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This study explored tourists' blogs to identify sustainability challenges and opportunities to inform best-practice management of the whale shark tourism industry worldwide. Few researchers have investigated blogs in the context of swim‐with whale shark experiences as recounted from the tourist perspective. This research was based on a content analysis of a sample of 58 tourist blogs, amounting to 31,509 words of content. The findings explored common sustainability themes within the whale shark tourist experience including proximity of the encounter, nature of the interaction, and whale shark tourist behavior. By comparing three whale shark tourism destinations–Mexico, the Philippines, and Australia–several sustainability challenges and opportunities were identified. The findings contribute to previous knowledge by advancing our understanding of whale shark tourists' perception of critical aspects during their swim-with whale shark experience, which guided recommendations for improved and sustainable management. [ABSTRACT FROM AUTHOR]

The presence of brominated flame retardants in Mexico is discussed and a prospective analysis is proposed. Through a bibliographic review of 16 scientific research articles, the presence of these compounds in coasts, soils, landfills, coastal lagoons and effluents from wastewater treatment plants, in the eggs of the aplomado falcon and in the skin of the whale shark has been reported. These compounds have also been found in the blood of Mexicans living in some states of the country. The presence of these contaminants in other Mexican environments and their effects on their biota are unknown. More studies are required to expand knowledge on this subject. [ABSTRACT FROM AUTHOR]

Measurements obtained from aerial imagery can be used to calculate body shape, condition and growth rates of large surface-associated marine megafauna. In this study, an unoccupied aerial vehicle (UAV) was used to obtain aerial images of an elasmobranch species, the whale shark (Rhincodon typus). Pre-caudal length (PCL) and multiple body width measurements were taken from aerial images of 26 juvenile whale sharks, obtained between November 2020 and February 2021 in the La Paz Bay, Mexico. PCL ranged from 2.98 to 6.43 m, with a mean of 4.93 m (SD = 1.00). Body width was found to be greatest in the region by the snout and anterior contacts of the pectoral fins. Body width decreased in a near-linear manner from ~ 18% PCL at the midpoint to ~ 10% PCL at the posterior end of the body. There was a significant linear relationship between whale shark dorsal surface area (SA) and PCL on the log–log scale (LM: F1,24 = 647.7, P < 0.001), showing that whale sharks increase exponentially in overall body size as they increase in body length. However, there was no effect of PCL on the relative body width at the different measurement sites, suggesting that body shape of whale sharks was similar across the size range measured in this study. Finally, the body condition of the sharks, measured as the residual of the relationship between SA and PCL, varied between − 21.6% and + 14.0%. This study highlights the benefits of using UAV photogrammetry to measure large marine fauna, to obtain valuable morphometric data to study their physiology and bioenergetics. [ABSTRACT FROM AUTHOR]

Whale sharks are known to feed primarily on zooplankton all over the world; however, recent findings suggest that they also prey on fish using behaviors that have not been fully described. Here, we provide detailed evidence of whale sharks interacting with schools of anchovy on four occasions in Bahia de Los Angeles, Baja California, Mexico. Three of these were predatory interactions in multi-species feeding frenzies, and one was a non-predatory interaction. In predatory interactions, whale sharks exhibited two types of feeding behaviors: (1) stationary suction-feeding, a previously described behavior for whale sharks, and (2) lunge-feeding, which has not been previously described in whale sharks, but has been observed among other large filter feeders, such as rorqual whales. The whale sharks moved simultaneously around the school of anchovy, lunging simultaneously or one after another into the school, with 66% (N = 17) of these lunges occurring in the same direction. In the non-predatory interaction, whale sharks exhibited "sit-and-wait" behavior. The evidence presented here, along with previous observations, suggests that whale sharks may change their feeding strategy from suction to lunge-feeding when other predators corner schooling fish. [ABSTRACT FROM AUTHOR]

