Tag: transect

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 10, 2023

– – ⚓ – –

Weather Data from the bridge:

July 7 (1200 PT, 1500 EST)
Location: 36° 00.4’ N, 122° 05.9’ W
16nm (21mi) West of Big Sur, CA

Visibility: 10 nautical miles
Sky condition: Overcast
Wind: 20 knots from NW 330°
Barometer: 1013.1 mbar
Sea wave height: 3-4 feet
Swell: 6-7 ft from NW 320°
Sea temperature: 14.0°C (57.2°F)
Air temperature: 14.4°C (57.9°F)
Course Over Ground: (COG): 323°
Speed Over Ground (SOG): 10 knots

July 8 (1200 PT, 1500 EST)
Location: 36° 34.5’ N, 122° 05.3’ W
17nm (20mi) Southwest of Monterey, CA

Visibility: 10 nautical miles
Sky condition: Few clouds
Wind: 19 knots from NW 330°
Barometer: 1013.8 mbar
Sea wave height: 5-6 feet
Swell: 6-7 ft from NW 330°
Sea temperature: 14.0°C (57.2°F) 13.7
Air temperature: 14.4°C (57.9°F) 14.3
Course Over Ground: (COG): 089°
Speed Over Ground (SOG): 10 knots

July 9 (1200 PT, 1500 EST)
Location: 37° 06.8’ N, 123° 00.5’ W
30nm (35mi) West of Pigeon Point Light Station, Pescadero, CA

Visibility: 10 nautical miles
Sky condition: Overcast
Wind: 13 knots from NW 332°
Barometer: 1016.0 mbar
Sea wave height: 2-3 feet
Swell: 4-5 ft from NW 310° 4-5
Sea temperature: 14.3°C (57.7°F)
Air temperature: 15.2°C (59.4°F)
Course Over Ground: (COG): 093°
Speed Over Ground (SOG): 10 knots

July 10 (1200 PT, 1500 EST)
Location: 37° 26.7’ N, 123° 06.4’ W
32nm (37mi) West of Pescadero, CA

Visibility: 8 nautical miles
Sky condition: Overcast, fog in vicinity
Wind: 20 knots from NW 330°
Barometer: 1015.9 mbar
Sea wave height: 2-3 feet
Swell: 3-4 ft from NW 320°
Sea temperature: 14.5°C (58.1°F)
Air temperature: 13.6°C (56.5°F)
Course Over Ground: (COG): 314°
Speed Over Ground (SOG): 3 knots

– – ⚓ – –

Science and Technology Log

In my July 6 blog post, I explained how NOAA Ship Bell M. Shimada is equipped to collect acoustic data in the form of echo grams. The acoustics team uses the data to determine if there are enough return signals to suggest fish are present and attempt a trawl. In this blog post, I will explain how we get the fish onboard, and what we do with the sample of marine life once it is collected from the net.

One question I had after learning about the acoustics and environmental DNA (eDNA) pieces of the survey mission was, “How does physically collecting and researching Hake samples fit into the puzzle of understanding their ecosystem and supporting sustainable fisheries?” (NOAA Fisheries quick facts and video here)

“While echosounders are useful, they do not provide certain quantitative data that researchers need to understand the ecology of these organisms and the midwater zone. To collect quantitative data, such as biomass, length and weight, and age class distributions, researchers must gather representational samples and take direct measurements of them. The best way to do this is by employing trawls.”

NOAA Ocean Exploration: “Trawls”

So, although acoustics and eDNA research is important to the overall survey, they are only pieces of the puzzle, and the puzzle is not complete without conducting trawls and physically researching samples. NOAA Ship Bell M. Shimada uses a midwater trawl net that is deployed from the stern over the transom, and towed behind the vessel. As the name suggests, midwater trawls occur in the middle section of the water column, versus surface and bottom trawls. The net is conical in shape and uses two metal Fishbuster Trawl Doors, and two sets of heavy chain links called Tom weights, in order to keep the trawl in the middle of the water column.

