Tag: acoustics

NOAA Teacher at Sea

Jenny Gapp (she/her)

Aboard NOAA Ship Bell M. Shimada

July 23 – August 5, 2023 

Mission: Pacific hake (Merluccius productus) Survey (Leg 3 of 5)
Geographic Area of Cruise: Pacific Ocean off the Northern California Coast working north back toward coastal waters off Oregon.
Date: Monday, August 14, 2023

Weather Data from Portland, Oregon
Friday, August 11, 2023 (one week from our final trawl)
Sunrise 6:06am PDT | Sunset 8:24pm PDT
Current Time: 2:53pm PDT
Location: 45. 59578° N, 122.60917° W (Portland International Airport)
Visibility: 10 miles
Sky condition: A few clouds
Wind Speed: 6.8 mph
Wind Direction: NW
Barometer: 1016.80 mb
Air Temp: 82° F
Relative Humidity: 37%
Speed Over Ground (SOG): 0 knots as I sit on my front porch at home!
Willamette River water temperature: 74°F

Monday, August 14, 2023
Sunrise 6:10am PDT | Sunset 8:19pm PDT
Current Time: 2:53pm PDT
Location: 45. 59578° N, 122.60917° W
Visibility: 10 miles
Sky condition: Clear
Wind Speed: 10 mph
Wind Direction: WNW
Barometer: 1010.10 mb
Outdoor Air Temp: 105°F (record ended up at 108°F)
Relative Humidity: 21%
Indoor Air Temp: 78°F (our AC consists of several Doug Fir trees)
Speed Over Ground (SOG): 0 knots as I sit at my computer in my home office space. 
Willamette River water temperature: 75.02°F

Science and Technology Log
I’ll start my last blog post with some vocabulary… and a sports analogy. Apologies in advance, I’m testing out some sports jokes to appeal to my 5th-grade sports fans who are skeptical about science. My hope is that the vocabulary (at least) will aid in understanding the following narrative about NOAA Ship Bell M. Shimada’s Leg 3 centerboard retraction.

Don’t worry, it’s not too complicated. It isn’t that different from how rookie Trail Blazer Ibou Badji (Center) was removed for knee surgery at the end of last season… or how the other Center, Jusuf Nurkic, was ejected after an altercation with an opponent and then retracted for the remainder of the same season with plantar fasciitis… Where have all the Centers on the board gone? At least there is more certainty of Shimada’s centerboard returning than Nurkic (even though he has three years on his contract left)!

Vocabulary

Acoustics – In our case, acoustics refers to an entire branch of physics concerned with the properties of sound. Yes, acoustics can also refer to how your voice sounds when singing in the shower.

Sonar – A system for the detection of objects underwater by emitting sound pulses and detecting or measuring their return after being reflected by the objects. The vocabulary words that follow are all related to the sonar system on the Shimada.

Centerboard – A retractable hull appendage, similar to the keel on a sailboat.

Ping – To emit a signal and then listen for its echo in order to detect objects. Sean Connery may have introduced you to the concept. “Give me a ping, Vasili. One ping only, please.” (Captain Ramius, The Hunt for Red October, 1990)

Hertz – One hertz (Hz) is equal to one event per second. The unit’s most common usage is to describe periodic waveforms (as is used in acoustics) and in musical tones. Kilohertz (kHz) is equal to 10³, megahertz (mHz) is equal to 10⁶ .

Transducer – A device that converts variations in a physical quantity, such as sound, into an electrical signal, or vice versa. On the Shimada, the transducer emits a ping.

Transceiver – A device that both transmits and receives communication. There are five transceivers on the Shimada, one for each frequency—measured in kHZ—that the scientists monitor. Walkie-talkies are one example of transceivers.

Note: I have a habit of calling things by their incorrect names, and had some confusion about how a “transponder” fits into these “trans” terms. A transponder is a blend between “transmitter” and “responder.” Essentially, a device that receives a radio signal and emits a different signal in response. They are used to detect and identify objects. If you have a car key fob that locks and unlocks your doors remotely (or starts your engine), then you are walking around with a transponder. Transponders are also commonly found in airplanes.

Echosounder – A type of sonar. The Shimada uses a wideband transceiver (WBT) scientific echosounder system for the hake survey.

Echogram – The visualization of sound once the transceiver “listens” to the acoustic return pinged off objects.

