AWT – NOAA Teacher at Sea Blog

July 13, 2015August 11, 2021

Andrea Schmuttermair, Pollock Processing Gone Wild, July 12, 2015

NOAA Teacher at Sea
Andrea Schmuttermair
Aboard NOAA Ship Oscar Dyson
July 6 – 25, 2015

Mission: Walleye Pollock Survey
Geographical area of cruise: Gulf of Alaska
Date: July 12, 2015

Weather Data from the Bridge:
Latitude: 55 25.5N
Longitude: 155 44.2W
Sea wave height: 2ft
Wind Speed: 17 knots
Wind Direction: 244 degrees
Visibility: 10nm
Air Temperature: 11.4 C
Barometric Pressure: 1002.4 mbar
Sky: Overcast

Science and Technology Log

I’m sure you’re all wondering what the day-to-day life of a scientist is on this ship. As I said before, there are several projects going on, with the focus being on assessing the walleye pollock population. In my last post I talked about the transducers we have on the ship that help us detect fish and other ocean life beneath the surface of the ocean. So what happens with all these fish we are detecting?

The echogram that shows data from the transducers.

The transducers are running constantly as the ship runs, and the information is received through the software on the computers we see in the acoustics lab. The officers running the ship, who are positioned on the bridge, also have access to this information. The scientists and officers are in constant communication, as the officers are responsible for driving the ship to specific locations along a pre-determined track. The echograms (type of graph) that are displayed on the computers show scientists where the bottom of the ocean floor is, and also show them where there are various concentrations of fish.

This is a picture of pollock entering the net taken from the CamTrawl.

When there is a significant concentration of pollock, or when the data show something unique, scientists might decide to “go fishing”. Here they collect a sample in order to see if what they are seeing on the echogram matches what comes up in the catch. Typically we use the Aleutian wing trawl (AWT) to conduct a mid-water trawl. The AWT is 140 m long and can descend anywhere from 30-1,000 meters into the ocean. A net sounder is mounted at the top of the net opening. It transmits acoustic images of fish inside and outside of the net in real time and is displayed on a bridge computer to aide the fishing operation. At the entrance to the codend (at the end of the net) a CamTrawl takes images of what is entering the net.

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Once the AWT is deployed to the pre-determined depth, the scientists carefully monitor acoustic images to catch an appropriate sample. Deploying the net is quite a process, and requires careful communication between the bridge officers and the deck crew. It takes about an hour for the net to go from its home on deck to its desired depth, and sometimes longer if it is heading into deeper waters. They aim to collect roughly 500 fish in order to take a subsample of about 300 fish. Sometimes the trawl net will be down for less than 5 minutes, and other times it will be down longer. Scientists are very meticulous about monitoring the amount of fish that goes into the net because they do not want to take a larger sample than needed. Once they have determined they have the appropriate amount, the net is hauled back onto the back deck and lowered to a table that leads into the wet lab for processing.

Here the scientists, LT Rhodes, and ENS Kaiser assess the catch.

We begin by sorting through the catch and pulling out anything that is not pollock. We don’t typically have too much variety in our catches, as pollock is the main fish that we are after. We have, however, pulled in a few squid, isopods, cod, and several jellies. All of the pollock in the catch gets weighed, and then a sub-sample of the catch is processed further. A subsample of 30 pollock is taken to measure, weigh, collect otoliths from, and occasionally we will also take ovaries from the females. There are some scientists back in the lab in Seattle that are working on special projects related to pollock, and we also help these scientists in the lab collect their data.

The rest of the sub-sample (roughly 300 pollock) is sexed and divided into a male (blokes) and female (sheilas) section of the table. From there, the males and females are measured for their length. The icthystick, the tool we use to measure the length of each fish, is pretty neat because it uses a magnet to send the length of the fish directly to the computer system we use to collect the data, CLAMS. CLAMS stands for Catch Logger for Acoustic Midwater Survey. In the CLAMS system, a histogram is made, and we post the graphs in the acoustics lab for review. The majority of our pollock so far have been year 3. Scientists know this based on the length of pollock in our catch. Once all of the fish have been processed, we have to make sure to clean up the lab too. This is a time I am definitely thankful we have foul weather gear, which consists of rubber boots, pants, jackets and gloves. Fish scales and guts can get everywhere!

