Tag: acoustics

Posted on

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!

Posted on

Jennifer Fry, July 26, 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 26, 2009

Weather Data from the Bridge 
Wind speed: 10 knots
Wind direction: 100° [from the east]
Visibility: fog
Temperature: 13.5°C (dry bulb); 13.5°C (wet bulb)
Sea water temperature: 10°C
Wave height: 1ft.
Swell direction: 315° Swell height:  6 ft.

Here I am checking HAB samples.
Here I am checking HAB samples.

Science and Technology Log 

We conducted a number of HAB, Harmful Algal Bloom sample tests. The Harmful Algal Bloom test takes samples at predetermined location in our study area. The water is filtered to identify the presence of toxic plants (algae) and animals (zooplankton). The plankton enter the food chain specifically through clams and mussels and can be a possible threat to human health.

We also conducted XBTs, Expendable Bathythermograph; and one  fishing trawl net. The trawling was successful, catching hake, squid, and Myctophids.  Fishery scientist, Melanie Johnson collected specific data on the myctophids’ swim bladder.  The swimbladder helps fish regulate buoyancy.  It acts like a balloon that inflates and deflates depending on the depth of the fish. Sharks on the other hand have no swim bladder. They need to swim to maintain their level in the water. Marine mammals such as dolphins and whales have lungs instead of a swimbladder.  Most of the sonar signal from the fish comes from their swimbladder.  The study of the swimbladder’s size helps scientists determine how deep the fish are when using the sonar signals and how strong their sonar signal is likely to be.

Commander Mike Hopkins, LTjg Oliver Brown, and crewmember John Adams conduct a marine mammal watch on the bridge before a fishing trawl.
Commander Mike Hopkins, LTjg Oliver Brown, and crewmember John Adams conduct a marine mammal watch on the bridge before a fishing trawl.

The scientists tried to conduct a “swim through” camera tow, but each time it was aborted due to marine mammals in the area of the net. During the “Marine Mammal Watch” held prior to the net going in the water, we spotted humpback whales. They were observed breeching, spouting, and fluking. The humpback then came within 30 feet of the Miller Freeman and swam around as if investigating the ship.

Animals Seen Today 
Fish and animals trawled: Hake, Squid (Cephalopod), and Myctophids.
Marine Mammals: Humpback whale.
Birds: Albatross, Fulmar, and Shearwater.

Posted on

Jennifer Fry, July 24, 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 24, 2009

Pacific White-Sided Dolphins
Pacific White-Sided Dolphins

Weather Data from the Bridge 
Wind speed: 24 knots
Wind direction: 355° from the north
Visibility: clear
Temperature: 17.3°C (dry bulb); 15.5°C (wet bulb)
Sea water temperature: 9.8°C
Wave height: 3 ft.
Swell direction: 350°
Swell height: 5-6 ft.

Science and Technology Log 

There is an abundance of marine life in the ocean today: sightings include a humpback whale breaching and spy-hopping.  Breaching is when a whale jumps out of the water.  Spy-hopping is when the whale’s head comes out of the water vertically and “takes a peek” at his surroundings. We also sighted the Pacific white-sided dolphins that appeared to be “playing” with the ship.  They would swim perpendicularly to the ship’s hull and at the last minute; veer away at a 90° angle. The dolphins were also swimming alongside the bow and the side of the ship.

Beautiful view
Beautiful view

The sonar signals indicate an abundance of marine life under the sea and the presence of marine mammals helps us draw that conclusion. All that life is probably their prey. We made 2 fishing trawls which included hake and 2 small squid, split nose rockfish, and dark, blotched rockfish. That was the first time I had seen rockfish.   They are primarily a bottom dweller. Scientists don’t want to catch too many rockfish because they tend to be over fished and their numbers need to be protected. Also, we only want to catch the fish species we are surveying, in this case, hake. The scheduled camera tow was cancelled because we did not want to catch marine mammals.  The camera tow is described as a net sent down to depth that is opened on both sides.  It takes video of the fish swimming by.  This helps the scientists determine what species of fish are at each particular depth, during which the fish are not injured for the most part.

Personal Log 

It was very exciting to see the humpback whale and dolphins today.  They appeared to be very interested in the ship and it looked like they were playing with it.  It was a perfect day with the sun shining and calm seas.

