NOAA Teacher at Sea
Aboard NOAA Ship OREGON II
August 13 – 28, 2016
Mission: Shark/Red Snapper Longline Survey
Geographic Area of Cruise: Gulf of Mexico
Date: Wednesday, August 17, 2016
Weather Data from the Bridge:
Latitude: 25 29.664 N
Longitude: 082 02.181 W
Air temperature: 84.56 F
Pressure: 1018.13 Mb
Sea Surface Temperature: 30.5 C
Wind Speed: 13.54 Kt East 12.72 degrees
The fishing process on the ship repeats itself in a well-defined cycle: cut bait, bait 100 hooks, drop hi-flyer, drop weight, attach 50 tags and baited hooks, drop weight, attach 50 more tags and hooks, drop weight, deploy hi-flyer. Put the CTD over the side and retrieve for water quality data. Wait an hour. Retrieve hi-flyer, retrieve weight, pull in first 50 hooks and detach tags logging any catch as they come in, retrieve weight, pull in next 50 hooks and detach tags logging any catch as they come in, retrieve last weight, retrieve last hi-flyer. Process the catch as it comes in, logging tag number, gender, species, lengths at 3 points, life stage, and tag number if the catch is a shark that gets tagged, return catch to water alive as quickly as possible. Transit to the next sample site. Wash, rinse and repeat.
That boils it down to the routine, but long line fishing is much more interesting and exciting than that! Bait we use is Atlantic Mackerel, caught farther north and frozen, thawed just before use and cut into 3 pieces per fish. A circle hook is inserted through each piece twice to ensure it will not fall off the hook…this is a skill that takes a bit of practice. Sometimes hooks are pulled in with bait still intact. Other times the bait is gone and we don’t know if it was eaten without the hook catching, a poor baiting job, or more likely eaten by smaller fish, too little to be hooked. When we are successful we hear the call “FISH ON!” and the deck comes alive.
The line with a catch is pulled up as quickly and carefully as possible. Some fish are not securely hooked and are lost between the water and the deck…not what we want to happen. If the catch is a large shark (generally 4 feet or longer) it is raised to the deck in a sling attached to the forward crane to minimize the chance of physical injury. For large sharks a camera with twin lasers is used to get a scaled picture for estimating length. There is a dynamometer on the line between the sling and the crane which measures pressure and converts it to weight. Both of these processes help minimize the time the shark needs to be out of water with the goal of keeping them alive to swim away after release. A tag is quickly attached to the shark, inserted under the skin at the base of the second dorsal fin. A small clip is taken from a fin, preferably from the pelvic fin, for DNA studies. The sling is lowered back to the water and the shark is free to swim away. All data collected is recorded to the hook-tag number which will identify the shark as to geographic location of the catch.
Sometimes the catch is a smaller shark or a bony fish: a Grouper, a Red Snapper, or any one of many different types of fish that live in this area. Each of these is brought onto the deck and laid on a measuring board. Species, length, and weight are recorded. Fin clips are taken. Many of them are on the list of species of recreational and commercial importance. These fish are retained for life history studies which will inform future management decisions. In the lab they are dissected to retrieve otoliths (ear stones) by which their age is determined. Depending upon the species, gonads (the reproductive organs) may be saved for study to determine the possibilities of future reproductive success. For certain species a good-sized piece of flesh is cut from the side for fraudulent species voucher library use.
After the smaller sharks are measured, fin clipped, gender identified, life stage is determined and weight is taken, they are tagged and returned to the water as quickly as possible. Tags on these sharks are a small, numbered plastic tag attached by a hole through the first dorsal fin.
This is a lot to get done and recorded and it all happens several times each shift. The routine never varies. The amount of action depends upon the success of the catch from any particular set. This goes on 24 hours per day. The only breaks come as we travel between the sites randomly selected for our sets and that time is generally spent in the lab.
(Thanks go to Kevin Rademacher, Trey Driggers and Lisa Jones, Research Fisheries Biologists, for contributing to this entry. File photo NOAA/NMFS)
I do not need 12 hours of sleep. That means I have several hours at the start or end of each shift to write in my journal, talk to the other members of the crew, take care of personal business such as laundry and communicate with home via email. Even so, every day seems to go by very quickly and I go to bed thinking of all the things I have yet to learn. In my next posts I will tell more about the different kinds of sharks and introduce you to some of the other people on the ship. Stay tuned.