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Personal Log

Here is one of many jellies that we caught. .

I am finally adjusting to my nighttime shift schedule, which took a few days to get used to. Luckily, we do have a few hours of darkness (from about midnight until 6am), which makes it easier to fall asleep. My shift runs from 4pm-4am, and I usually head to bed not long after my shift is over, and get up around noontime to begin my day. It’s a little strange to be waking up so late in the day, and while it is clearly afternoon time when I emerge from my room, I still greet everyone with a good morning. The eating schedule has taken some getting used to- I find that I still want to have breakfast when I get up. Dinner is served at 5pm, but since I eat breakfast around 1 or 2pm, I typically make myself a plate and set it aside for later in the evening when I’m hungry again. I’ll admit it’s a little strange to be eating dinner at midnight. There is no shortage of food on board, and our stewards make sure there are plenty of snacks available around the clock. Salad and fruit are always options, as well as some less healthy but equally tasty snacks. It’s hard to resist some of the goodies we have!

Luckily, we are equipped with some exercise equipment on board to battle those snacks, which is helpful as you can only walk so far around the ship. I’m a fan of the rowing machine, and you feel like you’re on the water when the boat is rocking heavily. We have some free weights, an exercise bike and even a punching bag. I typically work out during some of my free time, which keeps me from going too crazy when we’re sitting for long periods of time in the lab.

Up on the bridge making the turn for our next transect.

During the rest of my free time, you might find me hanging out in the lounge watching a movie (occasionally), but most of the time you’ll find me up on the bridge watching for whales or other sea life. The bridge is probably one of my favorite places on the ship, as it is equipped with windows all around, and binoculars for checking out the wildlife. When the weather is nice, it is a great place to sit outside and soak in a little vitamin D. I love the fact that even the crew members that have been on this ship for several years love seeing the wildlife, and never tire of looking out for whales. So far, we’ve seen orcas, humpbacks, fin whales, and Dall’s porpoises.

Did you know? Otoliths, which are made of calcium carbonate, are unique to each species of fish.

Where on the ship is Wilson?

Wilson the ring tail camo shark is at it again! He has been exploring the ship even more and made his way here. Can you guess where he is now?

July 11, 2012August 11, 2021

Amanda Peretich: More Trawling Treasures, July 11, 2012

NOAA Teacher at Sea
Amanda Peretich
Aboard Oscar Dyson
June 30, 2012 – July 18 2012

Mission: Pollock Survey
Geographical area of cruise: Bering Sea
Date: July 11, 2012

Location Data
Latitude: 58ºN
Longitude: 173ºW
Ship speed: 11.7 knots (13.5 mph)

Weather Data from the Bridge
Air temperature: 7.9ºC (46.2ºF)
Surface water temperature: 7.3ºC (45.1ºF)
Wind speed: 10.7 knots (12.3 mph)
Wind direction: 323ºT
Barometric pressure: 1007 millibar (0.99 atm, 755 mmHg)

Science and Technology Log
In a recent post, I talked about how one of the things we are doing on board the Oscar Dyson is trawling for fish. The video from that post showed what happens in the fish lab during a midwater trawl. Remember that there are two nets we have been using for a midwater trawl: first, the normal Aleutian Wing Trawl, or AWT, which catches plenty of pollock, but also the 83-112 to which adjustments are being made to use this bottom trawl net for midwater fishing. But what about using the 83-112 for its original purpose: bottom (or benthic) trawling?

Bottom Trawl

I’ve been lucky enough to see two bottom trawls on this cruise, although neither of them were actually during my shift. My wonderful roommate Carwyn, one of the other scientists on board, came to tell me about the bottom trawls so I could see all the neat creatures from below! A bottom trawl is used when the pollock are swimming much lower in the water column for one reason or another, but in trying to catch them, there are always many more “trawling treasures” that find their way onto the fish table. The process is basically the same as a midwater trawl, except the 83-112 net is lower down in the water towards the bottom of the sea floor (hence the term bottom trawl). The net is also much shorter in length than the AWT using in midwater trawling.