Trace elements were determined in three areas of the right (RL) and left (LL) lobe of the liver obtained from a whale shark (Rhincodon typus) stranded in Mexico. Mean ± standard error concentrations in µg g-1 wet weight were for zinc (Zn) RL: 22.5 ± 2.1; LL: 26.5 ± 7.1, arsenic (As) RL: 33.0 ± 1.6; LL: 20.0 ± 9.9 and cadmium (Cd) RL: 15.5 ± 0.9; LL: 11.3 ± 3.7; copper (Cu) RL: 3.2 ± 0.3; LL: 2.2 ± 0.8, selenium (Se) RL: 0.5 ± 0.1; LL: 1.2 ± 0.6, mercury (Hg) RL: 0.06 ± 0.02; LL: 0.05 ± 0.004 and lead (Pb) RL: 0.05 ± 0.02; LL: 0.05 ± 0.01. Concentrations showed significant (P < 0.05) differences within the same lobe but not between lobes. The trace element levels found in this whale shark represent the baseline levels of the trophic base's health status in the study area. [ABSTRACT FROM AUTHOR]

The whale shark is an endangered species that usually feeds in coastal areas of highly productive seas such as the Gulf of California, Mexico. This study aims to describe the effect of sea surface temperature, chlorophyll a, bathymetry and slope on the habitat suitability of whale sharks in three important aggregation sites of the Gulf of California. A total of 2396 records of occurrence of whale sharks were obtained from international databases and scientific literature between 1996 and 2018. These records were used for the creation of a species distribution model using MaxEnt for each of the three aggregation sites. The concentration of chlorophyll a explained 71% of the habitat suitability, followed by bathymetry and slope with a combined 17%, and sea surface temperature constituting 10% of the model. Habitat suitability was related to areas where nontargeted fisheries may impact whale sharks through bycatch, entanglement and ship strikes. The implications for the conservation of whale sharks should be considered for management decisions in terms of marine protected areas, fishing refugees or bans, and other regulations regarding fisheries activities. [ABSTRACT FROM AUTHOR]

The whale shark (Rhincodon typus) and the giant manta (Mobula birostris) are migratory species that occasionally occur in the same foraging habitat. Both planktotrophic elasmobranch species can be found seasonally in aggregations from 2 individuals to hundreds of animals in the northern Caribbean Sea off the Yucatan Peninsula of Mexico because of the abundance of food in this area. The aim of this study was to assess the distribution and abundance of the whale shark and giant manta by conducting aerial surveys from May through September during 2016-2018. A total of 953 whale sharks and 466 giant mantas were sighted during 17 aerial surveys. The largest groups of whale sharks and giant mantas were recorded in July 2017 and September 2016, respectively. Aerial survey data were used to estimate the mean density of each species in this aggregation area: 14 whale sharks/100 km2 and 8 giant mantas/100 km2. These values were used to estimate the spatiotemporal variability of the number of whale sharks and giant mantas feeding at the surface. The results of this study indicate that both species were not distributed homogeneously in the assessed area, a situation that often interferes with the implementation of suitable strategies for managing tourist activities. [ABSTRACT FROM AUTHOR]

Ecotourism can incentivize social and environmental benefits through marine conservation, in parallel with efforts to better manage fisheries, coastal development, and other human pressures. In Mexico's Gulf of California and Baja California Peninsula (GCBP), marine ecosystems support tourism activities in many communities, but to date there have been no region‐wide studies to estimate their benefits or identify key species. Based on data collected in this study, each year nature‐based marine tourism in the GCBP results in 896,000 visits, US$518 million in expenditures and at least 3,575 direct jobs from formal operations. In interviews with operators, over 40 species groups were named as important; sea lions, whale sharks, whales, and marlin were the highest ranked, highlighting the importance of ecosystem‐wide health for nature‐based tourism sustainability. Local employment and the ability to make economic and conservation goals compatible were noted by operators as significant opportunities provided by nature‐based marine tourism; challenges included pollution and declines in ecosystem health, a lack of infrastructure, poor resource management policies, and high operating costs. As nature‐based marine tourism expands, a wider transition to true ecotourism, a focus on equitable benefits and collaboration between stakeholders and a cross‐scale and ecosystem approach to management will be vital for achieving potential sustainable social, ecological and economic benefits. [ABSTRACT FROM AUTHOR]

