An Amazing Trip of Many Firsts

Wednesday, March 16th – Sunday, March 20th 2011

This five day long expedition was set in the Dry Tortugas, a small group of islands about 70 miles west of Key West. This area was chosen, and is particularly special, because of its status as a very well protected national park. In being such, special permits had to be obtained for this trip. The data we were most concerned with for these few days was the number of sharks we pulled in, and the times we would find on our hook timers.

The times on our hook timers represent how long a shark has been on the line. As soon as a shark takes the bait, the tension on the monofilament line pops the timer and it begins counting up. These hook timers, that we have attached to all our drumlines, allow us to gather important data as to the relative abundance of large predators in the area. If there are many sharks in the area, the bait will likely be taken quickly and we will find longer times on our hook timers as we bring in our drumlines. The number of sharks in the Dry Tortugas National Park is especially important to our data because of the level of protection that is in place there. Sharks are top predators and, as such, are crucial in regulating ecosystems from the top down, thus important indicators of the health of an ecosystem. This trip allows us to compare the relative abundance of sharks in a well protected area like the Dry Tortugas National Park to some of our other sites that are much less protected. With a higher level of protection we expect a higher abundance of large sharks.

During our Dry Tortugas trip we were able to catch and tag 32 sharks including: hammerheads, tigers, nurse sharks, Atlantic sharpnoses, Caribbean reef sharks, and a bull shark. In addition to its research potential, the trip was an incredible experience. Packing up the 40-ish foot boat with all our research gear, personal items, food, and six people was a task in itself, but eventually we were able to find a home for everything. We made good time on our eight hour boat ride out to the Dry Tortugas, stopping in Key West to refuel along the way, and thankfully, the weather was amazing all week (in contrast to the last attempted expedition out there when our team was chased back home by bad weather after deploying only 5 drumlines). This time we were able to put out about 50 drumlines each day, not a light or easy task we can now say from personal experience!

Measuring precaudal pit length (PCL), fork length (FL), and total length (TL) on an Atlantic Sharpnose shark. Click to enlarge.

While the trip was hard on our bodies, it was worth it in so many ways. First off, the sharks of course were the number one reason we were all there, and they did not disappoint. The Caribbean reef sharks were, as Captain Curt had warned “like blacktips on steroids.” Although their species is on the smaller end (when compared to tigers or bull sharks), they are very strong and feisty, and definitely kept us on our toes. The highlights of the trip, however, were the tiger and hammerhead sharks, both my favorite – I’m so torn between the two! This trip was extra special for me because for the first time I was able to get into the water with both a tiger and a hammerhead shark as we released them and watch them swim away. Both such magnificent fish – the distinctive “hammer” and dorsal of the hammerhead, and the gorgeous markings of a tiger shark – they really are absolutely breathtaking.

Tiger shark off the side of our boat. Click to enlarge.

Our Dry Tortugas team: Captain Curt, Dr. Neil, interns Robbie and Fiona, and lab manager Dominique. All minus Christine – someone had to take the photo! Click to enlarge.

Overall, watching sunrises and sunsets, eating awesome food, spending time with incredible people, getting great data, and experiencing amazing things, it really was a truly unforgettable trip. Thank you to everyone involved for all their hard work and for making this happen!

Looking forward to the next day out on the water and much sharky love,

Fiona, RJD Intern