Donna Knutson: Dredging, June 16, 2016

NOAA Teacher at Sea Donna Knutson
Aboard R/V Hugh R. Sharp
June 8 – June 24, 2016

 

2016 Mission: Atlantic Scallop/Benthic Habitat Survey
Geographical Area of Cruise: Northeastern U.S. Atlantic Coast
Date: June 16, 2016

 

Dredging

 

Mission and Geographical Area: 

The University of Delaware’s ship, R/V Sharp, is on a NOAA mission to assess the abundance and age distribution of the Atlantic Sea Scallop along the Eastern U.S. coast from Mid Atlantic Bight to Georges Bank.  NOAA does this survey in accordance with Magnuson Stevens Act requirements.

Me hat

Science and Technology:

Latitude:  40 32.475 N

Longitude:  67 59.499 W

Clouds: overcast

Visibility: 5-6 nautical miles

Wind: 7.4 knots

Wave Height: 1-4 ft.

Water Temperature:  53 F

Air Temperature:  63 F

Sea Level Pressure:  29.9 in of Hg

Water Depth: 103 m

 

Science Blog:

Paired with the HabCam, dredging adds more data points to the scallop survey and also to habitat mapping.   Various locations are dredged based on a stratified random sampling design.  This method uses the topography of the ocean bottom as a platform and then overlays a grid system on top. The dredged areas, which are selected randomly by a computer program, allow for a good distribution of samples from the area based on topography and depth.

Vic and Tasha sewing up the net on the dredge.

Vic and Tasha sewing up the net on the dredge.

A typical dredge that used for the survey is similar to those used by commercial fisherman, but it is smaller with a width of 8 ft. and weight of 2000 lbs.  It is towed behind a ship with a 9/16 cable attached to a standard winch.  Dredges are made from a heavy metal such as steel and is covered in a chain mesh that is open in the front and closed on the other three sides making a chain linked net made of circular rings.

A fisherman’s dredge has rings large enough for smaller animals to fall through and become released to the bottom once again.  The dredge in a survey has a mesh lining to trap more creatures in order to do a full survey of the animals occupying a specific habitat.

There are three categories of catch received in a dredge: substrate, animals and shell.  A qualitative assessment on percent abundance of each is done for every dredge.  Not all animals are measured, but all are noted in the database.

Dredge being dumped on sorting table.

Dredge being dumped on sorting table.

A length measurement is taken for every scallop, goosefish (also called monkfish), cod, haddock, as well as many types of flounder and skate. A combined mass is taken for each species in that dredged sample.  Some animals are not measured for length, like the wave whelk (a snail), Jonah crab, and fish such as pipefish, ocean pout, red hake, sand lance; for these and several other types of fish, just a count and weight of each species is recorded.

Sorting the dredged material.

Sorting the dredged material.

Other animals may be present, but not

counted or measured and therefore are called bycatch.  Sand dollars make up the majority of bycatch. Sponges, the polychaete Aphrodite, hermit crabs, shrimp and various shells are also sorted through but not counted or measured.

Ocean pout

Ocean pout

All of the dredge material that is captured is returned to the ocean upon the required sorting, counting and measuring.  Unfortunately, most of the fish and invertebrates do not survive the ordeal.  That is why it is important to have a good sampling method and procedure to get the best results from the fewest dredge stations needed.

Goosefish, often called Monkfish, eat anything.

Goosefish, often called Monkfish, eat anything.

The dredge is placed on the bottom for only fifteen minutes.  There are sensors on the frame of the dredge so computers can monitor when the collection was started and when to stop.  Sensors also make certain each dredge is positioned correctly in the water to get the best representation of animals in that small sample area.

Entering the name of the animals to be measured.

Entering the name of the animals to be measured.

Even with sensors and scientists monitoring computers and taking animal measurements, the dredging can only give a 30-40% efficiency rating of the actual animals present. Dredging with the aid of the HabCam and partnerships with many scientific organizations, along with data from commercial fisherman and observer data, create a picture of abundance and distribution which can be mapped.

Adductor muscle the "meat" of the scallop. This on is unhealthy.

Adductor muscle the “meat” of the scallop. This one is unhealthy.

In the scallop survey the emphasis is on where are the most scallops present and this aids fisherman in selecting the best places to fish.  The survey also suggests where areas should be closed to fishing for a period, allowing scallops to grow and mature before harvesting.

