Air temp 45F, sea depth 59 m , surface sea water temp 44F
Catching the Tiny Fish in the Big Sea
For the past two days, I helped out Robert Levine, PhD Student of Oceanography at the University of Washington, working with NOAA Alaska Fisheries Science Center. We sent out a Methot net to catch juvenile fish today. In the below picture, taken yesterday, I am helping Robert assemble the Methot net.
Teacher at Sea Roy Moffitt helps assemble the Methot net
For catching fish a centimeter or two long, the net seems huge. The opening of the net is approximately 2.2 meters by 2.2 meters or 5 square meters. The net itself is approximately 10 meters long. The holes in the net are only 2 mm. This means anything bigger than 2 mm will be caught up in the net.
Example of an Echogram
Before sending the net into the sea Levine takes an echogram survey. He lowers the recorder overboard and the attached cable sends the results back to the computer on board. Two different wavelengths are sent out and bounce off anything in the sea column. The smaller wavelengths will show where any of the smaller fish are hanging out. The results give an accurate depth measurement of the ocean and shows small organisms at about 28 meters in depth. The net is then lowered into the sea and trawled at that depth for about 15 minutes.
Inclinometer
My task during the net deployment was to measure the angle of the cable entering the water by using a hand held inclinometer. It is important to keep the angle around 45 degrees to keep the proper depth.
Photos of today’s catch: at top left, a view of the unsorted bucket; top right, a petri dish with fish sorted by species; bottom, juvenile fish displayed on measuring tape
Today was not considered a high population area, but we were still able to catch some fish and more marine life. All contents end up in a canister at the end of the net in a big slurry of sloppy stew. In the picture of the bucket the fish are hidden within moon jellyfish and all the little black dots that are crab megalopa. Crab megalopa is the second life stage of a crab before transformation into juvenile crabs to start their life on the sea floor. For fish today what was caught in the net were juvenile Cod, juvenile flat fish, and Sculpin. (Shown in picture with the round dish.)
The goal of this fish collection is to verify the presence of juvenile fish and better understand the geographic range of fish during their life cycle. The exact identification of each will take some time and many of the tiny fish are frozen and sent out to labs for further identification. Levine will also be releasing several bottom-moored echo sounders during the trip. These instruments will be able to monitor the presence of fish and record that data over the year.
Now and Looking forward
Future specimen collections on this trip will be happening using the Methot net to verify distribution and seasonal movement of fish population in the Chukchi Sea.
We have made it to the most northern point on the survey.
Mission: Juvenile Pollock Fishery Survey
Geographic area of cruise:
Western Gulf of Alaska
Date: August 29, 2017
Weather Data: 10.2 C, rainy/stormy
Latitude: 59 20.0 N, Longitude: 152 02.5 W
Science and Technology Log
The main focus of this survey is to gather information about juvenile walleye pollock, Gadus chalcogrammus. Juvenile pollock less than 1 year of age are called young-of-the-year, or age-0 juveniles. Age-0 walleye pollock are ecologically important. Many species of birds, mammals and other fish rely on them as a food source. Adult pollock have a high economic value. Pollock is commercially fished and commonly used in fish sticks and fish and chips. This study is interested in learning more about the size of current juvenile pollock populations, where they occur, and how healthy they are.
An age 0 juvenile pollock is shown below an adult pollock.
In order to collect a sample, a trawl net is lowered into the water off of the back of the ship. The deck crew and bridge crew work together to release the right amount of wire and to drive the ship at the right speed in order to lower the net to the desired depth. The net is shaped like a sock, with the opening facing into the water current. In order to keep the mouth of the net from closing as it is pulled through the water, each side is connected to a large metal panel called a “door”. As the doors move through the water, they pull on the sides of the trawl net, keeping it open. When the doors are ready to be put in the water, the fishing officer will instruct the winch operator to “shoot the doors”!
The deck crew bring the trawl net back on deck. One of the metal “doors” can be seen hanging off of the back of the ship.
Sensors help monitor the depth of the upper and lower sides of the net and relay a signal to computers on the bridge, where the data can be monitored.
Sensors on the trawl net relay data to computers on the bridge which show the position of the net in the water.
Once the net is reeled in with a large winch, the catch is placed on a sorting table, in a room just off of the back deck called the fish lab. Here, the science team works to sort the different species of fish, jellyfish, and other kinds of marine animals that were caught.
