Title: Jessica Cobley: “Camera, Nets, Science!” July 25th, 2019


NOAA ship Oscar Dyson

At sea from July 19th – August 8th

Mission: Midwater Trawl Acoustic Survey

Geographic Area of Cruise: Gulf of Alaska (Kodiak to Prince William Sound)

Date: 7/25/2019

Weather Data from the Gulf of Alaska:  Lat: 58º  50.39’ N  Long: 150º 14.72’ W 

Air Temp:  14.2º C

Personal Log

We have been out at sea now for 5 days and are getting into the swing of things. While the 3:30am alarm isn’t my favorite, everything else has been great!  A typical day starts with some sort of caffeine for everyone and a briefing from the night crew before we take over. Typically, we finish up the 4th camera drop (explained in science log) while it is still dark out and then head up to the bridge to watch the sunrise. 

Sunrise this morning. The bridge (where the ship is driven from) has one of the best vantage points. 

Meanwhile, Darin watches the acoustic readings and looks for schools of fish we might want to come back to and fish once it is light out. At 7am we pause for breakfast and by then Darin has told the crew where to drop the fishing nets. The process of putting the nets out, fishing, and pulling them in takes about an hour and a half at which point the scientists head out to start collecting the catch. I enjoy fishing in the morning because it makes the time go by quickly. We often break for lunch after the first set (a set is one round of fishing) and then get ready to fish again. 

Tossing back a chum salmon from the catch. Unfortunately, but understandably, we are not allowed to keep any salmon for eating. 

I am lucky enough to have a bit of down time between fishing and processing the catch. So far, I have been filling it with sketching, reading, and curriculum planning for this coming school year. I have also started to interview people with different roles on the boat to help give my students an idea of what working out here can entail. More to come on that later. I head back to school the week after this cruise finishes and so the free time to prep is greatly appreciated! 

Once the shift is over at 4pm, I try to exercise before dinner and then wind down before bed. I was pretty excited to see not only a treadmill on board, but a stationary bike, rowing machine and squat rack. Who knew working out would be so easy on a boat in the middle of the ocean! Note: running and doing yoga on a rocking ship is definitely testing my balance skills. 

Science and Technology Log

CAMERA….

As mentioned before, one of the first jobs in the morning is to complete the last camera drop. When it is dark out, the scientists don’t survey along acoustic transects or fish, as explained in my last blog. Instead, they do another project where fish species and densities are recorded in untrawlable areas with a camera near the seafloor. During the camera drop, a large stereo camera gets lowered off of the deck and into the water. Once at the bottom, a colored image is displayed live on our screens while being recorded in the cameras computer. Another part of this job is to communicate with the bridge about the camera movement. I was responsible for this job the other day and decided to write up a radio command cheat sheet to help me remember!

So far, we have spotted halibut, anemones, sea whips, sea stars, rockfish and skate on the camera.

Once finished with a recording session, all of the images are downloaded to be looked at and quantified later on. The images allow scientists to do species identification, counts, and length measurements.

NETS…

Next up? Fishing! And there is more to the fishing nets than you might think. First, there is one main net that narrows and has decreasing sized holes as you get to the end. The very end of the net, called the codend, is where the fish are collected and sampled from. In addition to the main net are pocket nets, also called recapture nets. These are attached to the sides of the main net and have even finer mesh. Pocket nets help scientists track escapement, or the types of fish that are escaping from the main net. Nets get pulled through the water for up to about 45min and are set in the middle of the water column where acoustics data are showing schools of fish.

Emptying one of the pocket nets. Photo Credit: Abigail McCarthy

SCIENCE!

There are a few things that need to happen before we can step on deck to empty the pocket nets. First, we must put on safety gear consisting of life jackets and head protection. Second, we must wait for the ok from Gus, the lead fisherman, who calls, “SCIENCE”, which we all enjoy.


A couple things we have caught so far. Left: Chrysaora Jellyfish. Right: Capelin 

Pocket net contents are emptied into corresponding numbered buckets to be analyzed. The same is done with the codend net. Once on the fish table, we sort out different species and do a combination of counting, weighing, and measuring the samples. 

Did you know?

Capelin fish smell like cucumber. The deck smells very fresh when you catch a lot of them 🙂  

Thanks for following along!

Cheers, Jess

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s