NOAA Teacher at Sea
Kate Schafer
Aboard NOAA Ship Oregon II
September 17 – 30, 2017
Mission: Shark/Red Snapper Longline Survey
Geographic Area of Cruise: Gulf of Mexico
Date: September 29, 2017
Weather Data from the Bridge:
Latitude: 29o 11.3′ N
Longitude: 88o 18.3′ W
Few clouds
Visibility 10 nautical miles
Wind speed 8 knots
Sea wave height 1 foot
Temperature Seawater 29.4 o Celsius
Science and Technology Log:
So, as my time on the Oregon II is winding down, I thought I’d share a bit about what it is like to do science on a boat. First of all, there is a tremendous amount of planning that must go into a successful survey in the weeks and months beforehand. In addition to all the logistics of going to sea for two weeks, there is the challenge of putting together a crew of scientists that can be away from their day to day jobs and lives, and agree to work 12 hour days, for weeks on end. Lisa Jones is the Field Party Chief for this survey and must figure out those logistics plus organize the science part as well. This survey has been going since 1995, and one of the keys to longitudinal data sets is that they keep standard methods throughout, or else the data aren’t comparable.
This can be challenging in all sorts of unforeseen ways. For example, a few years ago, it became difficult to find the mackerel used as bait on the longlines. During an experimental survey in the spring, they tried out squid as an alternative and caught a totally different composition of species. Fortunately, the mackerel became more available again, and the problem is no longer an issue, for now.
Lisa is also the one responsible for working with the captain and his crew to determine sampling locations and a plan for getting to those locations. There’s a plan at the beginning, but, of course, that changes frequently, due to weather, the locations of other ships and a myriad of other unforeseen circumstances. The goal is to reach 200 sites per year, with 50% between 5-30 fathoms (1 fathom=6 feet), 40% between 30-100 fathoms, and 10% between 100-200 fathoms. These percentages reflect the depths of the continental shelf area throughout the sampling region. Below is a sampling map for the 2015 longline survey.
During a longline set, the line is deployed for one hour before retrieval, with 100 baited hooks. As the line comes in, each fish is given three to four measurements (depending on the species) and is weighed. Many of the sharks are tagged, as this provides the possibility of someone finding the tagged shark in the future. With a tag retrieval, we can learn about how far the organism has traveled and how much and how quickly it has grown.
As I mentioned in my post about the red snappers, the snappers, groupers and tilefish are dissected for their otoliths and gonads. They can’t be successfully released in most circumstances anyway, due to barotrauma from pulling them quickly to the surface from depth.
Sharks are less affected by barotrauma because they don’t have swim bladders to maintain their buoyancy like the bony fishes we’ve been catching.
Here are a couple examples of our data sheets. As you can see, some sets have more fish than others (in fact the full one, was only one of three pages). Once all the data are collected, they have to be entered in the computer for later summary and analysis. Some days it can be a big challenge to get all the data entered before it’s time to start all over again. Other days, like today, include lots of travel time.
Personal Log:
For me, it has been truly wonderful to get to work as a scientist again, if just for a couple of weeks, especially with such an amazing group of scientists. I’ve learned so much from my fellow day crew members (Lisa, Christian, Nick and Jason). They have patiently answered all my questions, even when it was keeping them from getting to dinner. Lisa Jones has gone above and beyond in her support of me, even though she has had many other responsibilities on her plate. I also appreciate being made to feel welcome lurking around the night crew’s catches. Thanks especially to Christophe, Vaden, and Eric for allowing me to hang out in the measuring pit. I love my job as a teacher, but part of me definitely misses working as a field biologist. I am grateful for the opportunity and especially thankful for my wonderful family. I can’t tell you how much I appreciate your support and love.