Question of the Day 
What are ways scientists determine the health of the ocean?

Did You Know? Breaching is when a whale jumps out of the water.   Spy-hopping is when the whale’s head comes out of the water vertically and “takes a peek” at his surroundings.

Animals Seen Today 
Marine mammals: Pacific white-sided dolphins, California sea lion, and Humpback whale: spy hopping.
Birds: Fulmar, Shearwater, Albatross, and Skua.
Fish: Hake, Split nose rockfish, and Dark Blotched rockfish.

Ode to the Miller Freeman 
As the chalky white ship, the Miller Freeman cuts through the icy blue waters of the North Pacific Ocean,
I stand in wonderment at all I see before me.
A lone Pacific white-sided dolphin suddenly surfaces over the unending mounds of waves.
A skua circles gracefully negotiating up and over each marine blue swell
Off in the distance, the band of fog lurks cautiously, waiting its turn to silently envelop the crystal blue sky.
Watching this beauty around me I have arrived, I am home.

Posted on

Jennifer Fry, July 23, 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 23, 2009

Here I am in the lab helping with the HAB samples.
Here I am in the lab helping with the HAB samples.

Weather Data from the Bridge 
Wind speed: 15 knots
Wind direction: 350°from the north
Visibility: clear
Temperature: 12.0°C (dry bulb); 11.8°C (wet bulb)
Sea water temperature: 9.7°C
Wave height: 2 ft.
Swell direction: 000°
Swell height: 4 ft.

Science/Technology Log 

We began the day conducting 2 HAB (Harmful Algal Bloom) sample tests of the ocean. This tests the amount of plankton in the water.  Scientists test this because some plankton can carry harmful toxins that can get into the fish and sea life we eat, such as clams. Later we sighted numerous marine mammals including: 2 humpback whales (breaching), 12 Pacific white-sided dolphins, and California sea lions.

Acoustic data
Acoustic data

We made two trawls which provided plenty of hake for us to observe, measure, and collect data.  Acoustic Judging:  One important aspect of the acoustic hake survey is what scientists do when not trawling.  There is a process called judging that fishery biologist, Steve De Blois spends most of his day doing. While looking at acoustic data, he draws regions around schools of fish or aggregations of other marine organisms and assigns species identification to these regions based on what he sees on the acoustic display and catch information gathered from trawls.  He uses 4 different frequencies to “read” the fish signals—each shows different fish characteristics. Having started at the Alaska Fishery Science Center in 1991, this is Steve’s 19th year of participating in integrated acoustic and trawl surveys and his eighth acoustic survey studying Pacific hake. He’s learned how to read their signs with the use of sonar frequencies and his database. Steve tells us about the importance of science: “Science is a methodology by which we understand the natural world.” 

Pacific white-sided dolphin
Pacific white-sided dolphin

New Term/Phrase/Word Pelagic: relating to, living, or occurring in the waters of the ocean opposed to near the shore. In terms of fish, this means primarily living in the water column as opposed to spending most of their time on the sea floor. 

Steve De Blois, NOAA Research Fishery Biologist, shares acoustic datawith Julia Clemons, NOAA Oceanographer, aboard the Miller Freeman.
Steve De Blois, NOAA Research Fishery Biologist, shares acoustic data
with Julia Clemons, NOAA Oceanographer, aboard the Miller Freeman.

Did You Know?
Northern fur seals are pelagic for 7-10 months per year. Pelagic Cormorant birds live in the ocean their entire life.

Humpback whales
Humpback whales

Animals Seen Today 
Humpback whales (2), Pacific white-sided dolphin (12), California sea lions (6), and Northern fur seal.

Humpback whale breaching
Humpback whale breaching

In Praise of…Harmful Algal Bloom Samples 
Crystal cold ocean water running through clear plastic pipes
Be patient as containers are carefully rinsed out three times.
The various sized bottles are filled with the elixir of Poseidon
Accurate measuring is essential.
Consistency ensures accurate results.
Once the water is filtered, tweezers gently lift plankton-laden filter papers.
All samples await analysis in the 20°F freezer.
Data from each test is later recorded;
Levels of domoic acid,  Chlorophyll,
And types, populations, and species of phytoplankton and zooplankton.