DYK?: How do the scientists know exactly how far down the net is in the water column? One of the sensors attached to the net is called the SBE (Seabird) 39. This will measure the depth and temperature during the trawl and determine the average head rope depth (which is the top of the net) and average temperature during the trawl between EQ (equilibrium – start of the trawl) and HB (haul back – end of the trawl). The sensor is then uploaded on the computer and the data is used by the scientific party.

Headrope Haul 76 — This plot is used to determine the average head rope depth and temperature during the trawl (between EQ and HB). Depth is measured in meters and temperature in degrees Celsius on the y-axis versus time on the x-axis.

Field Guides — Field guides to classify various species found in the Pacific Ocean.

I attempted to classify all of these great bottom trawl treasures, and discovered that this was way easier said than done. There are some books in the fish lab with photos and descriptions just of the species that may be found around the Alaskan waters, and it was incredibly difficult to nail down a specific species for most of the finds!

In the bottom trawl, we found things such as the Oregon hairy triton, an unidentified pretty purple star fish, pink shrimp, basket stars, sheriff’s star, halibut, crabs, pacific cod, sculpin, Pribilof snail, sea anemone, scallop, sponge, sea pens, arrowtooth flounder, flathead sole, chiton, and seaweed.

Enjoy the slideshow below with photos of the bottom trawl treasures (and an interesting fact or two about some of them) or click on the link to open it in a new window!

Bering Sea Bottom Trawl Treasures

Methot Trawl

The other trawl we’ve done outside of the normal AWT (Aleutian Wing Trawl) midwater and 83-112 midwater comparison trawl is something called a methot trawl. This uses a completely different net because the others have mesh that is much too large to catch something so small. The methot net has very fine mesh and a hard square opening with a fixed height. The cod end (very end of the net) is actually a small white container because the organisms collected are so small. A methot trawl is done to collect euphausiids, otherwise known as krill. Sometimes other microscopic (small) organisms are collected as well, including jellies, salps, and amphipods, which must then be carefully sorted out.

DYK?: Krill are part of the phylum Arthropoda, which includes species with an exoskeleton and jointed legs such as spiders, crabs, insects, and lobsters. They are an important part of the ecosystem because these small, reddish-orange animals are a source of food for many larger animals.

Steps to process a methot trawl in the fish lab:
1. Dump contents of the hard cod end container into a large gray bin.
2. Remove any large jellyfish (and weigh those separately).
3. Rinse contents from the gray bin into the sieve to remove any water.
4. Using tweezers, sort through the small microscopic organisms on the sieve and remove anything that isn’t krill.
5. Weigh krill sample.
6. Collect a random subsample in a scoop and weigh it.
7. Count all of the krill in the subsample (yes, this is as tedious as it sounds!).

Processing a Methot — Processing a methot trawl: removing water with the sieve, sorting through all of the krill and pull out any amphipods, salps, or jellies with tweezers (to weigh separately).

Personal Log

Bowthruster — Heading down to check out the bowthruster on the *Oscar Dyson*!

It continues to be a little slow on the trawling during my shift, but that’s okay, because I was lucky enough yesterday to get a tour of some of the lower bridge levels from the 1^st Assistant Engineer, Tony.

DYK?: There are 8 levels on the Oscar Dyson. They are numbered, starting from the topmost deck, as follows:
O4 – flying bridge
O3 – bridge
O2 – staterooms (CO, XO, chief scientist)
O1 – staterooms (scientists), CTD winch, FRB (fast rescue boat), Peggy D (boat), liferafts
1 – galley, labs (acoustics, chem, dry, fish)
2 – engineering (machinery, centerboard, oceanic winch, trawl winch, and more), staterooms (deck crew and then some)
3 – engineering (machinery, bilge/ballast, workshop, and more)
4 – bowthruster, transducer, fuel oil tanks, ballasting tanks

I plan to share some of the facts I learned related to chemistry and biology from this tour (and other things on board) in one of my next blogs, so be sure to look for all of the info on the generators, sea water purification, MSD, cathodic protection system, and more.

