Whale shark regional research collaboration between Utila, Honduras and Isla Mujeres, México.

Background. Utila, Bay Islands, Honduras, is one of the few locations in the Western Hemisphere where whale sharks can be spotted year-round, while off the northeastern Yucatan Peninsula, Mexico, they aggregate during summertime in large numbers of up to several hundred. When our research on these sharks began, we hypothesized they migrate south to north from Honduras, then to Belize and finally to Mexico. Methods. From 2007-2013, we documented the presence of whale sharks in both locations using visual tags and photo-identification, to establish the connections between the sites. The international whale shark library ECOCEAN was an important tool for this research. Results. Our research collaboration began on 2007, we have registered and photographed 59 “encounters”, from these, 9 were “Belizeans” and 8 become new Honduran recruits. While 5 more remain as unassigned since positive individual identification has not been possible yet. From our database and ECOCEAN compare, we know that we share several individuals in between the two locations, and some even visit Belize. Conclusion. At least some individuals of the western Atlantic population travel between Honduras and Mexico, and some hang around Belize in between as well.We conclude that whale sharks wander in the Caribbean, the Gulf of México and the open Atlantic Ocean, and aggregate when food blooms are available.