Callie Harris: Jellyfish Landslide, August 15, 2019


NOAA Teacher at Sea

Callie Harris

Aboard NOAA Ship Oscar Dyson

August 13 – 26, 2019


Mission: Fisheries-Oceanography Coordinated Investigations

Geographic Area of Cruise: Gulf of Alaska

Date: 8/15/19

Weather Data from the Bridge

Latitude: 57° 16.15 N
Longitude: 152 ° 30.38 W
Wind Speed: 6.53 knots
Wind Direction: 182°
Air Temperature: 17.1°C
Sea Temperature: 15°C
Barometric Pressure: 1026 mbar


Science and Technology Log

Now that we have been out to sea for 3 days, I can better describe what my 12 hour ‘work shift’ is like. We average about three stations (i.e. research locations) per shift. Each ‘station’ site is predetermined along a set transect.

transect map of stations
Transect Map of all of our tentative stations to survey (red dots). Image credit: Matt Wilson

Before we can put any scientific equipment in the water, we have to get the all clear that there are no marine mammals sighted within 100 yards of the boat. I was thrilled yesterday and today that we had to temporarily halt our survey because of Humpback Whales and Harbor Porpoises in the area. I rushed from the scientific deck up to the bridge to get a better look. Today, we saw a total of 6 Humpback Whales, one of which was a newborn calf. Chief Electronics Technician Rodney Terry explained to me that you can identify the calf because the mother often times pushes the calf up to help it breach the surface to breathe. We observed one tall and one short breathe ‘spout’ almost simultaneously from the mother and calf respectively.

humpback whale spout
Humpback Whale breath spout off of bow.

Once we arrive at each station, we must put on all of our safety equipment before venturing out on the deck. We are required to wear steel-toed boots, a life preserver, and hardhat at all times. On scientific vessels, one must constantly be aware that there is machinery (A frames, booms, winches, etc.) moving above you overhead to help raise and lower the equipment in the water. We survey each station using bongo nets, a midwater trawl, and sometimes a CTD device. In future posts, I will go more into detailed description of what bongo nets and a CTD device entail. This post I want to focus on my favorite survey method: the midwater trawl, aka the ‘jellyfish landslide.’

A midwater trawl (aka a pelagic trawl) is a type of net fishing at a depth that is higher in the water column than the bottom of the ocean. We are using a type of midwater trawl known as a Stauffer trawl which has a cone shaped net that is spread by trawl doors.

trawl net
Trawl net aboard NOAA Ship Oscar Dyson

One of the survey’s goals over the next two weeks is to assess the number of age-0 Walleye Pollock (aka Alaskan Pollock.) These juvenile fish hatched in April/May of this year. As NOAA Scientist Dr. Lauren Rogers, my fellow shift mate, explains, this population of fish species tends to naturally ebb and flow over the years. Fisheries management groups like NOAA study each ‘year class’ of the species (i.e. how many fish are hatched each year).

Typically, pollock year classes stay consistent for four to five years at a time. However, every so often management notes an ‘explosion year’ with a really large year class. 2012 was one of these such years. Hence in 2013, scientists noted an abundance of age-1 pollock in comparison to previous years. Based on the data collected so far this season (2019), scientists are hypothesizing that 2018 was also one of these ‘explosive’ years based on the number of age-1 pollock we are observing in our trawl net samples. It is extremely important scientists monitor these ebbs and flows in the population closely to help set commercial limits. Just because there is a rapid increase in the population size one year doesn’t mean commercial quotas should automatically increase since the population tends to level itself back out the next year.

If you have ever gone fishing before, you probably quickly realized just because you want to catch a certain species doesn’t mean you are going to get it. That is why I have nicknamed our midwater trawl samples, “The jellyfish landslide.” After the trawl net is brought back onto the deck, the catch is dumped into a large metal bin that empties onto a processing table. I learned the hard way on our late night trawl that you must raise the bin door slowly or else you will have a slimy gooey landslide of jellies that overflows all over everywhere. At least we all got a good laugh at 11:15 at night (3:15AM Florida time).

Jellyfish Landslide
Jellyfish landslide! (I’m desperately trying to stop them from falling over the edge.) Photo credit: Lauren Rogers.
jellyfish landslide thumbs up
Jellyfish landslide, managed. Photo credit: Lauren Rogers

Once on the processing table, we sort each species (fish, jelly, invertebrate, etc.) into separate bins to be counted and weighed. Each fish specimen’s fork length is also measured on the Ichthystick.

Measuring fork length
Measuring fork length of pollock.

We then label, bag, and freeze some of the fish specimens to bring back for further study by NOAA scientists in the future. There is a very short time window that scientists have the ability to survey species in this area due to weather, so each sample collected is imperative.

Callie and salmon
Our first salmon catch in the trawl. Photo credit: Lauren Rogers.


Personal Log

This experience is nothing short of amazing. Upon arriving in Kodiak on Sunday, I got to spend the next two days on land with my fellow NOAA scientists setting up the boat and getting to know these inspiring humans. Everyone on the boat, scientists and the Oscar Dyson crew, are assigned a 12 hour shift. Therefore, you may not ever see half of your other ship mates unless it is at the changing of a shift or a safety drill. I did thoroughly enjoy the abandon ship safety drill yesterday where we had to put on our survival (nicknamed the orange Gumby) suits as quickly as possible.

Survival Suit Practice.
Survival Suit Practice. Photo credit: Lauren Rogers

Everyone has been commenting that I brought Key West here to Alaska. The last three days at sea have been absolutely beautiful — sunny, warm, and calm seas. I am sure I am going to regret saying that out loud, haha. At the end of my work shift, I am beat so I am beyond thrilled to curl up in my bunk for some much needed rest. Yes, it does finally get dark here around 10:30PM. I was told we might be lucky enough to see the Northern Lights toward the final days of our survey. I am also getting very spoiled by having three delicious homemade meals (and dessert J) cooked a day by Chief Steward Judy. That is all for now, we have another trawl net full of fun that is about to be pulled back onto the deck.


Did You Know?

NOAA CORPS Officer LT Laura Dwyer informed me of the ‘marine mammal’ protocol aboard the NOAA Ship Oscar Dyson. Scientists must temporary halt research collection if any marine mammal (i.e. a Humpback Whale, porpoise, orca, seal, etc.) is within 100 yards or less of the vessel; if a North Pacific Right Whale is within 500 yards; or if a polar bear (yes you read that correctly) is within half a mile on land or ice.


Challenge Yourself

Do you know how to convert Celsius to Fahrenheit? You take the temperature in Celsius and multiply it by 1.8, then add 32 degrees. So today’s air temperature was 17°C and the sea temperature 15°C. Therefore, what were today’s temperatures in Fahrenheit? Answers will be posted in my next blog.

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