Louise Todd, CTD and Samples, September 25, 2013

NOAA Teacher at Sea
Louise Todd
Aboard NOAA Ship Oregon II
September 13 – 29, 2013

Mission: Shark and Red Snapper Bottom Longline Survey
Geographical Area of Cruise: Gulf of Mexico
Date: September 25, 2013

Weather Data from the Bridge:
Barometric Pressure: 1008.6mb
Sea Temperature: 28.3˚C
Air Temperature: 26.3˚C
Wind speed: 8.73knots

Science and Technology Log:

After we set the line, the CTD (Conductivity, Temperature, Depth) is deployed at each station.

CTD

CTD ready to be deployed

This instrument provides information a complete profile of the physical characteristics of the water column, including salinity, temperature and dissolved oxygen.  The CTD is deployed from the bow of the boat using a winch.

Deploying the CTD

Deploying the CTD

When it is first lowered in the water it calibrates at the surface for three minutes.  After it is calibrated it is lowered into the water until it reaches the bottom.  The CTD records data very quickly and provides valuable information about the station.  Conductivity is used to measure the salinity, the amount of salt dissolved in the water.  The CTD also measures the dissolved oxygen in the water.  Dissolved oxygen is an important reading as it reveals how much oxygen is available in that area.  The amount of oxygen available in the water indicates the amount of life this station could be capable of supporting.  Dissolved oxygen is affected by the temperature and salinity in an area.  Higher salinity and temperature result in lower dissolved oxygen levels.  Areas of very low dissolved oxygen, called hypoxia, result in dead zones.  NOAA monitors hypoxia in the Gulf of Mexico using data from CTDs.

The otoliths and gonads are taken from all of the commercially and recreationally important fish like Snapper, Grouper and Tilefish.  Otoliths are used to age fish.  Aging fish provides information on the population dynamics for those species.  The otoliths are “ear bones” of the fish and are located in their heads.  It takes careful work with a knife and tweezers to remove the otoliths.

Removing otoliths

Removing otoliths

Once the otoliths are removed, they are placed in small envelopes to be examined in the lab in Pascagoula, MS.  Otoliths have rings similar to growth rings in trees that have to be carefully counted under a microscope to determine the age of the fish.

Otolith

Otolith

The gonads (ovaries or testes) are removed and the reproductive stage of the fish is determined.  The weights of the gonads are also recorded.  Small samples of the gonads are taken in order for the histology to be examined in the lab.  Examining the gonads closely will confirm the reproductive stage of the fish.  Gathering information about the reproductive stage of the fish also helps with understanding the population dynamics of a species and aids in management decisions.

Personal Log:

Taking the otoliths out of the fish was harder than I anticipated, especially on the larger fish.  It takes some muscle to get through the bone!

Otolith

Otolith removed from a Red Snapper

We have had a few very busy haul backs today.  One haul back had over 50 sharks!  My favorite shark today was a Bull Shark.  We caught two today but were only able to get one into the cradle long enough to get measurements on it.  We tagged it and then watched her swim away!  I can’t believe we are halfway through my second week.  Time is flying by!  I can’t wait to see what is on the line tomorrow!

Did you Know?

Yellowedge Grouper are protogynous hermaphrodites.  They start their lives as females and transform into males as they age.  Yellowedge Grouper are the only species of grouper we have caught.

Animals Seen

Here are a few of the animals we’ve seen so far!

Tilefish

Tilefish (Photo credit Christine Seither)

Sandbar

Sandbar shark in the cradle

Red Snapper

Red Snapper (Photo credit Christine Seither)

Yellowedge Grouper

Yellowedge Grouper (Photo credit Christine Seither)

Heather Haberman: Groundfish Surveying, July 7, 2011 (post #2)

NOAA Teacher at Sea
Heather Haberman

Onboard NOAA Ship Oregon II
July 5 — 17, 2011 


Mission: Groundfish Survey
Geographical Location: Northern Gulf of Mexico
Date: Thursday, July 07, 2011

Weather Data from  NOAA Ship Tracker
Air Temperature:  29.2 C      (84.6 F)
Water Temperature:  29.3 C    (84.7 F)
Relative Humidity:  72%
Wind Speed:  2.64 knots

Preface:  There is a lot of science going on aboard the Oregon II, so to eliminate information overload, each blog I post will focus on one scientific aspect of our mission.  By the end of the voyage you should have a good idea of the research that goes into keeping our oceans healthy.

In case you’re new to blogging, underlined words in the text are hyperlinked to sites with more specific information.

Science and Technology Log

Topic of the day:  Groundfish Surveying

To collect samples of marine life in the northern Gulf of Mexico, NOAA Ship  Oregon II is equipped with a 42-foot standard shrimp trawling net.  NOAA’s skilled fishermen deploy the net over the side of the ship at randomly selected SEAMAP (Southeast Area Monitoring and Assessment Program) stations using an outrigger.  The net is left in the water for 30 minutes as the boat travels at 2.5 to 3 knots (1 knot = 1.15 mph).

