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A was taken from approximately 600 m altitude and shows 220 whale sharks and 4 tourist boats. A was taken from lower altitude and shows 68 whale sharks, 1 tourist boats and 2 pairs of tourists snorkeling.
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Whale sharks, Rhincodon typus, are often perceived as solitary behemoths that live and feed in the open ocean. To the contrary, evidence is accumulating that they are gregarious and form seasonal aggregations in some coastal waters. One such aggregation occurs annually north of Cabo Catoche, off Isla Holbox on the Yucatán Peninsula of Mexico. Here...
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Genetic structure of sedentary marine organisms with planktonic larvae can be influenced by oceanographic transport, larval behaviour and local selection. We analysed the population genetic structure (based on mtDNA) of the invasive mussel Mytilus galloprovincialis and the indigenous mussel Perna perna along the southern African coastline. Low gene...
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... Although whale sharks have been shown to be wide-ranging, most research has focused on coastal aggregations. The predictable occurrence of whale sharks at many of these locations is driven predominantly by seasonal abundance of prey, for example, sergestid shrimps off Mafia Island, Tanzania (Rohner et al., 2015a), or a combination of copepods and sergestid shrimps (Motta et al., 2010), or little tunny (Euthynnus alletteratus) eggs (de la Parra-Venegas et al., 2011) Reef, Western Australia (Meekan et al., 2006), Inhambe Province, Mozambique (Rohner et al., 2015b), and multiple sites in the Philippines (Araujo et al., 2014;Araujo et al., 2017;McCoy et al., 2018;Araujo et al., 2019) amongst others. Most of these sites are juvenile male dominated, highlighting persistent knowledge gaps including the unknown areas where adults, neonates and juvenile females spend the majority of their time. ...
The world's largest fish, the whale shark (Rhincodon typus), is a circum‐tropically distributed and globally endangered species, that is widely studied at predictable aggregation sites. The main Hawaiian Islands are not known to have large aggregations of whale sharks; however, they have been anecdotally reported here with some regularity. To date, little is known about this charismatic species in Hawaiian waters. This study is the first effort to examine whale shark demographics and movements in a previously unstudied region of the world. Here, citizen science was used to investigate the abundance, seasonality (if any) and occurrence of whale sharks in the waters around the main Hawaiian Islands. A total of 309 individual whale sharks were identified from sightings between 1991–2020 by their unique spot patterns, most of which (74%) were reported between 2018 and 2020. Estimated whale shark total length ranged from 2–12 m (mean 6.1 m), with both juvenile and mature males and females represented in the dataset. The best‐fit Lagged Identification Rate (LIR) model for these data suggests that individuals sighted in Hawaiian waters are transient in nature, supporting the empirical data (88% of sharks sighted only once). Although using citizen science data can have inherent biases, these results present a conservative first assessment of the demographics of whale sharks in Hawaiian waters. For an Endangered species assessed as Largely Depleted by the IUCN Green Status of Species, highlighting Hawai’i as an important habitat for the whale shark – mainly as a migratory corridor or navigational waypoint – is a crucial step in understanding their ecology in the Pacific in order to develop effective management plans.
... En Quintana Roo (Caribe Mexicano), la agregación de Tiburón ballena ocurre sobre la plataforma continental de Cabo Catoche, área comprendida entre Isla Holbox e Isla Contoy y más al sur, en la parte norte del Caribe mexicano, cercana a Isla Mujeres (De la Parra-Venegas et al. 2011;Ramírez-Macías et al. 2012a;Hueter et al. 2013). ...
