Tag: High-frequency Acoustic Recording

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Karen Matsumoto, April 19, 2010

NOAA Teacher at Sea: Karen Matsumoto
Onboard NOAA Ship Oscar Elton Sette
April 19 – May 4, 2010

NOAA Ship: Oscar Elton Sette
Mission: Transit/Acoustic Cetacean Survey
Geographical Area: North Pacific Ocean; transit from Guam to Oahu, Hawaii, including Wake Is.
Date: Friday, April 16, 2010

Science and Technology Log

The research mission for this cruise is to follow a transit from Guam to O‘ahu, Hawai‘i via Wake Island, and conduct an acoustic (hearing) and visual (seeing) survey of cetaceans (whales and dolphins) along the way. A transit is similar to a transect line you use to monitor our beaches in our nearshore studies! This transit study will be conducted from April 19 to May 4, 2010. This project represents important and groundbreaking research for whale biologists, since very little is known about the distribution and vocal behavior (the sounds made by whales) of baleen whales in this part of the Pacific.

Our research mission has several objectives:

  • Collect data on the presence of whales/dolphins and their abundance (how many)
  • Collect tissue samples from whales/dolphins for genetic studies
  • Collect photo identification on any whales/dolphins observed
  • Collect acoustic (sound) data on whales/dolphins to help in species identification and understanding their vocalizations
  • Collect acoustic data on fisheries to understand the distribution of prey species along the transit line
  • Recover and install underwater acoustic monitoring equipment, called a HARP (High-frequency Acoustic Recording Package), near Wake Island that will remain there for a year.

The research team consists of 12 scientists who are trained in visual observations of cetaceans and acoustic monitoring. I am part of the research team, and will fill in for staff conducting the visual observations and routinely conduct the acoustic monitoring.

The visual observation team consists of eight biologists rotating between four stations: Two “big eye” (25 x 150) binocular stations, one on the port (left) side and one on the starboard (right) side; one station forward observing with the naked eye and 7X binoculars; and one station rear-facing looking behind the ship with naked eye and 7X binoculars. Scientists work on 2-hour shifts and rotate among the scientists.

Visual observation station on flying bridge.
Research team member Adam on a “Big Eye”.

The acoustic team monitors whale vocalizations using two different methods. One method uses a hydrophone array towed behind the ship 24 hours a day (mostly to monitor toothed cetaceans, including dolphins). This hydrophone array is similar to the ones installed at Seattle Aquarium, Neah Bay, and other locations to monitor orcas and other whales in Washington State.

The other acoustic monitoring method uses Navy surplus sonobuoys (which were originally developed to detect submarines) that are launched three times a day at 0900, 1300, and 1700. The sonobuoys have a wide range in frequency response. They are able to pick up sounds between 5 Hz (cycles per second) and 20,000 Hz. Although humans have a hearing range of about 20 Hz to 20 kHz (20,000 Hz), our hearing is most sensitive between the frequencies of 1 kHz (1000 Hz) and 10 kHz (10,000 Hz). So, we can hear some of the clicks, whistles, and ‘boings’ of some dolphins and whales (‘boings’ are made by minke whales), but we have to “visually hear” others that are too low for humans to hear. The vocalizations of some baleen whales are not audible to the human ear, but are detected by the sonobuoy and are visible on the computer with the use of special software. We visually monitor from a range of 10 Hz to 240 Hz, to detect the presence of baleen whales, while listening for higher frequency vocalizations. Signals picked up from the sonobuoys are transmitted to a radio receiver on the ship. All data, including measurements of a vocalization frequency range and duration are recorded on a computer program and also logged in a hand-written journal and rerecorded on an Excel spreadsheet. All data collected will be carefully analyzed in a lab at a later date.

So far on the research cruise, there has been very little cetacean activity observed by visual observers or the scientists conducting acoustic monitoring. These waters have not been widely surveyed for cetaceans, so any data will add to the collective knowledge base of this area. As a scientist, it is important to remember that “the absence of data is data” in understanding the presence/absence and abundance of cetacean species in these deep, low productivity ocean waters.

Personal Log

The Oscar Elton Sette received its sailing orders to leave at 1500 on Monday, April 19, 2010. The generator part we were waiting on finally arrived (by way of Japan!) and we set sail promptly at sailing time. I am finally getting used to using the 24-hour clock!

Sailing orders.
Leaving the dock at Guam.
Sette’s colors flying!

We left Guam with fairly calm seas, but the winds picked up and we were soon rockin’ and rollin’! We had our “Welcome Aboard” meeting, where we learned about ship protocols and safety, as well as getting to know some of the ship’s crew. Of course, a large part of sailing preparation is the “safety drill” and I had my first “close encounter” with a survival suit! The Safety officer, Mike promptly provided me with a survival suit that actually fits much better…the first one could have accommodated two of me!

Karen in survival suit made for 2 Karens.
…and out of the survival suit! Whew!

