Katie Turner, July 30, 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 30, 2008

Screen shot 2013-11-03 at 10.15.47 AMWeather Data from the Bridge 
Visibility:  10 miles
Wind Direction:  050
Wind Speed:  7 knots
Sea Wave Height:  0-1 foot
Swell Wave Height:  2-3 feet
Seawater Temperature: 8.3 ˚C.
Present Weather Conditions: partly cloudy

Science and Technology Log 

This was the final day at sea for this cruise and we have just returned Dutch Harbor.  The cruise has been challenging for the scientists as they have had to scale back their study, and even eliminate some experiments.  Fifteen days of cruise time were lost while repairs were made to the ship. Conditions while working at sea are unpredictable and require acceptance, patience, and flexibility.

Ship's cruise path

Ship’s cruise path

The Buoy Experiment 

In addition to the side by side comparison study, a unique experiment was designed and performed during this cruise to investigate how walleye pollock (Theragra chalcogramma) behave in the absence versus presence of either vessel, to augment the comparison study.  Transducers were mounted on a buoy, which was deployed from OSCAR DYSON, and allowed to drift while collecting acoustic data on pollock schools with the ships at a distance.  As the buoy drifted along, MILLER FREEMAN and OSCAR DYSON alternately passed by the buoy on a “racetrack” 6 nautical miles (nm) long.  Each ship passed the buoy within 10 meters along the racetrack about every 30 minutes, and maintained a position opposite one another.

The racetrack pass experiment will provide information on how fish respond to the ship as it approaches and passes over them, and then as it moves away. The acoustic data collected by the transducers on the buoy was monitored aboard OSCAR DYSON during the operation, and was downloaded in entirety once the buoy was retrieved for analysis. We made a total of seven buoy passes, which took about 3 ••• hours.  This experiment was done at night when pollock schools migrate up from the bottom of the ocean into mid-water regions.  It was interesting to observe the navigation operations from the bridge as ships maneuvered around the racetrack in the dark. The computer screenshot below shows the track (in red) of the MILLER FREEMAN after our 6th pass of the buoy.  The short, blue vertical line at the end of the red track line at the top of the screen represents the ship. (Green lines are depth contours.) After completing the buoy experiment we picked up the transect from where we had left off and continued the side-byside study.

View of Unalaska

View of Unalaska

On the bridge bringing MILLER FREEMAN into Captain’s Bay, Executive Officer Natasha Davis (official owner of ship’s cat) and Ensign Otto Brown

On the bridge bringing MILLER FREEMAN into Captain’s Bay, Executive Officer Natasha Davis and Ensign Otto Brown

Another Setback 

Later that day the ship developed engine problems and it was necessary to shut down the main engine to investigate. Leaks in the cooling system involving two separate cylinders had developed. This same problem occurred recently with a different cylinder, and was one of the problems that originally delayed our cruise out of Dutch Harbor.  The engineers repaired the system and we were underway again within a few hours.  At this point we were nearly 450 nautical miles from Dutch Harbor, with limited resources for additional repairs.  In the best interest and safety of all aboard, the Commanding Officer decided to discontinue our north and westward direction along the cruise course and head the ship back to Dutch Harbor.

Ship's cat

Ship’s cat

Personal Log 

Our final day in the Bering Sea was mostly sunny.  Dall’s porpoise and whales were occasionally sighted off in the distance, and we watched ash clouds rise from Okmok volcano off our starboard side all afternoon as we closed in on Unalaska.  The wind seemed to be carrying the ash cloud to the southwest, and we hoped that it would not affect flights out of Dutch Harbor for those of us who are flying home.  We arrived in Unalaska before 10 pm, leaving just enough time to anchor and repeat the acoustic calibration. After the scientists and I leave the ship in the morning, she will head back to her home port of Seattle, where she will have a maintenance check before the next cruise. I have thoroughly enjoyed my stay on MILLER FREEMAN and owe many thanks to the officers and crew for their hospitality. It has been a pleasure to get to know everyone and I will have good memories of this cruise, despite the breakdowns and delays. I am especially grateful to the scientists on board, Patrick Ressler and Paul Walline, for sharing their work, helping me understand a little about acoustic surveys, and for their friendship during this experience.

Katie Turner, July 26, 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 26, 2008

Rescue crew retrieves a dummy man overboard. It is a maritime custom to refer to the man overboard as “Oscar." This comes from an international regulation requiring the raising of the Oscar flag when a vessel is responding to a man overboard, warning other vessels to be on the lookout

Rescue crew retrieves a dummy man overboard. It is a maritime custom to refer to the man overboard as “Oscar.” This comes from an international regulation requiring the raising of the Oscar flag when a vessel is responding to a man overboard, warning other vessels to be on the lookout

Weather Data from the Bridge 
Visibility:  3 miles
Wind Direction:  050
Wind Speed:  8 knots
Sea Wave Height:  0-1 foot
Swell Wave Height:  2-3 feet
Seawater Temperature: 7.8˚ C.
Present Weather Conditions: cloudy

Science and Technology Log 

After leaving Captain’s Bay early Friday morning, the trip to the rendezvous point with OSCAR DYSON took nearly 20 hours. During that time we had our mandatory fire, abandon ship, and man overboard drills.  For our fire drill the Captain staged a mock fire, with smoke reported from the acoustics lab.  The fire fighting team had to respond, find the point of origin of the fire and figure out how to treat it. A debriefing was held afterward so that responders could discuss strategies and learn from the experience.