This management practice of opening closed areas on a rotational basis has been accepted as beneficial for science, management, and fishermen. This method of balancing conservation and fishing protects habitats while still supplying the world with a food supply that is highly valued.

Personal Blog:

Being part of a dredging team is exciting.  It is a high energy time from the moment the contents are dropped on the sorting platform to the end when everything is rinsed off to get ready for the next drop.

Katryn "Kat" Delgado

Kateryn “Kat” Delgado

I wanted to take pictures of everything, but with gloves on it was hard to participate and help out or just be the bystander/photographer. Kateryn Delgado from Queens NY, a volunteer/student/scientist/yoga instructor/photographer, was very helpful.  She was involved in other surveys and often took pictures for me.

I did find it sad that the animals we sorting were not going to live long once returned to sea, but that is a part of the dredging that is inevitable.  Raw data needs to be collected.  After measuring, a percentage of the scallops were dissected to get their sex, abductor muscle (meat), and stomach.  Shell size was compared to the meat and gonad mass and is also used to age the scallop.  The stomach was removed to test for microplastics.  Dr. Gallager and his research team are studying microplastics in the ocean.   Scallops filter relatively large particles for a filter feeder, and therefore are a good species to monitor the abundance of plastics at the bottom of the ocean.DSCN7891 (2)sunset

The weather has been nice, not very warm, but the waves are low.  Just the way I like them.  We are making our way back to Woods Hole to refuel and get groceries.  I didn’t realize we would split up the leg into two parts.  We should be in around 10:00 a.m.  I’m going to go for a long walk since there is not a lot of opportunity for exercise on the ship.  Hope it’s sunny!

 

Jennifer Fry: March 25, 2012 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 25, 2012

 

The plankton net is towed alongside of the ship. Scientists have collected what appears to be synthetic material in the tows. These are examined by scientists using a microscope.

The 1 meter oblique plankton net collects marine debris that is analyzed in the lab.

Microplastics Operations

NOAA scientist, Louise Giuseffi  heads the microplastic study aboard  the Sette.  She is monitoring plastics in the waters of American Samoa by conducting trawls both on the surface and at depth using several types of plankton nets:

  • The Manta Net is a smaller unit that collects plankton and plastics at the surface.
  • The Issacs Kidd is a larger surface net that filters greater volumes of water.
  • The 1-meter ring oblique net collects throughout the water column down to approximately 230 meters.

She hopes to conduct qualitative studies on plastics asking the question, “Are plastics present in the South Pacific Gyre?” Back in the lab, she plans to analyze each sample to conduct quantitative studies asking, “How much plastic is in the ocean?” In addition, she’s also looking to answer the question, “Are fish consuming plastic?” She will answer these questions by collecting plankton tow samples and analyzing stomach contents of fish caught in American Samoan waters.  Back in lab, she will determine if fish are in fact consuming plastics as part of their diet.

The theory is that different plastics have different densities depending on their chemical composition. If the plastic is less dense than salt water, it will float in the ocean. If the plastic is denser than salt water, it will sink. In this way, plastics are not necessarily at the surface. Plastics photodegrade and break into smaller pieces from sunlight and the elements.  It is important to note that plastic will never breakdown into its original chemical components.  Plastic will not biodegrade.

She hopes to find if there is a presence of plastic in the South Pacific Gyre, and bring awareness to the world-wide problem of plastics in our oceans and in our food chain. “To date we have found synthetic debris in nearly every sample using visual analysis.   There are pieces of debris that appear to be plastic, however this will need to be confirmed by  further investigation in the lab,”  says Louise.

Louise’s studies are on the cutting edge, and she is forging a new path in marine microplastics  studies.  To date, there is very little information on debris in the water of the South Pacific Gyre and Louise is attempting to expose the presence of plastics in the oceans as a world-wide problem.

For more information about marine plastics and debris go to:

NOAA’s Marine debris site:  http://marinedebris.noaa.gov/

Five Gyres Institute : 5gyres.org

Charles Moore website: http://www.algalita.org/about-us/bios/charles.html

 

Animals seen:

hatchet fish

sculpin

These sculpin fish and other deep water fish were caught in the Cobb net deep water trawl conducted in the early morning hours.

tang fish

Silver lancet fish

This silver lancet fish was caught during small boat fishing in the waters off American Samoa.

