Posted By Corey Eddy
22 April 2012
University of Massachusetts Dartmouth graduate student Corey Eddy is currently onboard a purse seinefishing vessel in the eastern Pacific Ocean. He is studying sharks, specifically the physiological stress response, survival, and post-release behavior of sharks captured during purse seining operations. Corey explains the focus of his project in this video.
It’s Earth Day and with that in mind, I’ve been asked to describe a typical day in the life of a graduate student/scientist working at sea.
If all goes well today, I’ll tag five silkies and take blood samples from another five more. I might take blood from some of the tagged sharks,butwe want to minimize the stress those few endure, so probably not. My tags are constantly on standby, waiting to be switched on when they hit the water. My needles, syringes, centrifuges, and all the rest are alwaysset aside, ready to go. It will take just oneglance at the sonar to know there is a huge aggregation of fish under the FAD off our port bow. After the boat pulls into position, the net tender will disengage the cable holding it in place, then pop off the stern, dragging the seine with it. The tender and ship will then move in separate directions, working together to completely encircle the aggregated fish. Following that, the cables will be drawn in to purse the seine shut and slowly haul it aboard. Once the net is sacked tightly against our side, the brail will rattle its way up and down into the net, moving tons of tuna from the sea and dumping them into our hold. I’ll stand aside, watching, waiting to hear the captain or crew yelling “tiburon, tiburon!”Every live silky that comes up in the brail will receive a satellite tag. After measuring the shark, and checking to see if it’s a male or female, I will attach the satellite tag by a small anchor, inserted into the muscle just below the dorsal fin. Once those few things are done, the shark is dropped over the side and set free. If enough silkies come up, I’ll be able to do some work for the stress physiology research too. That involves taking a blood sample, which is run througha handheld analyzer to measure the concentration of oxygen, pH, and various other things we use to measure the stress response. The remaining volume of blood is centrifuged to separate plasma from red blood cells, and stored for further analysis back in the lab at UMass. All told, this should only take a couple minutes.
In the afternoon, when the fishing is done and my equipment has been put away, I’ll be back in my room, reading scientific papers or writing grant proposals; most likely the latter. That’s how I spend most of my days. The proposals are an attempt to get funding for the other half of my doctoral thesis, for which I’m studying Galapagos sharks in Bermuda. I haven’t had much luck yet though. Some of that work is similar to this project, but most of it is different. The common denominator is that I’m studying the physiological response to stress that Galapagos sharks exhibit following capture. The capture event is different however, as that project uses gear similar to a commercial longline, but mine consists of no more than 15 hooks, not hundreds. Another similarity is that I will use satellite tags, but this time I’m primarily interested in long-distance migrations than vertical movements and temperature or depth preferences, although those are also objectives. I’m also studying their habitat use and local movements, feeding ecology, and genetic population structure. Anyway, that’s what I do when we’re not fishing; I read a lot of papers and write proposals. I guess I shouldn’t say that’s all I do. When I my eyes start to wander, my head begins to nod, and I need a break, I often sit on the bridge talking with the captain and whoever is around, usually the navigator and pilot. Other times, I’ll go up on the top deck and hang out with the fisheries observer and helicopter mechanic (did I mention this boat has a helicopter?). Then there are times where I take my coffee out to the side deck and just stare at the ocean for a few minutes, thinking about things. I’ve also got a couple books, but I’m saving them for after I finish a couple proposals; they’re something to look forward.
Well, it’s Earth Day, which of course means it’s a Sunday and, on Sundays, we barbeque. It’s a weekly tradition on the Via Simoun and the crew seems to love it. There’s usually chorizo, fresh guacamole, beans, salad, corn, and both chicken and beef to make burritos. The food has been great, but that’s not to say I don’t miss certain things; I’d love some fresh fruit and I’ve been craving a bacon cheeseburger for days. Oh, and root beer. I digress. I’ll tell you about our meals at another time.
Happy Earth Day.