Crew members stand below a winch and empty the catch from the trawl net into a large bin.The catch is then sorted on the sorting table in the fish lab.
Juvenile pollock are sorted into their own bin. If it is a small catch, we weigh, count, and measure the length of each one. However, if it is a large catch, we take a smaller sample, called a subsample, from the whole catch. We use the weight, lengths, and count of animals in the subsample to provide an estimate count and average size of the rest of the fish caught at that station, which are only weighed. This information is compiled on a computer system right in the fish lab.
Here I am measuring some fish.
Data from the catch is collected on computers in the fish lab.
The focus of this study is juvenile pollock, but we do catch several other species in the trawl net. The presence of other species can provide information about the habitats where juvenile pollock live. Therefore, data from all species collected are also recorded.
Here are some other interesting species we caught: 1. jellyfish (with a partially digested pollock inside it!) 2. lumpsucker 3. herring 4. spider crab
A small sample of juvenile pollock are frozen and saved for further study, once back on land. These fish will be analyzed to determine their lipid, or fat, content and calorie content. This data reveals information about how healthy these fish are and if they are getting enough food to survive through the cold Alaskan winters.
Other agencies within NOAA also conduct scientific surveys in this area. These studies might focus on different species or abiotic (non-living) properties of the Gulf of Alaska marine ecosystem. The data collected by each agency is shared across the larger NOAA organization to help scientists get a comprehensive look at how healthy marine ecosystems are in this area.
Personal Log
As we move from one station to the next, I have been spending time up on the bridge. This gives me a chance to scan the water for sea birds and marine mammals, or to just take in the scenery. Other members of the crew also like to come up to do this same thing. I have really enjoyed having this time every day to share in this activity (one of my favorite past-times) with other people and to learn from them how to identify different species.
Here I am outside of the bridge, posing with some glaciers!
Did You Know?
You can find the exact age of many fish species by looking at a bone in their ears! Fish have a special ear bone, called an otolith. Every year, a new layer will grow around the outside of this bone. As the fish ages, the otolith gets larger and larger. Scientists can find the exact age of the fish by cutting a cross section of this bone and counting the rings made from new layers being added each year.
A small otolith of an age 0 juvenile pollockLarger otoliths from an adult pollock
NOAA Teacher at Sea Alexandra (Alex) Miller, Chicago, IL Onboard NOAA Ship Bell M. Shimada May 27 – June 10, 2015
The full moon lights up the night on top of the flying bridge.
Mission: Rockfish Recruitment and Ecosystem Assessment Geographical area of cruise: Pacific Coast Date: June 3, 2015
Weather Data:
Air Temperature: 13.3°C
Water Temperature: 14.8°C
Sky Conditions: Partly Cloudy, I could still see some stars
Wind Speed (knots/kts), Direction: 5.5 kts, NNE
Latitude and Longitude: 43°29’84”, 124°49’71”
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Later on Monday, once all the night-shifters had risen from their beds and were beginning to get ready for the bongos and mid-water trawls, I took a tour of the engines with marine engineer and NOAA crewmember, Colleen. We started in the control room. With up to four engines operating at any one time, Colleen says it’s a relief that computer systems help to automate the process. As part of her four-year degree program at Seattle Maritime Academy, she learned how to operate the engines manually as well, but I think we can all agree computers make life easier.
Before moving on to the actual engine room, Colleen made sure I grabbed some ear protection. For a one-time visit they’re probably more for my comfort than to protect from any real damage, but because she’s working with the engines every night, it’s important to protect against early-onset hearing loss. Once the plugs were in, we were basically not going to be able to talk so Colleen made sure that I knew everything I was going to see before we proceeded.
Colleen in the control room.
First, we made our way past the fresh water tanks. I was really curious about how we get fresh water on the ship, since we’re in the middle of the Pacific Ocean. The Shimada produces freshwater using two processes. Reverse osmosis produces most of the water, using high pressure to push the seawater across a membrane, a barrier that acts like a filter, allowing the water molecules to pass through but not the salt. This is an energy intensive process, but the evaporators use the excess energy produced by the engines to heat the seawater then pass it through a condensing column which cools it, and voilá, freshwater!
Next, we came to the four diesel engines. Four engines. These four engines are rarely all on at one time but never will you find just one doing all the work. That would put too much strain on and probably burn out that engine. While they burn diesel fuel, like a truck, instead of using that energy to turn a piston like the internal combustion engine of that same truck, they convert that energy to electricity. That electricity powers the two motors that ultimately make the ship go.