The rescue boat is brought back aboard the MILLER FREEMAN

The rescue boat is brought back aboard the MILLER FREEMAN

The abandon ship drill is regularly performed so all crew are ready to respond to a severe emergency by mustering at their assigned stations and getting into survival suits to be ready to board life rafts. It’s a good way for new crew members, such as me, to make sure they know where to go and what to bring. We made our rendezvous with OSCAR DYSON late Friday evening in the Bering Sea and immediately moved into position to run the first side by side transect. We are working on a comparison study to determine whether acoustic estimates of pollock (Theragra chalcogramma) abundance made by MILLER FREEMAN and OSCAR DYSON are comparable.  Pollock may have different behavioral responses to these vessels during surveys due to the differences in the amount of noise each vessel radiates into the sea from its propeller, engines, and other equipment.  These behaviors could affect the acoustic estimates of abundance.  OSCAR DYSON is taking over the task of acoustic pollock surveys in the Bering Sea and has been built under new specifications that require a lower level of radiated noise. MILLER FREEMAN has been doing the Bering Sea pollock surveys since 1977.  This study is important because it will ensure that future biomass estimates will be continuous with those done in the past. During this cruise the two ships will continuously collect acoustic backscatter data while traveling side by side along a transect line where pollock schools are known to occur. The distance between the two ships is maintained at 0.5 nautical miles (nm), while they travel at about 12 knots. Every 50 nm along the transect, the vessels switch sides.

OSCAR DYSON from the bridge of the MILLER FREEMAN in the Bering Sea

OSCAR DYSON from the bridge of the MILLER FREEMAN in the Bering Sea

For this to happen one vessel will slow down and cross behind the stern of the other vessel, then catch back up on the other side. The beginning and end of each transect section must be carefully coordinated between the scientific team in the acoustics lab The remainder of our time on this cruise will be spent working with the OSCAR DYSON to cover as much of the study area as possible before returning to the port of Dutch Harbor.  After the study is complete, the acoustic data collected by each vessel will be carefully compared to see if there is any consistent difference between them. At the same time officers on the bridge are in constant communication to coordinate navigation and maneuvering of the ships.

The figure above shows the final transect path of MILLER FREEMAN in the Bering Sea as straight lines in red. The parallel lines running nearly north and south were traversed from the east to the farthest westerly point. The zigzag red line across the parallel lines represents the path taken as we head back to the southwest on our return. Other colored lines on the map are depth contour lines.  Red lines indicate depths from -75 to -100 meters, yellow to -130 meters, green to -155 meters, and blue greater than  -160 meters.

Ship transect

Ship transect

Personal Log 

During these few days at sea the scientists onboard have taught me a lot about acoustic studies. It’s a complex science that requires both an understanding of the physical science of acoustics and the technology involved, but also the biology, behavior, and ecology of pollock.

One of the opportunities I have especially enjoyed has been watching and photographing the seabirds. They are an important part of this ecosystem and one that can be observed without acoustics. We have seen mostly northern fulmar (Fulmaris glacialis) and black-legged kittiwake (Rissa tridactyla), but also an occasional long-tailed jaeger (Stercorarius longicaudus), and flocks of thick-billed murre (Uria lomvia). Northern fulmar (Fulmaris glacialis) exhibit a lot of variation in color from very light, to light, and dark versions, with gradations in between. These different color morphs all mate indiscriminately. They are gull sized birds with moderately long wings, a short, stout, pale bill, and a short rounded tail. A key characteristic is their dark eye smudge.  They are common in the Bering Sea but also in the northeast Atlantic.

Northern fulmar, light morph

Northern fulmar, light morph

Northern fulmar, dark morph

Northern fulmar, dark morph

Fulmars are well known among commercial fisherman for scavenging waste thrown off fishing boats, which explains why they have been nearly constant companions to the MILLER FREEMAN on this cruise. Fulmars are members of the family Procellariiformes, also known as the “tube-nose” birds, along with albatrosses, petrels, and shearwaters. The term comes from the tubular nostril, a structure that looks like a tube on top of their beak.  Their beak, as you can see in the photo, is made up of many plates. This specialized nostril is an adaptation that enhances their sense of smell by increasing the surface area within to detect scent. They also have enlarged brain structures that help them process those scents. Learn more at the Cornell and U.S.G.S. websites.

