For the past month we have been catching juvenile lemon sharks in specific mangrove creeks around South Eleuthera. We do this to determine the relative abundance of sharks in each creek and gather data that will help raise awareness of the current threatening situation these sharks face today. In many islands of the Bahamas, mangrove creeks have been dredged during coastal development for things like sandy beaches and seaside resorts. It is our hope that by collecting data on lemon shark habitat use and migration, we can prevent this from happening to our study creeks in the future. CPUE (catch per unit effort) plays a major role in our experiment. This formula we use can give us a comparative population estimate in the creeks. We are also interested in learning what prey species and abiotic factors attract sharks to these creeks.
We start our research days by boating or driving out to one of the five major creeks in South Eleuthera. As we wade out to the sandy beaches to set up we scout out the area to set our survey gear. We have learned how to cut the baitfish into proper portions for the small sharks. Then, we hook the bait, and get right back into the water to set up the gangions. Gangions are thin cables we use to hook the bait onto the survey gear. As we hook the gangions into place along the line we yell out “time” to our data collector who sits and watches from the beach. We check the gear every half an hour for two hours, while recording if the bait has been snagged by the tides or something a little more lively.
Last Friday, as we fished in Kemp’s Creek, we were surprised when one of our hooks had a Nurse shark on it. This was not our target species, but was still good data, and fascinating to watch. Ian corralled the 4.8 foot nurse shark into our cooler that was a little too small. As we measured the length, weight, and took a DNA sample, we were able to touch its sandy feeling skin and observe the nurse shark up close. It has been an exciting experience conducting real scientific research first hand. We are looking forward to catching more sharks throughout the semester, and contributing new information to this ongoing database.