We did have two trawls yesterday (July 10) – the first was an AWT midwater trawl that had caught so many fish it was actually a “splitter”! In a splitter, there’s an extra step between hauling in the net and getting it to the table in the fish lab. The cod end of the AWT net is opened over a separate splitting crate, where there is another net underneath that will only take about half of the fish to release on the table. The rest are then returned to the water.

Splitting an AWT midwater trawl that collected too many pollock.

We also had drills yesterday (these are required once a week) and after gaining permission from the bridge, I checked in to my muster station (which is in the conference room for the science party, away from all of the action) and then went and watched what everyone else on board does. When we have fire drills in school, the alarm sounds, we walk outside, and wait for the “all clear” before heading back in. When they have fire drills on the Oscar Dyson, they use a smoke machine to produce smoke, there is an on-scene crew (first responders), there may or may not be a “victim” involved, the hose team actually dresses out (with the help of another person on the alpha or bravo firefighting teams), and the fire hoses are actually used. It may seem like old hat to everyone else on board, but I found it incredibly interesting to watch!

Following the fire drill, there was an abandon ship drill, where everyone on board grabs their survival suit, PFD, and heads to one of three life rafts (there are actually 6 on the ship). The CO had me stay up in the TV lounge so that my life raft (#5) wouldn’t have a “full muster” until they sent out a search party to find me. Just as there are two people on hose team in both alpha and bravo for the fire drill, people must go in pairs for the search party, so Patrick and Rick came and found me. I think some people thought I’d actually not heard the alarm (I was wearing headphones), but I was instructed to be up there! We will have one more day of drills before we get back to Dutch Harbor, so maybe I’ll actually don my bright orange survival suit, which other Teachers at Sea in the past have affectionately called the “gumby suit” (even though Gumby was green).

Animal Love
In yesterday’s AWT midwater trawl, we had a new visitor in the fish lab. Introducing the lumpsucker!

The lumpsucker is in the family Cyclopteridae, which is derived from Greek words that mean circle and fin in reference to their round-shaped pectoral fins. There is a sucker on the bottom of them, so when we put this little sucker in some sea water while we were processing the fish, he stuck himself to the bottom of the container! Lumpsuckers are poor swimmers, so they are mostly benthic, meaning they stay at the bottom of the sea floor. However, that doesn’t mean they are incapable of swimming (especially since this one was caught during a midwater trawl). We took some photos and tossed this little guy back to sea, so hopefully he makes it!

June 25, 2011April 28, 2021

Tammy Orilio, Trawl Gear, June 24, 2011

NOAA Teacher at Sea: Tammy Orilio
NOAA Ship Oscar Dyson
Mission: Pollock Survey
Geographical Area of Cruise: Gulf of Alaska
Date: 24 June 2011

Weather Data from the Bridge:
Latitude: 54.14 N
Longitude: -164.16
Wind Speed: 9.73 knots
Surface Water Temp: 7.0 degrees C
Water Depth: 92.75 m
Air Temp: 7.2 degrees C
Relative Humidity: 101%

Science & Technology Log:
I’ve been talking a lot about trawling for fish, and I realize that some of you may not know exactly what I’m talking about, so let me explain. Trawling is a fishing method that pulls a long mesh net behind a boat in order to collect fish. Trawling is used to collect fish for both scientific purposes (like we’re doing) and also in commercial fishing operations. We have two types of fish trawls onboard the NOAA Ship Oscar Dyson– a mid-water trawl net and a bottom trawl net. We’ve used both types throughout our cruise, so let me tell you a little about each.

