George Hademenos: A Day in the Life…of a Marine Science Researcher, August 25, 2022

NOAA Teacher at Sea

George Hademenos

Aboard R/V Tommy Munro

July 19 – 27, 2022

Mission: Gulf of Mexico Summer Groundfish Survey

Geographic Area of Cruise: Eastern Gulf of Mexico

Date: August 25, 2022

In this post, I would like to walk you through my interactions and observations with the science research being conducted aboard the R/V Tommy Munro, in particular, the steps that were taken during a trawling process. The entire process involved three stages: Preparing for Sampling, Conducting the Sampling, and Analyzing the Sampling with each stage consisting of six distinct steps.

View the following steps in an interactive tour here: Trawl Sampling Process (Genially)

I. Preparing for Sampling

Step 1: The ship travels to designated coordinates for sampling sites as determined for the particular leg of the Survey by SEAMAP (Southeast Area Monitoring and Assessment Program).

screenshot of a computer screen showing the path that R/V Tommy Munro traveled among sampling sites. The ship's path is a bold blue line connecting sample sites marked in yellow. It's superimposed on an electronic nautical chart. This survey occurred southeast of Florida's Apalachicola Bay and St. George Island.
Ship Transport to Sampling Site

Step 2: Once the ship reaches the site, a Secchi disk is attached to a cable and lowered into the water off the side of the ship to determine visibility. When the disk can no longer be seen, the depth is recorded and the disk is raised and secured on ship. 

a scientist wearing a life vest stands on a small grated platform that has folded down off the fantail of R/V Tommy Munro. With his left land, he grasps a cable hanging from an A-Frame that extends out of the photo. The cable is attached to a white disk, about the size of an old record, with a weight underneath.
Deployment of Secchi Disk

Step 3: A CTD (Conductivity, Temperature, and Depth) unit is then prepared for deployment. It is a rectangular chamber with sensors designed to measure physical properties of the water below including dissolved oxygen, conductivity, transmissivity, and depth. 

a conductivity, temperature, and depth probe, mounted inside a rectangular metal cage about 1 foot square and about 3 feet high, sits on deck. a crew member wearing white shrimp boots hooks a cable onto the top of the CTD frame. Another person, mostly out of frame, touches the CTD frame with their right hand, covered in a blue latex glove.
Preparation of CTD Unit

Step 4: The CTD unit is powered on and first is submerged just below the surface of the water and left there for three minutes for sensors to calibrate. It is then lowered to a specified depth which is 2 meters above the floor of the body of water to protect the sensors from damage. 

the CTD unit, attached to a cable, sinks into dark blue water.
Deployment of CTD Unit

Step 5: Once the CTD unit has reached the designated depth, it remains there only for seconds until it is raised up and secured on board the ship.  

a science team member, wearing a blue hat, a blue life vest, and blue latext gloves, stands on the deployment platform out the back of R/V Tommy Munro. He grasps the top of the CTD frame as a cable lifts it back out of the water.
Recovery of CTD Unit

Step 6: The CTD unit is then turned off and the unit is connected through a cable to a computer in the dry lab for data upload. Once the data upload is completed, the CTD unit is flushed with deionized water using a syringe and plastic tubing and then secured on the side of the ship.   

the CTD unit sits on deck, now connected to a computer via a cable to upload the data it collected.
Data Upload from CTD Unit

II. Conducting the Sampling

Step 1: The trawling process now begins with the trawl nets thrown off the back of the ship. The nets are connected to two planks, each weighing about 350 lbs, which not only submerges the nets but also provide an angled resistance which keeps the nets open in the form of a cone – optimal for sampling while the ship is in motion.

a view of the fantail of R/V Tommy Munro, from an upper deck. we are looking through the rigging of the trawl frames. two large planks rest on the lower deck, connected to ropes and lines. the trawl net, connected to the planks, extends out the back of the fantail. It is just visible below the surface, a turquoise-colored cone submerged in a blue sea.
Preparation of the Trawling Process Part 1
another view of the fantail of R/V Tommy Munro from an upper deck, through extensive rigging and frames. the trawl net is further extended; now the large planks are lowering off the back deck as well, suspended by lines connected to a pulley in an A-frame. it is a clear day and the water is very smooth.
Preparation of the Trawling Process Part 2

Step 2: Once the trawl nets have been released into the water from the ship, the ship starts up and continues on its path for 30 minutes as the nets are trapping marine life it encounters.

a view of the fantail of R/V Tommy Munro from an upper deck. the trawl net is fully deployed and no longer visible. a crew member sweeps the deck.
Onset of the Trawling Process

