2009 Connectivity Developments

The summer of 2009 marked the first documentation of whale shark movement between the northern Gulf of Mexico and the southern Gulf of Mexico/Caribbean Sea. Since 2002 tagging studies have taken place in the northern and southern Gulf of Mexico, using both basic identification tags as well as satellite tags. Yet prior to July 2009 none of the tagged sharks were tracked between the two regions.

The Gulf of Mexico/Caribbean whale shark population connectivity was documented by two methods. The initial connection was made using acoustic telemetry data gathered from a project called Marine Meganet. Marine Meganet is a multi-national cooperative founded in 2007 that aids in the tracking of small and large-scale movements of large pelagic species. If a tagged animal comes within range of a receiver, the acoustic tag on the animal transmits a unique ID that is recorded in the receiver with the associated date and time. A whale shark that was tagged in Contoy, Quintana Roo, Mexico in July 2008 was picked up in the East Flower Garden Banks National Marine Sanctuary off of the Texas coast in August 2009. This represents the first direct evidence of whale shark movement from the southern to the northern Gulf of Mexico.

The second method of documentation of connectivity was through the Ecocean Photo-Identification Library. Two whale sharks where photographed off of the Orange Beach, Alabama/ Florida Panhandle during the 2009 "whale shark invasion" (insert link to invasion page) that were first photographed in Belize and Honduras (Utila). In the database, shark BZ-010 was photo-tagged in Gladden Spit, Belize in April 2003, photo-tagged again in the same area in 2005, and then photographed off of Pensacola, Florida in both July and August of 2009. The second whale shark H-045 was first photo-tagged in Utila, Honduras in 2002, then again in Utila in both 2006 and 2007, and again off the Florida coast in August 2009.

Although documenting this connectivity between the regions is a huge leap in understanding the movements of these sharks, it also points out the complexity and the mystery surrounding their behavior. Some animals are seen in the same areas, at the same time of year, during consecutive years and then may disappear from the grid for several years before being spotted again. Where do they go during this time? Is there an undocumented feeding ground? Are they spending time at depth and therefore go unseen by human observers? Hopefully, with continued support by "citizen scientists" throughout the world, researchers will continue to learn about these animals and solve some of these mysteries.