Tourists approaching wild animals can potentially cause disturbance as a result of the perceived predation risk. Risk effects arise when prey alter their behaviour in response to predators. This response may carry costs through its impact on fitness-related activities such as foraging. We recorded behavioural responses of whale sharks Rhincodon typus to experimental vessel and swimmer approaches. We simulated the disturbance caused by ecotourism in the foraging site of this planktivorous fish in Bahia de Los Angeles, Gulf of Baja California, Mexico. Stress-related behaviours (vigilance, change of direction, diving and acceleration) were more common directly after both types of disturbance than before, in particular after approach by a swimmer. Individuals were more likely to be vigilant when they were new to the bay, but we did not find evidence of within-season behavioural habituation. Sharks were 24% more likely to forage before human stimuli than after. Our study highlights negative effects of vessel and swimmer approaches on whale shark behaviour, with a short-term increase in stress-related behaviours potentially carrying energetic costs, combined with a decrease in food intake following the disturbance. Our results indicate concerns about the impact of ecotourism on large fish species. An important next step would be to determine whether these short-term behavioural responses to the perception of predation risk negatively affect fitness. Among other guidelines, we recommend preventing swimmers from approaching if whale sharks stop feeding when a vessel approaches. [ABSTRACT FROM AUTHOR]

The whale shark (Rhincodon typus) is a filter-feeding organism that can be considered a sentinel species, and Bahía de los Ángeles (BLA) in the Gulf of California is an important sighting site for these elasmobranchs. This filter-feeding organism can be considered a pollutant sampler from the marine environment. Persistent organic pollutants are toxic compounds with high mobility and environmental persistence, bioaccumulation and trophic transfer. Among these are polycyclic aromatic hydrocarbons (PAHs) and organochlorine pesticides (OCPs). The present work aimed to determine concentrations of PAHs and OCPs in whale shark skin biopsies, collected in 2021 at BLA. Mean detected levels of PAHs and OCPs were 279.4 ng/g dw (dry weight) and 1478.1 ng/g dw, respectively. Analysis of similarities between the ordered sizes (4.2-7.6 m) and the concentrations of PAHs and OCPs indicated no significant differences. Individual PAHs detected indicate pyrogenic and petrogenic sources; the presence of pesticides at levels higher than those of hydrocarbons may be related to agricultural activity in the areas surrounding the Baja California peninsula. This study is the first report of PAH levels in R. typus for the Gulf of California and Mexico., (© 2023. The Author(s).)

This paper is the first report with morphometric measurements in the Eastern Tropical Pacific of a deceased 5.48 m juvenile whale shark Rhincodon typus, from a rare stranding in La Paz Bay in the Gulf of California, Mexico. Biological measurements and age estimation are provided by the analysis of photographs and growth in rings from vertebrae. [ABSTRACT FROM AUTHOR]

The impacts of microplastics on filter feeders megafauna have recently received increased attention. These organisms are potentially exposed to plastic ingestion and the release of added/sorbed contaminants during feeding activities. An assessment of microplastic abundance and the chemical impact of Phthalates esters (PAEs) were performed in neustonic samples and skin biopsies of Balaenoptera physalus and Rhincodon typus inhabiting the Gulf of California (Mexico). Sixty-eight percent of the net tows contained plastics with a maximum of 0.24 items/m 3 mainly composed of polyethylene fragments. PAE levels were detected both in environmental and skin biopsy samples, with the highest values in the fin whale specimens (5291 ng/g d.w). Plasticizer fingerprint showed a similar distribution pattern between neustonic samples and filter-feeding species, with DEHP and MBP having the highest concentrations. The detection of PAE levels confirmed their potential role as plastic tracers and give preliminary information about the toxicological status of these species feeding in La Paz Bay., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

