Tag: Pollock

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Megan Woodward, July 1, 2009

NOAA Teacher at Sea
Megan Woodward 
Onboard NOAA Ship Oscar Dyson
July 1 – 18, 2009

Mission: Bering Sea Acoustic Trawl Survey
Geographical Area: Bering Sea/Dutch Harbor
Date: Tuesday, July 1, 2009

Science and Technology Log 

What is this trip all about?  Well, NOAA is working to collect a range of pollock fish samples from across the Bering Sea.  The samples collected will help set fishing regulations based on the estimated pollock fish population.  The fish are looked at to assess the male to female ratio, size and age.

Pollock, a member of the cod family, are mainly found in the Bering Sea. They are typically found between 328 to 984 feet depths. Pollock lives up to 17 years, and reach maturity around age 4. The maximum size of the pollock is slightly larger then 3 feet long.

The colors in the picture at right indicate the amount of return received from the 3 spheres seen towards the top. The other mass of colors at the bottom and surrounding the lines are fish, which are interfering with the read.
The colors in the picture at right indicate the amount of return from the 3 spheres seen towards the top. The other mass of colors at the bottom and surrounding the lines are fish, which are interfering with the read.

We are currently preparing to set sail.  Departure time is set for 15:00 (3:00 pm).  Our first anchoring will take place just a few hundred feet from where we are docked in Dutch Harbor.  At that time, the Chief Scientist and other members of the science team will calibrate (check the accuracy) the echo sound system used during the course of the survey.  Once the calibration is complete and the data is collected, we will continue to sail in search of pollock fish.

The echo sound system is used to measure the amount of return or “back scatter” from a ping (term to describe the sound sent down into the ocean).  Depending on the size of the return, the scientists are able to determine if they are detecting fish.  Pollock are known to give a return within a specific range, which provides the scientists with one of the clues that help them make an educated guess about the type of fish being detected.

In order to calibrate the echo sound system, three metal spheres that have an expected return level are lowered into the sea.  A ping is sent into the open sea, and the scientists are able to watch the amount of return from the spheres through their computer.  The amount of return can be seen using a color-coded scale. Red shows the highest level of return, and gray is the color indicating very little return. The scientists can then see if each sphere is giving the expected return. If a sphere is giving off more or less than the expected return, the scientists then know how to adjust the level of return they are getting from fish throughout the project.

Eagle or seagull? This guy sits and waits for a food meal on top of the hotel dumpster.
Eagle or seagull? This guy sits and waits for a food meal on top of the hotel dumpster.

Personal Log 

After a day and a half in Dutch Harbor, I’m glad to finally be getting under way.  Dutch Harbor is a small, small town.  There are a few restaurants, one hotel and a Safeway.  All of the other businesses are linked to the fishing industry in one-way or another. Flying into the island was an incredible experience. The plane hummed through the air between multiple tiny landforms.  The airport runway stretches out to the edge of the sea, allowing the passengers to think, for just one moment, they are making a water landing. The plane touched down just beyond the shore.

Since my arrival, I have been welcomed with warmth from all of the NOAA scientists and deck crew. Everyone has been more than wiling to answer even the most ridiculous of questions I’ve had. My time the past two evenings were spent getting to know several of the Oscar Dyson officers and crew members.  

A good chunk of Monday was spent hiking Ballyhoo with two of the officers from the ship.  Ballyhoo is a steep hill behind the airport (approx 1400 ft. elevation). The hill was littered with WWII shelters.  As we tromped up the hill, the wind began to pick up. By the time we were nearing the top, the wind was practically knocking me sideways.  The gusts were sustained and powerful. Certainly some of the windiest conditions I’ve encountered. The wildflowers growing on the hillside were reminiscent of the summer blooms found on Mount Rainier. The views from the top were breathtaking.  Several bald eagles swooped past the emerald hills, and the sun started to peak out as we made our way back to sea level.

Animals Seen in Dutch Harbor 

  • Ground Squirrel
  • Jelly Fish
  • Bald Eagles
  • Variety of Seabirds
  • Arctic Fox
  • Guard dog
This little ground squirrel wasn’t bothered as we walked by.
This little ground squirrel wasn’t bothered as we walked by.

New Vocabulary 

Echo Sound System – A tool used to measure the return or “back scatter” from a ping.  The amount of return helps determine what is hiding under the sea.

Ping – The name of the sound that is sent into the water to create an echo/return for the scientists to read. The ping is a constant, repeated sound wave.  Several different frequencies are used to detect objects.

Return  – AKA back scatter, is the amount of acoustic sound waves/echo bouncing back off an object beneath the water.

