In the new year of 2011 the Shark Research and Conservation program at the Cape Eleuthera Institute has observed changes in juvenile lemon shark capture rates during tidal creek sampling surveys. Since the month of November, there has been a marked decrease in the number of sharks caught in creeks around South Eleuthera. We hypothesize that due to cooler water temperatures during the winter months, the shark’s metabolic rates have decreased requiring them to feed less frequently and therefore, take the bait on our survey line less. The lemon sharks may also be using a smaller amount of habitat and traveling in and out of creek mouths less, where survey lines are set, in effort to conserve energy. This additionally would cause them to be less prone to come into contact with the baited survey line, and be caught.
This study of the relative abundance of juvenile lemon sharks across tidal creeks in South Eleuthera is an ongoing project, nearing its one-year anniversary in February. Because we do not have a data set spanning multiple years, at this time we are unable to say whether this decreasing trend in shark capture rates correlates to the drop in water temperature during the winter season, or is merely coincidental. Through continuing sampling for years to come , we hope in the future to determine whether or not juvenile lemon shark capture rates are directly affected by seasonal change.
Juvenile lemon shark conservation will be taught as a research course this spring semester at The Island School. The Shark Research and Conservation program staff are making preparations for the arrival of students at the end of February. During the course, the research team will expand their survey sites from the five creeks they are sampling consistently now to new creeks. They will then compare the relative abundance of lemon sharks found in creeks of varying habitat composition, such as sand flats, dense mangrove, and sea grass. Findings will be presented by students at the end of the semester during a research symposium.