Celebrations
We have had three celebrations.  Two of these were for birthdays celebrated on the ship.  The stewards made a cake for dessert in one instance and hosted an ice cream social in the second.  Another celebration was when we were in Prince William Sound to pick up net repair supplies.  Because we were near land for the first time in many days and the sun was shining, many people came on deck at the same time to take pictures.  Some spotted porpoises which added to the excitement.  Fellow Teacher at Sea, Julia Harvey, captured a wonderful video of this event.  

Did You Know?

The ship stewards are the people who plan and prepare the meals for those on board.  Adam (below) is the second cook on the Oscar Dyson.  He worked in various restaurants in Portland before coming to NOAA as a General Vessel Assistant (GVA) helping with the different crews on various ships as needed. When the spot as a steward opened on the Oscar Dyson, Adam got the job.  He has taken various NOAA training courses for stewardship and is on the ship nine months out of the year as it surveys both in the Bering Sea and the Gulf of Alaska.

Adam, Steward on the Oscar Dyson

Adam, Steward on the Oscar Dyson

Something to Think About: 

 Today’s episode of Trawling Zoology features the animal family, Cnidaria.  Cnidaria is a word that originates from the Greek word cnidos which means “stinging nettle.”   Although the cnidarians are a very diverse family, all the members contain nematocysts (combination of Greek words nema meaning “thread” and kystis meaning “bladder”), basically barbed threads tipped with poison.  If you have ever been stung by a jellyfish,  you have felt this stinging sensation.

There are four very diverse groups of cnidarians:  Anthozoa which includes true corals, anemones, and sea pens;  Cubozoa, the amazing box jellies with complex eyes and potent toxins;  Hydrozoa,  the most diverse group with siphonophores, hydroids, fire corals, and many medusae; and  Scyphozoa, the true jellyfish.  We have brought up several members of these groups in our trawling.

Anthozoa:  We have brought on deck both sea pens and sea anenomes.  In both groups there was only one species represented.

Sea Pens

Sea Pens

Sea Anenomes (hermit crabs in front are not anthozoans)

Sea Anenomes (hermit crabs in front are not anthozoans)

Schyphozoa:  We brought up a couple of different species of jellyfish; we used a classification field guide to help us identify them.

Jellyfish from the Invertebrate Field Guide for Alaskan Waters

Jellyfish from the Invertebrate Field Guide for Alaskan Waters

Many Jellies (members of the Aequorea genus) Found in the Methot Trawl

Many Jellies (members of the Aequorea genus) Found in the Methot Trawl

Jellyfish, Cyanea capillata

Jellyfish, Cyanea capillata

To learn more about the Cnidaria Family, click the Cnidaria on the picture below, and stay tuned for further exploration of this animal Tree of Life.

Can you spot the Cnidarian on the Tree of Life?  Click on it to learn more.

Can you spot the Cnidarian on the Tree of Life? Click on it to learn more.

Dave Grant: Sea State, Sick Bay and Longitude, February 26, 2012

February 15 – March 5, 2012

Mission: Western Boundary Time Series
Geographical Area: Sub-Tropical Atlantic, off the Coast of the Bahamas
Date: February 26, 2012

Weather Data from the Bridge

Position: 26.30N Latitude – 71. 55W Longitude
Windspeed:  15 knots
Wind Direction: South (bearing 189 deg)
Air Temperature: 23.2 C / 74 F
Atm Pressure: 1013.9 mb
Water Depth: 17433 feet
Cloud Cover: 30%
Cloud Type: Cumulus

Sea State, Sick Bay and Longitude

“Now would I give a thousand furlongs of sea
for an acre of barren ground.”
Shakespeare – The Tempest.

There is considerable excitement on board since the winds have come up; adding to the work load of the deck crew and scientists struggling to snag the mooring buoy and haul in the miles of cable and sensors that are arrayed below. With swells arriving from two directions and wind chop on top of that, the ship’s motion is unpredictable. So there is no room for error above or below the waterline and the heaving of the ship and spray mean everyone must be alert and ready to respond instantly if anything swings loose.