The number of individual whale shark Rhincodon typus sightings registered October 2015–March 2018 in Bahia de La Paz, Mexico, ranged from 73 to 129 animals per season (total 1662), with the majority of them identified as males. Density plot maps showed high correlations in sightings between sample seasons and revealed potential hotspot areas. Our study provides an essential baseline of information for the management of whale shark conservation and the associated touristic activities in the region. [ABSTRACT FROM AUTHOR]

Photo-identification and conventional tagging were used to estimate population size and structure of the whale shark Rhincodon typus near Holbox Island, Mexico. From 2005 to 2008, photographs of spot patterns behind the last gill slit and in a lateral view on the left side of each animal were used to identify individuals. Additionally, 578 R. typus were tagged using conventional marker tags. Of these and the 350 R. typus that were identified from 1184 photographs, 65% were male; 27%, female and 8%, indeterminate sex. Photographed R. typus ranged in size from 2·5 to 9·5 m total length. Size was bimodal with a large peak at 6 m and a smaller peak at 7 m. Photo-identification showed that there was considerable loss of marker tags. Few of these remained on the animals for more than a year, so that interannual re-sights using tagging could not be used in population modelling. Forty six interannual re-sightings were found in the photographic library; the interval between these re-sightings was typically 1 year. It was estimated that the R. typus aggregation near Holbox Island ranged from 521 to 809 individuals, based on mark-recapture models. From 13 to 33% of R. typus photographed had scars that were attributable to boat strikes. This study provides a baseline for assessing the status of R. typus near Holbox Island. This information is useful to understand drivers of local population size and distribution and potential concerns about increasing effects of tourism on R. typus in this area and for designing better management programmes for R. typus conservation. [ABSTRACT FROM AUTHOR]

Bahía de los Ángeles is located on the Baja Californian coast of the Gulf of California, adjacent to Ballenas Channel. The bay receives a dynamic tidal influence from the channel but is protected by numerous islands. It is a highly productive bay that harbors a high diversity of species, some of them protected such as the whale shark (Rhincodon typus). This study describes the seasonal variability of major zooplankton taxa and copepod and cladoceran species between May 2003 and October 2004. Copepods were dominant during winter and spring (83-99% of the zooplankton abundance), experiencing a dramatic decrease in autumn 2003 (37-66%) and summer 2004 (25-45%). Cladocerans were the second most abundant group, represented by Pseudevadne tergestina and Penilia avirostris. The former species occurred year-round with low abundance in winter, whereas the latter occurred only in summer and autumn. Other holozooplankton taxa contributed with less than 15% of the abundance in most of the samples, while merozooplankton contributed less than 8%, though in October of 2003 and 2004 there was a remarkable abundance of echinoderms and other larvae contrasting with their shortage in other seasons. In winter 2004, temperate-subtropical copepod species dominated, such as Calanus pacificus and Acartia tonsa. The high abundance of copepods during spring obeyed to Acartia clausi (median = 28,034 ind m-3); however, the maximal zooplankton abundance (40,468 ind m-3, 99.5% copepods) came from a sample collected south of Punta Arena, where two whale sharks were observed foraging. The shift in species composition during summer coincides with the predominance of easterly winds described in the literature inducing a reversed circulation and a probable transport of tropical species into the bay during summer and autumn (Centropages furcatus, Subeucalanus subcrassus, Acrocalanus longicornis, Temora discaudata, and Corycaeus amazonicus). [ABSTRACT FROM AUTHOR]

