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The 4th International Whale Shark Conference
- Conference date: 16-18 May 2016
- Location: Doha, Qatar
- Volume number: 2016
- Published: 15 May 2016
1 - 20 of 67 results
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Butanding Network's whale shark awareness conservation efforts and challenges in the Philippines
By Elson Q. AcaBackground The Philippines is an archipelagic country consisting of 7,107 islands with 36,289 kilometers of discontinous coastline. 14 out of 15 administrative regions (or 93%) are coastal regions, 62 out of 80 provinces (or 78%) are coastal provinces, while 832 out of 1,496 municipalities (or 56%) are coastal municipalities. It was estimated that the total coastal population will reach 73.3 million by 2011. Approach Initial awareness efforts through dialogue and lectures targeted staff of the regional offices of the Bureau of Fisheries and Aquatic Resources (BFAR), who has the mandate for the protection of whale sharks in the country through the Fisheries Administrative Order 193 (series of 1998). However, in 2010, through Administrative Order 282, several agencies were included in intensifying the protection of whale sharks, including the Department of Environment and Natural Resources (DENR), local government units (LGUs) and the academe, which become additional agents of the awareness campaign. Posters were distributed in areas visited to make the information more visible in the government offices and coastal areas. A website called Butanding Network (www.butandingnetwork.net) was created, and later converted to a page in the social media, to target people that are active in cyberspace. For the kids, awareness were done through storytelling sessions in schools and some public establishments. Collaborations were established with other non-governmental organizations (NGOs) and television shows to act as a resource speaker for whale shark information. Results 13 of the 14 coastal administrative regions were visited, of which either or both the BFAR and DENR regional offices were informed and encouraged to disseminate whale shark knowledge to their coastal jurisdictions. 15 State Universities and colleges (SUCs) around the country with biology, marine biology, environmental science and/or fisheries courses were encouraged to delve into whale shark research in their coastal waters. Children, ages ranging 6–12, were able to attend story telling sessions on 10 different occasions in 6 different locations. Whale shark related issues were relayed to the public through social media, television shows and documentaries. Conclusions The archipelagic nature of the Philippines makes it difficult to spread awareness in the country. The government agencies mandated to protect and conserve the whale sharks don't have a structured program for spreading awareness, and do not see conservation as a priority. Whale sharks and other large marine animals were not included or only discussed briefly in biology/marine biology/fisheries courses topics. Social media, television shows and documentaries are great ways to reach a larger audience, however, there is a need to standardize the contents and how it is presented to prevent misinformation of the public.
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On their way to pupping grounds?: Unprecedented parade of large female whale sharks at Darwin Island, Galapagos Marine Reserve
Background The Galapagos Whale Shark Project is a multi-institutional effort initiated in 2011 with the aim to characterize the presence, population structure and movement patterns of whale sharks within and around the Galapagos Marine Reserve. This specific study aimed to understand their occurrence, residency and habitat use around Darwin Island, located at the northern tip of the Galapagos Archipelago, where large individuals had been reported to be seasonally abundant. Approach This study followed a diversified methodology approach that included: analysis of a local underwater visual census database of pelagic species (2007–2013) to establish seasonality in their occurrence; specific whale shark surveys (2011–2013) to collect information about shark's size (laser photogrammetry), sex, behavior and signs of potential pregnancy; photo-ID records (2011–2013) obtained during these surveys to determine residency and abundance; and the deployment of acoustic tags for continuous tracking around Darwin Island to assess habitat use at the study site. Results Whale shark presence at Darwin Island follows a seasonal pattern. During the cool season (July–December), a strongly female-biased whale shark population, composed mostly (91.8%) by large individuals (11.35 m ± 0.12 m (TL ± SE)), pass through the study site. The great majority of these individuals show clear distended bellies, which could be a sign of a potential pregnancy. Population dynamics models for these apparently pregnant sharks estimated the presence of 3.76 ± 0.90 (mean±SE) sharks in the study area per day with an individual residence time of 2.09 ± 0.51 (mean±SE) days. Assuming constancy in these rates for the entire cool season, we can estimate a net abundance of 695 ± 166 (SE; 95%CI 442–1110) apparently pregnant whale sharks per season. Movement patterns analysis of four apparently pregnant individuals revealed an intense use of Darwin's Arch, where no feeding or specific behavior has been recorded or could be inferred from their dive profiles, together with periodic excursions around the island's vicinity. Sharks showed a preference for intermediate depths (20–30 m) with occasional dives mostly to mid-water, remaining the majority of their time at water temperatures between 24–25°C. Conclusions The lack of evidence of specific behavior observed at Darwin Island, together with the short residence time and strong intra-seasonal abundance and high turnover rate, indicate that this location is not an aggregation site but an important stopover in a migration. In the case of adult R. typus individuals observed, this migration might involve reproductive purposes, as all but one were apparently gravid.