We are “line-sailing” on this cruise, steaming back-and-forth while maintaining a straight course on Latitude 26.30; deploying and servicing various sampling devices on the electronic “picket fence” dividing the Atlantic. Watching the deck crew cutting heavy wire and even heavier  chain, banging on metal,  wrestling with equipment and sweating under the sun all day as they back-track along the same line doing back-breaking work, I can almost hear them singing an old Mississippi Delta field holler – Line ‘em:

“All I hate ’bout linin’ track
These ol’ bars ’bout to break my back
Moses stood on the Red Sea shore
Smotin’ that water with a two-by-four
If I could I surely would
Stand on the rock where Moses stood”

Line-sailing is also an old technique used when mariners could only accurately determine their latitude North or South of the equator by means of the sun and stars. Simply stated, one would sail North or South to the known latitude of a destination, then sail East or West until it was found.

The Polynesians perfected this – line-sailing the latitude of specific stars that they knew had islands beneath them. On clear nights we go out on the shadowy deck, so far away from the glare of lights on land, and marvel at the great spectacle of stars. The two brightest above us are Arcturus and Sirius – known to the Polynesians as Hōkūleʻa (Star of Joy) and Ka’ulua (Queen of Heaven). Navigators steered under Arcturus to reach Hawaii, and returned to Tahiti by sailing under Sirius.

Tahiti lies under Sirius, and Hawaii under Arcturus, providing navigators with bright sign posts to guide them to those jewels in the vast Pacific. From the deck on the Ron Brown it looks like our zenith star could be Pollux, one of twins in Gemini. This seems appropriate  “By Jiminy”  for good luck,  since early sailors swore an oath to those Twins – the protectors of ships.

Still, Longitude remained a problem because its measure is the time East or West from a fixed point –Greenwich, England and the Prime Meridian. Until accurate ship’s chronometers were perfected, navigators had to rely on repeated estimates of their speed and direction – Dead Reckoning.

Since early clocks relied on a pendulum and inferior materials, and the challenge of perfecting an accurate timepiece became apparent to me while weighing-in at Sick Bay. The roll of the ship has that up-down effect you feel in an elevator, and your weight on the scale fluctuates accordingly. (Mine swings between 165 and 225 pounds, depending on the size of the swells; so I’ll have to wait until we reach port for more accuracy.) Navigators had to wait until 1764 when watchmakers finally perfected sturdy, spring-powered and rust-resistant chronometers accurate enough to satisfy the British Admiralty to guide ships across the featureless ocean waters. Incidentally, William Harrison’s chronometer was hardly portable. It weighed 85 pounds (!).

I am going to try two experiments later. One, fashion a simply pendulum and see how the ship’s rocking affects it, and two, try some dead reckoning to determine current speed.

(Interesting coincidences: My office at work is in the shadow of Sandy Hook Lighthouse, the entrance to NY Harbor. This important beacon is the oldest continuously lit lighthouse in America – and first lighted in 1764 (!). Also, with the perfection of wireless communication;  in 1904, the US Navy established the first radio station to continuously broadcast the time for navigators to set their ship’s chronometers – at Navesink, NJ,  across Sandy Hook bay and within the sight of my office window.)

A Biologist’s Bouillabaisse

With the help of Danny, one of the ship’s engineers, I have struck gold sampling marinelife. He alerted me to the intake screen for sea water that he was removing to clear and I was able to sort through it. It is a bonanza, as you can see in the image.

Although most of the material is Sargassum weed, and some bits of plastic, there is a great assortment of material here to keep me busy for the rest of the day. I will start from the bottom. Besides the sargassum, there is other plant material swept here from shallow water. Sea grasses from around the islands support turtles and a thriving subtidal community. One colleague in Puerto Rico thinks that these meadows are as productive as an ecosystem in the ocean. Not obvious is the Aufwuchs community covering the grass blades, but under the microscope, one piece is enough to keep a class busy for hours identifying the specimens in this “fouling community.”


Bryozoa, worm tubes and coralline algae cover a slender blade of grass.


A tiny drifting animal from the surface, the Cnidarian – By-the-wind Sailor.

Perched on my fingertips, a larval crustacean ready
to drop out of the planktonic community.

A tiny larval crab viewed under the microscope (20 x’s)

An amphipod shrimp.

A Polychaete worm. One of the many annelids in the sample.
Not everyone’s favorite, unless of course, you are a fish.