Posted on

Jill Stephens, June 18, 2009

NOAA Teacher at Sea
Jill Stephens
Onboard NOAA Vessel Rainier 
June 15 – July 2, 2009 

Mission: Hydrographic Survey
Geographical area of cruise: Pavlov Islands, AK
Date: June 18, 2009

Weather Data from the Bridge 
Position 55° 10.089’N 161° 52.801’W
Broken cloud cover
Wind variable and light
Pressure 995.9
Temperature: Sea; 6.1°C;  Dry Bulb; 8.3°C; Wet Bulb; 7.8°C

The Reson monitor displays the sonar return captured by the receiver on the bottom of the boat.
The Reson monitor displays the sonar return captured by the receiver on the bottom of the boat.

Science and Technology Log 

The launch leaves the ship every day to go to spots within the survey area to collect data regarding the bottom for depth, possible anchorage sites and potential navigational hazards.  Our boat was responsible for covering the long area referred to as the fairway, which is necessary in this uncharted area so that the launches can transit to and from the working areas safely, and move on to another area upon completion.

The chart of the area is “painted” with color depicting the depth of the area based upon the return form the sonar. The goal is to “paint” your assigned area. The numbers in the lower right of the screen indicate the depth in meters.
The chart of the area is “painted” with color depicting the depth of the area based upon the return form the sonar. The goal is to “paint” your assigned area. The numbers in the lower right of the screen indicate the depth in meters.

The inside of the cabin of the launch reminds me of Star Wars. There are pieces of electronic equipment everywhere!  One of the survey team members sits in the command center to monitor and control the Reson collection and additional software that displays a 3-D image of the sea floor surface. As the coxswain pilots the boat over the surface of the water, low frequency sonar is emitted from the transducers.  The sonar hits the sea floor and is then bounced back to a receiver on the underside of the boat.  The pings are recorded by the equipment and stored in the computer. 

The CTD is attached to a cable operated by a winch. The CTD acclimates to the water surface temperature before being lowered steadily to the bottom. The equipment is raised to the surface using the winch and then brought aboard. The CTD is connected to the computer for data retrieval.
The CTD is attached to a cable operated by a winch. The CTD acclimates to the water surface temperature before being lowered steadily to the bottom. The equipment is raised to the surface using the winch and then brought aboard. The CTD is connected to the computer for data retrieval.

There are factors that affect the accuracy and quality of the information.  Boat speed, conductivity of the water, pitch and roll, yaw, and tides must be accounted for in order obtain usable data. There is equipment on board that collects the pitch, roll, yaw, and geographic position information to correct merge with the data to make corrections.  The CTD apparatus is placed into the water while the boat is stopped. The cast of the CTD will collect salinity, temperature, and pressure information at depths from the surface to the bottom. This information is also sent to the computer to provide a more accurate reading of the sonar data received by the Reson system.  Casts of the CTD must be made a minimum of every four hours to account for any changes between points in the survey area.

Personal Log 

Here I am manning the computers onboard the launch used to collect sonar depth and bottom information in the Pavlof Islands, Alaska.
Here I am manning the computers onboard the launch used to collect sonar depth and bottom information in the Pavlof Islands, Alaska.

Shawn, Todd, and Dennis were on my launch today. Once the equipment was powered up and the software programs selected, I was able to sit at command center and control collection and storage of data. The raw data is merged with the corrective information and submitted to Caris, another software program that also creates models of the findings. We were using a laptop to merge the data and begin field processing of the data. I was able to assist with this process too.

Two whales surfaced near the survey launch early in the morning near Bluff Point in the Pavlof Islands.
Two whales surfaced near the survey launch early in the morning near Bluff Point in the Pavlof Islands.

Animal Sightings 

This morning was a great day to see whales!! We spotted 5 blows!  We were then able to see the whales breach the surface at a distance.  Three of the whales moved closer to us. There were two adults and a juvenile. The juvenile was very playful and kept poking his head above the surface.  The two adults came closer to the launch and we were able to get some great shots of their bodies!! On the way back to the ship, we saw four more blows. Total sightings of whales: 9 Puffins as always are out there. They are very strange, somewhat silly birds…. 

New Vocabulary Gain: how hard an object is listening to the sound emitted by the sonar Sound Speed: speed at which sound is able to travel (This will vary in water depending upon the factors like salinity and temperature.)

Absorption: refers to how much of the sound is absorbed by the medium and varies with the medium’s composition and other factors including temperature.