NOAA Teacher at Sea
Onboard NOAA Ship Oregon II
July 27 – August 8, 2012
Mission: Longline Shark Tagging Survey
Geographic area of cruise: Gulf of Mexico and Atlantic off the east coast of Florida
Date: July 29, 2012
TRAINING AT SEA
In my last blog I mentioned we would be at sea three days to get to where we will begin the longline survey. I thought I would take a little time to share some of the training before we ever start a longline survey. Everybody pitches in to make sure we have a safe, successful journey.
First we learned the different parts to the longline. The line starts with a high-flier buoy and a weight. Gangions (also known as a branch line or leader) are snapped to the line. Another weight is placed midway, with more gangions, then finally another high-flier buoy at the end. There are 100 gangions used for the NFMS Bottom Longline Survey. While there are several variations when using longline gear, the NFMS Bottom Longline Survey has used this standardized set-up in order to minimize variables. By using the same gear year after year they are able to compare fish catch data, minimizing any bias attributed to changing gear that may fish differently.
This just isn’t your average fishing trip! The longline itself is one nautical mile long! How long is this on land? In addition, each end is also calculated into the total length. This will vary depending on how deep the ocean floor is where we are fishing. The longline is left for one hour then retrieved.
Before we begin, everything needs to be ready and in place. Each gangion has to be placed in a barrel so they do not get tangled taking them out. A tangled bunch of gangions is a big problem. First, the AK snap of the gangion goes into the bucket. Next, let the line go into the bucket. Finally, place the hook in the notch in the bucket, making sure it points in toward the bucket. We certainly do not want anyone passing by caught by a hook.
There are many data scientists use in their research. We need to make sure we collect accurate data; consistent with the 18 years this study has been going on. First we learned how to measure the length (in millimeters) of a shark. We used an Atlantic Mackerel as a measurement example. There are three length measurements to be taken: Total Length (from tip or nose to tip of tail), Fork Length (from tip of nose to notch in tail), and Standard Length (from tip of nose to where body ends and tail begins). The shark is placed on a two meter long measuring board. If the shark is longer than two meters, a measuring tape is used to measure length. The three lengths are recorded.
In addition to the three length measurements, we must also identify the species of shark, measure weight, condition when caught, sex, maturity (for males), hook number, and any tag information if the shark had been tagged before. For some species, if the shark isn’t tagged, we will tag it. We also need to record which vessel we are on, which survey, which station, and the date. Data is also being collected on many aspects of the water. Other samples may be taken that will determine the age of the shark (vertebrae).
The last thing we learned was how to bait a hook. These hooks are big! Atlantic Mackerel are used for bait. We must be careful to double hook the bait or it will fall off.
There you have it. Tomorrow I will begin working the longline actually fishing for sharks!
After three days in the Gulf of Mexico we see land! We passed near enough to be able to see the coastline of Miami. It all seems so peaceful here aboard the Oregon II when looking out into what I know is the hustle and bustle of Miami, Florida.