Katie Turner, July 25, 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 25, 2008

Bald eagles are abundant around the port in Dutch Harbor

Bald eagles are abundant around the port in Dutch Harbor

Weather Data from the Bridge 
Visibility: 10 nautical miles
Wind Direction: 075
Wind Speed: 13 knots
Sea Wave Height: 1-2 feet
Swell Wave Height: 3 feet
Seawater Temperature: 7.1˚C.
Present Weather Conditions: Cloudy, 9.3˚C, 94% humidity

Science and Technology Log 

After spending 3 weeks at the dock in Dutch Harbor, MILLER FREEMAN finally began the cruise with less than a week left to complete the study. We pulled away from the dock Thursday afternoon, 24 July, and sailed to nearby Captain’s Bay to calibrate the acoustic instruments.

A line diagram of MILLER FREEMAN showing the location of the centerboard below the hull

A line diagram of MILLER FREEMAN showing the location of the centerboard below the hull

Background 

Acoustics is the scientific study of sound: its generation, transmission, and reception.  Sound travels in waves at known rates, and the physical properties of the material the waves travel through affect the speed of sound.  These properties of sound waves enable their use in medical diagnosis, testing critical materials, finding oil-bearing rocks underground, and counting fish in the ocean. Sound travels through seawater of average salinity about 5 times faster than through air (~1,500 m/s, or about 15 football fields in one second).  Many animals that live in the ocean rely on sound more than vision for communication and survival. You are probably already familiar with echolocation and communication vocalizations in whales and porpoises.

Picture of the transducers in the centerboard, which is lowered when the ship is at sea. Lowering the transducer away from the hull reduces the noise interference of bubbles running along the hull while underway.

Picture of the transducers in the centerboard, which is lowered when the ship is at sea. Lowering the transducer away from the hull reduces the noise interference of bubbles running along the hull while underway.

The speed of sound in water increases as temperature and salinity increase.  It also increases with depth due to the increase in pressure.  Therefore, in order to know the speed of sound at a given location in the sea, you need to know the temperature, salinity, and depth. There are other factors that are important to consider as well.  As sound travels through seawater it loses energy because of spreading, scattering and absorption.  When sound waves strike bubbles, particles suspended in the water column, organisms, the seafloor, and even the surface, some of the energy bounces off or is scattered. When the sound energy is scattered at angles greater than 90 degrees it is referred to as backscatter.

Fish Assessment 

Scientists use acoustics to measure fish abundance in the ocean by emitting sound waves at specific frequencies and then measuring the amount of backscatter.  Different organisms and other objects will have a characteristic backscatter that is dependent on many biological factors as well as the physical properties of the medium. The most important biological factor is presence and the size of a swim bladder, but also the organism’s size, shape and orientation.  If scientists know the backscatter signature of the target species (which can be determined experimentally or by mathematical models), they can use sound to identify and measure certain fish populations in the ocean. Onboard the ship, sound waves are emitted from an instrument called a transducer, which is located in the centerboard of the ship. The transducer generates sounds directly beneath the ship into the water column below (pings).  When these sound waves are backscattered from the fish below back to the transducer, they are converted to an electrical signal that is sent to the scientist’s computer.  There, a profile can be created that represents the fish in a graphical image.

Chief Scientist, Patrick Ressler, attaches calibration spheres to the line that will be lowered beneath the ship.

Chief Scientist, Patrick Ressler, attaches calibration spheres to the line that will be lowered beneath the ship.

Before making any actual measurements during this study, it is necessary to calibrate the acoustic instruments on board the ship. Calibrations of instruments and other measuring devices are done by using a known standard to compare the output of the instrument. So for example, if I wanted to calibrate a stick as a measuring device, first I would compare its length to a known standard such as a ruler. We anchored in Captain’s bay, on both bow and stern to keep the ship from moving much, and spheres with known acoustic properties were suspended beneath the ship at a known distance below the transducers. Acoustic data were then collected on backscatter from the spheres. Knowing the distance to the spheres, their acoustic qualities (how they will backscatter the sound), and the physical qualities of the medium (seawater temperature and salinity) allowed the scientists to standardize their equipment.   While acoustic calibrations were performed by the scientists, the survey technicians collected seawater temperature and salinity. The way these properties are measured is standard practice on research vessels.  An instrument package called a “CTD” measures conductivity (which is converted to salinity), temperature, and depth.  Sensors for each of these make up the package, and are mounted on a metal frame called a rosette. The rosette is lowered into the water column by a crane, and the data collected is transmitted via a cable to a computer on board. Once the calibration and CTD measurements were completed, we pulled anchor and headed northwest into the Bering Sea to meet up with NOAA Ship OSCAR DYSON.  We expect to reach our rendezvous point by late Friday to begin our study.

Survey Technician Tayler Wilkins monitors the CTD data transmission while communicating with the crane operator as the rosette is lowered through the water column. The computer automatically produces a profile of temperature and salinity with depth.

Survey Technician Tayler Wilkins monitors the CTD data transmission while communicating with the crane operator as the rosette is lowered through the water column. The computer automatically produces a profile of temperature and salinity with depth.

Personal Log 

The long stay in Dutch Harbor made the departure that much more exciting.  I am looking forward to what little time is left.  The crew of MILLER FREEMAN have all made me feel welcome, and have been helpful in answering my questions and educating me on shipboard operations.

New Terms 

acoustics, calibration, backscatter, centerboard, transducer, CTD rosette

Learn more here 

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