Beth Spear, August 7, 2010

Weather Data from the Bridge Time: 1400 (2:00 pm) Position: Latitude 32 degrees 20’N, Longitude 078 degrees 57’W Present Weather: Partly Cloudy Visibility: 10 nautical miles Wind Speed: Variable, light Wave Height: 1 foot Sea Water Temp: 30.7 degrees C Air Temperature: Dry bulb = 27.7 degrees C; Wet bulb = 25.2 degrees C Barometric Pressure: 1013.2 mb

Science and Technology Log We have caught around 300 sharks so far. Most of those are Atlantic Sharpnose sharks. All shark species seen so far include Atlantic sharpnose, sandbar, tiger, nurse, blacknose, silky, bull, and hammerhead. When the shark is caught and brought on board the hook is removed; this is the most difficult part. Shark skin is so tough that the barb on the hook has to pass back through the original hole in the shark skin. If you are unable to do that a small incision is made to widen the original hole made by the hook. The data collected for each shark includes: length, weight, and gender. Some sharks are tagged before they are released. Sharks that do not survive are used for other studies.

One researcher who uses the sharks that do not survive is Dr. Ian Davenport, Xavier University of Louisiana. Dr. Davenport is studying the reproductive system of female sharks. The photograph below shows a three month old embryo collected from the uterus of a female Atlantic sharpnose shark (note the feathery gills on either side of the head). Dr. Davenport will be able to use samples collected during this survey for the classes he teaches and his research back home in Louisiana.

Ryan Ford is another researcher onboard the Delaware II. Ryan is a graduate student from the University of North Florida studying the diet of blacknose sharks with Dr. James Gelsleichter. While volunteering on this NOAA cruise Ryan was able to collect information for his thesis project. Unfortunately we have not seen many blacknose sharks so far. The photo below shows Ryan (on the right) collecting a muscle biopsy just below the dorsal fin from a blacknose shark.

The Atlantic sharpnose is relatively easy to handle. You grasp the shark right behind the jaws and in front of the gills. It is very important to be careful of the gills so the shark can be released live. If the shark is very active you can control the animal with your other hand near the tail. I am collecting the weight for an Atlantic sharpnose in the photo below.

Personal Log I was finally brave enough to handle the sharks myself on my third watch. As I grabbed a shark, calmly laid it out to collect data, and called out the data, it was hard to believe I was actually doing this. Too cool!!! I have to admit after throwing each shark back I took the time to watch them swim off safely. I couldn’t help but compare grabbing the shark to picking my cat up by the scruff of the neck.

On Friday I woke to a little rougher sea and felt a little bit funny. I kept drinking water, took some ginger pills, and stayed out in the fresh air. I began to feel better by the time the sun rose. I think I was more dehydrated than sea sick. On Saturday we had a fire drill, an abandon ship drill, and a man (the captain) overboard drill. It was not fun wriggling into the survival suits after a 12 hour work shift.

I also got a quick lesson from Richie, one of the deck crew, on splicing lines together. It was similar to braiding hair, just a little more complicated. When they sent out the high flyer with my spliced line I was really worried. Thankfully everything held together, so far at least!

When I started this cruise I really didn’t know what to expect. I was worried that I would just be in the way or get my finger chewed off by a shark. However I feel great knowing I contributed, at least in a small way to this long-term study. The science and procedures aren’t terribly complicated or inaccessible. This is what I want my students to understand about science. Science can be difficult and confusing, but it’s also fun, exciting, and anyone can do it.

Question of the Day Do you know how to determine the gender of a shark? Shark gender is determined by the presence (males) or absence (females) of claspers used during mating. The photographs below illustrate the difference between gender for the Atlantic sharpnose shark. The arrows in the top photo below are pointing to the claspers found only on male sharks. The claspers are absent on females as seen in the last photo below.