In a previous post, I briefly mentioned that acoustics helps Oscar Dyson scientists locate aggregations of pollock. I didn’t know much about acoustics surveying before I arrived on board but think its pretty cool.The Oscar Dyson has 5 transducers on its center board and 1 temporary transducer on the side of the center board that looks horizontally. The transducers allow us to see where the fish are. Because of where the transducers are placed, we can only see the pollock from 16m to the bottom. This means that if there are any fish between the surface and 16m they will not be detected. This is the near surface “dead zone”. At right you will see a picture of the acoustic data picked up by the transducers. Why this happens? The transducers are mounted on the bottom of the centerboard about 9 m below the water line, and near the transducer face (first 7 m), no good data are collected. Why it’s okay? Pollock tend to hang out in mid-water. Although a few baby pollock might be in the near surface “dead zone,” the majority of pollock will be in the area we are watching. There is also a bit of a “dead zone” at the other end near the ocean floor.
Acoustic Data
Why acoustics?
Ideally, the acoustic data collection would allow us to track aggregations of pollock without actually having to fish them out of the water. All parties involved (scientists, fish, bank accounts) would benefit from this change but scientists are still in the process of perfecting this process. The Oscar Dyson is part of a fleet of five boats that was specifically designed for acoustics. Specifically, it is considered a “quiet boat” where the engine noise is decreased to prevent scaring the fish. Other acoustic projects include: Pacific hake off the coast from California to Vancouver Island (run as a joint project with Canada), herring in the northwest Atlantic, and krill in the Antarctic. Acoustics are used throughout the globe and many countries depend on acoustics for their fish surveys.
Sonar
Looking in more than one direction
Along with the transducers, there is also a multibeam SONAR that produces the same information as the transducers but with a wider angle range. Scientists use this program to help separate species in the water column. The multibeam ME70 sends its signal out after the transducers information is sent and returned. They alternate about 1.5 seconds apart. Scientists around the world are working to improve this technology and we use information from a group at University of New Hampshire along with a program from Tasmania to analyze these data. Scientists utilize the multibeam ME 70 along with the transducers and fish trawling to ensure they are capturing an accurate picture of the mid-waters.
How the survey data we collect are used.
The data we collect on the Oscar Dyson during the summer pollock surveys are used by scientists and policy makers to determine the fishing quota (the “take”) of pollock for the next season. Quotas are important for maintaining the population of pollock (and other species) for this generation and generations to come. The data we collect on the Oscar Dyson help ensure that maximum stock can be taken without negatively impacting the Eastern Bering Sea pollock population.Thought Question: What could happen if we didn’t regulate the amount of fish that could be caught? Bonus points for anyone who can identify an area where overfishing has impacted the ecosystem.
Now that we are at sea, I work a shift each day (as do all members of the crew and science team). I began my shift this morning at 0400 and reported to the Acoustics Lab to meet with chief scientist, Neal Williamson. In addition to Neal, my shift includes Abigail McCarthy, NOAA research fisheries biologist, Katie Wurtzell, awesome biologist and my fellow TAS, Michele Brustolon.We began the shift by observing our first CTD (Conductivity Temperature Depth) profiler which will be deployed at least 10 times throughout our trip. The CTD measures conductivity, temperature, and depth (used to calculate salinity) and gathers samples to measure dissolved oxygen. In other words, it measures many of the physical properties of the seawater mixture in a specific column of water. In addition, fluorescence is measured to monitor chlorophyll up to a 100 m from the surface.How it works: The CTD is lowered down to the ocean floor, collecting data on the way down. Then, on the way back up, the survey tech stops the CTD at specific depths to collect water for the samples. Upon its return, the water is collected and treated for future analysis.
Here is our CTD sensor before its launch
After our first CTD, we completed our first Methot trawl. A Methot trawl is named after the scientist who designed the net used. Here is a picture of the methot getting hauled back on deck (please note, it does actually get dark here. I woke up in the dead of night and had to wait two hours for sunrise. Sunrise is at the “normal” time of 6:30 am and I think that’s because we are on the western edge of the time zone)
Here Comes the Methot
A Methot net grabs the creatures and collects them into a codend (to make it easier for us to process) at 30-40 m below the surface – our Methot collected jellies and euphausiids (also known as krill). My first duty was to sort through the “catch” to pick out jellies. Next, we measured the weight of the krill before counting a small sample. We also preserved a couple samples for use in larger studies.