... La Reserva de la Biosfera Tiburón Ballena localizada al norte de Isla Holbox, Cabo Catoche e Isla Contoy, el área marina cercana a Isla Mujeres al norte del Caribe Mexicano (figuras 7.2 y 7.3).México, por tanto, es un país privilegiado por contar con numerosas áreas de agregación de la especie en aguas bajo su jurisdicción.Los periodos del año en los que la especie se agrega son distintos para las tres zonas. En Bahía de los Ángeles ocurre de junio a noviembre, en Bahía de la Paz de agosto a febrero se dan avistamientos, siendo los meses con más abundancia de tiburones, de noviembre a enero(Ramírez-Macías et al. 2012c) y en el Caribe Mexicano los podemos encontrar de junio a septiembre(De la Parra-Venegas et al. 2011;Ramírez-Macías et al. 2012a).En el sur del Golfo de California, concretamente en la Isla Espíritu Santo en Banco Gorda, se agregan hembras (entre nueve y 15 m de lt) de abril a julio, también se reúnen en el Archipiélago de Revillagigedo(Ramírez-Macías et al. 2012c).Otros lugares en México, como la costa central de Nayarit y San Luis Gonzaga (Baja California), cuentan con agregaciones de la especie, pero noFigura 7.2. Localización de las zonas de agregación de Tiburón ballena en el Caribe Mexicano, al norte de Cabo Catoche, Isla Contoy e Isla Holbox y más al sur cerca de Isla Mujeres. ...
El Tiburón sedoso, Carcharhinus falciformis, tiene una distribución circunglobal, se localiza tanto en el Atlántico Occidental y Pacífico Oriental. En México, C. falciformis se encuentra en el Pacífico Mexicano, incluyendo el Golfo de California, así como en el litoral del Golfo de México y Mar Caribe. Los tiburones sedosos habitan generalmente plataformas continentales e insulares, pendientes e incluso se han registrado ocasionalmente en aguas someras (18 m) hasta profundidades de 550 m.
La edad máxima estimada para C. falciformis varía considerablemente para las distintas poblaciones, desde ocho a 11 años hasta más de 30 años. Los parámetros de crecimiento son también altamente variables, con longitudes asintóticas que van de 240 cm a 340 cm de LT (longitud total). El Tiburón sedoso presenta una estrategia de reproducción vivípara placentaria, con un periodo de gestación de 11 a 12 meses y una fecundidad de una a 25 crías con tallas entre 50 y 83 cm (LT). En el 2014 C. falciformis fue enlistada en el Apéndice II de la Convención sobre la Conservación de las Especies Migratorias de Animales Silvestres (CMS) y en 2017 se incluyó en el Apéndice II de la Convención sobre el Comercio Internacional de Especies Amenazadas de Fauna y Flora Silvestres (CITES). En México, la falta de información de captura y esfuerzo pesquero específico ha complicado la evaluación
del estado de las poblaciones de tiburones, en donde C. falciformis no es la excepción. Por ello, es necesario hacer registros específicos de las capturas,
esfuerzo pesquero, datos biológicos-pesqueros, con el fin de realizar análisis demográficos y proyecciones del efecto de la pesca en el stock e identificar
áreas de importancia para su protección.
... En Quintana Roo (Caribe Mexicano), la agregación de Tiburón ballena ocurre sobre la plataforma continental de Cabo Catoche, área comprendida entre Isla Holbox e Isla Contoy y más al sur, en la parte norte del Caribe mexicano, cercana a Isla Mujeres (De la Parra-Venegas et al. 2011;Ramírez-Macías et al. 2012a;Hueter et al. 2013). ...
... La Reserva de la Biosfera Tiburón Ballena localizada al norte de Isla Holbox, Cabo Catoche e Isla Contoy, el área marina cercana a Isla Mujeres al norte del Caribe Mexicano (figuras 7.2 y 7.3).México, por tanto, es un país privilegiado por contar con numerosas áreas de agregación de la especie en aguas bajo su jurisdicción.Los periodos del año en los que la especie se agrega son distintos para las tres zonas. En Bahía de los Ángeles ocurre de junio a noviembre, en Bahía de la Paz de agosto a febrero se dan avistamientos, siendo los meses con más abundancia de tiburones, de noviembre a enero(Ramírez-Macías et al. 2012c) y en el Caribe Mexicano los podemos encontrar de junio a septiembre(De la Parra-Venegas et al. 2011;Ramírez-Macías et al. 2012a).En el sur del Golfo de California, concretamente en la Isla Espíritu Santo en Banco Gorda, se agregan hembras (entre nueve y 15 m de lt) de abril a julio, también se reúnen en el Archipiélago de Revillagigedo(Ramírez-Macías et al. 2012c).Otros lugares en México, como la costa central de Nayarit y San Luis Gonzaga (Baja California), cuentan con agregaciones de la especie, pero noFigura 7.2. Localización de las zonas de agregación de Tiburón ballena en el Caribe Mexicano, al norte de Cabo Catoche, Isla Contoy e Isla Holbox y más al sur cerca de Isla Mujeres. ...