Cleaning up is often a sign of good things coming to an end. Whether it’s scraping glitter glue off the tables of my library, or fish scales off stainless steel in the Shimada, both signal the end of a productive work period. On Friday night, August 4th, the Wet Lab crew conducted a deep clean of the space after the last trawl. On Saturday, the net was streamed one last time (for Leg 3 anyway) on our way back to Newport, Oregon. Creatures like pyrosomes, flatfish, and young-of-the-year (YOY) hake that had been stuck in the net were flushed out after a period of time waving goodbye in surface waters. YOY is used interchangeably with the term “fingerlings” in the vocabulary of fish development.

Another event that occurred Saturday was the raising of the centerboard. The centerboard is always raised at sea and cleaned once in port. “Biofouling mitigation” is the fancy term for centerboard cleaning. This is to ensure sea life, such as barnacles, do not adhere themselves to the surface. A build-up of these stowaways could interfere with the sonar. Hmm, I sense potential here for another sports analogy… something about fouls.  

The Survey Crew coordinates with the bridge and the engineers to retract the centerboard. Transducers are mounted on the centerboard so they can be lower than the hull. This reduces bubbles and noise. In the Shimada’s case, bubbles are air pockets created by the movement of the ship’s bow. A centerboard extends the distance between sonar equipment and the activity of bubbles gathered near the hull. When seas are rough enough there can actually be a data dropout that appears as a white line on the echogram.  

Fully extended, the centerboard is 3.4 m below the hull of the ship and 9.15 m below the baseline sea surface. There is a manual option for retracting the centerboard, but it is generally only used if there’s a problem. Automatic operations are the norm, and were used when I observed the procedure.

Officers on the bridge slow the ship to 0 knots. The bridge confirms with survey technicians which position the centerboard should be moved to. A control panel for the centerboard is located one deck below the acoustics lab. I stood with Senior Survey Technician, Elysha Agne, to observe the process for retraction. NOAA Corps crew actually push the button on the bridge for retraction, but Agne communicates over the phone with them to confirm what the centerboard control panel is indicating.

Just down the passageway from the control panel are the double watertight doors that provide access to the instrument pod on the retracted centerboard. I include a picture of these doors in the Hook, Line, and Thinker section of blog post, “Let’s Get Specific in the Pacific.”

Once the button is pushed and the centerboard is ostensibly moved, Agne confirms the indicator lights on the control panel and looks through the porthole on the watertight doors nearby to confirm the white letter “R” (for “retracted) is visible on the appendage. Agne turns off the transducers (no pinging) before retraction starts in case the transducers accidentally go out of the water.

This is important because sound travels differently through air than in water. If the transducer were still pinging while a crewmember had their head through the open centerboard access doors—that wouldn’t be good for human ears. The transducer can actually be damaged beyond repair if it pings in the air. The centerboard actually has holes in it, so it fills with water when lowered, then drains as it is raised. I could hear the water draining during the retraction process. 

Career feature

Joshua Slater, CO (Commanding Officer)
Give us a brief job description of what you do on NOAA Ship Bell M. Shimada.

I’m responsible for the safety of the ship and its 41 crewmembers (depending on the voyage), including safe navigation, accomplishment of science missions, project management, budget, personnel, and training of the crew.

What’s your educational background?

I have a Bachelor’s in Marine Biology and a Master’s in Marine Sciences both from the University of North Carolina, Wilmington. I grew up in a Navy family, so we moved all around the world. I don’t consider one place home over another. After graduation, I wanted to go to either California or Hawaii. I got a job as a contractor with NOAA doing free-diving and scuba in Hawaii as a Marine Debris Technician. I removed derelict fishing gear and nets off the coral reefs of the northwestern islands. I joined NOAA Corps after that. I attended the U.S. Merchant Marine Academy in King’s Point, New York. In the Corps, there’s a 2:3 rotation ratio in years spent on assignments at sea and on land.

I started out on NOAA Ship McArthur II. We sailed from Seattle out to Hawaii, down to South America, Mexico, and up the West Coast of the U.S. to Canada. My assignment after that was emergency response for incidents at sea such as hurricanes and chemical spills. One of those projects was on the Deepwater Horizon oil spill response down in the Gulf of Mexico. My next ship was in South Carolina on NOAA Ship Nancy Foster, where I worked from Massachusetts to Key West, to Galveston, Texas. After that were land assignments in Washington DC, then Chief of Operations at NOAA’s Marine Operations Center for the Pacific (MOC-P) in Newport, Oregon. I’ve bounced between MOC-P and the Shimada in that land-to-sea ratio since then.