Trawl – The phrase used when talking about catching fish using a large net

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Tamil Maldonado, July 22, 2005

NOAA Teacher at Sea
Tamil Maldonado
Onboard NOAA Ship Fairweather
July 18 – 28, 2005

Mission: Hydrographic Survey
Geographical Area: North Pacific
Date: July 22, 2005

Science and Technology Log

FOCI… Today I have been working hand in hand with scientists, throwing nets, collecting depth, pressure, temperature, and chlorophyll data.  We have also been washing nets, getting survey of larvae, writing it down in sheets database, labeling, freezing larvae and chlorophyll samples.  We analyze some graphs we were getting from the experiments.

Here are some questions I have… how is global warming affecting ecosystems? How do fish overcome these changes?  Do they go up or down in the ocean columns?  Are they changing their nursery places?  How is their behavior in comparison to other years? Which parameters affect them most: salinity or temperature?  Some of these questions are being answered by the scientists, and others are still unanswered for which we are trying to find the answers. It seems that Alaskan fish can adapt easily to salinity changes.  Remember that glaciers are melting more continuously than before and fresh water (since it is less dense than seawater) stays in the surface, which means there is a change in salinity and temperature in the ocean.  Therefore there could be changes in fish behavior and in their ecosystem.  It seems the larvae and fish will be affected by temperatures.  They could be moving from ocean columns to get to the right temperature.  But they also need food like plankton that maybe stays at a different column of seawater.  That will be a survival problem.

Scientists are focusing their work on commercial fish such as Pollock and Pacific Halibut. It is the first time they have done this survey during summer.  They want to have a template for next year to compare data with.  Later we could do some statistical models, and mathematical models to compare in terms of years or data columns.

Navigation… This afternoon I as actually sailing the boat…  I had the power on my hands.  I needed to be really focused and follow instructions at all times.  We also calculated times for some positions, stations where we were going to do survey.  I also calculated True Speed, which depends on relative speed, wind speed, angles and locations of the boat.

I had the chance to see whales, little fish and a jelly fish of the size of my 4 fingers.

I also did some hydrographic studies of the region,  got some data, pictures and depths of the ocean.

We had problems with the coaxial cable again and I got some other information about sonars that I started to read.  I even worked out today!

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Jilliam Worssam, July 7, 2004

NOAA Teacher at Sea
Jillian Worssam
Aboard NOAA Ship Miller Freeman
July 5 – August 1, 2004

Day: Two
Wednesday July 7th, 2004 20:05

Longitude: 60° Sea Wave Height: 3′
Latitude: 172° 18 Swell Wave Height: 0-1′

Visibility: closing 5-8 nm fog Sea Water Temperature: 7.9C
Wind Direction: 214 Barometric Pressure: 1028 strong high pressure
Wind Speed: 5 kts Cloud Cover: complete

Science and Technology Log:

The plan for tonight is to run a MOCC trawl to test the equipment prior to live sampling, but lets back up a moment and look at the device used for this fish collecting experiment. Originally known as the KMOCC (Karp Multiple Opening and Closing Codend), the MOCC as it is commonly known is a scientific piece of equipment designed to allow scientists to selectively sample specific layers in the ocean. MOCC has the ability to collect fish samplings from a maximum of three different stratum, allowing the scientists choice. Pollock of different sizes tend to congregate at different oceanic layers and through the use of equipment like the MOCC scientists can look at sonar and choose from which population they would like to sample, without contaminating the haul with fish from different size groups. This form of selective sampling will aid the researchers in observing specific fish (pollock) populations.

Today there have been no fish trawls as according to the sonar data the ships transects have not passed any significant fish populations.

Personal Log:

I am on a 215 foot research vessel, touring the Bering Sea looking for walleye pollock, and can sit at this computer for an hour, watching the sonar all alone. With over thirty individuals living on this floating community it never ceases to amaze me that the schedules can be so well devised as to allow people their individual space. With a spare moment one might even be seen sitting in their stateroom relaxing. This amazing personal space is a person’s home away from home and usually has two residents. Each individual will work mirror hours so that while one person is sleeping, the other is working. Why is this fact so important? Well let me explain to you how many staterooms on the Miller Freeman are designed.

As you enter a stateroom there is on one side a set of berths, similar to a bunk bed, but Spartan by necessity. Each berth is approximately three feet wide and two feet high. Not a lot of room for movement, but functional in the processing of sleep. After the berth there is a spartan sink, a small desk, and two built in closets, all in a space that is eleven feet long and approximately five and a half feet wide. (Please realize that the 5.5’ included the beds, closets everything, so walking space is at its best at 2.5’ in the very middle.) The closets are not standard sized actually they are miniature and already contain your personalized life jacket and survival suit. Once inside the survival suit though you might have more room than in your berth. Space aside the rooms are functional, and a little cozy. I have slept in my berth for a few nights, and with the rocking of the boat and the lull of the engine it is as comfortable as an old porch hammock, on a warm summer evening as the breeze lulls you to sleep.