La presente obra es resultado de la participación de expertos provenientes del sector gubernamental, académico y privado, con un total de 36 autores que compilaron información contenida en investigaciones científicas y material bibliográfico (tesis de posgrado, libros y artículos científicos).
Sin duda, el contenido facilitará significativamente la labor de la Autoridad Científica cites de México, pues aporta elementos para analizar y emitir DENP de manera oportuna, además de apoyar a las autoridades Administrativa y de Aplicación de la Ley de México para su efectiva implementación de la cites, cuyo tratado internacional es uno de los más efectivos para la gestión de nuestro patrimonio natural, del cual dependen la subsistencia y modos de vida en el largo plazo de las comunidades pesqueras.
... In our study, zooplankton sampling was performed by vertical hauls because of the distribution of zooplankton and the behaviour of the sharks. In fact, in Nosy Be, zooplankton seems to be concentrated in small (30-50 m) patches (chasse), as also reported in other areas of whale shark aggregation by some authors (Clark and Nelson, 1997;Rowat et al., 2007;Nelson and Eckert, 2007;De la Parra Venegas et al., 2011;Gleiss et al., 2013;Gleiss et al., 2013;Rohner et al., 2015;Cade et al., 2020a). Therefore, long trawls, resulting in transects of a few hundred meters, would cross such small patches and underestimate zooplankton density (Cade et al., 2020b). ...
Zooplankton assemblage was studied during seasonal aggregation of the whale shark Rhincodon typus in Nosy Be Island, a hotspot area in the Mozambique Channel. Two different sampling sites were identified in the outer neritic zone: a Feeding area, where whale shark was commonly sighted, and a Control area, never frequented by R. typus. The aim was to investigate zooplankton variability, in terms of composition, biomass and size spectra, in the two areas.
Mesozooplankton was collected vertically form 10 m depth to the surface, in November–December 2018–2019 in Control and Feeding areas. A total of 36 zooplankton samples were collected during both campaigns; two different size classes, ≤2 mm and >2 mm and biomass (dry and wet weights) were analysed. Taxonomic composition was performed on 12 samples collected each year. In Feeding and Control areas mesozooplankton composition was similar and mainly represented by Copepoda. Wet and dry weights were higher in Control area compared to the Feeding, with a significant contribution of organisms >2 mm. A decrease of the total number of individuals was recorded in 2019, compared to 2018, characterized by a decrease in copepod abundance (−10%). Biomass decreased of 36.4% in 2019 with respect to 2018, mainly due to a decrease of organisms >2 mm. Similar mesozooplankton assemblage was recorded in the Control and Feeding areas of whale shark, whereas a significant increase in mesozooplankton size in Control area, evidenced by the highest biomass of organisms > 2 mm, could be due to the absence of predators. A decrease of biomass observed in 2019 needs to be further monitored, but the lack of significant differences between mesozooplankton assemblage in Control and Feeding areas suggests a possibility of multiple prey sources. Analysis of prey/predator interaction is recommended for understanding feeding habits and abundance of whale sharks in tropical regions.
... Microbiome diversity patterns in whale sharks may also be shaped by inherent aggregation effects including diet, as is seen in other sh species 38 . Whale sharks in the Philippines39 andTanzania 40primarily eat sergestid shrimp, while La Paz whale sharks feed on copepod blooms 41 , and the aggregation near Cancun ingests sh eggs42 . Genetic structure was moderate predictor of microbiome structure. ...
