Tag: acoustic survey

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Jennifer Fry, July 15, 2009

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Miller Freeman (tracker)
July 14 – 29, 2009 

Mission: 2009 United States/Canada Pacific Hake Acoustic Survey
Geographical area of cruise: North Pacific Ocean from Monterey, CA to British Columbia, CA.
Date: July 15, 2009

Weather Data from the Bridge 
Wind Speed: 19 kts.
Wind direction: 355° north
Temperature: 15.4°C (dry bulb); 13.2°C (wet bulb)

Science and Technology Log 

This picture shows the Miller Freeman in Alaskan waters. On our cruise, it’s working off the coast of California.
This picture shows the Miller Freeman in Alaskan waters. On our cruise, it’s working off the coast of California.

Our cruise was delayed for a day due to poor weather conditions and heavy seas. We began with a meeting of the scientific team which consists of 8 members all with their specific scientific knowledge and expertise. We will be conducting several types of oceanographic sampling during our cruise:  2-3 hake tows per day, weather permitting, an open net tow where fish are viewed through a camera, XBTs: Expendable Bathythermograph, HABS: Harmful Algal Bloom Sampling, and CTD: Conductivity, Temperature, and Density. The ship conducted Man Overboard and Fire drills.

The research vessel Miller Freeman set sail from Eureka, California on Wednesday, July 15th at approximately 12:30. Each person aboard is assigned a specific job and place to report on the Miller Freeman during such an event. Our assignments are posted on our stateroom door. During a Fire/Emergency Drill the signal is a 10 second blast of the general alarm and/or ship’s whistle. I am to report or muster to the Chemical Lab.

In the event of an Abandon Ship Drill, I am assigned to life raft #2 and muster on the O-1 deck, port (left) side. The Abandon Ship signal is more than 6 short blasts followed by one long blast of the general alarm and/or ship’s whistle. If a Man Overboard Drill is called, we will hear 3 prolonged blasts of the general alarm and/or ship’s whistle.  The muster station is the Chemical Lab. If we personally see a person go overboard the ship there are three things to do immediately: Throw a life ring overboard, call the bridge, and keep your eyes on the person. 

These things all need to be done as simultaneously as possible to assure the safety and recovery of the person who is in the sea. It is important to conduct these emergency drills so that everyone is ready and prepared in the case of an emergency event.

Personal Log 

I am sharing a stateroom with Julia Clemons, an oceanographer on board the Miller Freeman. She works for NOAA Fisheries in Newport, Oregon.  Her educational background includes a Bachelors’ degree in Oceanography and a masters’ degree in Geology. The scientists and crew on board are so professional and willing to teach and tell about their job.  They are an amazing group of people.

New Term/Phrase/Word 
Domoic acid

Questions of the Day? 
What does a hake look like in person?

Animals Seen Today 
5 Egrets
1 great blue heron
Numerous gulls

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Jennifer Fry, July 14, 2009

NOAA Teacher at Sea
Jennifer Fry
Onboard NOAA Ship Miller Freeman (tracker)
July 14 – 29, 2009 

Mission: 2009 United States/Canada Pacific Hake Acoustic Survey
Geographical area of cruise: North Pacific Ocean from Monterey, CA to British Columbia, CA.
Date: July 14, 2009

NOAA Ship Miller Freeman
NOAA Ship Miller Freeman

Weather Data from the Bridge 
No data (In port)

 Science Log 

After arriving at the Eureka airport I found my way to the Miller Freeman thanks to many friendly Eurekan locals. What a lovely town with many interesting sights including the dock area, downtown with its renewed turn of the century architecture.   Upon arriving at the Miller Freeman I was greeted by Ensign Heather Moe who graciously gave me a tour of the ship.

There were four decks or levels to the ship which include:

  • Flying Bridge Deck: observations take place as well as storage
  • Bridge Deck: Navigation can take place from the bridge or the trawl house.  The trawl house faces toward the stern of the ship and is used to control the ship during “fishing.”
  • Boat Deck: Officers’ & Chief Scientist’s staterooms.  A stateroom is where you would sleep on a boat or ship. Your bed is called a “rack.”  Most staterooms on the Miller Freeman have bunk beds. The boat deck is where the small launches/rescue boats are stored.
  • There is: a FRB, Fast Rescue Boat, and a small launch.
  • Quarterdeck/ Main Deck:  Ship’s store, survey officers’ staterooms and the back deck, used for fishing. *The term quarterdeck was originally, in the early 17th century, used for a smaller deck, covering about a quarter of the vessel. It is usually reserved for officers, guests, passengers. It is also an entry point for personnel. Lower/ Galley Deck: Crew’s and scientists’ staterooms, library, two lounges, galley, where everyone eats their meals.
  • Hold: Gym for exercising and engineer’s storage area.