I was ill prepared for what was to come. With high seas, and no “sea legs” I was struck by seasickness, which sent me right to my bunk to sleep—in fact that was about all I could do! We are fortunate to have a wonderful Doc on board, who provided me with the right meds and advice to be able to recover and feel human again! The greatest comfort I’ve gotten in a long time was to know that “the survival rate for seasickness is 100%!”

Doc Tran who took care of all of the seasick scientists!
My bunk, where I spent most of two days recuperating!

New Term/Phrase/Word of the Day: sonobuoy

Question of the Day: Did you know that sonobuoys were first developed by the U.S. Navy, made to be dropped from aircraft, and designed to locate submarines during WWII?

Something to Think About:

Whales migrate to tropical waters to give birth in winter and spring, and travel to colder, food rich waters for feeding during the summer.

Animals Seen Today:

• Spotted dolphin (Stenella attenuata)

Did you know?

…that scientists take tissue biopsy samples from cetaceans by using a crossbow to shoot a special dart with a metal tip that penetrates the skin and blubber then pops out. The dart has a float and string attached to one end so that it can be retrieved easily with the tissue sample (about the size of a pencil eraser) still inside the tip. Whale research scientists have to be good archers! Don’t worry, the animals rarely notice when they are darted!

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Christine Hedge, August 7, 2009

NOAA Teacher at Sea
Christine Hedge
Onboard USCGC Healy
August 7 – September 16, 2009 

Mission: U.S.-Canada 2009 Arctic Seafloor Continental Shelf Survey
Geographical area of cruise: Barrow, AK, 71°18N 156°47W
Date: August 7, 2009

Weather Data 
Cloud cover: Overcast
Temperature: 450F
Winds: E, 17 mph

Science and Technology Log 

Bringing the HARP aboard
Bringing the HARP aboard
Bringing the HARP aboard
Bringing the HARP aboard

Although the primary mission of this trip is to map the ocean floor, there are also other scientists on board doing other research. Ethan Roth is doing just such research.  He is from the Scripps Institution of Oceanography in San Diego, California.  Ethan’s specialty is ocean acoustics.  He planted two acoustic sensors on the seafloor in September of 2008 and today he retrieved both instruments.  This device is known as a HARP (High-frequency Acoustic Recording Package).  Basically, this instrument has been “listening” to the sounds of the ocean north of Barrow for almost a year.  The HARP sat at a depth of about 300 meters for all this time and today it saw daylight for the first time!  The seafloor frame sits on a steel plate, which act as ballast to keep it under the water and moored to the seafloor.  When Ethan wants it to surface, he sends it an acoustic signal to release the ballast and the HARP floats up to the surface.  A small rigid hull inflatable boat (RHIB) is used to retrieve the instrument and tow it back to the ship where it is lifted aboard.

An inside look at the HARP
An inside look at the HARP

You might be wondering why anyone would care what kinds of sounds are happening underwater in the Arctic Ocean. When the surface is frozen with sea ice, it is a very quiet place. The ice/water interface acts differently than the ice/air interface. The acoustic environment of the Arctic Ocean may be changing due to the disappearance of much of the multiyear sea ice.  In addition to losing the insulating quality the ice has for sound the amount of human activity is likely to change, as there is less ice. As the ice begins to disappear, shipping and exploration will likely increase, adding more sounds to the ocean. Less ice means more noise in the ocean environment AND less ice will mean more human activity and even MORE NOISE. It is unknown what effect this might have on marine mammals, such as whales that depend on sound for survival. Organisms in the Arctic have evolved in a certain acoustic environment.  They use sound as a tool to obtain food, migrate and communicate. If the Arctic becomes a much noisier place, how will this impact their lives?

The landing craft that took us to the Healy
The landing craft that took us to the Healy

In any science endeavor it is important to collect “baseline data”.  In other words, what were things like before one of the variables changed?  It is important data that these HARPs collect.  Knowing the acoustical environment today can help us to interpret changes in the future.

Personal Log 

Here I am in my mustang suit
Here I am in my mustang suit

The trip from Barrow, Alaska out to the USCGC Healy is usually accomplished by helicopter.  But Mother Nature was not cooperating with us. Our fresh food (delivered by plane) and the helicopter were both delayed because of weather conditions. There was heavy smoke around Fairbanks due to forest fires and fog elsewhere making flying just too risky. Being a group of problem solvers, the leaders of the science team started asking around and found a landing craft that would fit our luggage, the food cargo, and us. The Healy evaluated the plan and agreed. In a wonderful act of generosity, the Bowhead Transportation Company (a subsidiary of Ukpeagvik Inupiat Corporation) offered to take our science party and cargo to the Healy and bring the “old” science party back to shore. If we had traveled by helicopter, we would have transported a few at a time and had to make many repeat trips.  But, using the landing craft we didn’t have to worry about weight and the entire science party and cargo were able to travel at once.  Thanks to the crew of the Greta and the Bowhead Transportation Company for getting us to our destination.