Launching the XBT
Following our Methot, I assisted with the completion of an XBT (eXpenable Bathymetric Thermograph). At left, you will see that I actually “launched” the XBT overboard. The XBT is used to collect quick temperature data from the surface to the sea floor. The data are graphed at depth vs. temperature to highlight the thermocline, that is where colder water meets water warmed by the sun. Here in the Bering Sea, the thermocline is not always noticeable as the water column is subject to mixing from heavy winds and shallow depths.
Lucky for us, it was a calm day on the water and we were able to see a distinct thermocline:
The thermocline
I think the CTDs and XBTs are really cool because they are pretty routine. Both processes are conducted all over the globe at consistent locations year after year. As you can see from the chart below, the CTDs and XBTs are marked out for the area the Oscar Dyson covers throughout the summer. (As I mentioned in my blog description, theOscar Dyson must travel the same route year after year for the pollock survey to ensure consistency in data collection).
XBT CTD locations
Beyond the Oscar Dyson, these data are collected on every NOAA cruise that I read about and that data can be used to measure how a body of water is doing in general as well as how the water column of a specific location has changed over time. For example, longitudinal data are needed to note climate change within the Bering Sea. Pretty cool huh?
Vocabulary Note: I tried to define all the new terms I used in my entry. Did you notice a term I didn’t define? Ask me about it in the comments and I will make sure to provide you with a definition.
Thought Question: In the XBT data graph, why is the X axis labeled on the top rather than the bottom? (think about your coordinate plane)
Weather Data from the Bridge Time: 1600 hrs Latitude: 57.16 N Longitude: 169.09 W Cloud Cover: Dense fog Wind: 11.56 knots Air Temperature: 5.3°C (41.5°F) Water Temperature: 5.09°C (41.16°F) Barometric Pressure: 1005.02 mb
Did I mention I completed all the tasks in the previous post before lunch? That left us time to fish for pollock in the afternoon.
Fish face
Why pollock? Walleye pollock (Theragra chalcogramma) is an important fish for Alaska (and the entire United States). Although you may not know it, you’ve probably eaten pollock when you have enjoyed fish sticks or a fish sandwich at a fast food restaurant. Also, sushi lovers, artificial crab is made from pollock surimi. Walleye pollock produce one of the largest catch of any single species within US waters and accounts for over half the groundfish catch in Alaska (see:http://www.afsc.noaa.gov/species/pollock.php for more information)
How the Oscar Dyson helps? By surveying the pollock populations within the Bering Sea, scientists can gather data on these important fish – including size, gender distribution, maturity, location, and diet.
How do we find the fish? Scientists work around the clock gathering data through acoustics to identify the locations of aggregations (or schools). The Oscar Dyson has five transducers located across the bottom of the ship on its centerboard. These transducers send out signals and the data are graphed on large computer screens in our acoustics lab (more information on the acoustics lab will come in a later post) While on shift, we eagerly await word that a fish aggregation has been identified and await the trawl.
Large Jellyfish
And the trawl… As mentioned above, we were lucky enough to spot fish during my first shift and we conducted the trawl in the afternoon. A trawl is a method where a large net is cast off the back and towed behind the boat until it fills with fish. The take varies based on the aggregations (or schools) identified and the net may be out for two minutes or an hour. This first trawl was out for 45 minutes before the crew hauled it in. It was amazing how many seabirds were swarming around the net as it was pulled up and how many jellyfish were caught in the lines. The first task, once the catch is brought on deck and placed in the fish table, is to sort the specimens. We had pollock, Pacific cod, and 2 types of jellies (including theChrysaora melanaster shown at right)
Once the catch was sorted, the fish were weighed and then sexed. After they were sorted into Blokes and Sheilas (males and females), the fish also had to be measured. A small sample was dissected to remove stomachs and otoliths (ear bones of pollock that are used by scientists to determine the age of the fish) for further study.
Animals Seen on First Shift
Euphausiids (krill)
Jellies
Pollock!!!
