Nikki Durkan: Fish Heads and Otoliths, June 21, 2015

NOAA Teacher at Sea
Nikki Durkan
Aboard NOAA Ship Oscar Dyson
June 11 – 30, 2015

Mission: Midwater Assessment Conservation Survey
Geographical area of cruise: Gulf of Alaska
Date: Sunday, June 21, 2015

Weather Data from the Bridge:
Wind speed (knots):  13.01
Sea Temp (deg C):  10.45
Air Temp (deg C): 9.46

Career Highlight

Meet:  Patrick Ressler PhD, Chief Scientist on board the Oscar Dyson

Employed by: Resource Assessment and Conservation Engineering Division
Alaska Fisheries Science Center, NMFS, NOAA

Hails from: Seattle, Washington

Fun in the fish lab!  Happy Father's Day, Patrick!

Fun in the fish lab! Happy Father’s Day, Patrick!

What are your main responsibilities as Chief Scientist? As chief scientist I’m responsible for the scientific mission and for the scientific party.  In terms of the science, it’s my job to make sure that everything that needs to happen does happen, before as well as during the cruise, and that the scientists have positive and productive interactions with each other and with the ship’s crew.  Some of the decisions that need to be made are scientific or technical, some are logistical, some are managerial.  Though I don’t and can’t do all of the different jobs myself, I need to have some understanding of all the elements of our survey work and research projects, and pay attention to the ‘big picture’ of how it all fits together.   I am also the main line of communication between the scientific party and the ship (principally the captain), and between our scientific party and the lab back onshore.

What do you enjoy about your profession? Science involves a great deal of creativity and collaboration. The creativity comes into play when designing a study and also when problem solving; complications always arise in research, and it is part of Patrick’s job to address the issue or know who to ask to assist in overcoming the obstacle.  He also enjoys doing literature reviews because the process involves more than data collection and meta-analysis; the studies tell stories in a way, scientists leave clues about their interests, bias, and even personalities in their pursuit of research topics.

Do you eat fish? Yes! — Patrick uses the seafood guide when making decisions about purchases and eats salmon often. He smokes his own fish and looks forward to cooking at home with his wife and two children.

Vinny (TAS) and Emily Collins bringing in the catch of the day.

Vinny (my co-TAS) and Emily Collins bringing in the catch of the day.

Otolith extraction - the head incision is made just in front of the operculum (gill covering)…not my favorite part of the day, but as close as I’ll ever get to be a surgeon.

Otolith extraction – the head incision is made just in front of the operculum (gill covering)…not my favorite part of the day, but as close as I’ll ever get to be a surgeon.


Science and Technology Log

Fish heads and more fish heads: Once on board, the fish are sorted by species and we then determine length, weight, sex, and gonad development for the Pollock. The next step is to extract the otoliths, a calcium carbonate structure located in the skull that allows the fish to hear and provides orientation information. These small structures provide scientists with data on ages of the Pollock populations and environmental fluctuations. Understanding how Pollock populations respond to stresses such as the pressures of commercial fishing operations or variations in prey availability, help fisheries managers make informed decisions when setting quotas each year.


Pollock otolith

Pollock otolith

These structures are analogous to the human ear bones; the otoliths allow the fishes to determine horizontal and vertical acceleration (think of the feeling you experience while moving up and down in an elevator). The otoliths pull on the hair cells, which stimulate an auditory nerve branch and relay back to the brain the position of the head relative to the body. A disturbance in this function is also why we humans experience motion sickness. Many of you may also be familiar with the growth rings of a tree and how scientists can measure the width of the rings to determine age and growth rate; similarly, each year, a fish will accumulate deposits on the otoliths that can be interpreted by scientists back in the lab. NOAA has a neat program you can try: Age Reading Demonstration. My co-Teacher at Sea (Vinny Colombo) and I will be bringing back samples to use in our classrooms!

My cod-face with a Cod that tried to swallow a Pollock. Photo credit:  Patrick Ressler

My cod-face with a Cod that tried to swallow a Pollock. Photo credit: Patrick Ressler

For some species, the information gathered from these otoliths can also be used to infer characteristics about the environment in which the fish travels. Climate scientists use similar data from trees, ice cores, coral reef cores, and sediment deposits to produce geochemical records used in modeling paleoclimates and projecting future changes in climate. Likewise, the otoliths contain a geochemical record because the calcium carbonate and trace metals correlate with water samples from certain areas. Scientists can then ascertain the otolith’s chemical fingerprint using a mass spectrometer and uncover information on the fishes’ spawning grounds and migration routes. In some cases, these data are even used to establish marine protected areas.

Personal Log

I have great appreciation for the hard work the crew puts in on a daily basis and am thankful for the humor they continue to provide! I’ve seen more than a few impressions of overly stuffed Puffins and fish faces, shared laughs while Rico pulls fish scales out of my hair, danced to Persian pop songs, and continued to laugh at the ridiculously overused puns in the Bridge. Humor is vitally important out here! The ship operates 24 hours a day and shifts are long, with spurts of demanding physical labor. A lot of coffee is consumed on board and the Oscar Dyson even has a fancy espresso machine! Sadly, I figured out early on that coffee makes me quite nauseated on board. I am a firm believer in the health benefits of coffee and thanks to John Morse (a fellow teacher at Steamboat Mountain School), I have accumulated many scientific articles to back up my claims; however, in this case I had no choice, and after a few headaches, I am free from the bean addiction…for now!

Trying out the engine room sound powered phone



Did you know? In the event of a power failure, the Oscar Dyson is equipped with sound powered phones – the sound pressure created when a person speaks into the transmitter creates a voltage over a single wire pair that is then converted into sound at the receiver – no electricity necessary!

2 responses to “Nikki Durkan: Fish Heads and Otoliths, June 21, 2015

  1. Hi Niks! I am really enjoying your blog and learning lots of new stuff. Your entries often stimulate me to research related topics and sometimes I laugh out loud at the pictures and the faces you make. I showed your pictures to mom and she says she can’t believe how grownup you look!
    Here is some info on telecommunications and electricity you might enjoy:
    The sail drones remind me of windsurfing and trying to go faster by trimming the sail most efficiently. With our gusty and shifting wind I wonder if adding the trim gadget to the back of my sail would improve the speed. Hmm.. Maybe a new hobby here on Maui awaits.
    Lots of love!

  2. Hi NIkki,
    Looks so very interesting. What a great opportunity. NPR just ran a story on the overly beloved fish we so often choose to eat.
    You look happy and I am so happy for you. It has gotten hot in Steamboat. Boo hoo.

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