“The midwater region is especially important because the creatures that inhabit it constitute the majority of the world’s seafood. Understanding the ecology of midwater organisms and their vast environment can provide us with better information to manage these important natural resources and prevent their overexploitation.”

NOAA Ocean Exploration: “Trawls”

Deck department assisting in recovering the trawl net after a successful deployment.

Once the net is onboard, the net is emptied one of two ways depending on the size of the sample. For large samples, marine life is deposited into a hopper and subsequent conveyor belt. For smaller samples, the Hake will be put into a large basket then divided into smaller baskets of approximately 100 Hake each. Any other marine life like Salps, Myctophids, Pyrosomes, Rockfish, King of the Salmon, and small bony fish, etc. are recorded in the database and returned to the ocean.

“The ship’s wet lab allows scientists to sort, weigh, measure and examine fish. The data is entered directly into the ship’s scientific computer network.”

NOAA Office of Marine and Aviation Operations (OMAO): “Bell M. Shimada”

Large basket containing a sample of Hake with a few (red) Splitnose Rockfish.

With our boots and bright orange rubber pants and gloves on, our first task is to distribute the sample of Hake into baskets of about 100 each. Based on how many baskets we fill, a random selection of baskets will be kept, and the others will be returned to the ocean. With the remaining groups of Hake, we determine their sex and length.

In order to do this, we use a scalpel to make an incision on the underside/belly of the Hake. Once open, we are able to examine their organs, including the gonads to determine if the fish is male or female, and if they are developmentally immature or mature. Young Hake are difficult to sex, and it takes practice to get over any initial fears of cutting into an animal; let alone being able to locate and identify the gonads. Hake usually spawn in early winter, so many of the smaller Hake we sample from during the summer are age one or younger.

Our largest Hake thus far was a developmentally mature female, measuring 50cm (20in). In order to accurately and consistently measure the length of the sample, we use a waterproof, magnetic plastic board with metric (centimeter and millimeter) markings called an Ichthystick (think: high-tech meter stick). The fish is placed on the board with its mouth touching the black board at 0cm, then a magnetic stylus is placed at the fork of the fish’s tail. Once the magnetic stylus is placed on the board, the length to the nearest millimeter is displayed on the LCD screen and automatically entered into the database program. The length data is grouped with the date, time, and identified sex for later observation and comparison.

Additional information, abstracts and outline about Ichthystick here

Ichthystick’s LCD display, motherboard, magnetic board, and magnetic stylus. Digital scale in background.

An even smaller subgroup is then selected and examined to record weights of individual Hake, collect ear bones called Otoliths for aging, stomach samples for diet, liver for RNA, and ovaries for maturity development. Otolith bones help determine the age of the Hake because they grow a new “layer” of bone each year, similar to coral structures and annual tree rings. Organs and bones removed from the Hake are sent to NOAA Fisheries centers for analysis and included in databases with the date, identified sex, length, weight, and location in which they were collected.

This data is used to build more of the puzzle, along with acoustical information, water samples, and eDNA data in order to further understand the ecosystem, biomass, diet, and

“support sustainable populations of Pacific hake on the West Coast.” (…)
“It provides vital data to help manage the migratory coastal stock of Pacific hake. The hake survey, officially called the Joint U.S.-Canada Integrated Ecosystem and Pacific Hake Acoustic Trawl Survey, occurs every odd-numbered year.”

NOAA Fisheries: “Joint U.S.-Canada Integrated Ecosystem and Pacific Hake Acoustic Trawl Survey”

– – ⚓ – –

Personal Log

Although this subtopic of explaining the Integrated Ecosystem and Pacific Hake Acoustic Trawl Survey is a bit easier to understand than my July 6 Acoustics Lab post, it certainly does not mean it’s an easy task!

When I had a tour on July 4, I remarked how clean and organized the Wet Lab is. I hadn’t see it in action yet, but noticed how everything had its place and use. On July 6 we conducted our first trawl and collected a sample of 11 baskets of Hake (approximately 1,100 Hake since we group about 100 Hake together in each basket.) From that sample, we kept four baskets and counted, sexed, and measured 541 Hake.

