Louise Todd, Haul Back, September 23, 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 23, 2013

Weather Data from the Bridge:
Barometric Pressure: 1009.89mb
Sea Temperature: 28˚C
Air Temperature: 28.2˚C
Wind speed: 8.29knots

Science and Technology Log:

The haul back is definitely the most exciting part of each station.  Bringing the line back in gives you the chance to see what you caught!  Usually there is at least something on the line but my shift has had two totally empty lines which can be pretty disappointing.  An empty line is called a water haul since all you are hauling back is water!

After the line has been in the water for one hour, everyone on the shift assembles on the bow to help with the haul back.  One crew member operates the large winch used to wind the main line back up so it can be reused.

Line on the winch
Winch holding the main line

The crew member operating the winch unhooks each gangion from the main line  and hands it to another crew member.  That crew member passes it to a member of our shift who unhooks the number from the gangion.  The gangions are carefully placed back in the barrels so they are ready for the next station.  When something is on the line, the person handling the gangions will say “Fish on”.

Nurse Shark on the line
Nurse Shark on the line

Everyone gets ready to work when we hear that call.  Every fish that comes on board is measured. Usually fish are measured on their sides as that makes it easy to read the markings on the measuring board.

Measuring Grouper
Measuring a Yellowedge Grouper (Photo credit Christine Seither)
Measuring a Sandbar
Christine and Nick measuring a Sandbar Shark

Each shark is examined to determine its gender.

Sexing a shark
Determining the sex of a sharpnose shark (Photo credit Deb Zimmerman)

Male sharks have claspers, modified pelvic fins that are used during reproduction.  Female sharks do not have claspers.

Claspers
Claspers on a Blacktip

Fin clips, small pieces of the fin, are taken from all species of sharks.  The fin clips are used to examine the genetics of the sharks for confirmation of identification and population structure, both of which are important for management decisions. 

Shark Fin Clip
That’s me in the blue hardhat taking a fin clip from a Sandbar Shark(Photo credit Lisa Jones)

Skin biopsies are taken from any dogfish sharks  in order to differentiate between the species.  Tags are applied to all sharks. Tags are useful in tracing the movement of sharks.  When a shark, or any fish with a tag, is recaptured there is a phone number on the tag to call and report the location where the shark was recaptured.

Some sharks are small and relatively easy to handle.

Cuban Dogfish
Small Cuban Dogfish (Photo credit Christine Seither)

Other sharks are large and need to be hauled out of the water using the cradle.  The cradle enables the larger sharks to be processed quickly and then returned to the water.  A scale on the cradle provides a weight on the shark.  Today was the first time my shift caught anything big enough to need the cradle.  We used the cradle today for one Sandbar and two Silky Sharks.  Everyone on deck has to put a hardhat on when the cradle is used since the cradle is operated using a crane.

Silky Shark
Silky shark coming up in the cradle
Sandbar Shark
Sandbar Shark in the cradle

Personal Log:

I continue to have such a good time on the Oregon II.  My shift has had some successful stations which is always exciting.  We have had less downtime in between our stations than we did the first few days so we are usually able to do more than one station in our shifts.  The weather in the Gulf forced us to make a few small detours and gave us some rain yesterday but otherwise the seas have been calm and the weather has been beautiful.  It is hard to believe my first week is already over.  I am hopeful that we will continue our good luck with the stations this week!  The rocking of the boat makes it very easy for me to sleep at night when my shift is over.  I sleep very soundly!  The food in the galley is delicious and there are plenty of options at each meal.  I feel right at home on the Oregon II!

Did You Know?

Flying fish are active around the boat, especially when the spotlights are on during a haul back at night.  Flying fish are able to “fly” using their modified pectoral fins that they spread out.  This flying fish flew right onto the boat!

FlyingFish
Flying Fish

Steven Frantz: Sharks at Sea, August 3, 2012

NOAA Teacher at Sea
Steven Frantz
Onboard NOAA Ship Oregon II
July 27 – August 8, 2012

Mission: Longline Shark Survey
Geographic area of cruise: Gulf of Mexico and Atlantic off the coast of Florida
Date: August 3, 2012

Weather Data From the Bridge:
Air Temperature (degrees C): 28.79
Wind Speed (knots): 14.14
Wind Direction (degree): 199.05
Relative Humidity (percent): 070
Barometric Pressure (millibars): 1017.95
Water Depth (meters): 58.0
Salinity (PSU): 35.635

Location Data:
Latitude: 3409.72N
Longitude: 17611.11W

SHARKS AT SEA

Our 300th mission aboard the Oregon II is a Longline Shark Survey.  Stratified randomly selected sites have been generated using Arc GIS Software. This eliminates potential bias in sampling and each area has an equal opportunity to be sampled. Two depth strata zones (A: 5-30 fathoms, B: 30-100 fathoms) have been factored for the Atlantic. In order to avoid all sampling sites randomly bunched all together, the area has been divided into 60 nautical mile geographic zones from southern Florida to North Carolina. 60% of our effort (ex. time at sea) is put toward “A” stations and 40% of our effort is put toward “B” stations. This method of picking stations is called proportional allocation.