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Establishing the ecological connectivity of whale shark aggregations across the Indian Ocean – a photo-identification approach
Background The seasonal aggregations of whale sharks that occur at coastal sites throughout the tropics are the focus of growing ecotourism industries. Genetic and modelling studies suggest that these aggregations may be linked by migration, although the temporal and spatial scales at which this occurs is unknown. Here, we utilized a continuously expanding photoidentification database collected by citizen scientists and researchers to assess connectivity and residency patterns of five whale shark aggregation sites across the entire Indian Ocean at timescales of up to a decade. We also investigated the effectiveness of such an approach in detecting different levels of migration given the population size at each aggregation site. Approach We used the semi-automated program I3S (Individual Interactive Identification System) to compare 6,519 photographs of the unique natural marking patterns of individual whale sharks collected from aggregations at Mozambique, the Seychelles, the Maldives, Christmas Island (Australia) and Ningaloo Reef (Australia). We searched the database for matches between aggregations (migration) and matches between years within aggregations (residency). A Monte Carlo simulation approach utilizing population sizes of aggregations reported by previous studies was used to examine the sample sizes that would be required to reliably detect varying levels of migration rates among four of these aggregations. Results We found no evidence of connectivity of whale shark aggregations at ocean-basin scales within the time frame of the study, and evidence for only limited connectivity at regional (100s–1000s km) scales. A male whale shark sampled in January 2010 at Mozambique was resighted eight months later in the Seychelles and was the only one of 1,724 individuals to be photographed at more than one site. On average, 35% of individuals were re-sighted at the same site in more than one year. The Monte Carlo simulation study showed that the power of this photo-identification approach was strongly dependent on both the number of individuals identified in aggregations each year and the size of resident populations. The simulation also indicated that there was a higher chance of detecting migrants (if they were present) in aggregations at Ningaloo Reef and the Maldives than the Seychelles and Mozambique given the current numbers of individuals identified each year. Conclusions The weight of evidence from both our photo-identification study and previous tagging studies suggests regional or small-scale movements (10–100s km) may be more common in whale sharks than movement at ocean-basin scales. We recommend that the management of whale sharks in the Indian Ocean occur at regional scales, and photo-identification databases are expanded to include additional sampling sites within each region.
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Temperature-depth-recorder tags reveal modified diving behaviour by whale sharks at a provisioning site in Cebu, Philippines
Authors: Gonzalo Araujo, Jordan Thomson, Jessica Labaja, Sally Snow, James Montgomery and Alessandro PonzoBackground Whale shark tourism is increasingly popular at coastal predictable aggregations around the world. However, only one description accounts for provisioning of whale sharks (Rhincodon typus), which is at Oslob, Philippines, where sharks are provisioned between 6 am and 1 pm daily within a demarked tourist interaction area. Understanding the potential effects of provisioning on the behaviour of this species is important for their conservation. Approach To investigate whether whale shark diving behaviour was affected by the provisioning, four whale sharks with known extended residency at the study site were tagged with CEFAS G5 temperature-depth-recorder (TDR) tags. Three individuals were juvenile males with estimated total lengths of 4.5, 5.0 and 6.5 m (P-432, P-480 and P-403 respectively), and a fourth individual was a juvenile female measuring 5.5 m (P-385). A Hawaiian-sling spear pole was used to deliver stainless steel anchors with a tether carrying a swivel 10 cm into the subdermal layer of the whale sharks on the ventral side between the first dorsal fin and the first lateral ridge. Three TDR tags were randomly deployed amongst the individuals over a period of 18 months. Linear mixed effect models were used to test how attendance at the provisioning site affected shark depth use and variability. Results Tags were deployed for an average duration of 49.5 provisioned days (sharks present daily at the site) and 33.8 non-provisioned days (sharks were absent from the site). The deepest dive was recorded by P-403 to 1,251 m, at a minimum temperature of 12.1 °C. The tags revealed a pronounced shift in habitat use by individuals when away from the provisioning site. Specifically, during provisioned days, time spent at the surface (0 – 2 m) between 6 am and 1 pm was ca. six times longer than during non-provisioned days. During provisioned days, deep dives occurred mostly near or at the end of the provisioning activities (i.e. 10 am to 2 pm), whereas on non-provisioned days, deep dives occurred mostly between 4 am and 10 am. This shift could suggest that whale sharks have a need to thermoregulate following a prolonged period of time at the surface where temperatures regularly exceed 31 °C. Conclusions The use of TDR tags on whale sharks revealed modified diving behaviour at Oslob, a unique provisioning site. This behavioural modification should be considered when developing guidelines for sustainable tourism and conservation measures for the species.
