Heidi Wigman: Bandit Reels, CTDs, and Camera Drops . . . Oh My! May 29, 2015

NOAA Teacher at Sea
Heidi Wigman
Aboard NOAA Ship Pisces
May 27 – June 10, 2015

Mission: Reef fish surveys
Geographical area of Cruise: Gulf of Mexico (29°38.27’N 087°19.31’W)
Date: May 29, 2015

Weather: 81° @ surface, SE winds @ 8-13 knots, seas 2-3ft, chance of showers, average depth 92m

Science and Technology Log:

The science operations aboard the Pisces is an around the clock event.  For 12 hours each day (0700-1900) we are involved in a series of survey drops at predetermined reef sites, contained within blocks of 100 sq. Nautical Miles.  At each, randomly chosen 0.1sq. Nm site, a set of deployment operations commences.  The first piece of equipment that goes over the side is the camera rig.  This circular housing (diameter/height) contains 4 cameras that take pictures and video.  This rig “soaks” on the bottom for about 40 minutes, capturing the life on the reef, which will later be analyzed by the team, looking for the commercially important species.  One lucky camera is chosen, with the criteria being that there are no obstructions in the frame, and that it is looking at the reef.  From the footage of this camera the scientist will determine the fish abundance and types at the location.  This data is shared with outside agencies for assessment and review of the reef health.

A second deployment at the reef site is the CTD (Conductivity, Temperature, Depth) probe (diameter= 1m/ height=144cm).  This probe is lowered over the side, and does a quick calibration soak just below the surface.  After about 3 minutes, it is lowered to within 2m of the ocean floor and captures data on the descent and ascent that measures conductivity (salinity), temperature, depth, oxygen levels, and turbidity.

The third, and most fun, of the deployments are the bandit reels.  This is when we try to entice fish to be the test subjects of the reef site.  Baited with mackerel, each 10 hook bandit reel is placed along the starboard side at 3 points (forward, aft, and stern. Each of the reels has a different hook size on (small, medium, large)) and is lowered to the bottom for a 5 minute soak.  Any fish that are caught, are brought aboard, and dissected to determine rate of growth and reproductive cycle.  The otoliths, or ear bone, is extracted to determine the age based on the lines that appear across the surface — much like the rings of a tree to determine its age.

Math at Sea: When I was up on the bridge this morning to hang out with am watch we did some math to determine at what distance the Pensacola Lighthouse would be visible to us.  Lucky for us, there is a math formula to determine this! To determine the geographic range (in nautical miles) you would first need to know 2 variables: height of beacon (h1) (above sea level) and observer’s height-of-eye (h2) above sea level. geographic range = 1.17√[(h1)+(h2)] {the product of 1.17 and the square root of the sum of the two heights} Math question of the day: at what distance would a sailor be able to spot  a 119′ high beacon from a 36′ height-of-eye (if weather conditions were clear)? Up next . . . A closer look at the Science, Technology, Engineering, and Mathematics of the sidescan sonar