NOAA Teacher at Sea
Aboard NOAA Ship Oregon II
June 22 – July 3
Mission: Groundfish Survey
Geographical area of cruise: Gulf of Mexico
Date: June 26, 2012
Ship Data from the Bridge:
Wind Speed: 5.86 knots
Wind Direction: E/SE
Surface Water Salinity: 35.867 PPT
Air Temperature: 28.8 C
Relative Humidity: 86%
Barometric Pressure: 1010.51 mb
Water Depth: 96.5 m
Science and Technology Log
Opisthonema oglinum, Lagadon rhomboides, Chloroscombus chrysurus…..yes, I have officially started dreaming about taxonomic names of our fish. It’s day 4 and I now have a much better grasp at identifying the variety of critters we pull up in our trawls. I am always excited to be out on deck when they bring up the trawl to see what interesting critters we catch. Surprises are great!
Do you want to know where the Oregon II is headed?
Check out Ship Tracker at http://shiptracker.noaa.gov/
If you click on the link above, you can see the path that our ship is taking to hit all of our stations for the survey. We often have station after station to hit- meaning as soon as we are done sorting and measuring, we have to bring in the next catch. Because some stations are only 3-5 miles apart, we sometimes have to do “double dips”, where we put in the trawl for 30 minutes, pull it up, and put it right back in again.
It’s been interesting to note the variety of our catches. Croakers, bumperfish, and shrimp have been in high abundance the last 2 days as we were in shallower water. Before that we had a couple of catches that had a high abundance of pinfish. When we take our subsample, we typically enter data for up to 20 of that particular species. We take length measurements on each fish, and on every fifth fish. We will also weigh and sex it (if sexing is possible).
When we were in shallower waters, we had a significant increase in the number of shrimp we brought up. Tuesday morning was the first catch that did not have well over 200 shrimp (this is because we’ve been moving into deeper waters). For the 3 commercial shrimp, white (farfantepenaeus setiferus), pink (farfantepenaeus duorarum), and brown (farfantepenaeus aztecus), we take 200 samples, as opposed to our high-quantity fish, where we will only take 20 samples. For each of the commercial shrimp we catch, we measure, weigh and sex each shrimp. I’ve gotten very good at identifying the sex of shrimp- some of the fish are much more difficult to tell. The information we get from this survey will determine the amount of shrimp that boats can take during the shrimping season in Louisiana and Mississippi. During the first leg of the groundfish survey, the data collected determined the amount of shrimp that could be caught in Texas. The groundfish survey is crucial for the shrimping industry and for ensuring that shrimp are not overfished.
Students- think of the food chain. What would happen if we overfished and took out too many shrimp? (Hint: Think of predators and prey.)
We’ve now started doing 2 different tows in addition to our trawls. Some of the stations are trawl stations, whereas others are plankton stations.
At a trawl station, we lower the trawl from the stern down to the ocean floor. The trawl net is meant for catching larger critters that live at the bottom of the ocean. There is a chain, also known as a “tickler”, which moves lightly across the ocean floor to lure fish to leave their hiding spots and swim into our net. The trawl is down for 30 minutes, after which it is brought back on deck to weigh the total catch, and then brought back into the wet lab for sorting.
Another important mission of the groundfish survey is to collect plankton samples. To do this, we use a Neuston tow and a bongo tow.
The Neuston tow has a large, rectangular frame with a fine mesh net attached to it. At the end of the net is a large cylindrical bucket, called a codend, with a mesh screen meant for catching the organisms. In comparison to the trawl net, which has openings of 41.4mm , the Neuston’s mesh is only 0.947mm. This means the mesh is significantly finer, meant for catching some of the smaller critters and plankton that would otherwise escape the trawl net. The Neuston tow is put on the surface of the water and towed for 10 minutes. Half the tow is in the water while half is out. We end up picking up a lot of Sargassum, or, seaweed, that is found floating at the water’s surface. When we gather a lot of Sargassum, we have to sift through it and spray it to get out any of the organisms that like to hide in their protective paradise.
After we’ve completed the Neuston tow, we do the bongo tow. The bongo’s mesh is even finer than the Neuston tow’s mesh at only 0.333mm. The bongo has 2 parts- a left and a right bongo (and yes they do look a little like bongo drums- hence their name). The top part of the bongo is a large cylinder with an open bottom and top. The net is attached to this cylinder, and again at the bottom of each side is cylindrical tube called codends meant to catch the plankton. The bongo tow is meant to take a sample from the entire water column. This means that instead of riding on the surface of the water, it gets sent down to about 3 meters from the ocean floor (there is a sensor at the top that is 2m from the bottom of the net) and brought back up immediately.
For both tows, it is important to rinse the nets to get any lasting organisms we might not see with our own eyes into our sample. Once we’ve done this, we bring the tubes back into the wet lab where we continue to rinse them through a sieve so that only certain items are leftover. In the Neuston, we often find small fish (usually less than 3mm), baby shrimp, crabs and Jessica’s favorite, the Sargassum fish. Most recently a few flying fish got caught in our Neuston tow. Prior to pulling it up, I was enjoying watching them flit across the water- they were about all we could see in the water in the middle of the night. After being rinsed thoroughly through the sieve, we preserve them by placing the sample in a glass jar with either ethanol or formaldehyde solutions. They are preserved in ethanol for DNA work and in formaldehyde for long-term preservation. These samples are then saved to send to a lab in Poland, which is the sorting center for the SEAMAP samples.
Well, I think I am finally getting used to the schedule of working the night shift. I am thankful that my bunk is on the bottom floor of the ship- which means it is completely dark- so that I can sleep during the daytime. Yesterday was probably one of the least busy days we’ve had so far, and because we were in deeper waters, our trawls were much smaller. This means I had a little more time to work on my blogs, which at times can be hard to fit in. It amazes me that we have internet access on the ship, and it’s not even as slow as I expected. It goes down from time to time, especially when the waters are rough. We’ve been fortunate to have pretty calm waters, aside from the first day.
You may have heard about Hurricane Debby on the news as it prepared to hit the Gulf. On Sunday, we were heavily debating heading back to Galveston to “bunker down” and ride out the storm. However, the storm that was forming seemed to dissipate and head in a different direction, thank goodness. I was not thrilled about the possibility of heading back to port!
We had our first drills the day after we set sail. The drills- fire and abandon ship are distinguished by different types of bells, similar to using Morse code. The abandon ship drill was fun. We got to put on our survival suit, which is like a big orange Gumby suit. It not only protects you in cold water, but also makes you highly visible. I remember reading some of the former TAS blogs, and this picture was always in. Of course, I’ve got to add mine as well.
I’ve been having fun exploring different areas of the ship, even though there is only so far you can go on the ship. Yesterday, I went up to the bridge, which is the front of the ship where the captain or the NOAA Corps officers steer the ship from. You can think of it like a control center of an airplane. There are navigation charts (both computerized and paper) and radars that help guide the ship so it knows what obstacles are out there. There is a great view from the bridge that you don’t get anywhere else on the ship. It’s also fun to watch the folks down on deck when they are deploying the CTD or either of the 2 tows.
We’ve caught such an abundance of critters, I thought I’d share some of my favorite catches thus far:
Critter Query Time!
Critter Query #1: What is a fathom (in your own words please)?
Critter Query #2: What are the differences between skates and rays?