Dawn White: Pinging for Populations, June 29, 2017

 

NOAA Teacher at Sea

 Dawn White

Aboard NOAA Ship the Reuben Lasker

June 19 – July 1, 2017

 

Mission: West Coast Sardine Survey

Geographic Area of Cruise: Pacific Ocean; U.S. West Coast

Date: June 29, 2017

 

Weather Data from the Bridge

Date: June 29, 2017                                                         Wind Speed: 7.7 kts

Time: 6:15 p.m.                                                                 Latitude: 4805.5N

Temperature: 12.7oC                                                      Longitude: 12520.07W

 

Science and Technology Log

The technology present on this ship is amazing and at the same time quite overwhelming.  These systems allow for data to be collected on a wide range of variables both continuously and simultaneously.  Below are a couple of photos of the acoustics room where multiple sensors are monitoring the feedback from sonar systems placed below the ship’s hull.  One of the acoustic probes sends out sound waves in a cone-like formation directly below the ship.  Another unit emits sound waves in a horizontal pattern.  The ship was designed to run as quietly as possible so as to not disturb the marine life present in the waters as the ship passes by and also to reduce the interference of the ship’s sounds with the acoustics feedback.

 

 

Acoustics technician Dan Palance managing the multiple computers that are constantly collecting data.

Multiple programs help to eliminate the “noise” received by the probes until all that remains are images that represent schools of fish and their location relative to the ocean floor.

 

The images above were taken from a poster on board the Reuben Lasker. They illustrate the range of the water column surveyed by the various acoustic systems.

 

The “soundings” are received by the ship, processed and “cleaned up” using a series of program algorithms. The image below shows the feedback received from one of the systems.

Displays of feedback from an acoustics system

Once the background “noise” has been eliminated, the resulting image will show locations of fish, school size, and the depth (y axis) at which they can be found.

Graph of acoustic feedback, with background “noise” eliminated, depicting depth and size of fish schools

 

Extension question for my students reading this:  Approximately how deep are the schools of fish being picked up by the sonar at this location?

Acoustics aren’t the only tools used to try pinpoint the locations of the fish schools.  As I wrote about on an earlier blog, the CUFES egg sampler is used to monitor the presence of fish eggs in the waters that the ship passes over.  Water samples are analyzed every half hour.  If egg samples appear in an area where there is also a strong acoustics signal, then that may be a location the ship will return to for the night’s trawl.  The main focus of this trip is to monitor the anchovy and sardine populations, so extra attention is paid to the locations where those eggs appear in the samples.

Personal Log:

Each time we drop the net for an evening trawl it is always retrieved with a bit of suspense:  What’s going to be in the net this time?  How big is the haul?  Will we capture any of the key species or haul in something completely different?

I can honestly say that while on board there were no two hauls exactly the same.  We continued to capture large quantities of pyrosomes – unbelievable amounts.  Check out the net-tearing load we encountered one night.  We literally had to weigh them by the basketful!

Here I am getting ready to help unload this large catch.

TAS Dawn White prepares to help unload large catch

 

Net-tearing load of pyrosomes!

Above is the codend of the net filled with pyrosomes and fish.  A 5-basket sample was pulled aside for analysis.  The remainder was simply classified and massed.

While I was certainly don’t need to see another pyrosome any time soon, there were plenty of other times when some very unique species made an appearance!

Pacific Jack Mackerel

Solitary Common Salp

TAS Dawn White holds a Blue Shark

Dogfish Shark

Did you know?

The dogfish shark (pictured above) was one of about 50 or so that were caught in the same haul.  We had trawled through a school that was feeding on the small fish found at the ocean surface during the evening hours.  This is the same species of shark that is commonly provided to students for dissection.  Use the search terms “dogfish shark dissection” and see what you find!

Jennifer Fry: March 15, 2011, Oscar Elton Sette

NOAA Teacher at Sea
Jennifer Fry

Onboard NOAA Ship, Oscar Elton Sette

March 12 – March 26, 2012

Mission: Fisheries Study
Geographical area of cruise: American Samoa
Date: March 15, 2012

Pago Pago, American Samoa

Science and Technology Log:

Nighttime Cobb Trawling : Day 4

We began the trawling around 8:30 p.m.  The data we collect tonight will replace the previous trawl on day 2 which was flawed in the method by which the experiment was collected. The Day 2 experiment was when the winch became stuck and the trawl net was left in the water well over 2 ½ hours, long past the 1 hour protocol.

Here’s is what the science team found.

Tonight the trawl nets went into the ocean and were timed as all the other times.

During the sorting we found some very interesting species of fish which included:

  • Pyrosomes: chordate/Tunicate
  • Two Juvenile cow fish (we placed them into a small saltwater tank to observe interesting species caught in the net.)

This is a great place to make further observations of these unique animals.

The data collected included:

Name of fish: Numbers Count Volume (milliliters) Mass (grams)
Myctophids 120 700 650
Non-Myctophids 148 84 115
Crustaceans 77 28 40
Cephalopods: 16 64 50
Gelatinous zooplankton 71 440 400
Misc. zooplankton n/a 840 900

The Cobb trawl net was washed, rinsed and the fish  strained through the net. They were then brought inside the web lab for further sorting.

The white-tailed tropic bird is a regular visitor to the South Pacific islands.

We were close to finishing the sorting, counting, and weighing when suddenly we heard something at the back door of the lab.  Fale, the scientist from American Samoa went to the door and proceeded to turn the latch, and slowly opened the door.  There huddled next to the wall, near some containers was a beautiful black and white Tropic bird, a common bird of this area.  Its distinctive feature was the single white tail feather that jutted out about 1 foot in length.  He looked just as surprised to see us and we were of him.  He did not make a move at all for about 10-15 minutes .  We took pictures and videos to mark the occasion, yet he still didn’t budge or act alarmed.

With a bit more time passing, he began to walk, or more like waddle like a duck. His ebony webbed feet made it difficult to maneuver over the open slats in the deck.  He attempted flight but appeared to get confused with the overhanging roof.

I quickly found a small towel and placing it over his head, gently carried him to a safe spot on the aft deck where he would have no trouble flying away.

The time was about 2:00 a.m. when we were distracted by the ship’s fire alarm, and  we quickly reported to our muster stations.  Luckily, there was no fire and  we returned resuming our trawl data collection.  Upon reaching the wet lab, we noticed at the stern of the ship, our newly found feathered friend had flown off into the dark night.

It was a great way to end our night with  research and early hour bird watching.  How lucky we all are to be in the South Pacific.

Animals Seen:

Ppyrosome

Pictured here is a Pyrosome which many came up in our Cobb net.

Cow fish

Our trawl net caught three juvunile cow fish specimans which were quickly placed in our observation tank for further study.

Tropical bird

The Tropic bird, with its distinctive long tail feather, is common in the South Pacific.