NOAA Teacher at Sea
Lisa Carlson
NOAA Ship Bell M. Shimada
July 5, 2023 – July 19, 2023
Mission: Fisheries: Pacific Hake Survey (More info here)
Geographic Region: Pacific Ocean, off the coast of California
Date: July 13, 2023
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Weather Data from the bridge:
July 11 (1200 PT, 1500 EST)
Location: 37° 46.7’ N, 123° 26.6’ W
43nm (50mi) West of San Francisco, CA
Visibility: 2 nautical miles
Sky condition: Overcast, fog
Wind: 20 knots from N 250°
Barometer: 1015.2 mbar
Sea wave height: 2-3 feet
Swell: 6-7 ft from NW 320°
Sea temperature: 12.2°C (57.2°F)
Air temperature: 12.7°C (57.9°F)
Course Over Ground: (COG): 270°
Speed Over Ground (SOG): 10 knots
July 12 (1200 PT, 1500 EST)
Location: 38° 06.8’ N, 123° 01.6’ W
7nm (8mi) North of Point Reyes Lighthouse, Inverness, CA
Visibility: 2 nautical miles
Sky condition: Overcast, fog
Wind: 12 knots from N 350°
Barometer: 1016.0 mbar
Sea wave height: 1-2 feet
Swell: 3-4 ft from W 280°
Sea temperature: 11.0°C (57.2°F)
Air temperature: 11.5°C (57.9°F)
Course Over Ground: (COG): 270°
Speed Over Ground (SOG): 10 knots
July 13 (1200 PT, 1500 EST)
Location: 38° 17.3’ N, 123° 06.1’ W
2.5nm (4mi) Southwest of Bodega Bay, CA
Visibility: 3 nautical miles
Sky condition: Few clouds, fog
Wind: 13 knots from NW 300°
Barometer: 1015.9 mbar
Sea wave height: 1-2 feet 1-2
Swell: 3-4 ft from NW 300°
Sea temperature: 10.7°C (51.3°F)
Air temperature: 13.7°C (56.6°F)
Course Over Ground: (COG): 340°
Speed Over Ground (SOG): 10 knots
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In my July 6 post, I explained how NOAA Ship Bell M. Shimada is equipped to collect acoustic data in the form of echo grams and therefore find fish to trawl for. In my July 10 post, I explained how we get the fish onboard, and what we do with the sample once it is collected from the net. These entries described what work is done in the Acoustics Lab and the Wet Lab, but there is one more Lab onboard to explore and explain: the Chemistry Lab.

Science and Technology Log
Each morning after breakfast, we usually gather in the Acoustics Lab, determine what transect we are on, if we are inshore or offshore, and in some ways: hurry up and wait. Once certain patterns and blips show up on the echo grams, the Acoustics team talks with the bridge and may request to turn around and attempt a trawl. After all marine mammal observations are completed, the net is retrieved, and the samples are brought to the Wet Lab, we sort and collect data on the samples. These operations usually take place between 0800 and 2000. (8am to 8pm)
So what happens at night? In the Chemistry Lab, scientists work with the Deck and Surveys Departments to deploy a collection of electronic instruments and 12 Niskin bottles (open bottles used to collect and hold water samples, about one meter long) secured to a cylindrical frame called a rosette. It is deployed from the side sampling station instead of the stern. Scientists onboard NOAA Ship Bell M. Shimada use the instruments and collection of water samples in two ways: measuring Conductivity, Temperature, and Depth (CTD) within a water column to study oceanography, and collecting environmental DNA (eDNA).
“Nighttime operations primarily consists of deploying the Conductivity-Temperature [-Depth] (CTD) rosette which gathers oceanographic data such as conductivity, temperature, dissolved oxygen, and chlorophyll fluorescence. The CTD can also be triggered to collect water at specific depths.”
NOAA Fisheries: “eDNA Part 2: There’s a Lot of Water in the Sea – and the Chemistry Lab”
Conductivity, Temperature and Depth: CTD
CTD stands for conductivity (ability to pass an electrical current), temperature, and depth. Scientists use the rosette frame, which is attached to the ship by cables, and has the CTD and 12 Niskin bottles attached, to collect electronic data and multiple water samples.
“A CTD device’s primary function is to detect how the conductivity and temperature of the water column changes relative to depth. Conductivity is a measure of how well a solution conducts electricity and it is directly related to salinity. By measuring the conductivity of seawater, the salinity can be derived from the temperature and pressure of the same water. The depth is then derived from the pressure measurement by calculating the density of water from the temperature and the salinity.”
NOAA Ocean Exploration: “What does “CTD” stand for?”