Microbiomes confer beneficial physiological traits to their host, but microbial diversity is inherently variable, challenging the relationship between microbes and their functional contribution to host health. Here, we compare diversity and architectural complexity of the epidermal microbiome from 74 individual whale sharks (Rhincodon typus) across five aggregations, globally. We hypothesised co-occurrence patterns would occur independently of diversity patterns. Whale shark aggregation was the most important factor discriminating taxonomic diversity patterns. Microbiome network architecture was similar across all aggregations with degree distributions matching Erdos-Renyi graphs. However, networks had greater modularity than expected, indicating definitive microbiome structure. In addition, whale sharks hosted 35 ‘core’ microbiome members supporting the high modularity observed in microbiomes. Therefore, while variability in microbiome diversity is high, network structure and core taxa are inherent characteristics of the microbiome in whale sharks. We suggest host-microbiome and microbe-microbe interactions which drive self-assembly of the microbiome are, in part, the result of emergent functions that support functionally redundant key core microbial members.
Teaser Sentence: The skin microbiome of whale sharks has emergent co-occurrences structure despite distinct diversity patterns.
... Aggregations can be dynamic and shift location between seasons (e.g. de la Parra Venegas et al., 2011). Here, we used a collaborative approach to understand their residency behaviour across 25 sites highlighting that whale sharks tend to reside for longer at some sites whilst they might use other sites to navigate through en route to other areas of importance. ...
... Other sites with modelled n of more than 100 include offshore Qatar in the Arabian Gulf and St. Helena in the South Atlantic. The former site is associated with the sharks feeding on mackerel tuna Euthynnus affinis eggs (Robinson et al., 2013;Robinson et al., 2016), similar to the Yucatan site (de la Parra Venegas et al., 2011). The drivers for the latter are not yet fully understood, but St Helena is unique in hosting a mostly adult 1:1 male to female aggregation where courtship and attempted mating behaviours have been reported (Perry et al., 2020). ...
The world’s largest extant fish, the whale shark Rhincodon typus, is one of the most-studied species of sharks globally. The discovery of predictable aggregation sites where these animals gather seasonally or are sighted year-round – most of which are coastal and juvenile-dominated – has allowed for a rapid expansion of research on this species. The most common method for studying whale sharks at these sites is photographic identification (photo-ID). This technique allows for long-term individual-based data to be collected which can, in turn, be used to evaluate population structure, build population models, identify long-distance movements, and assess philopatry and other population dynamics. Lagged identification rate (LIR) models have fewer underlying assumptions than more traditional capture mark recapture approaches, making them more broadly applicable to marine taxa, especially far-ranging megafauna species like whale sharks. However, the increased flexibility comes at a cost. Parameter estimations based on LIR can be difficult to interpret and may not be comparable between areas with different sampling regimes. Using a unique data-set from the Philippines with ~8 years of nearly continuous survey effort, we were able to derive a metric for converting LIR residency estimates into more intuitive days-per-year units. We applied this metric to 25 different sites allowing for the first quantitatively-meaningful comparison of sightings-derived residence among the world’s whale shark aggregations. We validated these results against the only three published acoustic residence metrics (falling within the ranges established by these earlier works in all cases). The results were then used to understand residency behaviours exhibited by the sharks at each site. The adjusted residency metric is an improvement to LIR-based population modelling, already one of the most widely used tools for describing whale shark aggregations. The standardised methods presented here can serve as a valuable tool for assessing residency patterns of whale sharks, which is crucial for tailored conservation action, and can cautiously be tested in other taxa.
... We saw up to 49 different whale sharks in a day, demonstrating that large aggregations do occur, but these were rare. Fewer individuals in an aggregation make it easier to identify all individuals present, which is less the case where large aggregations of >100 individuals occur such as off Isla Mujeres in Mexico, and off Qatar (de la Parra Venegas et al. 2011, Robinson et al. 2013. It is an advantage for CMR studies when fewer sharks are missed. ...
