Horizontal Movements, Migration Patterns, and Population Structure of Whale Sharks in the Gulf of Mexico and Northwestern Caribbean Sea

Abstract

Whale sharks, Rhincodon typus, aggregate by the hundreds in a summer feeding area off the northeastern Yucatan Peninsula, Mexico, where the Gulf of Mexico meets the Caribbean Sea. The aggregation remains in the nutrient-rich waters off Isla Holbox, Isla Contoy and Isla Mujeres, Quintana Roo for several months in the summer and then dissipates between August and October. Little has been known about where these sharks come from or migrate to after they disperse. From 2003–2012, we used conventional visual tags, photo-identification, and satellite tags to characterize the basic population structure and large-scale horizontal movements of whale sharks that come to this feeding area off Mexico. The aggregation comprised sharks ranging 2.5–10.0 m in total length and included juveniles, subadults, and adults of both sexes, with a male-biased sex ratio (72%). Individual sharks remained in the area for an estimated mean duration of 24–33 days with maximum residency up to about 6 months as determined by photo-identification. After leaving the feeding area the sharks showed horizontal movements in multiple directions throughout the Gulf of Mexico basin, the northwestern Caribbean Sea, and the Straits of Florida. Returns of individual sharks to the Quintana Roo feeding area in subsequent years were common, with some animals returning for six consecutive years. One female shark with an estimated total length of 7.5 m moved at least 7,213 km in 150 days, traveling through the northern Caribbean Sea and across the equator to the South Atlantic Ocean where her satellite tag popped up near the Mid-Atlantic Ridge. We hypothesize this journey to the open waters of the Mid-Atlantic was for reproductive purposes but alternative explanations are considered. The broad movements of whale sharks across multiple political boundaries corroborates genetics data supporting gene flow between geographically distinct areas and underscores the need for management and conservation strategies for this species on a global scale.

Whale Shark (Rhincodon typus) Seasonal Occurrence, Abundance and Demographic Structure in the Mid-Equatorial Atlantic Ocean

“…The blue triangle indicates the satellite-tag pop up location from a female whale shark tagged in Caribbean Mexico [56]. The green stars indicate the location of recorded neonates [104,105].…”

Spatial ecology and conservation of Manta birostris in the Indo-Pacific

“…Most ecological studies focus on the smaller, coastally associated reef manta ray (Manta alfredi), and demonstrate patterns of residency with few long-distance movements (Dewar et al, 2008;Deakos et al, 2011;Jaine et al, 2014;Braun et al, 2015). Oceanic manta rays tend to occupy more pelagic, offshore habitats than their coastal sister species (Kashiwagi et al, 2011), and they are presumed to be highly migratory based primarily on the behaviors exhibited by species similar in habitat preference, foraging strategies and size (Skomal et al, 2009;Hueter et al, 2013;Thorrold et al, 2014).…”

Theoretical and computational fluid dynamics of an attached remora ( Echeneis naucrates )

“…This is likely due to the boundary layer thickness being a stronger function of free-stream velocity than position. Even at moderate host speeds near 50 cm/s, comparable to the migratory speeds of remora hosts (Klimley et al, 2002;Weng et al, 2007;Carlson et al, 2010;Hueter et al, 2013), the viscous boundary layer was so thin that most of the remora was exposed to the free stream, and therefore little benefit was realized. Although differences between the most anterior and posterior attachment sites investigated were as high as 80%, these large relative differences 14 occurred at low host speeds where the drag is already so low that such differences are likely imperceptible to the remora.…”

“…Tagging studies on different shark species provided estimates of average swimming speeds on the order of 10-100 cm/s (Klimley et al, 2002;Weng et al, 2007;Carlson et al, 2010;Hueter et al, 2013), whereas maximum shark speeds may range between 100 and 1000 cm/s (Webb and Keyes, 1982;Klimley et al, 2002;Brunnschweiler, 2005). Therefore, the remora model was exposed to free-stream velocities ranging between 0.5 and 500 cm/s to include both the average and near top speed of many remora hosts.…”