Panoramic view of the engine room, engines 1 and 3 can be seen in foreground and engines 2 and 4 in the background.
A ship the size of the Shimada requires a lot of power to get moving, but Colleen tells me it gets decent mileage. Though the ship’s diesel tank can hold 100,000 gallons, there’s only about 50,000 gallons in the tank right now and the ship only needs to refuel every couple of months.
After a quick pass by the mechanics for the rudder, the fin-shaped piece of equipment attached to the hull that controls the direction the ship is traveling we arrived at our last stop: Shaft Alley. Those two motors I told you about work together to turn a giant crankshaft and that crankshaft is attached to the propeller which pushes water, making the ship move. When I was down there the ship was on station, where it was holding its location in the water, so the crankshaft was only turning at 50 RPM (rotations per minute).
It was a pleasure getting a tour from Colleen!
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Throughout the night, the Shimada revisits the same transect stations that it visited during that day, but uses different nets to collect samples at each station. To the right, you can see a map of the stations; they are the points on the map. Each line of stations is called a transect. Looking at the map it’s easy to see that we have a lot of work to do and a lot of data to collect.
The transects and stations within them that the Shimada will survey at.
Why does this have to happen at night? At night, the greatest migration in the animal kingdom takes place. Creatures that spend their days toward the bottom layers of the ocean migrate up, some as far as 750 m (almost 2,500 ft)! Considering they’re tiny, (some need to be placed under the microscope to be reliably identified) this is relatively very far. And they do it every day!
To collect data on these organisms, three types of nets are used, two of which are not used during the day. Along with the surface-skimming neuston (which is used during the day), the bongo net, so named because it has two nets and looks like a set of bongo drums, and the Cobb trawl which is a very large net that needs to be deployed off the stern (back of the boat).
The operation of the bongo net is similar to the neuston, it is lowered off the starboard (when facing the bow, it’s the right side) side of the boat. Dropping down to 100 m below the surface and then coming back up, the bongo is collecting zooplankton, phytoplankton and fish larvae. The samples are poured from the cod-end into a strainer with a very fine mesh and since the water is full of those tiny bits, the straining can take a bit of time and some tambourine-like shaking.
The Cobb trawl on deck, waiting to be deployed.
These samples are then fixed (preserved) in ethanol and they will be analyzed for diversity (how many different species are present) and abundance (how many individuals of each species is present). The bongo is the net of choice for this survey because once scientists go to process the data, the double net provides a duplicate for each data point. This is important for statistical purposes because it ensures that the area that is sampled by one side of the net is similar enough to the area sampled by the other side of the net.
Below you can see video of the bongo net after it’s been hauled back. Scientists are spraying it down to make sure all organisms collect in the cod-end.
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Once the bongos are done, comes the real action of the night shift. The mid-water trawls take 15 minutes. I’ve become really great at communicating with the bridge and survey technicians who are operating the nets so that I can record data for the beginning and ending of the trawls. Once the catch is on deck, the survey technicians empty the cod-end into a strainer. The scientists prepare to sort, count and measure the species of interest. If the catch is large or particularly diverse, this can be a significant task that requires all hands on deck.
With four trawls a night, some with 30-50 minutes transit time with nothing to do in between, fatigue can set in and make the work hard to finish. To make it through the night, it takes great senses of humor and playful personalities. A little theme music doesn’t hurt either. The scientists of the night shift, under the direction of Toby Auth, a fisheries biologist with Pacific State Marine Fisheries Commission working as a contractor to NOAA and Chief Scientist Ric Brodeur, are Brittney Honisch, a marine scientist with Hatfield Marine Science Center, Paul Chittaro, a biologist with Ocean Associates working as a contractor to NOAA, Tyler Jackson, a fisheries science graduate student, and Will Fennie.
The data collected during these trawls provides a snapshot of the ecosystem. This data will help NOAA Fisheries Service understand the health of the ocean ecosystem as well as how large certain populations of commercially important fish are such as hake and rockfish.
In the meantime, it provides for some late night fun. Over the course of the nights that I’ve spent in the wet lab, we have uncovered some bizarre and fascinating creatures.
A tiny larval octopus (Octopus sp.)! I will call him Squishy and he will be my Squishy.
Krill (Euphausiids) with phytoplankton in their stomachs (green).