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Daily abundance and residency patterns of whale sharks (Rhincodon typus) at a unique provisioning site in the Philippines
Authors: Jordan Thomson, Gonzalo Araujo, Jessica Labaja, Emer Mccoy, Ryan Murray and Alessandro PonzoBackground Shark viewing tourism is a burgeoning global industry. Numerous operations provision sharks to increase sightings yet the effects of provisioning on shark behaviour are often poorly understood. At a unique provisioning site in Oslob, Cebu, Philippines, whale sharks (Rhincodon typus) have become the focus of a mass tourism operation since late 2011, receiving over 185,000 tourists a year. Approach To better understand and advise management bodies on the effects of provisioning on these animals, we used photographic identification (photo-ID) to assess the daily abundance and site visitation patterns of the sharks. Principal coordinate analysis (PCoA) based on co-occurrence matrices was used to investigate visitation patterns amongst individuals and define groupings. Modified maximum likelihood methods were then used to model mean residency for these different groups. Results Between March 31st 2012 and March 31st 2015, we identified 209 (165 males, 34 females and 10 of unknown sex) individuals at the site (a 0.065 km2 demarked area located 50 – 100 m from shore), with an average of 12.4 (SD = ± 4.8, range = 2 – 31) sharks sighted per day. Daily shark abundance increased over time and showed strong seasonal variation, with annual peaks occurring between May and November. We documented a spectrum of site visitation patterns ranging from single sighting (21% of sharks identified) to year-round residency (5% of sharks identified). For frequently sighted sharks, PCoA revealed two primary residency groupings: highly resident sharks (N = 9), which were seen year-round with few prolonged absences, and seasonal sharks (N = 21), which were primarily present between May and November. The daily abundance of highly resident sharks varied nonlinearly over time with no clear trend, while the daily abundance of seasonal sharks showed a clear increase during peak season in each year of the study. Mean residency for highly resident sharks was estimated at 55.5 ± 175.5 SE (95% CI 49.5 – 730.0) days, 58.3 ± 161.7 SE (95% CI 23.2 – 81.4) days for seasonal individuals, and 16.8 ± 1.8 SE (95% CI 14.8 – 22.2) days for infrequent sharks (N = 130). Conclusions The difference in residency patterns between frequently sighted and infrequent individuals was almost fourfold. This shift in residency could have long-term implications for ca. 15% of identified whale sharks at the site. We provide insight into the impacts of provisioning on shark movements and inform the debate surrounding the future of this controversial activity.