This lancet fish was caught today during small boat operations.

Personal Log:

My time on NOAA ship Oscar Elton Sette has been such an incredible learning experience for myself  personally, and for what I will bring back to my students.   My profound gratitude goes out to the dedicated science team, NOAA Corps, and crew aboard the  Sette  for all they have taught me.

Wishing you fair winds and following seas.

Jennifer Fry: March 9, 2012, 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 9, 2012

Personal Log

Pago Pago

With the morning light, the island’s landscape came into view.  Looking back toward land was the single road, a variety of buildings, consisting of numerous churches, restaurants, schools, and hotels.  I have come to learn that each small village has its own church and outdoor meeting hall.  Behind the buildings the topography extended upward forming a steep hillside covered with green, lush tropical plants, including a variety of palms and fruit trees laden with mangoes and papayas.

After a hearty Samoan breakfast with ten of the scientists that will be on the research vessel, we met with representatives from the local marine sciences community at the American Samoan government building.  Chickens, chickens, and a small clutch of baby chickens happily pecked on the lawn in front of the building which put a smile on my face.

These chickens found their home in front of the Government Building of Pago Pago, American Samoa.

Scientific Log

The chief scientist, Dr. Donald Kobayashi, began by introducing the team of scientists and gave a brief overview of the upcoming mission aboard NOAA Ship Oscar Elton Sette.

The variety of investigations that will be conducted during these next 2 weeks which include:.

  1. Midwater Cobb trawls:  Scientists, John  Denton, American Museum of Natural History, and Aimiee Hoover, acoustics technician , Joint Institute for Marine and Atmospheric Research of the University of Hawaii, will conduct nighttime tows that will focus on epipelagic and pelagic juvenile reef fish and bottomfish species.
  1. Bot Cam: Using a tethered camera that is later released to float to the surface, and using acoustics–a.k.a. sonar readings–scientists Ryan Nichols, Pacific Islands Fisheries Science Center , Meagan Sundberg, Joint Institute for Marine and Atmospheric Research of the University of Hawaii, and Jamie Barlow , Pacific Islands Fisheries Science Center, will collect samples of fish at selected sites during the cruise.
  1. CTD experiments: “Conductivity, Temperature, and Depth.”   At predetermined locations scientists Evan Howell, Pacific Islands Fisheries Science Center, and Megan Duncan, Joint Institute for Marine and Atmospheric Research at the University of Hawaii, will collect water samples called “profiles” taken of the water column at different depths.  This data is very important in determining the nutrients, chlorophyll levels, and other chemical make-up of the ocean water.
  1. Plankton tows:  Using plankton and Neuston nets, scientists Louise Giuseffi, Pacific Islands Fisheries Science Center, and Emily Norton,University of Hawaii, Manoa, Biological Oceanography department, will conduct day and nighttime plankton tows focusing on plankton and microplastic marine debris.  Scientists will be  looking at a specific species of plankton called the copepod.  This study will also be collecting microplastic pieces, some of which are called “nurdles” which are small plastic pellets used in the manufacturing process. Unfortunately most plastic debris will never degrade and just break into smaller and smaller pieces potentially working their way into the food web, making this research and its findings very important to environmental studies.
  1. Handline fishing using a small boat, the Steel Toe: Scientists Ryan Nichols, Pacific Islands Fisheries Science Center, Meagan Sundberg, Joint Institute for Marine and Atmospheric Research at the University of Hawaii, and Jamie Barlow, Pacific Islands Fisheries Science Center, will conduct daily fishing expeditions obtaining scientific data on bottomfish, grouper and snapper species.   They will be focusing on life history factors including age, growth, male/female ratios, length and weight.  This is very exciting research since the last data collected from this region was from the 1970s and 80s.

I am very excited and fortunate to be part of this important scientific research project, and the significant data collected by the scientists.

Did You Know?
American Samoa pronunciation: The first syllable of “Samoa” is accented.
Pago Pago (capital of American Samoa): The “a”  pronunciation uses a soft “an” sound as in “pong.”

Animals Seen Today
Frigate birds
Common Myna
“Flying Foxes” Fruit bats
Kingfisher
Brown tree frog
Dogs, various
Chickens, various