NOAA Teacher at Sea
Germaine Thomas (she/her)
Aboard NOAA Ship Oscar Dyson
August 7 – August 21, 2023
Mission: Acoustic Trawl Survey (Leg 3 of 3)
Geographic Area of Cruise: Pacific Ocean/ Gulf of Alaska
Date: Friday, August 18, 2023
Lat 58.18 N, Lon 148.82 W
Sky condition: Partially Cloudy
Wind Speed: 10.55 knots
Wind Direction: 32.58°
Air Temp: 14 °C
Science and Technology Blog
Meet Sandi Neidetcher, she is a fish biologist investigating fish reproductive status. Why care about fish reproduction? Well, the seafood industry is extremely important to Alaska and other coastal states. And they would not have an industry if those “little fishes” could not reproduce. But the ocean is changing due to climate and different types of pollution.
Climate change is making our oceans a warmer place—just a couple of degrees, but that may be enough to really change how fish reproduce and spawn. A few degrees in temperature could change when and where fish reproduce, and then cascade to the fishing industry, the food market, and the people who depend on them as food.
NOAA wants to have background information on fish reproduction so they can recognize whether the fish have changed their reproductive strategies over time and how that could impact fisheries.
Sandi received her Masters degree studying the ovaries of Pacific cod to determine the phenology and geography, or the timing and location, of spawning. She specialized in histology, which is the study of microscopic tissue structures, for her it was specifically the ovaries. To understand the reproductive process and ovary maturation, she studies slides with ovary tissue mounted and stained to show oocyte (unfertilized egg) structures that develop as the spawning season progresses.
Now she is involved in a study looking at the reproductive states of Walleye Pollock. Pollock are multi-batch spawners. They have the ability to spawn (lay eggs) more than once in a season. So the female ovaries can be in different stages of reproduction throughout the season.
The first step in this analysis is to collect the ovaries from the pollock.
In the photo above, the fish will be measured for length and weight, then the ovary and the liver will be removed, weighed, and saved for analysis. The fish’s ear bones (otoliths) will also be removed and used to determine its age. Samples are sent back to Sandi at NOAA AFSC (Alaska Fisheries Science Center) in Seattle, Washington. Half of the ovary will be sent to a histology lab where technicians will prep the tissues and return the sides ready to be analyzed. The other half of the ovary is scanned on the ship.
Sandi is comparing the histological samples to Raman Spectroscopy Analysis that she does aboard the Oscar Dyson. A long time ago when I was an undergraduate student in chemistry, Raman spectrometers were very large. The one I worked with in my physical chemistry class was in the basement of a building on a special concrete slab that stopped any vibrations from disturbing the path of the laser. Did I mention that the whole setup took up almost half of the basement?
Raman spectrometers have come a long way since my undergrad. Today, Sandi has a small wand that contains a laser connected to a spectrometer the size of a donut box. A small desktop computer connected to the spectrometer will give an immediate readout of the analysis.
The wand with the laser is held over the ovary to collect data on large macromolecules like lipids, proteins, and DNA.
The analysis that Sandi does is to compare the molecular composition identified through the spectral patterns with the structures seen in the histology samples, and to determine if the maturation status can be identified through the spectral patterns. The ultimate goal would be to have a small hand-held spectrometer that a scientist could use right as the ovaries are extracted. This would greatly increase the amount of ovaries analyzed quickly and efficiently and reduce the cost and time required for histological analysis
Pollock have variability in their reproductive strategies and may be impacted by environmental conditions. One strategy is down regulation, where a fish will reabsorb a number of eggs during maturation and, as a result, reduce the resources spent on reproduction. This reduces the fecundity, or number of eggs released by that fish in a season. Knowing how fecund a fish population is helps managers determine how many fish can be removed by a fishery. Atresia is the resorption of an oocyte and can be seen histologically. Mass atresia is where a whole ovary of oocytes is be reabsorbed. If the fish is not finding enough food or the temperature is not correct then, then a female fish can save energy by reducing, or stopping the whole process of reproduction.
Recent warming sea temperatures have been seen in the Gulf of Alaska, and this may be impacting fish reproduction. In 2020, the number of Pacific cod predicted had dropped so low that the federal waters fishery was closed. That same year, crew fishing for Pacific cod reported seeing a number of Pacific cod with mass atresia. Scientists do not know if the observation of atresia, during a warming period, is related to the population crash but studies like this will give more information for the future. Predicting population crashes that may be related to climate change, fish health or temperature differences are an important part of fisheries management and impact us all because the ocean is an important resource.
Crew Members in the Spotlight
The Commanding Officer runs the ship, but there are many important jobs that the Oscar Dyson would not function without. Engineering is one of them. There is a small team of Engineers aboard that are constantly monitoring the ship when on shift.
Juliette is a member of the Oscar Dyson’s Engineering department and may have been on the staff the longest. Her personality is direct, friendly and capable. Before becoming an Engineer, she attained her bachelor of science degree at the University of Washington. After receiving her degree she did not really have a clear plan for a job. So she went to a community college and received the equivalent associates degree of a Junior Unlicensed Engineer. Eventually, through NOAA, she can be a fully qualified Engineer with time aboard ships.
Juliette has a wildly creative side and interest in science. The scarf she is wearing in the picture has different layers present in sedimentary rock. She is also a big fan of dinosaurs, placing several all over the ship for people to find when work is slow. Honestly, it is the kind of humor that keeps everyone moving around with a smile. Some dinosaurs even have sweaters that she knitted, in her down time. Her knitting is extremely impressive.
Ben is the Survey Technician for the ship. Survey Technician is the kind of job you would never know exists as a high school student. There are jobs out there in this world that people would never specifically train for in high school or college , but are highly needed where you have different groups collaborating in complex situations. Ben’s job description is a pretty long list; calibrate scientific instruments, collect data, assist scientists, help the deck crew, and act as a liaison between science and the deck crew.
How did he arrive at this position? He attained a bachelor of science in Wildlife Biology and worked in the field for a while. Unfortunately, he found the job hard to make a living with the low pay. Fishing’s siren song came in the form of factory trawling and other crew positions in smaller boats. Because of his academic training and work experience the “perfect storm” of a Survey Technician was born.
Soon we will be taking our last trawl sample and heading to port in Kodiak. There have been moments on the cruise where time crawled in the dead of night while I was struggling to stay awake. Mostly, it has been a trip of a lifetime, with an incredibly capable and adaptive team of scientists and crew members willing to share stories that keep you awake and lull you to sleep, dreaming about tomorrow.