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Testing the affinity of whale sharks, Rhincodon typus, to offshore oil platforms in a newly discovered aggregation site off the cost of Qatar in the Arabian Gulf
Authors: Steffen S. Bach, David P. Robinson, Ali A. Abdulrahman and Mohammad Al-JaidahBackground A large aggregation of whale sharks in the central part of the Arabian/Persian Gulf has recently been documented by the Qatar Whale Shark Research project. Observations made by offshore workers have indicated a continuous presence of whale sharks close to platforms in the Al Shaheen oil field during the summer months. It has been established that the sharks come here to feed on fish eggs of the Mackerel tuna, Euthynnus affinis. The Al Shaheen location is characterized by numerous offshore platforms that could attract the spawning Mackerel tuna and thereby influence the numbers and distribution of whale sharks in the area. Understanding the movement and residency patterns of whale sharks is critical for their management, particularly in an offshore oil field. Approach In the period from 2012–2015 a total of 104 whale sharks were fitted with acoustic V16 tags. The sharks were all tagged in the Al Shaheen oil field during the aggregation period from May to September and ranged in size from 4 to 10 meters TL. The movement pattern of sharks within the Al Shaheen field was monitored using an array of up to 15 VR2W receivers placed a minimum of 4 km apart. The receivers were placed on the seabed at different distances from selected offshore installations and recovered using remotely activated releases. Results Of the 104 tagged sharks, 102 were detected by the deployed receivers during the study period. The maximum detection distance was estimated to be between 500–1000 m from the receiver. More than 99% of the detections occurred between the months of April–September. Average annual residence time in the Al Shaheen area was 38.5 days (±27.5 SD) with some sharks showing a continued presence during the entire April–September period. Conclusions The results indicate that the whale sharks are almost only present in the Al Shaheen area during the April–September period, confirming the visual observations made by workers on the offshore installations. Aggregations, sometimes numbering more than 100 individuals, have only been observed while the whale sharks were feeding on Mackerel tuna spawn. The long residence time indicates that the Al Shaheen area is a highly important feeding ground. The sharks showed a high affinity for the same platforms throughout the study period, while their presence was only rarely recorded at other platform locations. This could indicate that the Mackerel tuna are spawning in a confined location within the study area and that the whale shark distribution within Al Shaheen is strongly associated to the spawning site and the prevailing currents. The platforms themselves may concentrate whale shark presence in the spawning area, but their full importance for the behavior of whale sharks is still to be determined. Mitigating measures have been established in order to minimize potential impacts on whale sharks related to offshore activities.
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An overview of whale shark movement ecology projects in the Red Sea Research Center
More LessBackground The Red Sea Research Center is part of a relatively new university on the Saudi Arabian Red Sea coast, the King Abdullah University of Science and Technology (KAUST). KAUST officially opened in 2009 but began global collaborative research projects in 2007. Among the early discoveries arising from these collaborative projects was the identification of a whale shark aggregation site in the Red Sea. KAUST researchers have been studying this aggregation site since 2008. Approach KAUST researchers have employed various methods and technologies to track whale sharks, including acoustic tagging, satellite tagging technologies, genetics, and some technologies integrating the use of autonomous vehicles. Our whale shark studies include determining the population demographics of the sharks visiting our sites, the site fidelity of the sharks, and any potential connections with populations outside of the Red Sea. In 2012, KAUST began a collaborative effort with colleagues in the Marine Megafauna Foundation to study a whale shark aggregation at Mafia Island, Tanzania. Results The results from our movement studies highlight the pros and cons of various methodologies, and overall emphasize the importance of using multiple methods simultaneously to maximize the clarity of results. In Saudi Arabia, the whale sharks are very near to 50% male and 50% female, unusual compared to most aggregations. Satellite tracking suggests that the Saudi sharks migrate away from the site in the “off-season” and some are confirmed to have left the Red Sea. However, the majority of the sharks remain within the southern half of the Red Sea. Acoustic tracking of whale sharks at Mafia Island, in Tanzania, shows unexpected cryptic residency with many sharks being detected year-round despite a clear seasonal pattern in the sightings of whale sharks in boat-based surveys. These and brief summaries of our findings from other methods will be discussed. Conclusions The results from the Saudi aggregation are strikingly different from results of an aggregation we have been studying at Mafia Island, Tanzania. Future studies of plankton dynamics and fine-scale analysis of whale shark behavior may reveal fundamental differences in the sites that explain these differences in residency. Many emerging technologies hold great promise for improving our ability to learn more about the world's largest fish.