Abstract: The feeding anatomy, behavior and diet of the whale shark Rhincodon typus were studied off Cabo Catoche, Yucatan Peninsula, Mexico. The filtering apparatus is composed of 20 unique filtering pads that completely occlude the pharyngeal cavity. A reticulated mesh lies on the proximal surface of the pads, with openings averaging 1.2mm in diameter. Superficial to this, a series of primary and secondary cartilaginous vanes support the pads and direct the water across the primary gill filaments. During surface ram filter feeding, sharks swam at an average velocity of 1.1m/s with 85% of the open mouth below the water''s surface. Sharks on average spent approximately 7.5h/day feeding at the surface on dense plankton dominated by sergestids, calanoid copepods, chaetognaths and fish larvae. Based on calculated flow speed and underwater mouth area, it was estimated that a whale shark of 443cm total length (TL) filters 326m3/h, and a 622cm TL shark 614m3/h. With an average plankton biomass of 4.5g/m3 at the feeding site, the two sizes of sharks on average would ingest 1467 and 2763g of plankton per hour, and their daily ration would be approximately 14,931 and 28,121kJ, respectively. These values are consistent with independently derived feeding rations of captive, growing whale sharks in an aquarium. A feeding mechanism utilizing cross-flow filtration of plankton is described, allowing the sharks to ingest plankton that is smaller than the mesh while reducing clogging of the filtering apparatus. [Copyright &y& Elsevier]

Abstract: In some places around the world, whale shark ecotourism has become an important economic activity. Specific cases are present in Mexico, the most important being Bahia de los Angeles, Baja California; Bahia de La Paz, Baja California Sur, both in the Sea of Cortes and near Holbox and Contoy Island, Quintana Roo in the Caribbean Sea. Observation and swimming activities with whale sharks in Bahia de los Angeles have been offered for approximately 14 years, although these activities have only recently become more popular. Several studies have been carried out, since 2001 to present economic alternatives for the people living in this coastal community based on whale shark aggregations. This bay is one of the very few known and accessible places around the world where whale sharks congregate on a regular and predictable basis. However, human-related activities, including tourism pressure may also affect the behavior of individual sharks and consequently, have a negative impact on the industry. The present study led to the implementation of a “Code of Conduct” for interaction activities with whale sharks so they could ensure a safe, enjoyable experience for participants and to prevent the animals from being harmed or disturbed. Also, it enabled the establishment of a continuous data set collected directly by the tour operators, which is updated each year in collaboration with independent researchers. The guidelines within this “Code of Conduct” have formed the basis of similar management practices in other places of Mexico, and are enforced to reduce the chance that the animals will be negatively affected through human interaction. It is concluded that community-based projects are important for long-term conservation. [Copyright &y& Elsevier]

Abstract: A highly variable fragment of the mtDNA control region of the whale shark was sequenced to investigate genetic population structure at three localities in the Gulf of California. We found high levels of variation with 14 haplotypes among 36 individuals (h =0.90, π =0.005). AMOVA analysis did not detect significant structuring among Gulf of California whale sharks (P >0.12, Φ ST 0.029), which indicates a single, highly mobile population. Genetic analysis, along with field observations, suggests natal philopatry of female whale sharks in the Gulf of California. [Copyright &y& Elsevier]

I Aquilolamna milarcae i - a combination of "eagle shark" and the name of the museum that will host the specimen - was a plankton eater that lived toward the end of the era of the dinosaurs, some 90 million years ago. PHOTO (COLOR): Oscar Sanisidro If you've ever seen a manta ray, you may be able to imagine what the ancient eagle shark looked like in action: a giant, ghostly figure flapping through Cretaceous era seas near present-day Mexico. [Extracted from the article]

Concentration of essential (Se, Zn and Cu) and non-essential (As, Cd, Hg and Pb) trace elements were measured in selected tissues of two dead whale sharks (Rhincodon typus) stranded in the Gulf of California (GC) in 2017 and 2018. Concentrations of Cd and Pb in the skeletal muscle of the whale shark from La Paz Bay, GC were higher compared to a previous study on whale shark from China. The shark from La Paz Bay also presented higher concentration of Pb in the epidermis, compared to the same tissue of the other whale shark stranded in Punta Bufeo, GC. The Hg in all analysed tissues was lower than those documented in carnivorous sharks. Molar ratio Se:Hg shows an excess of Se over Hg in all the tissues sampled in both sharks.