Will holds a Pacific mackerel (Trachurus symmetricus)
A Medusafish (Centrolophidae sp.)
Shortbelly (Sebastes jordani) and canary rockfish (Sebastes pinniger), actual rockfish! In juvenile form.
The flat ones are larval Pacific sanddabs (Citharichthys sordidus) and the long skinny ones are larval anchovies (Engraulis mordax).
A Praya siphonophore.
A heteropod (Pterotracheoidea sp.)
Clockwise from right: Mature hake, young lanternfish, King-of-the-Salmon, curlfin turbot, poacher.
Moon jelly (Aurelia labiata)
A Leptocephalus larvae of deep sea eel.
But in my opinion the real star of the trawls was the young female dogfish. A dogfish is a type of shark. I know what you’re thinking and no, she did not try to bite us. But dogfish do have two spines, one at the base of each dorsal (back) fin. We all fell in love, but, ultimately, had to say goodbye and return her to the sea.
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Thank you for your patience as I’ve gathered the images and video to make this and future posts as informative as possible. Stay tuned for Episode 5 coming soon!
Personal Log
First off, a heartfelt CONGRATULATIONS to the first 8th grade class at Village Leadership Academy. I wish I could be there when you walk across that stage on June 4th.
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Little did I know when I started hanging out with the scientists of the night shift that it would become a way of life. Each night I managed to stay up later and later and finally last night I made it through all four catches and almost to 0800, the end of the night’s watch. After dinner (some call it “breakfast”), I slept a full eight hours, and it felt completely normal to be greeted with “Good Morning!” at 3:30 in the afternoon.
Speaking of the night’s watch, I’m really grateful that someone was able to get one of my favorite TV shows last Sunday. And Game 7! The Blackhawks are in the finals! Even though I can’t call anyone back home to discuss my theories or that amazing goal by Seabrook in the third period, I can email and it feels like I’m missing less.
The only person I can’t email is my cat, Otto! I can’t wait to snuggle him until he scratches me.
Otto the cat. He loves snuggling.
Question of the Day:
Comment with answers to these questions and I’ll shout your name out in the next post!
What is your favorite animal we have seen so far?
Acknowledgements:
Thanks to Paul Chittaro for assisting in the use of iMovie for this post!
NOAA Teacher At Sea: Thomas Ward Aboard NOAA Ship Miller Freeman
Mission: Fisheries Surveys Geographical Area of Cruise: Eastern Bering Sea Date: September 16, 2010
Question and Answer for the Teacher at Sea (NOAA)
Let’s jump right in, and not into the Bering Sea, it is too cold.
We have not seen any NOAA buoys, or at least I have not. NOAA does maintain numerous buoys but our mission aboard the Miller Freeman is strictly biological, juvenile flat fish to be specific. The types of little fish that we have caught and persevered for further study (remember the freezer) are; Yellowfin Sole, Pacific Halibut, Northern Rock Sole, Flathead Sole, Alaska Plaice, Arrowtooth Flounder, Kamchatka Flounder Greenland Turbot, and larvae of Long Head Dab. These fish that are being saved are relatively small, about 1-3 inches long, they are juveniles. The scientists are trying to determine the mechanism that controls the development of these juveniles into adults. I was also happy to learn that the scientists that are doing the sampling are also the same scientists that are going to be doing the work back in the lab. The identification of these youngsters seems to be effortless by the group of scientists I am working with, they really know their stuff. I have not seen too many ships here while we are out to sea. Last night I did see a light in the distance and assumed it was another ship but did not confirm it with the bridge. We do not fish to catch food for us on board. In fact there are so many regulations regarding fishing that we just focus on the mission and let the cooks in the galley do what they do, and let me tell you it is good. We often do get a glimpse of land, the pictures of the volcanoes on previous blogs are taken from our ship.
This video shows me measuring flat fish on the magnetic measuring board that I mentioned in an earlier blog. After imputing the species and other pertinent data, on a touch screen monitor, the fish is laid on the board and a device is touched to the board where the tail is. The length of the fish is recorded electronically. The fish that you see in the video are adults of the juveniles related to this FOCI Research Project and we still gather quantitative data on them. After we catalog them they are returned to the ocean where they have a very good chance of surviving. Keep those questions coming.