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Communities and corporates for conservation: A decade of conservation effort to save whale shark. Success story from Gujarat, India
Background Prior to 2001, due to the lack of legal protection, whale sharks were brutally and extensively hunted across the shores of Gujarat state in western India. Wildlife Trust of India (WTI) actively lobbied the Ministry of Environment and Forests (MoEF), Government of India, for legal protection of the species by placing it in Schedule I of the Wildlife (Protection) Act, 1972. Approach A brief survey during 2004 along the coastal town of Veraval, the hub of the whale shark slaughter, revealed a low awareness level (19%) of poaching and the protection status of whale sharks among the fishers. Following the survey, WTI launched a large-scale whale shark awareness campaign in 2004, with a special focus on Veraval, with the funding support of Tata Chemicals Ltd (TCL), which led to the training of 1500 fishers into an organised information providing network. Results The whale shark campaign spread awareness on the plight of the species and its protected status in Gujarat. The campaign not only helped convert Gujarat fishermen into protectors of the whale shark by bringing about a major change in the perception and attitude of local people, but also helped in local protection of the species. As a result of the campaign, seven coastal towns adopted the whale shark as their city mascots. The campaign led to a model relief programme that offered monetary support to fishers whose nets were damaged or had to be cut open during the rescue and release of whale sharks. To speed up the release and reduce stress on the sharks, a self-photo documentation process of whale shark rescue for fishers was started. 1200 waterproof cameras were distributed to fishers to document the rescue and release of whale sharks. The captured images of a rescue by fisher folk served as evidence to prove the damage to nets. The photos also helped fishermen claim financial relief from the government scheme to repair/replace nets. From its inception until 2015, 571 whale sharks had been rescued and voluntarily released by fishers with not a single record of whale shark slaughtering. To further strengthen the whale shark conservation activities among fishers, fourteen “Vahlino Mitro” clubs (Vahlino Mitro =Friends of whale sharks) were registered in the fishing villages of Veraval and Mangarol (seven clubs each), with an objective of motivating fishers to fish in a whale shark friendly manner, and to make coastal school children understand the importance of coastal ecosystems and involve them in action based programmes related to whale shark conservation. This project has won several conservation laurels. These include the Bombay Natural History Society (BNHS) Green Governance Award in 2005, the Gujarat Ecology Commission (GEC) Award during 2012 and the UNDP Indian Biodiversity Award to the Gujarat Forest Department for co-management in 2014. Conclusions The whale shark conservation project with the support of fishing communities and corporate house has stopped the killing of whale sharks along the Gujarat coast. The project also instilled a sense of pride among fishing communities along Gujarat coast and ongoing annual International whale shark day celebrations and Gujarat whale shark celebrations are keeping the whale shark conservation message alive among the communities and coastal school students.
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Inferring feeding habits of the whale shark (Rhincodon typus) using fatty acids, in the Northern Mexican Caribbean
Background In the Mexican Northern Caribbean, whale sharks feed on abundant plankton. Assessing the trophic role of this species is key to understanding its general ecology. Non-lethal sampling combined with biochemical methods such as analysis of fatty acids (FA) are promising approaches for investigating the assimilated diet of the whale shark. Approach During 2010 and 2011, a total of 68 whale shark samples (dermal tissue) were collected from free-swimming individuals while they were feeding. Zooplankton samples were collected near feeding whale sharks at the surface. These samples were divided in two categories: mixed zooplankton - several groups of zooplankton, and fish eggs - more than 95% of sample components were fish eggs. FA profiles were assessed from biopsies and zooplankton. ANOSIM was performed to identify the level of significant difference among the different groups of FA composition. Non-metric multi-dimensional scaling (MDS) plots were used to visualize grouping among whale sharks, zooplankton and fish eggs FA profiles. Results The FA profiles of R. typus and their potential prey were dominated by saturated FA. Whale shark FA profiles were significantly different from mixed zooplankton items (ANOSIM R value= 0.87). Fish egg and whale shark FA profiles formed separate groups with overlapping values (ANOSIM R value= 0.67). Whale shark and fish egg FA profiles registered high levels of oleic acid. Arachidonic acid (ARA; mean + SE=8.3+0.8) was the polyunsaturated fatty acid present at the highest level in the whale shark FA profile. These levels did not match the levels of mixed zooplankton and fish eggs. Conclusions The FA profile of the whale shark differs from other zooplanktivore animals whose profiles are usually dominated by polyunsaturated fatty acids. Results of the FA analysis suggest that R. typus is feeding mainly on near surface zooplankton. This is supported by whale shark behavioral observations and low levels of bacterial FA in R. typus profiles. The fact that levels of ARA registered in superficial zooplankton did not explain the ARA content found in biopsies suggests that the whale shark could have other complementary feeding sources, such as demersal zooplankton, in this aggregation area.