Many large marine species are vulnerable to anthropogenic pressures, and substantial declines have been documented across a range of taxa. Many of these species are also long-lived, have low individual resighting rates and high levels of individual heterogeneity in capture probability, which complicates assessments of their conservation status with capture-�mark-�recapture (CMR) models. Few studies have been able to apply CMR models to whale sharks Rhincodon typus, the world’s largest fish. One of their aggregation sites off Mafia Island in Tanzania is characterised by unusually high residency of this Endangered species, making it an ideal target for CMR methods. Three different CMR models were fitted to an 8 yr photo-identification data set to estimate abundance, population trend and demographic parameters. As anticipated, resighting rates were unusually high compared to other aggregations. Different CMR models produced broadly similar parameter estimates, showing a stable population trend with high survivorship and limited recruitment. Tagging and biopsy sampling for concurrent research did not negatively affect those sharks’ apparent survival or capture probabilities. Scenario-based power analyses showed that only pronounced abundance trends (±30%) would be detectable over our study period, at a 90% level of probability, even with the relatively high precision in yearly abundance estimates achieved here. Other, more transient whale shark aggregations, with reduced precision in abundance estimates, may only be able to confidently detect a similar trend with CMR models after 15-20 yr of observations. Precautionary management and long-term monitoring will be required to assist and document the recovery of this iconic species.
... The most vulnerable elasmobranch species were the whale shark and the giant oceanic manta ray, followed by the scalloped hammerhead because of their high susceptibility and low productivity. Whale sharks and the giant oceanic manta rays had high susceptibility values as they are planktonic filter feeders that form large seasonal feeding aggregations (Carpenter, 2002;De la Parra Venegas et al., 2011;Couturier et al., 2012;Hueter et al., 2013). Furthermore, according to the IUCN assessments, both are categorized as endangered species (Pierce and Norman, 2016;Marshall et al., 2020), which led to a maximum score in the conservation/population status attribute. ...
Exposure risk is assessed based on modeling suitable habitat of large pelagic fish and oil spill scenarios originating at three wells located in the western GM's deep waters. Since the fate of the oil depends on the oceanographic conditions present during the accident, as well as the magnitude and duration of the spill, which are not known a priori, the scenarios used are a statistical representation of the area in which oil spilled from the well could be found, given all possible outcomes. The ecological vulnerability assessment identified a subset of bony fish with low-medium vulnerability and elasmobranchs with medium-high vulnerability. The oiling probability and exposure risk of both bony fish and elasmobranchs hotspots vary by well analyzed. Thus, these results provide essential information for a risk management plan for the assessed species and others with economic or conservation importance distributed in the GM and worldwide.
... Sequeira et al. (2013) sustentan que el turismo de naturaleza, basado en TB, ha demostrado el verdadero valor de tener a los especímenes vivos, existe una transformación al turismo de naturaleza en los sitios, donde la especie se agrega, las operaciones de turismo establecidas continúan expandiéndose y, están generando ingresos relacionados que reemplazan a los que antes proporcionaban las pesquerías dirigidas (o ribereñas). Algunos sitios turísticos conocidos de agregación de TB se encuentran en Australia (Rowat y Engelhardt, 2007;Catlin y Jones, 2010), Seychells (Rowat y Maldivas (Cagua et al., 2014), Belice (Topelko y Dearden, 2005) y México, en donde particularmente la actividad ha crecido desde 1980 (Cisneros-Montemayor et al., 2013;Parra-Venegas et al., 2011). El turismo de naturaleza con tiburones tiene el potencial de contribuir significativamente a la conservación y las economías locales, y nacionales, aunque esto depende de un esfuerzo concertado para implementar una gestión basada en la sustentabilidad (Cisneros-Montemayor et al., 2020b). ...
Los beneficios económicos de la actividad de turismo de naturaleza con tiburón ballena (Rhincodon typus) en la Bahía de La Paz no ha sido cuantificado monetariamente. Los objetivos del presente estudio son: 1) calcular los beneficios económicos de los servicios ecosistémicos recreativos de la actividad de turismo de naturaleza con tiburón ballena y, 2) establecer una línea base que coadyuve a proponer cuotas diferenciadas de acceso por procedencia del visitante. Se realizaron 134 entrevistas turistas que practicaron dicha actividad. Se incluyeron aspectos sociodemográficos, calidad del sitio y percepción de la experiencia. Los beneficios económicos de la actividad de turismo de naturaleza con tiburón ballena se estimaron utilizando el método de precios de mercado y ascienden a 3.292 millones de US$, destacando que los visitantes nacionales perciben mayor beneficio por la actividad que los extranjeros. Las pruebas de hipótesis indican que no existe diferencia estadísticamente significativa entre el costo de viaje y el costo total; pero sí existe diferencia estadísticamente significativa entre el costo de viaje y el costo total entre turistas nacionales y extranjeros respectivamente. El ANOVA exhibe que sí hay una diferencia estadísticamente significativa para el costo de viaje promedio por procedencia del visitante (nacional, norteamericano, canadiense, europeo y otro); pero no hay diferencia estadísticamente significativa en el costo total promedio por procedencia del visitante. Estos resultados abren la posibilidad de cimentar una línea base para plantear cuotas de acceso diferenciadas por procedencia del visitante, lo cual coadyuvaría y fortalecería la sostenibilidad financiera del área de protección del tiburón ballena en la Bahía de La Paz, si se llegaran a implementar.