In the NOAA Corps, you start out as an Ensign (pronounced “en-sin”). Within 2-3 years you usually get promoted from ensign to Lieutenant junior grade. During your first sea tour, you need to learn how to drive the ship, keep everyone safe, and understand the basics of ship operations. During your second sea tour, you help coordinate logistics for operations. On the third sea tour you’re running all the administrative functions (hiring, firing, discipline), and on the fourth time out hopefully you are experienced enough to be considered for the ship’s Captain, overseeing the safety of the whole ship, and making sure operations are done efficiently. So, as you work your way through your career you also get promoted. Beyond the rank of Lieutenant junior grade, there’s Lieutenant, Lieutenant Commander, Commander, Captain, and then Admiral.

For civilians, Ship Captain and CO may be viewed as interchangeable. In NOAA Corps you can be a commanding officer and be any number of different ranks. In the civilian world, the ship’s boss is called “Captain” or “Master.” Since NOAA Corps stems from military origins, they use “Commanding Officer.”

What took you by surprise about sailing on the ocean?

What took me by surprise was the amount of operations we could do in less-than-ideal weather. You might have a calm day on shore, but at sea it’s usually windy and you have waves of some sort. We do the best we can given the situation.

Why are conditions rougher further out at sea?

A few things. Currents. Wind. Sometimes headlands protect you from wind when you’re closer to shore. How big the waves get is a combination of how strong the wind blows, how long it blows, and over what distance of water. That’s called the fetch. That gives the time needed for the swell to fully develop based on the wind. Wind at a short distance is a wave. Once you get beyond where the wind is that localized phenomenon, further away it’s the swell. While our wind may be calm here, we may still have a big swell because there’s a storm off Hawaii or Alaska. We’re not feeling the wind but we’re feeling the side effects. Or we could just be in the wind, it’s blowing 50, and not that bad right now, but give it 12 hours to develop, 24 hours, and it’s going to be a lot worse. You do what you can given what you have to work with. The ship is seaworthy and can handle a lot of different conditions. 

What’s the biggest weather you’ve been in on the Shimada?

Probably 20-foot waves, although waves are not consistently one height, they’re a range. They may be normally 16-18 feet, but you might get a 22-foot wave come through. The ones I’ve been in consistently were about 20.

At what point is it not safe to conduct operations?

It depends what the wind is, what the swell is, whether they’re from the same direction or opposing directions, or 90 degrees off. Sometimes our whole project is in the trough, which means the waves are hitting us from the sides, so we’re rolling a lot. The way transects are laid out for trawling and sampling gets us rolling a lot. If it’s really bad we’ll angle our way from one location to another. We do have safety standards for operations. Once the wind is above a certain limit, or the waves above a certain range in height, we’ll reassess. Usually, we reassess the operation if wind is over 30 knots, but we’ve done ops in 40 knots before. We’ve also done ops in 16-foot waves. There are a lot of variables to be considered, including the type of operation we’re attempting to execute.

We’ll get people who have never been out here before, or we’ll get people that are so focused on the science, they don’t think about safety. My job is to make sure they don’t forget about safety! We have a daily safety meeting of department heads on the ship. There are weekly drills at sea. During monthly safety meetings, we go over accidents in the NOAA fleet. It’s a lot easier to learn from other people’s mistakes. We all want to come home with our fingers and toes!

What advice do you have for a young person interested in ocean-related careers?

Grow where you’re planted. In NOAA Corps, you don’t get to necessarily choose the jobs where you go next. A board of officers chooses for you, based on your skill set and the needs of the service at that time. For example, I can list my preferences, but there’s no guarantee I will get any of them. There have been many times where officers haven’t even received their second or third choice. My advice to everyone is, you may not want to go to a particular assignment or a particular part of the country, but you’re there, so make the most of it. Every place I have been assigned has good qualities, good things to offer. Those are what I choose to focus on. When I talk to some people, they never seem happy no matter where they are.  I think that is a mindset issue. One of my favorite quotes is, “Positivity is a superpower.” The term “Shimada-tude” got its start in the early days of the ship’s service to NOAA and is all about positivity. We want to like what we do and want people to like coming out to sea. We want them to have a good experience, and treat everyone with respect. 

Do you have a favorite book?

Growing up I often looked for the Newbery Prize Medal seal or the Newbery Honor seal on a book cover when I was walking through the library. I figured if somebody liked it I might as well try it. It’s hard to pick just one book. I tried a lot of the classics and have made my way through most of “The 100 Greatest Books Ever Written.” Some were enjoyed while others were not. I remember taking an interest in The Odyssey and The Iliad, by Homer; Robinson Crusoe, by Daniel Defoe; Shipwrecked, by Robert Louis Stevenson; The Phantom of the Opera, by Gaston Leroux; and Dracula, by Bram Stoker—to name a few. 

Lately, I’ve been reading more and more about financial education. One book I recommend is The Richest Man in Babylon, by George Samuel Clason. It uses fictitious ancient parables to give you sound monetary advice, and that is something that I don’t think is really taught anymore.

