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Cancún, Mexico

Tyminski J.P.,Center for Shark Research | De La Parra-Venegas R.,Chooj Ajauil AC | Cano J.G.,Proyecto Domino | Hueter R.E.,Center for Shark Research

The whale shark (Rhincodon typus) is a wide-ranging, filter-feeding species typically observed at or near the surface. This shark's sub-surface habits and behaviors have only begun to be revealed in recent years through the use of archival and satellite tagging technology. We attached pop-up satellite archival transmitting tags to 35 whale sharks in the southeastern Gulf of Mexico off the Yucatan Peninsula from 2003-2012 and three tags to whale sharks in the northeastern Gulf off Florida in 2010, to examine these sharks' longterm movement patterns and gain insight into the underlying factors influencing their vertical habitat selection. Archived data were received from 31 tags deployed on sharks of both sexes with total lengths of 5.5-9 m. Nine of these tags were physically recovered facilitating a detailed long-term view into the sharks' vertical movements. Whale sharks feeding inshore on fish eggs off the northeast Yucatan Peninsula demonstrated reverse diel vertical migration, with extended periods of surface swimming beginning at sunrise followed by an abrupt change in the mid-afternoon to regular vertical oscillations, a pattern that continued overnight. When in oceanic waters, sharks spent about 95% of their time within epipelagic depths (<200 m) but regularly undertook very deep ("extreme") dives (>500 m) that largely occurred during daytime or twilight hours (max. depth recorded 1,928 m), had V-shaped depth-time profiles, and comprised more rapid descents (0.68 m sec-1) than ascents (0.50 m sec-1). Nearly half of these extreme dives had descent profiles with brief but conspicuous changes in vertical direction at a mean depth of 475 m. We hypothesize these stutter steps represent foraging events within the deep scattering layer, however, the extreme dives may have additional functions. Overall, our results demonstrate complex and dynamic patterns of habitat utilization for R. typus that appear to be in response to changing biotic and abiotic conditions influencing the distribution and abundance of their prey. © 2015 Tyminski et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Fox S.,Utila Whale Shark Research | Foisy I.,Utila Whale Shark Research | De La Parra Venegas R.,Chooj Ajauil AC | Galvan Pastoriza B.E.,Chooj Ajauil AC | And 4 more authors.
Journal of Fish Biology

There were 479 reported whale shark Rhincodon typus encounters between 1999 and 2011 at the island of Utila, which forms part of the Meso-American Barrier Reef System (MBRS) in the western Caribbean Sea. The majority of R. typus were found to feed on small bait fish associated with various tuna species. Ninety-five individual R. typus, ranging from 2 to 11m total length (LT), were identified through their unique spot patterns. A significant male bias (65%) was present. There was no significant difference between the mean±s.d. LT of female (6·66±1·65m) and male (6·25±1·60m) R. typus. Most R. typus were transient to Utila, with 78% sighted only within a single calendar year, although some individuals were sighted in up to 5years. Mean residency time was modelled to be 11·76days using maximum likelihood methods. © 2013 The Fisheries Society of the British Isles. Source

Hacohen-Domene A.,Centro Interdisciplinario Of Ciencias Marinas Cicimar | Galvan-Magana F.,Centro Interdisciplinario Of Ciencias Marinas Cicimar | Cardenas-Palomo N.,CINVESTAV | de la Parra-Venegas R.,Chooj Ajauil AC | And 2 more authors.
Environmental Biology of Fishes

The Mexican Caribbean is considered one of the most important sites for whale shark aggregations. Whale shark groups of over 300 individuals have been recorded frequently. There is little published information regarding the ecology of the whale shark in Mexico, and the role that the Mexican Caribbean plays as habitat for this species. This area has been recognized as important for the whale shark and therefore it is necessary to determine the environmental factors that shape the distribution of these animals. The aim of this study was to identify key environmental factors associated with whale shark feeding aggregations and to determine the patterns in habitat suitability for whale sharks in the Mexican Caribbean through the modeling approach of maximum entropy. Whale shark data obtained for this study included 250 records during April to September (2008–2012). The MaxEnt model performed better than random and produced an area under the curve (AUC) score of 0.946. Primary productivity and sea surface temperature were the variables most strongly related to whale shark sightings. The model predicted a high suitability in areas located to the north of Isla Contoy and the offshore area east of Isla Contoy named “Afuera” (>0.75), with medium suitability north of Cabo Catoche (>0.5) and lower suitability for the northeast of Cabo Catoche (<0.5). The habitat suitability maps also indicated seasonal variations, showing a higher prediction of whale shark sightings during the rainy season (June to October), when primary productivity is higher in the area. © 2015 Springer Science+Business Media Dordrecht Source

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