Question of the Day 
Where did the word quarterdeck* originate? (see answer above)

Animals Seen Today
Egrets Blue Heron Gulls

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Megan Woodward, July 12, 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 12, 2009

Any bycatch in a haul has to be measured and weighed if there are more than 25 of the same species caught.
Any bycatch in a haul has to be measured and weighed if there are more than 25 of the same species.

Weather/Location 
Position: N 60.35.172; W 174.08.187
Air Temp: 6.1 (deg C)
Water Temp: 5.24 (deg C)
Wind Speed: 25 knots
Weather: Overcast, rain

Science and Technology Log 

How is all the data collected from a trawl and acoustic lab used?  By collecting data about weight and length from a sample, scientists are able to connect the size of fish caught to the amount of return seen in the acoustic lab. The return is assigned a name (PK1, PK2, etc.) and all schools showing a similar acoustic pattern are given the same name.  In the end, scientists can estimate the number of fish and their size for a given area based on the acoustic and fish lab data collected.  This is repeated throughout the survey resulting in an estimate for the total number of fish in the survey area.  

Both during and after the survey estimates of abundance in the same location over the past several years are compared.  Scientists evaluate the data and determine if the pollock population in the survey area is increasing, declining or stable.  Their conclusions are used to make a recommendation about pollock fishing limits for the upcoming year. In the past few years the pollock population has been lower than in previous years.  Due to the decline, the fishing quota has been reduced.  However, the 2006 year-class is proving to be strong. At 4 years of age pollock are considered mature and fishable.  Therefore, the fishing quota is predicted to rise in the next year or two.

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Personal Log 

While discussing the acoustic survey project with the scientists on board, I was quite surprised to hear the pollock survey had been going since 1979.  Acoustic technology has changed and improved, but in essence the project has remained the same. Modern computer technology has allowed collection and analysis of enormous data sets and greatly reduced the amount of paper work needed for the project’s success.

The concept of strong vs. weak year-class is also quite interesting.  There doesn’t seem to be a direct connection between a year-class’ success and environmental factors.  Environmental factors that are potentially influential are water temperature, available zooplankton, ice cover, storms and predators.  The fish currently being caught by commercial fisherman are 5-7 years old. Can you figure out which year classes those fish are from?

We continue to spot plenty of seabirds and a few more minke whale pods. I was able to watch a group of Dall’s porpoises play in the wake of the bow for half an hour yesterday. There haven’t been any new animal sightings during the past few days.
We continue to spot plenty of seabirds and a few more minke whale pods. I was able to watch a group of Dall’s porpoises play in the wake of the bow for half an hour yesterday. There haven’t been any new animal sightings during the past few days.

Although we are out here working in the best interest of pollock, I have found it difficult to watch thousands of pollock come through the fish lab.  I have to remind myself that sampling the fish is truly for the good of the order. In addition, after being measured the fish are sent back into the ocean where they become food for other organisms such as crab or birds. One of their natural predators is having a good meal, something that was likely to happen anyway.

Animal Sightings 

  • Seabirds
  • Dall’s porpoises

New Vocabulary 

Bycatch  – Anytime something is caught during a trawl other than pollock it is labeled bycatch.  Jellyfish has been the most common form of bycatch.

Year-class – All the fish born in a given year are members of that year-class.  We have caught a lot fish from the 2008 year-class (1 year old fish).

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Megan Woodward, July 10, 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 10, 2009

The pollock are carefully loaded onto the table.
The pollock are carefully loaded onto the table.

Weather/Location 
Position: N 56.30.202; W 172.34.37
Air Temp: 7.4 (deg C)
Water Temp: 7.4 (deg C)
Wind Speed: 19 knots
Weather: Overcast

Science and Technology 

Once the fish are onboard a rigorous data collection process begins.  All of the data collected are recorded via instruments linked to a computer network in the fish lab.  Below is a series of photos showing the process used in the fish lab to collect valuable data.

Once the fish are on the table, we carefully look through the fish for any species other than pollock caught in the trawl.  These non-pollock species are sorted into bins and accounted for. The fish are weighed one basket full at a time as they reach the end of the conveyor belt.  Initially, we take a count of how many fish fill one basket.  There is a scale connected to a computer program that records the basket’s weight.

The sorting begins. The pollock are sorted between male and female.
The sorting begins. The pollock are sorted between male and female.

After weighing the pollock, we move on to sorting a sample of approximately 300 fish by sex.  To find the sex of a fish we cut open its belly and look for either male or female reproductive organs. The sexed fish are then placed in the appropriate bin. Next, each pollock from the male/female sort is measured in centimeters.  We use a measuring board linked to a computer that records the size of each fish. There is a small tool in my hand that gets placed at the “v” of the fish tail.  Sensors on the board detect the placement of the measuring wand, and send a length measurement to the computer so it can be recorded.  This program also keeps track of how many fish we measure, so we get an accurate sample count.