NOAA Teacher At Sea: Thomas Ward Aboard NOAA Ship Miller Freeman
Mission: Fisheries Surveys Geographical Area of Cruise: Eastern Bering Sea Date: September 14, 2010
After the Catch
This segment is devoted to what happens to the organic material we acquire once we get it on board. The benthic sled has a very fine mesh net, plankton net, attached to it and has a container at the end of it, a cod end. This is where the epibenthic invertebrates end up. Once the gear is on board the crew washes down the net with sea water to get any invertebrates to wash down into the cod end. It took getting used to that the garden hoses around deck have salt water in them. Growing up all your life using hoses outside with fresh water in them and then being on board here and getting an occasional spray to the face and it is salt water is a reminder of where I am really at. Any how, the sample in the cod end is put into a jar and preserved in a buffered Formaldehyde solution.
The beam trawl is used to study settlement and nursery areas for age-0 flatfishes. This is probably what most people would associate with net fishing. When the haul comes up there is an assortment of organisms in it. The catch is dumped in to a kiddie pool and we gather around it and start to sort, flopping flat fish and all.
Sorting
These pictures are a good example of what we are doing. Remember that we are primarily studying juvenile species and what is the primary mechanism in nature that helps these little ones become adults.
The fascinating thing is the differences in the catches per location. Once the fish that are the focus of this study have been sorted, they are measured, weighted, bagged and frozen. They are carefully labeled and frozen at a temperature of -80 degrees Celsius in the rough lab. After 24 hours they can be moved to a “warmer” freezer, -20 degrees Fahrenheit, which is in the slime lab.
Keepers
The catch comes on board at the stern of the ship, which is the open rear of the ship where the majority of the heavy equipment is, like cranes and such. After the catch is sorted it is brought into the wet lab for measuring, weighing and bagging. The measuring board that we have in this lab is very cool. There are touch screen monitors that are set up where the species that we are concerned with is selected. The correct species is chosen and the fish are individually placed on this electronic board. The scientist then puts the individual fish nose at one end and takes a hand held device and places it near the tail. The machine makes a funky sound and the length of the fish is recorded electronically. Very cool, quick and convenient. With a good team working this station, a fish can be measured about one every second, pretty efficient.
The benthic grab is specifically used to sample subtidal soft-bottom benthic macroinvertebrates. This is done to determine what is in the substrate. This is the layer just below the surface. This is what the juvenile flat fish feed on. When determining what causes a population’s numbers to fluctuate it is important to study what it eats
Jellyfish
The jellyfish above are very cool but not of much interest to this study. The sole above is one of the larger flat fish that we have caught. We do catalog them but we do not save them for future study. The interesting thing that I want to point out about the picture of the sole is the location of their eyes. Both eyes are on the same side of their body. These fish lay on the bottom and wait for prey to swim by. It is and was a huge evolutionary advantage for them to have both eyes on one side of their body.
Yellowfin Sole
Life on board ship is a very different experience. Yesterday was proof of that for me when the seas turned to 7-9 feet and my body could not handle it. The crew amazed me because word of my illness spread around and many pepole have been asking me how I have been feeling today. It is what I would call a concerened, caring, working family. At first coming aboard, getting around the ship was very confusing. There are numerous stairways that lead to different decks and there is a very similar look to things on the ship. I am getting used to it and to stepping through a bulkhead to walk through the ship. These bulkhead doors are water tight doors that are closed to protect parts of the ship in case of an accident. The sleeping quarters are sufficent. I am in a 4 man room with 3 other guys, with a bathroom attached to it. I have my own personal locker which contains my personal effects and my life jacket and survival suit. On the door the crew placed a billet which is a document that is specifally designed for the individual. Among other things it gives my lifeboat station which we would have to muster to if an emergency occurred. We have practiced this drill and hope that it does not become real any time soon. I am in a lower bunk. The noise and the motion of the ship is the hardest thing to get used to. I occasionally sleep with ear plugs but that does not seem to help much. A solid, uninterupted 8 hours of sleep will be very much appreciated when I return. But, as any one that knows me knows that I can definately catch up on sleep by napping, and just about anywhere.
Remember that if you have any questions you can ask through this blog. I believe you have to sign up for a Google account but it seems to do anything on the web these days you either have to register or sign on in some manner. Just click the commnets icon towards the bottom of the blog and follow the prompts, it is not too cumbersome. I hope you have enjoyed reading this and I am almost done describing the science so I hope the questions start rolling in. Hope for flat seas for me.
