Jennifer Goldner: Sharks 101, August 18, 2011

NOAA Teacher at Sea
Jennifer Goldner
Aboard NOAA Ship Oregon II (NOAA Ship Tracker)
August 11 — August 24, 2011

Mission: Shark Longline Survey
Geographical Area: Southern Atlantic/Gulf of Mexico
Date: August 18, 2011

Weather Data from the Bridge
Latitude: 26.05 N
Longitude: 84.05 W
Wind Speed: 5.20 kts
Surface Water Temperature: 30.30 C
Air Temperature: 31.20 C
Relative Humidity: 67.00%

Science and Technology Log

Living in the landlocked state of Oklahoma, I am unfamiliar with sharks.  Thus today, with the help of the scientists, I’m going to give some basics of sharks that I have learned this week.  Class title:  Shark 101.  Welcome to class!

Let me start by telling you the various sharks and amount of each we have caught this week in the Gulf of Mexico. We have caught 7 nurse sharks, 2 bull sharks, 4 sandbar sharks, 73 Atlantic sharpnose sharks, 15 blacknose sharks,  5 blacktip sharks, 5 smooth dogfish, 2 silky sharks, and 4 tiger sharks.  For those of you that took the poll, as you can see the correct answer for the type of shark we have caught the most of is the Atlantic sharpnose shark.   The sharks ranged in size from about 2 kilograms (Atlantic sharpnose shark) to 100 kilograms (tiger shark). Keep in mind a kilogram is 2.24 pounds. 

In addition to the sharks caught we have also caught yellowedge, red, and snowy grouper, blueline tilefish, spinycheek scorpionfish, sea stars, and a barracuda.

From the last post you now know that we soak 100 hooks at a time. Throughout the survey we have had as little as no sharks on the line in one location and up to 25 on the line in other locations.

When a shark is brought on board, it is measured for total length, as well as fork length (where the caudal fin separates into the upper and lower lobes).  The sex of the shark is also recorded.  A male shark has claspers, whereas a female shark does not.  The shark’s weight is recorded.  Then the shark is tagged. Lastly, the shark is injected with OTC (Oxytetracycline) which can then be used to validate the shark’s age.  It should be noted that for larger sharks these measurements are done in the cradle.  For perspective, I had Mike, fisherman, lay in the cradle to show the size of it. Also on this trip, some of the scientists tried out a new laser device.  It shoots a 10 cm beam on the shark.  This is then used as a guide to let them know the total length.  Thus, the shark can actually be measured in the water by using this technique.

Here are some things I learned about each of the sharks we caught.

1.  Nurse shark:   The dorsal fins are equal size.  They suck their food in and crush it.  Nurse sharks are very feisty.  See the attached video of Tim, Lead Fisherman and Trey, Scientist, holding a nurse shark while measurements are being taken.

The skin of nurse sharks is rough to touch.  Incidentally, all  types of  sharks’ skin is covered in dermal denticles (modified scales) which is what gives them that rough sandpaper type feeling.  If you rub your hand across the shark one way it will feel smooth, but the opposite way will feel coarse.

2.  Bull shark– These are one of the most aggressive sharks.  They have a high tolerance for low salinity.

3. Sandbar shark– These sharks are the most sought after species in the shark industry due to the large dorsal and pectoral fins.  The fins have large ceratotrichia that are among the most favored in the shark fin market.

4.  Atlantic sharpnose shark– The main identifying characteristic of this shark is white spots.

5.  Blacknose shark– Like the name portrays, this shark has black on its nose.  These sharks are called “baby lemons” in commercial fish industry because they can have a yellow hue to them.

6.  Blacktip shark- An interesting fact about this shark is that even though it is named “blacktip,” it does not have a black tip on the anal fin.  The spinner shark, however, does have a black tip on its anal fin.

7. Smooth dogfish– Their teeth are flat because their diet consists of crustaceans, such as crabs and shrimp.

8. Tiger shark– Their teeth work like a can opener.  They are known for their stripes.

9.  Silky shark- Their skin is very smooth like silk.

Another thing I got to see was shark pups because one of the scientists on board, Bianca Prohaska, is studying the reproductive physiology of sharks, skates, and rays.  According to Bianca, there are 3 general modes of reproduction:

1.  oviparous–  Lays egg cases with a yolk (not live birth).  This includes some sharks and all skates.

2.  aplacental viviparous – Develops internally with only the yolk.  This includes rays and some sharks.  Rays also have a milky substance in addition to the yolk.  Some sharks are also oophagous, such as the salmon shark which is when the female provides unfertilized eggs to her growing pups for extra nutrition.  Other sharks, such as the sand tiger, have interuterine cannibalism (the pups eat each other until only 1 is left).

3. placental viviparous– Develop internally initially with a small amount of yolk, then get a placental attachment.  This includes some sharks.

Yet another thing that scientists look at is the content of the shark’s stomach. They do this to study the diet of the sharks.

Personal Log

Anyone who knows me realizes that I appreciate good food when I eat it.  Okay, on NOAA Ship Oregon II, I have not found just good food, I have found GREAT cuisine!   I am quite sure I have gained a few pounds, courtesy of our wonderful chefs, Walter and Paul.  They have spoiled us all week with shrimp, steak, prime rib, grilled chicken, homemade cinnamon rolls, turkey, dressing, mashed potatoes, and gravy, and the list goes on!   Just talking about it makes me hungry!

Walter is a Chef de Cuisine.  I want to share with you two of the wonderful things, and there are many more, he has prepared for us this week.  The first is called ceviche.  On our shift we caught some grouper.  Walter used these fish to make this wonderful dish.

In addition to the grouper, the ingredients he used were lemon juice, vinegar, onions, jalapeno, kosher salt, and pepper.  He mixed all the ingredients together.  The citric acid cooks the raw fish.  It has to be fresh fish in order to make it.  Instead of lemon juice, apple juice or orange juice can be substituted.  All I know is that since I arrived on NOAA Ship Oregon II, I heard from the entire crew about how great Walter’s ceviche was and it did not disappoint!

Another thing Walter is famous for on board NOAA Ship Oregon II are his macaroons.  These are NOT like ANY macaroons you have ever tasted.  These truly melt in your mouth.  Amazingly, he only has 4 ingredients in them: egg whites, powdered sugar, almond paste, and coconut flakes.  They are divine!!

On another note, I would like to give a shout out to my 5th grade students in Jay Upper Elementary School!  (I actually have not had the chance to meet them yet because I am here as a NOAA Teacher at Sea.  I would like to thank my former student, Samantha Morrison, who is substituting for me.  She is doing an outstanding job!!)

Jay 5th Grade:  I cannot wait to meet you!  Thank you for your questions!  We will have lots of discussions when I return about life at sea.  Several of you asked if I have been seasick.  Fortunately, I have not.  Also, you asked if I got to scuba dive.  Only the dive crew can scuba dive.  We are not allowed to have a swim call (go swimming) either.  As you can see, there is plenty to do on board!  Also, you may have noticed that I tried to include some pictures of me tagging some sharks.  Lastly, this dolphin picture was requested by you, too.  Dolphins LOVE to play in the ship’s wake so we see them every day.

Enjoy the view!

I LOVE the scenery out here!  I thought I’d share some of it with you today.