Pacific Cod
On our way out of Dutch Harbor and Captain’s Bay, I spent some time on the bow with Katie, Michele and birder Nate Jones. As I know very little about birds, I quizzed him on every flying specimen we encountered and used his binoculars to observe the birds up close. After a few sightings, I was able to identify the Fulmar by its unique wing movement (quick quick quick soar). We also saw tufted puffins and a black-footed albatross. There are two birders (Nate and Marty from US Fish and Wildlife Service) on this leg who are responsible for scanning the horizon and counting and identifying the seabirds they observe from the bridge.Here is bird observer Nate Jones scanning the horizon for seabirds:
Nate Jones observing
We were distracted from our bird watching by a call of orcas. We hustled up to the “flying bridge” to join the marine mammal observers. There are three “mammals” (Paula, Yin and Ernesto from the National Marine Mammal Laboratory) on this leg and they are constantly scanning the horizon with their “big eyes” to observe and identify cetaceans. I was able to observe two separate groups of orcas and heard that porpoises were also spotted.Here is marine mammalian observer Ernesto Vazquez looking through the big eyes on the flying bridge:
Ernesto observing mammals
Although I am technically on the fish shift, I hope to check in with the “birds” and “mammals” later in the cruise. After spotting birds and mammals, it’s time for the first installment of the “animals seen” list:Animals Seen in Dutch Harbor
Bald eagles
Ground Squirrel
Sea Urchin
Sea Stars
Sea Cucumber
Pigeon Guillemot
Oyster Catchers
Mussels
Chiton
Limpets
Hermit Crabs
Snails
(but no horses…)Animals Seen in Transit
Orcas
Fulmars
Black Footed Albatross
Tufted Puffin
UPDATE
As many of you know, I am a horrible speller. When I went to check the spelling for the birds I had seen, I spotted a Thick-billed Murre from the bridge. Okay, in reality, the observation and identification went more like this:
Me: “Hey that’s a bird”
Nate: “Yes, it was a Thick-billed Murre”
I am impressed by the seabird and marine mammal observers’ abilities to spot and identify birds and mammals from such far distances. Like any recall-related skill, I recognize that animal identification takes both an innate talent and years of practice. But the animal observers also need to have extreme patience to maintain a clear focus, a methodologically-sound routine and a sense of possibility (as the weather is not always in their favor). We’re lucky to have such talented scientists counting species in the Bering Sea.
As we say goodbye to land, we know the real adventure is about to begin
NOAA Teacher at Sea Richard Chewning Onboard NOAA Ship Oscar Dyson June 4 – 24, 2010
NOAA Ship Oscar Dyson Mission: Pollock Survey Geographical area of cruise: Gulf of Alaska (Kodiak) to eastern Bering Sea (Dutch Harbor) Date: June 23rd, 2010
Weather Data from the Bridge
Position: Bering Sea, east of St. George Island Time: 0450 Latitude: N 56 38.000 Longitude: W 168 28.030 Cloud Cover: overcast with patchy fog Wind: 14.0 knots from the east Temperature: 5.8 C Barometric Pressure: 1006.6 mbar
Science and Technology Log
Combining science, technology, and leadership, NOAA Commissioned Officer Corps provides skilled leaders for NOAA’s diverse programs. Numbering around 300 individuals, this group of dedicated professionals has a wide range of duties and responsibilities including operating NOAA’s ship and aircraft, managing research projects around the world, conducting diving operations, and manning staff positions on the shore. Officers are rotated every 2-3 years between ship-based and land-based positions. Before joining the Dyson as the Executive Officer for instance, Lieutenant Jeffrey Shoup worked with a satellite-based international search and rescue system as his NOAA shore assignment.
NOAA Corps emblem
All of these officers have completed rigorous training and have degrees in various fields of study relating to NOAA science such as physical oceanography, marine biology, chemistry, fisheries science, engineering, and meteorology. For example, the Dyson’s Commanding Officer, CDR Mike Hoshlyk, studied biology and geology at the University of Rochester.
Part of the U.S. Department of Commerce, NOAA Corps is one of the nation’s seven uniformed services of the United States. You are undoubtedly familiar with the other six: U.S. Public Health Service, Army, Navy, Coast Guard, Air Force, and Marines. During times of war or national emergency, NOAA Corps officers can assume duties with the Armed Forces. NOAA Corps officers have leadership and command positions on NOAA’s various vessels, aircraft, and instillations and manage programs and research efforts.