Shrimp trawl net attached to an outrigger. Notice the large wooden “doors” that help spread the net as it is lowered into the water.

Bottom trawling is a good method for collecting a random sample of the biodiversity in the sea because it is nonselective and harvests everything in its path.  This is excellent for scientific studies but poses great problems for marine ecosystems when it is used in the commercial fishing industry.

One problem associated with bottom trawling is the amount of bycatch it produces.  The term bycatch refers to the “undesirable” fish, invertebrates, crustaceans, sea turtles, sharks and marine mammals that are accidentally brought up to the surface in the process of catching commercially desirable species such as shrimp, cod, sole and flounder.  At times bycatch can make up as much as 90% of a fisherman’s harvest.  To address this problem, NOAA engineers have designed two devices which help prevent many animals from becoming bycatch.

Bycatch photo: NOAA

All sea turtles found in U.S. waters are listed under the Endangered Species Act and are under joint jurisdiction of NOAA Fisheries and the U.S. Fish and Wildlife Service.  In an effort to reduce the mortality rate of sea turtles, NOAA engineers have designed  Turtle Exclusion Devices (TED).  TEDs provide these air-breathing reptiles with a barred barrier which prevents them from going deep into the fishing net and guides them out of an “escape hatch” so they won’t drown.  TEDs have also proven to be useful in keeping sharks out of  bycatch.

Loggerhead sea turtle escaping a trawling net through a TED.

Another device that was introduced to the commercial fishing industry is the Bycatch Reduction Device (BRD).  BRDs create an opening in a shrimp trawl net which allows fishes with fins, and other unintended species, to escape while the target species, such as shrimp, are directed towards the end of the capture net.

Notice the location of the TED which prevents the turtle from entering into the net and the BRD that allows swimming fish to escape. Illustration provided by the University of Georgia Marine Extension Service

This is a very small catch we harvested from 77 meters (253 feet).

Once the trawl net is brought back on board the Oregon II, its contents are emptied onto the deck of the ship.  The catch is placed into baskets and each basket gets weighed for a total weight. The catch then goes to the “wet lab” for sorting.  If the yield is too large we randomly split the harvest up into a smaller subsample.

Each species is separated, counted, and logged into the computer system using their scientific names.  Once every species is identified, we measure, weigh, and sex the animals.  All of this data goes into the computer where it gets converted into an Access database spreadsheet.

My team and I sorting the catch by species.

Amy entering the scientific name of each species into the computer.

I measure while Amy works the computer. Collecting data is a team effort!

When the Oregon II ends its surveying journey, NOAA’s IT (Information Technology) department will pull the surveying data off the ship’s computers.   The compiled data is given to one of the groundfish survey biologists so it can be checked for accuracy and consistency.  The reviewed data will then be given to NOAA statisticians who pull out the important information for SEAMAP (Southeast Area Monitoring and Assessment Program) and SEDAR (Southeast Data and Review)

SEAMAP and SEDAR councils publish the information.   State agencies then have the evidence they need to make informed decisions about policies and regulations regarding the fishing industry.  Isn’t science great!  Most people don’t realize the amount of time, labor, expertise and review that goes into the decisions that are made by regulatory agencies.

Personal Log

Day crew from left to right: Chief Scientist Andre, college intern Brondum, myself, Team Leader Biologist Brittany and Biologist Amy

During our “welcome aboard” meeting I met the science team which consists of a Chief Scientist, four NOAA Fisheries Biologists, three volunteers, one college intern, one Teacher at Sea (me) and an Ornithologist (bird scientist).

I was assigned to work the day shift which runs from noon until midnight while the night shift crew works from midnight until noon.  This ship is operational 24 hours a day in order to collect as much information about the northern Gulf fisheries as possible.  The Oregon II costs around $10,000 per day to operate (salaries, supplies, equipment, etc.) so it’s important to run an efficient operation.

I am learning a lot about the importance of random sampling and confirming results to ensure accuracy.   Amy and Brittany taught me how to use the CTD device (Conductivity, Temperature and Depth), set up plankton nets as well as how to sort, weigh, identify and sex our specimens.

The food has been great, the water is gorgeous and I love the ocean!  Stay tuned for the next blog post about some of the most important critters in the sea!  Any guesses?

Species seen (other than those collected)

Birds:  Least Tern, Royal Tern, Sandwich Tern, Laughing Gull, Neotropical Cormorant, Brown Pelican, Magnificent  Frigatebird

Go to http://www.wicbirds.net for more information about the various bird species seen on this trip.

Mammals: Common bottlenose dolphin