Stephen Tomasetti: Red Grouper and Red Tide, August 21, 2014

NOAA Teacher at Sea
Stephen Tomasetti
Aboard NOAA Ship Oregon II
August 11 – 25, 2014

Mission: Shark/Red Snapper Longline Survey
Geographical Area of Cruise: Gulf of Mexico
You can view the geographical location of the cruise here at anytime:
Date: Thursday, August 21, 2014

Weather Data from Bridge:
Air Temperature: 30.2 Degrees C
Water Temperature: 29.9 Degrees C
Wind Speed: 7 Knots
Barometric Pressure: 1018.7 Millibars

Science and Technology Log

On the Discovery Channel shark week ended last Sunday night, but on the ship shark week continues. We are approaching a stretch of stations that should be loaded with sharks (if they haven’t moved to other areas due to the red tide…more on that later) over the next few days so I am going to hold off on the shark post until later in the week when I’ll have compiled many more pictures for sharing. Although one of the main goals of the mission is to catch sharks (to monitor trends in population abundance) the ship is constantly, twenty four hours a day, collecting a myriad of oceanographic and weather data that is used by other scientists and organizations.

One fish that we have been catching quite frequently is red grouper, or Epinephelus morio. Typically when we catch one it is brought on board to measure its mass and length. After the measurements are taken we remove the fish’s otoliths for future age examination. Additionally, the gonads are removed to determine its sex and reproductive status.

Red Grouper
Red Grouper

An otolith or “ear bone” is not actually a bone at all, but rather a calcium carbonate structure located near the fish’s brain. Similar to the human inner ear, otoliths help the fish to balance and orient itself. There are three pairs of otoliths in each teleost (bony fish) but we remove the largest pair. The first time I tried I pulverized the otolith, but after some practice I can do it now (although I’d hesitate to say with ease).

The otolith contains bands that correspond to the age, much like rings of a tree trunk. Also, the shape of the otolith varies depending on the species. So if otoliths are found in the stomach of an animal that eats fish, the species it’s eating can often be determined.

The fish’s internal sexual structures, or gonads, also must be removed and saved. These structures are used to determine the sex of the fish, if it’s mature, and its current reproductive condition.

In addition to catching and studying wildlife aboard the Oregon II, a large amount of data is collected on water and weather conditions. To do so, a large, expensive piece of equipment called a “CTD”, for conductivity-temperature-depth, is lowered by a fisherman into the water until it hovers a few meters off the ocean floor. It collects data such as salinity, temperature, dissolved oxygen, water clarity, and chlorophyl concentration in real time and can be studied separately or alongside the results of the fish/shark survey.

Chuck Godwin with the CTD
Skilled Fisherman Chuck Godwin with the CTD

Skilled Fisherman Chuck Godwin and Fisherman Eloy Borges are two of the guys I’ve worked closely with during my time on the Oregon II. Chuck and I are pretty much from the same town in Central Florida! Chuck graduated from UF before serving in the Coast Guard for over ten years. He’s been working for NOAA for a while and after about ten minutes with him you can see why! He is fun and affable and a pleasure to be around. He makes the long days of hard work go by quickly.

Fisherman Eloy Borges worked on commercial freighters for a while before joining NOAA. He’s a laid back, diligent crew member. He’s considerate and encouraging; we work together while slinging bait and attaching the gangions to the mainline or while deploying the hi-flyers. And we bond a lot over our mutual love for Cuban food.

Fisherman Eloy Borges controlling the CTD
Fisherman Eloy Borges controlling the CTD

Personal Log:

Yesterday in between sets, the Bridge watchstanders noticed dead fish in the water everywhere. The dead fish continued for over ten miles. They were the result of red tide in the Gulf. Red tide is caused by an algal bloom, and can devastate marine life, especially near the coast. The ship stopped while a fisherman and two scientists took a smaller boat to investigate and gather samples. They filled a large bag with dead fish and wrote down the GPS coordinates, as well as the date and time, marking it FISH KILL. These samples will be reviewed back in the lab in Pascagoula. Sometimes doing science means changing your plans and adjusting to the circumstances you find yourself in.

Spending twelve hours a day, every day, with the same group of people may seem daunting, but we’ve developed a great team chemistry. The days go by fast! In between sets while we’re cruising to the next location we’ve developed a bunch of activities to keep us busy. I learned how to play Sudoku and a game called Heads Up. Additionally, I’ve begun a daily exercise routine with some of the other scientists and volunteers. The workout is a precautionary measure because I’ll put on ten pounds in two weeks with all of the excellent food we’ve been eating on this cruise (thanks Mark and Steve).

Scientist Andre Debose leading the crew in some exercises
Scientist Andre Debose leading the crew in some exercises

Did You Know: Most grouper species change their sex from female to male as they age!

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