Personal Log
I wish to extend a heartfelt thank you to all the NOAA Corps officers, crew, and scientists of the NOAA ship Oscar Dyson for their support of my Teacher at Sea experience. I greatly appreciate their time and efforts making my stay comfortable and informative. I recognize that they not only allowed me to observe and learn about their workplace, but they also welcomed me into their home.
Ensign Russell Pate performing a safety demonstration
I have been continuously impressed by the professionalism and dedication of the Dyson’s NOAA Corps officers. Ensuring a safe and successful cruise for all onboard, I am grateful for the many efforts of CO Mike Hoshlyk, XO Jeff Shoup, Field Operations/Acting XO Officer Sarah Duncan, Navigation Officer Nathan Witherly, Safety Officer Russell Pate, and Medical Officer Amber Payne. I credit the entire engineering and electronics departments for their hard work ensuring that the Dyson remained in fine working order throughout the cruise. Jerry, Fred, Jim, Bob, Walter, Dave, Terry, and Steve comprised the Dyson’s engineering and electronics departments. The deck crew deserves recognition for always being ready to fish anytime day or night and for keeping the Dyson in ship shape over the last three weeks. The deck crew included Willie, Dennis, Joel, Glen, Mike, and Buddy. Special thanks to the scientists for sharing their passion for maritime research and for welcoming me as a part of their team. Paul, Patrick, Darin, Rick, Misha, Bill, Liz, Patti, Yin, Paula, and Ernesto each demonstrated personal dedication to better understanding our world’s seas and oceans. Gathering data and assisting the deck crew during the Dyson’s many deployments, Kathy and Jonathan deserve recognition for their many efforts as members of the survey department. Finally, I wish to express a word of thanks to the Dyson’s two stewards, Rick and Floyd, for keeping the crew well fed.
LTjg Nathan Witherly working on a chart
I wish to say a final word of thanks to the NOAA Teacher At Sea staff whose many efforts on my behalf made this experience possible. NOAA’s TAS program director is Jennifer Hammond. Elizabeth McMahon is the deputy director, and Elizabeth Bullock is the program support specialist. Thank you for bringing this amazing experience to life for so many teachers and students around the country.
Richard holding a Chinook salmon
Kodiak and Dutch Harbor As my TAS experience draws to a close, I reflect on where our cruise began and will conclude. Kodiak and Dutch Harbor are regular stops for the Oscar Dyson as she conducts research in the Bering Sea and Gulf of Alaska. Each community has a unique history and serves as a vital link to the outside world for the crew of Dyson.
St Paul Harbor, Kodiak, AlaskaGray whale skeleton on display at Kodiak National Wildlife Refudge Visitor Center
Kodiak is the main city on Kodiak Island and is the home port of the Oscar Dyson. Carved by retreating glaciers during the last ice age, Kodiak’s most famous resident is the massive Kodiak brown bear. The Alutiiq called this area home for thousands of years before the Russian fur traders arrived in the early 1700s. Kodiak was the capital of Russian Alaska before becoming a US territory in 1867. In 1964, Kodiak suffered a devastating tsunami from the powerful 9.2 magnitude Good Friday Earthquake. Today Kodiak is a quaint commercial fishing community surrounded by beautiful untamed wilderness.
Priest Rock marking the entrance to Dutch HarborChurch of The Holy Ascension, Dutch Harbor
Located on the on the island of Amaknak in the Aleutian Islands, Dutch Harbor is an industrial fishing outpost on the outskirts of the city of Unalaska. Dutch Harbor is a major industrial seaport serving fishing vessels of every description. Dutch Harbor is steeped in history. Hunting, fishing, and gathering for many generations, the Aleuts lived here long before Russian fur traders arrived in the mid 1700s. The Church of the Holy Ascension was built Dutch Harbor in 1825 and is the oldest Russian Orthodox church in the United States. Japanese and American military forces fought over the Aleutian Islands during the early months of the United States entry into World War II. Many concrete pill boxes and gun emplacements can still be seen along the surrounding hillsides. Dutch Harbor is defined by fishing and at one time was the largest fishing port in the US. Most people today recognize Dutch Harbor as the home of the crab fishermen portrayed in the Discovery Channel’s popular show, The Deadliest Catch.