The mid-water trawl net is just as it sounds- it collects fish from the middle of the water column- not those that live on the seafloor, not those that live at the surface. The technical name for the net we have is an Aleutian Wing Trawl (AWT)- it’s commonly used by the commercial fishing industry. The end of the net where the fish first enter has very large mesh, which is used to corral the fish and push them towards the bag at the end. The mesh gets progressively smaller and smaller the further into it you go, and at the very end (where the collecting bag is), the mesh size is 0.5 inches. The end (where the bag is, or where the fish are actually collected) is called the codend. This is the kind of net we use when we want to collect a pollock sample, because pollock are found in the water column, as opposed to right on the seafloor (in other words, pollock aren’tbenthic animals). Our particular net is also modified a little from a “normal” AWT. Our trawl has three codends (collecting bags) on it- each of which can be opened and closed with a switch that is controlled onboard the ship. The mechanism that opens and closes each of the 3 codends is called the Multiple Opening and Closing Codend (MOCC) device. Using the MOCC gives us the ability to obtain 3 discrete samples of fish, which can then be processed in the fish lab. One other modification we have on our mid-water trawl net is the attachment of a video camera to the net, so we can actually see the fish that are going into the codends.

The MOCC apparatus, with the 3 nets extending off.

Part of the mid-water trawl net as it's being deployed. — Part of the mid-water trawl net as it’s being deployed.

The camera apparatus hooked up to the trawl.

When we spot a school of fish on the acoustic displays, we then radio the bridge (where the captain is) and the deck (where the fishermen are) to let them know that we’d like to fish in a certain spot. The fishermen that are in charge of deploying the net can mechanically control how deep the net goes using hydraulic gears, and the depth that we fish at varies at each sampling location. Once the gear is deployed, it stays in the water for an amount of time determined by the amount of fish in the area, and then the fishermen begin to reel in the net. See the videos below to get an idea of how long the trawl nets are- they’re being reeled in in the videos. Once all of the net (it’s VERY long- over 500 ft) is reeled back in, the fish in the codends are unloaded onto a big table on the deck using a crane. From there, the fish move into the lab and we begin processing them.

The end of the trawl net. These are the lines that basically hold on to the net!

One of the codends before being opened up.

The other type of trawl gear that we use is a bottom trawl, and again, it’s just as it sounds. The bottom trawl is outfitted with roller-type wheels that sort of roll and/or bounce over the seafloor. We use this trawl to collect benthic organisms like rockfish, Pacific ocean perch, and invertebrates. There’s usually a random pollock or cod in there, too. As I mentioned in my last post (“Today’s Catch”), the net can sometimes get snagged on rocks on the bottom, resulting in a hole being ripped in the net. Obviously, we try to avoid bottom trawling in rocky areas, but we can never be 100% sure that there aren’t any rogue rocks sitting on the bottom 🙂

The mesh and the wheels of the bottom trawl.

Personal Log:
It’s been a quiet couple of days. On Wednesday, we didn’t see any fish until late in my shift, then we did a mid-water trawl. We ended up actually busting the bag- that’s how many fish we ended up collecting!! Once the codends were opened, we immediately began processing- first separating the pollock from everything else we caught. After sorting, I got to work on sexing the fish- it’s a kind of gruesome job, because you have to take a scalpel and cut them open (while they’re still alive!), exposing their innards- definitely NOT like the preserved organisms we dissect in class. I’m not a huge fan of cutting them open, so I moved on to measuring the length of the male fish- there were so many males in our catch, I was the last one working! After I cleaned up, that was the end of my shift. We were near some islands at the end of my shift, and the bridge called down to the lab to tell us that there some whales off the starboard side of the ship. I grabbed my camera and ran up to the deck, scanning the water for whales. Finally, I spotted a pod waaaay off the starboard side- they were too far off to get a good picture, and I couldn’t even tell what kind they were, but I was able to see them spouting water out of their blowholes, and it looked like one of them breached. The officers up on the bridge said they thought they were minke whales.

Thursday we didn’t see any fish (well, not enough to put our gear in the water) all day, so no fishing for me. Right now, it’s about 9:30 a.m. on Friday, and we’re just cruising to begin our next set of transects. I just read that there was an earthquake in the western Aleutian Islands last night- magnitude 7.2! Holy moly, I was just there! Apparently, people felt the earthquake as far east as Dutch Harbor on the island of Unalaska, and they had a tsunami warning go off. It’s crazy to think that I was in that area a couple days ago!

Question of the Day:

Speaking of tsunamis…What would cause the East Coast of the U.S. to be hit by a megatsunami?