... They estimated that whale sharks could travel >10,000 km/year for 2-4 years, assuming they moved at a constant speed, and excluding the longest track on record of movement of >13,000 km from the Gulf of California to the Western Pacific in 1,144 days (Eckert and Stewart, 2001). Additional information is also required to understand the factors that promote the aggregation of whale sharks along specific areas of the Pacific (Taylor, 1996) and Atlantic Oceans (de la Parra Venegas et al., 2011) and to evaluate nomadic individuals and compare them to those in other well-known aggregation areas within the Eastern Pacific, such as Mexico and the Galapagos (Ramírez-Macías et al., 2012Acuña-Marrero et al., 2014). Whale sharks have a circumtropical distribution (Rowat and Brooks, 2012), but it is unknown whether the species is composed of a single panmictic population or several reproductively isolated subpopulations. ...
... Although nomadic individuals are currently found in Pacific Panama waters, in 2009, a group of 30 individual sharks was observed in the Gulf of Panama (east Pacific Panama) in the open sea far from coastal areas during the upwelling season. Many studies have recorded new foraging grounds for whale shark aggregations corresponding to spawning events of other species, indicating adaptability to highly productive areas (Taylor, 1996;Heyman et al., 2001Heyman et al., , 2005Hoffmayer et al., 2007;de la Parra Venegas et al., 2011). Transient whale sharks may increase in numbers in such highly productive areas in response to climate change (in particular, increases in warming water temperature, upwelling, and productivity) which provides an opportunity to improve our sample size. ...
The whale shark (Rhincodon typus) is an endangered and highly migratory species, of which solitary individuals or aggregations are observed in oceans worldwide and for which conservation efforts are hindered by a lack of comprehensive data on genetic population connectivity. Tissue samples were collected from wandering whale sharks in Pacific Panama to determine genetic diversity, phylogeographic origin, and possible global and local connectivity patterns using a 700–800 bp fragment of the mitochondrial control region gene. Genetic diversity among samples was high, with five new haplotypes and nine polymorphic sites identified among the 15 sequences. Haplotype diversity (Hd = 0.83) and nucleotide diversity (π = 0.00516) were similar to those reported in other studies. Our sequences, in particular haplotypes PTY1 and PTY2, were similar to those previously reported in the Arabian Gulf and the Western Indian Ocean populations (a novel occurrence in the latter case). Haplotypes PTY3, PTY4, and PTY5 were similar to populations in Mexico and the Gulf of California. In contrast, the only populations to which our Panamanian sequences were genetically dissimilar were those from the Atlantic Ocean. The absence of reference sequences in GenBank from southern sites in the Eastern Tropical Pacific, such as Galapagos (Ecuador), Gorgona and Malpelo Islands (Colombia), and Coco Island (Costa Rica), reduced our capacity to genetically define regional patterns. Genetic differentiation and connectivity were also assessed using an analysis of molecular variance (AMOVA), which showed a similar population structure (five groups) to the neighbor-joining tree. Other population features based on neutrality tests, such as Tajima’s D and Fu’s Fs statistics, showed positive values for Panama of 0.79 and 1.61, respectively. Positive values of these statistics indicate a lack of evidence for population expansion among the sampled individuals. Our results agree with previous reports suggesting that whale sharks can travel over long distances and that transboundary conservation measures may be effective for species protection.