As for children’s literature, I’ve recently read a few of the Harry Potter books with my son. I remember reading and enjoying The Chronicles of Narnia series, by C.S. Lewis, Island of the Blue Dolphins, by Scott O’Dell; and Where the Red Fern Grows, by Wilson Rawls. 

Floating (Food) Facts (& Opinions)

Here’s the part where we “Let them eat hake.” If you can get your hands on some hake through a company like Pacific Seafood (headquartered in Clackamas, Oregon), then you can decide for yourself whether all this fuss over hake is worth the hype.

Hake (Pacific Whiting) is the most abundant commercial stock on the Pacific Coast.

If you aren’t into hake but consume other seafood, use Fish Watch. NOAA Fisheries hosts sustainable seafood profiles with current information on marine fish harvested in the U. S.

The first couple of paragraphs on the Fish Watch site define “sustainable seafood:”

“Sustainable seafood is wild-caught or farmed seafood that is harvested or produced in ways that protect the long-term health of species populations and ecosystems. The United States is a global leader in sustainable seafood. U.S. fishermen and seafood farmers operate under some of the most robust and transparent environmental standards in the world. If the seafood you purchase is caught or farmed in the United States, you can feel confident you’re making a sustainable seafood choice. 

Marine wild-capture fisheries in the United States are scientifically monitored and regionally managed. They are enforced under 10 national standards of sustainability through the Magnuson-Stevens Act—exceeding the international standards for eco-labeling of seafood.”

You may have stood in front of the seafood counter and noticed those green (best choice) and yellow (good alternative) labels. I have yet to see red, which means avoid, which seems counter to the marketing impulse of grocery stores. These labels are based on the Monterey Bay Seafood Watch guidelines. Here’s a pocket guide for my West Coast friends. There are a handful of seafood guides you can consult, but not all are created equal. This article from 2017 captures the frustration consumers sometimes have about what fish to choose.

Part of my confusion is often based on the many names a single species has! For example, I just now learned (on the NOAA Fish Watch site) that Bocaccio are rockfish and are the Oregon Red Snapper I recall from shopping trips and meals as a kid. For me, the thing that makes NOAA’s Fish Watch site superior to the rest is the comprehensive overview of each species profiled. You get detailed sections on Population Status, Appearance, Biology, Where They Live, Fishery Management, and Harvest all in one place. Bon appetit!

Personal Log

Fog persisted on our steam north back to Newport. Without the temptation of visibility on the flying deck, I took extra time vacuuming the stateroom… that’s a joke because vacuuming a 4-person stateroom takes all of 5 minutes. In truth, my roommate and I took care to leave our space Pine-Sol fresh for Leg 4. After packing away my gear I bounced around the ship like you might in a hotel room—surreptitiously checking drawers for items you may have forgotten. That last nautical mile seemed to take forever. I kept looking out of the portholes in the acoustics lab to see nothing but white. Excitement for home began to build once it was time to gather on the flying deck and peer through the misty water vapor. Yaquina Bay Bridge slowly materialized, an elevated street floating in the sky, weirdly disembodied from the solid ground that usually frames it. As we went under the bridge the fog disappeared. Beyond, an 80° Oregon summer in the Willamette Valley beckoned. The Wet Lab Crew ate dinner together while the crew of the Shimada safely docked and worked with the port crew to reattach the gangplank. After hugs and handshakes all around it was time to part. My drive home was uneventful save a dramatic sky. 

A HUGE thank you to the Shimada crew aboard Leg 3! You welcomed me, answered my questions, allowed me to look over your shoulder, tolerated me taking photographs of you, and clarified things I didn’t understand. You all are amazing. I appreciate your labor and am thrilled to have witnessed you all working in sync to do science! My students at Peninsula thank you as well—even if they don’t know it yet. Your time and attention will enhance not just one, but many ocean-related lessons I share with them in the forthcoming year. A special thanks to my blog editors: Chief Scientist Steve de Blois and XO CDR Laura Gibson. Your feedback polished these meanderings and gave me confidence that I correctly represented NOAA and the hake. 

You Might Be Wondering…

What Next?

To complete my commitment to NOAA as a Teacher at Sea I agree to blog, write one science-related lesson, one career-related lesson, and either present at a conference or publish an article about my experience. I’m back in my school building this week and will soon be working on lessons. At least part of the science lesson will follow the path of hake otoliths (ear bones) from the ocean to the lab back on land. Many thanks to Liz Ortiz, Fisheries Technician, for helping me connect the dots on how the otolith contributes to our understanding of Pacific whiting (hake) life cycles. I’ve decided to publish an article, although I will likely also present at a conference in years to come. I have reviewed children’s books for the national journal, School Library Connection, since 2011, and will start my query for publication there.