Five of us were working together in the Wet Lab for that haul. I’ll admit I probably didn’t sex 100+ Hake. It took a few minutes of watching the others carefully and swiftly cut into the underside of a fish, open the two sides, and know what to look for to determine the sex of very young Hake. Eventually I found the courage to slice in and take a look. By the fourth or fifth Hake, the uneasiness had subsided and I found the process very interesting and educational. Although young samples are hard to sex as they are often undeveloped, the others encouraged me and answered my questions and guesses with enthusiasm and support.

While working on measuring the lengths of our samples, one Science Team member paused and remarked how beautiful he found the fish. Although they do not have vibrant, bold colors, shimmering scales, or anything else particularly remarkable, he found the beauty in them. He digressed into a conversation of their role in the ecosystem, how they are living and breathing creatures, and how they probably all have their own personalities and slight physical differences. I noticed some of their eyes were shiny and sparkling, and how their faces and expressions were noticeably unique the more you looked. That “down to earth”, heartfelt discussion was very special and demonstrated how the crew respects the process of catching and sampling Hake, while keeping each other and marine mammals safe.

From the NOAA Corps Officers, to the deck department, to the engineers, electronics, science team, survey team, galley crew, volunteers, and everyone in between; the crew on NOAA Ship Bell M. Shimada is special. They take pride in their vessel and job, and always seem to have a smile and kind greeting. Being away from land and loved ones for weeks and months at a time will certainly take a toll on the body and mind, but this team is there for each other. To all of the crew, thank you for making me feel so welcomed and appreciated. We’re almost halfway through the mission, and as tired as I may get after (sometimes) 12+ hour days, I sleep well knowing the crew trusts their vessel and each other; and look forward to learning and becoming more and more acquainted each day with the people that make this mission possible. Thank you!

– – ⚓ – –

Did You Know? (FAQs)

1. Are you finding schools of them?

We’ve had seven successful trawls out of nine attempts for Pacific Hake fish. They often come with pyrosomes (Sea Pickle) myctophids (Lanternfish), and salps in the net too. Some trawl attempts are successful without a hitch, but more often than not we have to restart our Marine Mammal watches a few times before deploying in order to keep our ocean life safe and not get tangled in the net. Two trawl attempts have been abandoned because of the amount of persistent marine mammal life and playfulness near the ship. (I think they know we’re watching and show off for our cameras.)

2. What’s your average depth?

The transects (Set and numbered longitudinal east-west lines NOAA Ship Bell M. Shimada navigates on while collecting acoustic data) usually range from 50m – 1,500m (164ft – 4,921ft) in depth.

• However, right now one of the displays in the Acoustics Lab, the depth reading is 3,240m which is about 10,630ft or just over two miles deep! 
• This depth is only 1,870ft shallower than the wreck of the RMS Titanic! 
• (We were on a long transect, we do not often see depths this great.)

3. Have you gotten seasick? Seasickness should subside after about 3 days.

I’ve never gotten seasick thankfully! Knock on wood and all the other premonitions, please.

4. What is the Hake role in the ecosystem?

More info on this coming in later posts after explaining our Chemistry lab and technology aboard! 

• However, as predators, they can be cannibalistic towards their own kind. 
• As far as their role in human consumption: They are often used as a substitute for Cod and Haddock, and in fish sticks and imitation crab meat.

– – ⚓ – –

Animals seen July 5-July 10:

Mammals: Sea Lions, Harbor Seals, Dall’s Porpoise, Risso’s Dolphins, Pacific White-Sided Dolphins, Northern Right Whale Dolphins, Humpback Whales

Birds: Gulls, Black-Footed Albatross

Bony Fish: Hake, Lanternfish (Myctophid), Flatfish, King of the Salmon, Split Nose Rockfish, Chili Pepper Rockfish

Other Marine Life: Giant or Humboldt Squid (15 foot tentacles in trawl), Spiny Dogfish Shark, Shrimp, Plankton, Krill, Sea Pickle (Pyrosome), Salp, Eel Larva