The stomach of a pollock is prepared for preservation.
The stomach of a pollock is prepared for preservation.

Several scientists have asked us to collect pollock for various research projects. One project, designed to study the diet of pollock, requires us to sex, measure, weigh and take the stomach of 20 pollock from each haul. A label with all of the information is placed in a bag with the stomach.  They are placed in a freezer for preservation purposes.

Here I am using the measuring board. The stomach of a pollock is prepared for preservation.
Here I am using the measuring board.

We also use a similar process for scientists examining one-year-old pollock. This study asks for the entire fish to be preserved, not a specific organ. In one 12-hour shift there is a maximum of 3 trawls if fish sign is identified in the acoustics lab. Each trawl takes 2 to 3 hours to process. It’s possible another trawl could happen while finishing up the data collection from the previous haul. This makes for a very busy, fish filled shift.

Personal Log 

I was in charge of weighing the fish!
I was in charge of weighing the fish!

Working in the fish lab has provided for a tremendous amount of new learning to take place. I’ve learned to identify species of fish that mix in with pollock (capelin, flatfish, skate and cod), and have seen several crustaceans and jellyfish, too.  All of the measuring technology has been straight forward and user friendly. Sexing the fish has been the most difficult job, but has become easier with practice. Examining the innards to identify male or female reproductive organs seems nearly impossible in the young fish, and it’s not always clear in the older fish.

Today I was in charge of weighing the fish as they came down the conveyor belt. I was certainly mistaken when I thought it would be a simple task. First off, I had to count the fish as they dropped into the basket at a speed faster than I could count. At the same time I had to control the speed of the belt and open the gate so more fish would move down the line.  When the basket was full, I stopped the belt and placed the full (semi-accurately counted) basket on the scale and waited for the scale’s “steady” signal to come on.  Since the boat is constantly in motion the steady light rapidly blinks on and off. It took me three tries before I managed to get the basket weighed.  Meanwhile the rest of the team patiently waited.  Maybe I’ll give it another try tomorrow.

This average sized skate was flapping his wings making him difficult to hold. Look closely at the fish on the conveyor belt and you will see hermit crabs and seastars.
This average sized skate was flapping his wings making him difficult to hold. Look closely at the fish on the conveyor belt and you will see hermit crabs and seastars.
Basketstars were brought up in a bottom trawl. Hermit crabs and snails were also caught in the bottom trawl.
Basketstars were brought up in a bottom trawl.
Hermit crabs and snails were also caught in the bottom trawl.
Hermit crabs and snails were also caught in the trawl.

Animals Seen 

  • Minke Whale
  • Skate
  • Pacific Cod
  • Tanner Crab
  • Snow Crab
  • Basketstar
  • Sturgeon Poacher
  • Snails
  • Hermit Crabs
  • Arrow Tooth Flounder
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Megan Woodward, July 7, 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 7, 2009

This map depicts the path the Miller Freeman will take on our cruise.
This map depicts the path the Miller Freeman will
take on our cruise.

Weather/Location 
Position: N 56.18.292; W 171.46372
Air Temp:  7.3 (deg C)
Water Temp:  6.9 (deg C)
Wind Speed: 17 knots
Weather: Overcast

Science and Technology Log 

We are traveling on designated lines in the north/south direction looking for pollock (travel lines are illustrated above). The samples we pull in are compared to the amount of fish found in the same location over 20+ years.  The process used to “go fishing” is not as easy as one might think.  Several things need to align for a successful trawl to take place. As of today, I have been a part of three successful trawls.  Below is an explanation of the fishing process.

