cam-trawl – Page 2 – NOAA Teacher at Sea Blog

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

Mission: Summer Pollock III

Geographical Area: Bering Sea

Date: July 24, 2010

Time: 1837 ADT
Latitude: 62°11N
Longitude:177°52W
Wind: 15.1 knots (approx. 17.4 mph)
Direction: 156° (SW)
Sea Temperature: 8.3°C (approx. 47°F)
Air Temperature: 7.4°C (approx. 45.3°F)
Barometric Pressure (mb): 1007
Wave Swells: 4 – 5 feet
Wave Height: 1 – 2 feet
Combined: 5 – 6 feet

Scientific Log:
Today started out with the launching of another CTD (Conductivity, Temperature, Depth) and XBT to measure the salinity and temperature of the ocean. On average we typically deploy a little more than one per day, depending on whether we are wanting to hit key locations. Today when we launched two and contrasted locations where there were pollock to locations where there weren’t so we could better analyze how sea temperature affects where the pollock prefer to hang out.

Survey Tech, Robert Spina, taking samples from the CTD

We attempted to launch the Cam-Trawl this morning but as is typical with new equipment, we encountered some problems once it was in the water. And as my students have learned, sometimes it’s necessary to make modifications and try the science experiment again! Even the pro’s must go through the Scientific Method multiple times before they can publish their findings!

At approximately 1030 we deployed the AWT and went fishing for more pollock. This time we were able to gather a variety of different ages between the years 1-3. Once the fish are dumped from the codend, they are placed on a type of conveyor belt that allows us to do a preliminary sort through the fish. For example, jellyfish are commonly caught in the net and so we place them in a separate bucket to measure later. Sometimes we accidently catch other fish in the net, this is called bycatch, and they too need to be separated. At the end of the conveyor belt another person weighs baskets of fish and records the weights in the computer. Afterward, we take a random sample of about 400 fish and sex them. This sample is used to determine how many fish of each size are in the sample. Unfortunately we do not have a way to identify the sex of the fish without having to cut into them to see. In addition to measuring, weighing, and sexing the fish, we again took samples of pollock stomachs and otoliths. We conducted two fish hauls during my shift and we will probably do two more tonight.

When we finish collecting the data we must clean the lab. The best part of this cleanup is that the dissected fish become food for the numerous Northern Fulmars trailing our ship and then the lab is simply hosed down, including the computers! We clean the lab after every fishing event because if the fish scales dry out, they become impossible to remove, much like cereal crusted in a bowl! Not to mention all the fish parts would become unbearable stinky when we have a rare, sunny, warm day!

Pollock stomach contents: Amphipods (dark) and some type of fish.

Personal Log:
When I walked outside to observe the activity on the deck (where the fishing nets are located in the back of the ship) the fog was very thick. Of course, living in Dutch Harbor, I have become accustomed to such conditions but being out on the boat gave me an entirely new feeling. The boat rocked calmly, pitching every-so-often and overall there was an eerie silence among the crashing of the waves. The fog creeped aboard the boat drifting like fingers into every space available and subtly created a chill when it brushed against your neck. I can understand why sailors are prone to superstitious beliefs.

Northern Fulmars trailing the boat on the starboard side.

Later, the weather cleared into a gorgeous blue sky and the golden sun glistened on the water. I had an exciting day as I was allowed to launch an XBT and able to advance my skills in fish dissecting as I extracted stomachs and otoliths along with my regular fish duties of sorting, sexing, and measuring.
Today was a full day of work and when I when I walked into the mess hall for supper, I could not believe my eyes. There is nothing better than having a chef aboard a ship that cares for his crew. There was turkey, ham, bread dressing, mashed potatoes, cranberry sauce, candied yams, salmon tetrazzini, brown gravy, Tom Yumm Soup, dinner rolls, and corn bread! In addition, we had the lovely view of food art as our chef Ray Capati created a swan out of an apple, bouquets of baby bok choy and celery, “water lilies” made of grapefruit or oranges and mixed with flowers, and palm trees made of carrots and green bell peppers! I feel like I’m eating in a 5-star restaurant aboard the Oscar Dyson!

Ray Capati behind another fantastic, aesthetically pleasing buffet!

Animals Spotted Today:
Today is known by the “birders” from the US Fish and Wildlife folks as the Day of the Jaeger because we were able to see all three species: Longtail, Parasitic, and Pomarine!
Northern Fulmars
Black-legged Kittiwake
Common Murre
Thickbilled Murre

Least Auklet
Slaty-backed Gull (Russian seagull)
Jellyfish (Chrysaora Melanaster)
Walleye Pollock
Rock Sole
Silver Salmon (Coho)
Arrowtooth Flounder
Digested shrimps, euphausiids, amphipods, and copepods from pollock stomachs!

Something to Ponder:
Random samples are important in scientific observations because we want to obtain a general idea of what is in the ocean. Imagine if a scientist only selected the largest pollock caught in the codend. How would that skew the data samples and the information given to the public about the pollock in the ocean?

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?

Tag: cam-trawl

Story Miller, July 24, 2010

Story Miller, July 22, 2010