NOAA Teacher at Sea
Aboard NOAA Ship Pisces
May 1-May 12, 2017
Mission: SEAMAP Reef Fish Survey
Geographic Area of Cruise: Gulf of Mexico
Date: May 10, 2017
Weather Data from the Bridge
Latitude: 2804.2177 N, Longitude: 9042.0070 W
Wind Speed: 10.2 knots, Barometric Pressure: 1016.8 hPa
Air Temperature: 26.1 C, Water Temperature: 24.89 C
Salinity: 36.49 PSU, Conditions: Some cloud, light wind, 2-4 foot waves
Science and Technology Log
Research vessels do not just work during the day. It is a 24/7 operation. Tonight I checked in with the night shift to learn more about the sonar mapping that has been done in the dark ever since I boarded NOAA Ship Pisces.
The first thing I noticed entering the dry lab was a pad of paper with math all over it. Todd, the survey technician I interviewed earlier, had noticed the the picture the ship’s sonar was producing had a curved mustache-like error in the image. Details like temperature need to be taken into account because water has different properties in different conditions that affect how sound waves and light waves move through it. He used the SOH-CAH-TOA law to find the speed of sound where the face of the transducer head was orientated. He found a six meter difference between the laser angle and what the computer was calculating. Simple trigonometry on a pad of paper was able to check what an advanced computer system was not.
NOAA Ship Pisces is also equipped with an advanced multibeam sonar. (Sonar stands for SOund NAvigation and Ranging.) In fact, there are only eight like it in the world. One of Todd’s goals before he retires from NOAA is to tweak it and write about it so other people know more about operating it. Since they are so few and you need to go to them, there are fewer publications about it.
Another mapping device is the side scan sonar. It is towed behind the vessel and creates a 300 meter picture with a 50 meter blind spot in the center, which is what is underneath the device. Hydrographic vessels have more sonars to compensate for this blind spot. The purpose of the mapping is to identify new habitat areas, therefore expanding the sampling universe of the SEAMAP Reef Fish Surveys.
Up on the bridge looks much different. The lights are off and monitors are covered with red film to not ruin the crew’s night vision. Everything is black or red, with a little green coming from the radar displays. This is to see boats trying to cross too close in front of NOAA Ship Pisces or boats with their lights off. Lieutenant Noblitt and Ensign Brendel are manning the ship.
Ensign Brendel noted to me that, “We have all of this fancy equipment, but the most important equipment are these here binoculars.” They are always keeping a lookout. The technology on board is built for redundancy. There are two of most everything and the ship’s location is also marked on paper charts in case the modern equipment has problems.
There are international rules on the water, just like the rules of the road. The difference is there are no signs out here and it is even less likely you know who is following them. Each boat or ship has a series of lights that color codes who they are or what they are doing. Since NOAA Ship Pisces is restricted in maneuverability at night due to mapping, they have the right of way in most cases. It is also true that it takes longer for larger vessels to get out of the way of a smaller vessel, especially in those instances that the smaller one tries to pass a little too close. This did happen the night before. It reminds me of lifeguarding. It is mostly watching, punctuated with moments of serious activity where training on how to remain calm, collected, and smart is key.
It has been a privilege seeing and touching many species I have not witnessed before. Adding to the list of caught species is bonito (Sarda sarda) and red porgy (Pagrus pagrus). I always think it is funny when the genus and species is the same name. We have also seen Atlantic spotted dolphins (Stenella frontalis) jumping around. There are 21 species of marine mammals indigenous to the Gulf of Mexico, most in deep water off of the continental shelf. I also learned that there are no seals down here.
One of the neatest experiences this trip was interacting with a sharksucker (Echeneis naucrates). It has a pad that looks like a shoe’s sole that grips to create a suction that sticks them to their species of choice. The one we caught prefers hosts like sharks, turtles…and sometimes science teachers.
Did You Know?
Fishing boats use colored lights to indicate what kind of fishing they are doing, as the old proverb goes red over white fishing at night, green over white trawling tonight. Vessels also use international maritime signal flags for communication during the day.