  1. The Fisheries Research Biologist and his team recognize a series of acoustic returns as potential pollock schools while sitting in the acoustics lab. Then they decide if the amount of fish being seen is enough to fish on. If yes, go to step 2.
  2.  Next the team questions if the weather conditions are calm enough, are the fish far enough off the bottom of the sea floor, and have we traveled at least 30 miles from our last fishing point.  If conditions are aligned, move to step 3.
  3. The team contacts the bridge to prepare the crew for fishing. The bridge receives the exact location (longitude/latitude) the nets should enter the water for the best possible fishing.  By now we have traveled over the top of the fish we saw on the acoustic screen.  A decision must be made about the best direction to travel so the nets work properly:  Do we flip a u-turn and fish up the line, or do we circle back to where we saw fish and retrace our path on the line? The water’s current and prevailing winds impact how the nets will function, which are some of the deciding factors in choosing the direction we will tow the nets.  Fishing in motion, continue to step 4.
  4.  Up to the wheelhouse. Here the lead fisherman, the ship’s Officer of the Deck (person in charge of driving the ship) and the fisheries team can work together to create the best fishing scenario. The same acoustic information can be viewed in the wheelhouse as in the acoustic lab.  Based on the depth of the acoustic return, the fisheries team can inform the fisherman how far to lower the nets in the water. Keep going to step 5. We almost have fish…we hope!
  5. Once the net is in the water, there are two acoustic screens closely watched. These are pictured below with the explanation of the information received.  The net is continually raised or lowered based on the depth of the return. A trawl lasts for 20 minutes and covers 1 mile on average. The fisheries team is aiming for 300 fish per trawl.  They are careful to not over fish. Almost done, bring the fish aboard.
  6. The final step is bringing the nets back in and unloading the fish.  If all went as planned, the next few hours will be spent in the fish lab collecting information about the sample. Unfortunately the system is not perfect.  It’s possible to bring in a water haul or a stuffed sausage. Neither one is good news.
This is the acoustics lab. The top screens are displayed in the bottom monitors as needed. The top two left monitors show the acoustic return from the 5 frequencies (pings) sent out.
This is the acoustics lab. The top screens are displayed in the bottom monitors as needed. The top two left monitors show the acoustic return from the 5 frequencies (pings) sent out.

Personal Log 

Now that I have participated in three trawls, I’m feeling much more comfortable with the whole fishing process. Rather than looking at the acoustic screens with a puzzled look, I’m able to recognize what the return from a school of pollock looks like. Jellyfish show up on the screen as blue-green clusters, and have been present in the top 40 meters of water the majority of time we’ve been at sea.  I can only imagine how many of those creatures are down there.

There seems to be a bit of humor in all we do at sea.  There are two awards given out based on the hauls we bring in: The water haul and the stuffed sausage awards.  You really don’t want to be the recipient of either one. The water haul award goes to the team that brings in the haul with the least fish (mostly water). This happened yesterday when we attempted to catch pollock close to the surface.  There wasn’t but a single pollock in the net. Of course there were numerous jellyfish.

This is an acoustic screen showing a return typical of pollock. The several clusters with the trail of return on the left are showing a good fishing opportunity. The dark red across the middle of the screen is the sea floor.
This is an acoustic screen showing a return typical
of pollock. The several clusters with the trail of
return on the left are showing a good fishing
opportunity. The dark red across the middle of the screen is the sea floor.

The stuffed sausage is just the opposite of a water haul. As you may have guessed, the stuffed sausage award goes to the team that brings in the most over-stuffed net.  If we were looking to make money off of our catch, this would be considered a success. However, we really only want a sample of about 300 fish. A stuffed sausage means too many fish were brought in.  It is possible to be the “winner” of both awards.

Animals Seen 

  1. Red-legged kittiwake  
  2. Blacklegged kittiwake
  3. Albatross
  4. Fulmar
  5. Fur Seal
  6. Capelin (they smell like cucumber)
This screen shows the return from a signal that sweeps left to right like a pendulum. The bottom of the net is the ½ circle shape. During a trawl you can see if a school of fish enters the net.
This screen shows the return that sweeps left to right like a pendulum. The bottom of the net is the ½ circle shape. During a trawl you can see if a school of fish enters the net.
When the net is in the water, there is return from the top and bottom of the net. This screen shows a vertical return. We can see we are at the correct depth, but maybe we are too far to the left or right.
There is return from the top and bottom of the net. This screen shows a vertical return. We can see we are at the correct depth, but maybe too far to the side.

New Vocabulary 

Acoustic Lab: AKA “The Cave” because there are no windows.  This is where the Fisheries Research Biologist and his team watch the acoustic return monitors.

Bridge/Wheelhouse:  This is where the officer on duty drives the ship using several navigational tools. Named the wheelhouse because the ship’s steering wheel is found here.  The bridge is located on the top level of the ship. The Methot and trawl nets are also operated from the bridge.

Haul:  This is how the fish are referred to when they are caught in the net.  One might ask, “How was the haul?”  “It was a (big haul, small haul, water haul, stuffed sausage).”

Water Haul:  A net lacking fish following a trawl.

Stuffed Sausage: An overstuffed net, too many fish caught.

Hauling in the net
Hauling in the net
This fur seal followed the boat for about 30 minutes while we were trawling for pollock. He was hoping for a free dinner.
This fur seal followed the boat for 30 minutes while we were trawling. He was hoping for a free dinner.
The center bird is a blacklegged kittiwake, identified by the black wing tips, white underwing and the light gray color on its back.
The center bird is a blacklegged kittiwake, identified by the black wing tips, white underwing and the light gray color on its back.