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Distribution and feeding habitat characterization of whale sharks Rhincodon typus in the Northern Mexican Caribbean
Background The conservation of whale sharks, like other endangered species, requires, among others factors, an understanding of the effects that variability in habitat have on long-term species viability. In the Mexican Northern Caribbean, a Habitat Monitoring Program for the whale shark was established in 2005 to describe the spatio-temporal variability of environmental data and whale shark distribution. Approach From 2005–2014, when whale sharks were present in the region (May to September), monthly trips were made to record whale shark sightings and hydrological data (sea surface temperature, salinity and dissolved oxygen). Water samples were collected to determine nutrients (nitrite, nitrate, ammonium, silicates and phosphates), as well as chlorophyll-a (Chl-a) and zooplankton biomass. We compared the environmental variables at sites with and without whale sharks present. Maps of zooplankton biomass were produced for each year in order to explore their relationship with the distribution and abundance of whale sharks. Results Areas with high whale shark abundance have been identified inside the study region. At these sites the whale shark feeds, taking advantage of the abundance of zooplankton, as a result of two events: the intensity of the Yucatan upwelling and the presence of dense masses of fish eggs. The whale shark aggregation areas influenced by the upwelling were characterized by high Chl-a concentrations (mean±SE 0.9±0.4 mg/m3), high nutrients and mixed zooplankton in which several groups were present (usually copepods were the most abundant group). In the whale shark aggregation area called “Afuera”, the zooplankton samples were dominated by fish eggs. This area registered significantly higher zooplankton biomass (mean±SE 3356.1±1960.8 mg/m3) in comparison with that recorded in upwelling areas (mean±SE 103.5±57.2 mg/m3). Zooplankton biomass was the most influential environmental variable to determine whale shark abundance, supporting the close relationship between this species and their food availability. Spatio-temporal changes in distribution and abundance of whale sharks have been recorded in the region, as well as changes in their food availability. Conclusions The whale shark uses selected areas within the Mexican Caribbean. These areas have different hydrobiological characteristics. Changes in distribution and abundance of whale sharks inside the study area may make it more difficult to implement suitable management strategies. We need more data to understand the reason for these changes, for example increased knowledge about the ocean circulation patterns at this site and other factors that may influence and characterize spawning inside the aggregation area. The continuity of hydrobiological monitoring is key to ensure the integrity of this critical habitat.
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Further evidence of the importance of St. Helena as habitat for whale sharks
Background Remote oceanic islands may play important roles in the life history of whale sharks; they have been hypothesized to be the site of mating or pupping in this species. One such island is St. Helena in the South Atlantic, which was recently discovered to play host to a seasonal population of adult male and female whale sharks. Approach Two collaborative expeditions have been conducted to St. Helena since the 3rd International Whale Shark Conference. The goals of these were: to document whale shark abundance and population composition, to characterise behaviour and habitat use around the island, and to determine regional scale movement patterns using satellite telemetry. Results The whale shark population observed at St. Helena consisted of an approximately equal mix of mature males and females. The animals were 8.5–11 m in length, i.e. larger than the sub-adults seen in most coastal aggregation sites, but smaller than the large female animals seen regularly in the Galapagos. Two reliable eyewitness accounts of mating behaviour have been recorded at St. Helena, but we have not directly observed this behaviour during the expeditions. An acoustic array was deployed around the island in January 2016 to determine local habitat use patterns, but data are not expected to be available from this effort until the end of 2016. Conclusions Preliminary satellite telemetry results suggest that St. Helena whale sharks travel to the west coast of Africa, not to the east coast of South America. We propose that regional movement patterns are similar to those observed in the eastern Pacific, with animals apparently feeding in coastal upwelling zones, and travelling to remote oceanic islands to fulfill aspects of the reproductive cycle. Environmental regulations have recently come into effect that completely protect the whale shark in waters surrounding St. Helena.