We are here to find sharks. This is important because so very little is known about them, or many of the other animals living in an extreme environment (extreme for people to live in).

One if the first sharks we caught was a blacknose shark, Carcharhinus acronotus. It is relatively small, a uniform gray color, and has a black tip on its nose.

Black-Nose Shark
Here I am holding Black-Nose Shark

The most common shark found so far has been the sharpnose shark, Rhizoprionodon terraenovae. Both sharpnose and blacknose sharks are considered to be small coastal sharks by the National Marine Fisheries Service. While similar in size to the black nose shark, the sharpnose shark is spotted. When brought on board, their size is nothing compared to their strength. I guess you have to act tough when you’re little!

Sharpnose being Weighed
Sharpnose being Weighed

Tough though they may be, we caught several sharp-nose sharks that have become bait themselves! I wonder what (kind of shark?) it was that ate the back half of this sharp-nose?

Shark as "Bait"
Shark as “Bait”

One of the many data we are collecting is the sex of the sharks. Pictured below are a male (top), then female (bottom). The male shark has claspers, which are used for internal fertilization. Claspers are also used to determine a male’s age depending on how calcified they are.  This is the standard way to determine sex on all the sharks we have caught thus far.

Male Sharpnose Shark
Male Sharpnose Shark
Female Sharpnose Shark
Female Sharpnose Shark

Another piece of data collected is a clip of flesh from a fin. This is a non-lethal way for scientists to obtain DNA for genetics studies and possibly for use in population structure for identification purposes.

Fin Clipping
Fin Clipping

As we saw above, some sharks don’t make it on board alive. While this is uncommon, the opportunity does present itself for more invasive study not done on living animals. Sharpnose sharks give birth to live young (viviparous). Pictured below are young sharks taken from a female. It is interesting to note that whether the shark is male or female can be determined at this early stage. Remember, not all sharks reproduce this way.

Baby Sharpnose
Baby Sharpnose

Sandbar sharks, Carcharhinus plumbeus, have been the next most common sharks caught. These are quite a bit larger than sharp-nose sharks, averaging 150 centimeters long and 35 kilograms in mass.

Sandbar Shark
Sandbar Shark

We must be safe when collecting data. Shark’s skin is like sandpaper, so if the teeth or tail doesn’t get you, you can also be given a pretty red rash by the scrapping of their skin against your skin.

Measuring a Sandbar Shark
Measuring a Sandbar Shark
Tagged Sandbar Shark
Tagged Sandbar Shark

Sandbar sharks were popular with the shark fin soup industry because they have a very large dorsal fin compared to their body size. Sharks were caught, their fin was cut off, and then the still-living shark was released back into the ocean to die. This practice has been outlawed in U.S. waters.

Sandbar Shark & Me
Sandbar Shark & Me

Watch the video below as a sandbar shark is caught and brought to the Oregon II.

The prettiest shark (at least to me) I’ve seen so far is the tiger shark, Galeocerdo cuvier. They can get very large. Three meters long or more! The ones we’ve found have been smaller. The one I’m holding is very young. The umbilical scar was still visible! Tiger shark teeth are different from most sharks in that a tiger shark’s teeth are made to slice their prey, like the shells of sea turtles.

Tiger Teeth
Tiger Teeth
Tiger Shark & Me
Tiger Shark & Me

Sharks don’t have eyelids, like we have eyelids, to protect their eyes. They have what is called a nictitating membrane to protect their eyes. Here is a picture of the nictitating membrane partially covering a sharpnose shark’s eye.

Nictitating Membrane
Nictitating Membrane

The most unusual shark we’ve caught has been the scalloped hammerhead shark, Sphyrna lewini. Once on board the Oregon II they seemed to be docile (for a shark), however, their eyes on the far ends of their head were always looking, watching what was going on.

Why is their head shaped like it is? Even scientists don’t know for sure. Some think it acts as a hydrofoil to help it move through the water. Other scientists think (because of its large size) it helps detect electrical impulses in the water (like a sixth sense). Do you have any ideas why their head is shaped the way it is?

Scalloped Hammerhead Shark
Scalloped Hammerhead Shark
Scalloped Hamerhead Shark
Scalloped Hammerhead Shark
Scalloped Hamerhead Shark
Scalloped Hammerhead Shark

I have been working the day shift: from noon to midnight. The other crew is the night shift. In addition to what we have seen so far, the night shift has also seen a great hammerhead, Sphyrna mokarran and a silky shark, Carcharhinus falciformes.

We still have five days of fishing left. What will we catch next? I’ll let you know!