Kristin Hennessy-McDonald: Nurse Sharks, Tiger Sharks, and Sandbars, Oh My, September 27, 2018

NOAA Teacher at Sea

Kristin Hennessy-McDonald

Aboard NOAA Ship Oregon II

September 15 – 30, 2018

 

Mission: Shark/Red Snapper Longline Survey

Geographic Area of Cruise: Gulf of Mexico

Date: September 27, 2018

 

Weather Data from the Bridge

Latitude: 2840.20N

Longitude: 8439.79W

Sea Wave Height: 0m

Wind Speed: 2.2 knots

Wind Direction: 39.04 degrees

Visibility: 10 nautical miles

Air Temperature: 30.045

Sky: 75% cloud cover

 

Science and Technology Log

We have moved from the coast of Texas, past Louisiana, Mississippi, and Alabama, to the coast of Florida.  When watching the video from the CTD, we have seen the sea floors go from mostly mud to sand.  The water has decreased in turbidity, and the growth on the sea floor has increased.  The make-up of our catches has changed too.  We moved outside of the productive waters associated with the Mississippi River discharge, so our catch rates have decreased significantly.

Yesterday, we had a fun day of catching sharks I had never seen.  Our first catch of the day brought up a juvenile Tiger shark (Galeocerdo cuvier).  I was excited to be able to see this shark, which is listed as near threatened by the International Union for Conservation of Nature.  On our later catch, we brought up three sharks large enough to require the cradle.  First, we brought up a Sandbar shark (Carcharhinus plumbeus).  Then, we were lucky enough to bring up a Nurse Shark (Ginglymostoma cirratum).  The mouth of the nurse shark has barbles, which it uses to feed from the sea floor.  Our final shark of the evening was a much more developed Tiger Shark.  I was lucky enough to help with the tagging of the animal.

Last night, we set a line at the end of day shift, and night shift brought it in.  A few of the day shift science team members decided to stay up and watch some of the haul back, and were rewarded with seeing them bring in, not one, but two Silky sharks (Carcharhinus falciformis), back to back.  From the upper deck of the ship, so that I was not in their way, I was able to observe the night shift work together to bring up these two large animals.

The night shift has gotten some pretty amazing catches, and they have enjoyed sharing them with us at shift change.  The two shifts spend about half an hour together around noon and midnight sharing stories of the time when the other shift was asleep.  The other day, the night shift caught Gulper Sharks (Centrophorus uyato) and Tile Fish (Lopholatilus chamaeleonticeps).  These are two species we have not seen on the day shift, so it was fun to look at their pictures and hear the stories of how they caught these fish.

 

Personal Log

When we have a long run between stations, once I have gotten done sending emails and grading student work, we will spend some time watching movies in the lounge.  The ship has a large collection of movies, both classic and recent.  Watching movies keeps us awake during the late night runs, when we have to stay up until midnight to set a line.

The day shift has started to ask one another riddles as we are baiting and setting lines.  It’s a fun way to bond as we are doing our work.  One of my favorites have been: “1=3, 2=3, 3=5, 4=4, 5=4, 6=3, 7=5, 8=5, 9=4, 10=3.  What’s the code?”

Did You Know?

Sharks don’t have the same type of skin that we do.  Sharks have dermal denticles, which are tiny scales, similar to teeth, which are covered with enamel.

Quote of the Day

Teach all men to fish, but first teach all men to be fair. Take less, give more. Give more of yourself, take less from the world. Nobody owes you anything, you owe the world everything.

~Suzy Kassem

Question of the Day

I have a lot of teeth but I’m not a cog
I scare a lot of people but I’m not a spider
I have a fin but I’m not a boat
I’m found in the ocean but I’m not a buoy
I sometimes have a hammerhead but I don’t hit nails

What am I?