Step 3: After 30 minutes has transpired, a siren sounds and the ship comes to a stop. The two weighted planks are pulled upon the ship followed by the trawl nets.

a view of the A-frame at the fantail R/V Tommy Munro as the trawl net rises from the ocean. The two spreader panels are suspended from separate lines running through the central pulley. behind those, the top of the trawl net is visible above the water. a crew member guides the spreader doors with his left hand, holding the lines with his right hand.
Conclusion of the Trawling Process Part 1
the spreader doors are now resting on the fantail deck again. two crewmembers, wearing life jackets, pull the trawl net back on board.
Conclusion of the Trawling Process Part 2

Step 4: The trawl nets are raised and hoisted above buckets for all specimens to be collected. Then begins the process of separation. In the first separation, the marine life is separated from seaweed, kelp and other debris. The buckets with marine life and debris are then weighed and recorded.

a crewmember (only partially visible) empties the contents of the trawl net into a blue plastic basket. it looks like it's mostly sargassum.
Content Collection from the Trawl Part 1
four plastic baskets on deck hold the sorted contents of the trawl. one has larger fish; another contains only a single fish; a third is a jumble of seaweed and sargassum, and may represent the remainder to sort; the contents of the fourth are not visible. a crewmember wearing a life vest and gloves leans over the baskets. another crewmember, only partially visible, looks on.
Content Collection from the Trawl Part 2

Step 5: The bucket(s) with marine life are emptied upon a large table on the ship’s stern for separation according to species.

a pile of fish on a large metal sorting table. we can see snappers, a trigger fish, and many lionfish. a stack of white sorting baskets rests adjacent to the pile.
Separation Based on Species Part 1
a gloved hand reaches toward the pile of fish on the metal sorting table. (this photo was taken from the same vantage point as the previous one.)
Separation Based on Species Part 2

Step 6: Each species of marine life is placed in their own tray for identification, examination, and measurements inside the wet lab. 

two gloved crewmembers sort fish into smaller white baskets on a large metal sorting table. the table is on the back deck of the ship, and we can see smooth ocean conditions in the background. the crewmember in the foreground considers a small fish he has picked up from the remaining unsorted pile. the other crewmember looks on.
Species Sorted in Trays Part 1
a close-up view of the sorting basket containing only lionfish.
Species Sorted in Trays Part 2

III. Analyzing the Sampling

Step 1: After all species were grouped in their trays, all trays were taken into the wet lab for analysis. Each species was positively identified, counted, and recorded.  

a direct view of three fish of different species, lined up on the metal sorting table. the third is a spotfin butterflyfish.
Tray Transport to Wet Lab

Step 2: Once each species was identified and counted, the total number of species was weighed while in the tray (accounting for the mass of the tray) and recorded on a spreadsheet to a connected computer display system.   

a view of a scale.
Total Weight Measurements

Step 3: For each species, the length of each specimen was recorded using a magnetic wand with a sensor that facilitated the electronic recording of the value into a spreadsheet.   

two hands, wearing latex gloves, measure a small lionfish on the electronic measuring board. the scientist holds the fish against the board with his left hand and with his right hand marks the length with the magnetic stylus.
Individual Length Measurements

Step 4: Weights of the collected species were recorded for the first sample and every fifth one that followed.   

the gloved arm places the small lionfish on the scale behind the fish measuring board.
Individual Weight Measurements

Step 5: If time permitted between samplings, the sex of selected specimens for a species was determined and recorded.   

gloved hands cut into a small lionfish to remove the fish's gonads.
Individual Species Sex Identification

Step 6:Once the entire sampling was analyzed, selected samples of specimens were placed in a baggie and stored in a freezer for further analysis with the remaining specimens returned to a larger bucket and thrown overboard into the waters. The separation table was cleaned with a hose and buckets were piled in preparation for the next sampling. 

view out the fantail of R/V Tommy Munro from the lower deck. the trawl net and spreader doors lay on the deck, not currently in use. the sun shines on calm seas.
Finalize Process and Prepare for Next

In this installment of my exercise of the Ocean Literacy Framework, I would like to ask you

to respond to three questions about the fifth essential principle (The ocean supports a great diversity of life and ecosystems.), presented in a Padlet accessed by the following link:

https://tinyurl.com/427xp9p3

Remember, there are no right or wrong answers – the questions serve not as an opportunity to answer yes or no, or to get answers right or wrong; rather, these questions serve as an opportunity not only to assess what you know or think about the scope of the principle but also to learn, explore, and investigate the demonstrated principle. If you have any questions or would like to discuss further, please indicate so in the blog and I would be glad to answer your questions and initiate a discussion.

Leave a Reply

%d