“For more detailed analyses back in the lab, each of the large gray bottles captures a water sample at a different depth. The data provide scientists important information about the local aquatic environment.”
NOAA: “Photo story: Virtually cruise aboard a NOAA ship for a fish trawl survey”
Depending on the depth at which the vessel is currently operating, the rosette will descend to one to five predetermined depths (50m-500m) for sampling. For example, if the vessel depth reads 400m, water samples will occur at 50m, 150m, 200m, and 300m (more information in Table 1 below). A water sample is also taken just below the ocean surface using a through hull fitting, which allows seawater to be collected via a hole in the hull that feeds directly to the Chem Lab.

While the rosette descends, data is recorded from multiple sensors and are later used by scientists to compare with Acoustic and Wet Lab data and compile and categorize new information from the survey. Pressure, depth, temperature, conductivity, salinity, oxygen, fluorescence, and turbidity were all being recorded during this leg of the survey mission.

Environmental DNA: eDNA
During the day, Hake stay in deeper waters, averaging around 200-350m, but at night the nocturnal feeders start their daily migration through the water column to shallower depths. They feed primarily on zooplankton, shrimp, myctophids (Lanternfish), and even young Hake at this depth. As Hake move throughout the water column, they leave behind DNA in the water that can be collected later as sort of a signature of their presence in that location. The collection, filtering, and preservation of sampled water in the ocean environment is categorized as collecting eDNA. This environmental DNA can be in the form of gametes (reproductive cells), fish scales, feces, etc.
Collecting water samples at different depths in the same vertical column can show what marine life was present at that location, and what depth they were at. I relate it to reviewing school security cameras or talking to other teachers at the end of the school day, to determine where a student was at a certain time and why.

When the rosette is back on deck, scientists use gloves and new collection bags called Whirlpacks, to collect approximately 2.5L of water from each 10L Niskin bottle. This process is conducted with a great emphasis on sterility, including wiping the bottle spigot with DNAway to remove any contaminants, using new materials, and not allowing fingers or the spigot to touch the collection bag.


Once the collection bags are filled and brought to the Chem Lab, filtration occurs using 1.0 micron filters. Although this size of filter, compared to smaller filters, allows some cells to pass through and not be collected, it is faster and results in less breakage of cells and loss of DNA. After 2.5L of the water sample is poured through individual filters for each depth sample, they are placed in pre-labeled (location and depth information) tubes with 2mL of preservative buffer. The tubes are stored at room temperature and away from UV light until NOAA Ship Bell M. Shimada is back in port and the samples can be further researched in on-land laboratories. Results from additional studies help to compile lists of marine life that was present in the water column and can be compared to acoustic data and species caught and logged in the Wet Lab.
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Personal Log
So, there you have it. Three Labs onboard that conduct very different research, but fit together in the puzzle of Hake development, migration, diet, niches, ecosystem, biomass, and supporting sustainable commercial fisheries. Each additional piece of data; whether it be echo sounds, physical samples, eDNA, or CTD information, strengthens the others and helps to create a cohesive summary of the data.
This was a lot to learn in the first few days, but as I’ve said before, all of the crew has been welcoming, supportive, and educational. Having a strong team that works together is priceless, and thoroughly noticed and appreciated.
A few days into the mission my Mom asked me what the best part of my day was. I had three answers and haven’t had a day yet with only one answer. I replied that it was the great salmon dinner, clean clothes, and seeing Risso’s Dolphins for the first time.
We are now a little more than halfway through the mission and it has truly flown by. We’ve shared riddles and daily Final Jeopardy questions. We’ve laughed over daily experiences and the faces Hake fish make. We’ve played music and watched baseball during dinner. We enjoy watching marine life and breathe in the salt air while strengthening our sea legs. Sometimes we just drink coffee and snack and enjoy this opportunity with each other, and that makes every part of the day the best part.
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Did You Know?
Although Hake are occasionally cannibalistic, they are not at the top of their food chain. Humboldt Squid (Remember those 15 foot long tentacles in my Wet Lab post?), Dogfish Sharks, and marine mammals are all predators, as well as commercial fishing.
Today well over 100 Spiny Dogfish Sharks were inadvertently caught in the trawl, in the same location as the baskets of Hake we sampled from.
Maybe there were baby Hake fish in the sharks’ stomachs… we didn’t attempt to find out.


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New Terms/Phrases
Although I had learned the terms a few days earlier, I got to help Wet Lab Lead Ethan Beyer collect otolith and stomach samples for the first time from a sub-sample of Hake the other day.
I watched and learned, then helped scan barcodes of otolith sample bottles, add 95% ethanol that is diluted 50/50 with water, and delicately pick up the ear bones with tweezers and place them in the bottle.
Additionally, each Hake in the sub-sample has its weight recorded, along with length, sex, and developmental stage. From that sub-sample, five stomachs are removed for later analysis, and five have their stomachs opened and their diet is recorded. We often find Lanternfish (Myctophids), Krill (Euphausiidae) and small Hake.