Hook, Line, and Thinker

Do you eat or consume products harvested from the ocean? Where do those products come from?

If the country of origin for products consumed isn’t the U.S. does that country have an equivalent of NOAA that gathers data and prioritizes sustainability in its policies? For context, consider this recent article from NPR: Demand for cheap shrimp is driving U.S. shrimpers out of business. I’m doing a homemade pad thai recipe this week and reading this motivated me to pay attention to where my shrimp came from. All the shrimp choices at Fred Meyer (Kroger) were imported so I went elsewhere (paid more) and found some from the Gulf of Mexico, harvested in U. S. waters. 

While you’re eating your own pad thai with U. S. shrimp, or Pacific whiting mac ‘n cheese, consider NOAA Fisheries first-ever National Seafood Strategy, just released on August 9th, 2023.

A Bobbing Bibliography: Reflections of a Librarian at Sea

Additions to the Science Crew’s Reading Recommendations:

Chris Hoefer, OSU marine mammal & seabird project – The Three-Body Problem, science fiction by Liu Cixin (Scientific American article about the concept behind the name.)

Samantha Engster, eDNA Scientist – The Shell Collector, short stories by Anthony Doerr

***

Parting thoughts from your Teacher-Librarian at Sea as inspired by quotes from a few children’s literature classics.

“Look at that sea, girls—all silver and shadow and vision of things not seen. We couldn’t enjoy its loveliness any more if we had millions of dollars and ropes of diamonds.”
― Lucy Maud Montgomery, Anne of Green Gables

In my current reading of this quote, I can’t help but immediately extract the tension between commerce and being. It seems to be a theme I have returned to again and again throughout my blog posts. To be, to exist on our planet, is dependent on a healthy ecosystem, and a healthy ocean. NOAA Fisheries leans on the scientific method to tackle a barrage of pressures: consumer demand, climate change, economic prosperity, pollution.

We would do well to remember that NOAA is made up of ordinary people. The government, by the people and for the people. Many of these you have met in my interviews. I was at a dinner party recently (since I’ve returned to land) and there’s always someone in the crowd who makes half-joking remarks about “the government.” What? You killed fish in the name of science? What? Do the fisherman have the same opportunity to trawl? C’mon. Who do you think “the government” is made up of? Your uncle with a Ph.D. in physics. Your daughter with a passion for birds. “Things not seen,” are confusing, intimidating, sometimes scary. NOAA is utterly transparent. The amount of unfettered data available for citizen scientists to freely examine on the internet is mind-boggling. Keep asking questions, then ask more questions! Then do some research—ask a librarian for help!

“The sea, the sea, the sea. It rolled and rolled and called to me. Come in, it said, come in.”
― Sharon Creech, The Wanderer

It said “Come in” the loudest when smooth and glassy. While there were no swimming opportunities on board the Shimada, I have since returned to swimming at my local health club. While doing laps and staring at the dirt, hair bands, and Band-Aids at the bottom of the pool I thought about the chemicals, hair bands, and Band-Aids at the bottom of the ocean. This is not what the sea meant when she said, “Come in.” NOAA Fisheries is an integral part of the solution to the problems that face us as a species. Homo sapiens is only one of many species that have a right to thrive—both for our benefit and their own.

“The castle of Cair Paravel on its little hill towered up above them; before them were the sands, with rocks and little pools of salt water, and seaweed, and the smell of the sea and long miles of bluish-green waves breaking for ever and ever on the beach. And oh, the cry of the seagulls! Have you ever heard it? Can you remember?”
― C.S. Lewis, The Lion, the Witch and the Wardrobe

While perusing a glossary of nautical terms in the downtime after a marine mammal watch, I discovered “caravel” a small, highly maneuverable sailing ship used by the Portuguese in the 15th and 16th centuries. The Niña and the Pinta, of 1492 notoriety, were caravels. I wondered whether this term had inspired C. S. Lewis’ naming of Cair Paravel. I will not remember the cry of seagulls so much as I will the cat-like meow of the common murre, at least that’s what they sounded like to me at the time. I’m a compulsive Googler, so that’s how I came upon this Minecraft version of Cair Paravel.

It made me think of my students and how NOAA scientists are the stars of real-world exploration and discovery. Scientists are also world-builders of a sort—reports on their findings influence policy-makers, lawmakers. As science moves forward, it continuously corrects itself as new things are discovered. Listening to the latest science can make or break the world.  

And oh, the cry of the scientists! Have you ever heard it? Can you remember?