Mission : Shark/Red Snapper Bottom Longline
Geographical area of cruise: Western Atlantic Ocean and Gulf of Mexico
Date: Aug. 23, 2013
Weather: current conditions from the bridge:
Lat. 29.31 °N Lon. 84.18 °W
Temp. 83 °F (28.8 °C)
Wind speed 10-15 kts
Barometer 30.03 in ( 1017.15mb)
Visibility 10 mi
Science and Technology Log:
The weather hasn’t been cooperating with us too well as we have run in to an occasional squall. It is amazing just how quickly that wind can pick up. Yesterday in the course of hauling in the line the wind increased from 18 to 34 knots (A knot is similar to mph, but it uses a nautical mile as a distance. One knot = 1.15 mph).
But the fish have been cooperating. The lull is over and the catch has increased. For the most part we are catching Red Grouper, an occasional Red Snapper and a variety of sharks. Click here to see the shark species found in the Gulf of Mexico. The majority of the sharks have been large enough to cradle. When we hear “hard hats that means it’s a big one” and our team jumps into action. Some of the sharks come up in the cradle quietly, but others come up thrashing about. They are quickly held down by the fishermen of the deck crew which keeps the sharks quiet and safe. Then the science team steps in to collect the data and insert a tag. As the cradle is lowered back down it is paused to obtain the shark’s weight. There is an electronic scale located at the top of the cradle. It is then lowered into the water and the shark swims away. I’m still amazed at how efficient the process is. The sharks are measured, tagged and weighed in a matter of just a few minutes.
There is a level of excitement when catching any of these fish and sharks, but the exceptional catch raises that level. This occurred a couple of days ago. We had something on the line and it was big – really big. Even the crew was yelling about its size. I knew it was something special. As it got closer to the boat it was identified as a huge Tiger Shark (Galeocerdo cuvier). The crane operator was bringing the cradle and the science team was getting ready when ……it was gone. It had bitten through the line. I guess there always has to be that big one that got away.
The level of excitement rose again when the next day we caught a Great Hammerhead shark (Sphyrna mokarran). Any of the larger Hammerheads or Tiger Sharks are being fitted with a satellite tag. This is attached to their dorsal fin (the large fin on their back). Whenever the shark comes to the surface, the tag will transmit its location via radio waves to a satellite. The satellite will then send the signal back down to a receiving antennae and on to various labs. This is a type of remote sensing that is commonly used to track animals. It gives scientists information about animal’s behavior and migration patterns. These particular satellite tags are from the Louisiana Department of Wildlife and Fisheries. It is a collaborative effort to get the tags on as many sharks as possible so they can study where they go after being caught.
While working with the scientists I noticed that they use a combination of metric units, maritime units and imperial units. The fish are measured in millimeters, the electronic scale measured in pounds (normally it measures in kilograms, but there was a technical issue that required changing to pounds), the handheld scale measure in kilograms, the water current is measured in knots, the depth for the CTD is measured in meters, the distance is measured in nautical miles and the survey areas are divided by fathoms ( 1 fathom = 6 feet), just to name a few. It is helpful to be familiar with all of them and be able to convert from one type of unit to another. It has made me think that we should be practicing our metric conversions even more than we currently do in class. So, my incoming freshmen, get ready.
Personal Log :
The time is passing so quickly here on the ship. I think that is because there is always something happening here. My daily routine consists of rising around 7:30 am, grabbing a light breakfast and then going to see what the night shift is doing. Often times they are preparing to haul in the line and I can’t resist watching that. I have an early lunch since my shift will begin at noon, but we are usually prepared to go before that time. For the next twelve hours we will set the line, run the CTD, haul in the line and move on to the next site. Dinner is at 17:00 ( 5:00 pm) but if we are busy we can request a plate be set aside for us. The distance between sites can be anywhere from less than a nautical mile (nm) to over 60 nm. The ship can travel about 10 knots depending upon the wind and the current. So, there are times when we have a number of hours between sites. On these occasions I check my email, work on my blog, edit my pictures or just stand on the deck and look out over the water. I always have my eyes open for animals, but it isn’t often that I see any. Just water as far as the eye can see. It gives me a sense of the vastness of the ocean. And I am seeing lots of beautiful cloud features and sunsets.
I had the special privilege of getting a tour by the Chief Marine Engineer, Sean Pfarrer, of the engine room. It is very loud down there so we had to wear ear plugs. Sean pointed to different things and I took pictures. Then upstairs, in the relative quiet of the galley, he took the time to explain to me the role of each component. We had a really interesting discussion. Any mechanical questions that arose after that, Sean was the one I’d go to. When I return, anyone interested in mechanics can listen to my presentation of the engine room – it’s more interesting than you may think.