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Population structure of a Red Sea whale shark aggregation
Background The Red Sea has received little study when compared to other areas. This holds true for sharks in general and for whale sharks in particular. The discovery of a seasonal aggregation off the Saudi Arabian coast has made the targeted study of Red Sea whale sharks more feasible. Assessing the size and structure of this aggregation is a first step toward understanding the basin-scale population within the Red Sea and how that population fits into the wider Indian Ocean. Approach Photo-ID records were collected from 2010 through 2015. These were analyzed and fit to several population models. The most parsimonious model was then used to describe the aggregation. Demographic data, including the size and sex of individual sharks was collected and compared to reports from other aggregations. Size was visually estimated to the nearest half-meter and sex was determined by the presence or absence of claspers between the pelvic fins. Results From 2010 to 2015, 305 encounters with whale sharks were recorded within the aggregation. From these, 267 suitable photos were used to identify 136 individuals. Sharks were divided evenly between the sexes and the distribution of sightings showed no evidence of sexual segregation. All individuals were immature based on size estimates and, in males, juvenile clasper morphology. An open population model was found to best represent the data and estimated a daily abundance between 15 and 34 whale sharks during the aggregation season, with local residence times ranging from 4 to 44 days. Residence times away from Shib Habil ranged from 15 to 156 days with a permanent emigration/mortality rate between 0.07 and 0.58 individuals per year. Conclusions These results are broadly similar to those from other aggregations of R. typus, although the observed sexual parity and integration found at this site are unique for the species and need further study.
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Tracking whale shark movements in a southern Maldivian atoll: An opportunistic feeder or reliant on the local fishing industry?
Authors: Francesco G. Comezzi, Hamish Taggart, Samantha D. Reynolds and Bradley M. NormanBackground Whale sharks (Rhincodon typus) are generally sighted during daytime. In the southern atolls of Maldives they are instead sighted primarily at night inside the atoll. Tuna fishermen attract baitfish with a strong halogen lamp, creating substantial plankton concentrations. Whale sharks opportunistically feed near the surface under fishing boats anchored in a 40 m deep lagoon, often disturbing bait collection. This unique occurrence is well known locally but not internationally and it has yet to be the focus of a targeted research program, due in part to the remoteness of the area. This study aims to provide preliminary answers for the following question: Are whale sharks simply moving through Thaa Atoll or do they remain inside for an extended period? Approach Two sharks were tagged in December 2015, while feeding at night under the light of fishing boats inside Thaa Atoll. Wildlife Computers SPOT 5 satellite tags, secured via non-invasive fin clamps, were deployed on the first dorsal fin of two sharks to monitor their geographic movements. This pilot tagging project was undertaken in conjunction with a photo identification study (using Wildbook for Whale Sharks), to compare to other photo ID data collected during other sighting events before and after tagging. Results The first shark (M-109) retained the tag for a period of 25 days, and appeared to remain inside the atoll during this period. Frequent movements within the atoll were recorded, up to 20 km over a 24 h period. M-109 was regularly recorded at the northeast area within the atoll, near a consistent baitfish collection ground where this individual was originally tagged. However, on occasion, M-109 was recorded far from bait collection areas and/or during rough nights with no fishing activity, suggesting natural surface feeding behavior. Despite no data forthcoming from the second tagged shark (likely because of tag dislodgement through interaction with fishers nets), this individual was resighted (confirmed through photo-identification) feeding under fishing nets, at a similar location to the first sighting, 22 days later. Conclusions 1) Satellite data, for M-109, and photo-identification data, for the second shark, confirmed both sharks inside the atoll over a 25 and 22 day period respectively, leading to the possibility of an extended stay throughout the Maldivian dry season. 2) Tagged whale shark M-109 was confirmed via satellite uplinks inside Thaa Atoll on 24 of 25 days for which we have data, suggesting it did not leave the atoll during the 25 day monitoring period. M-109 showed extensive movement within the atoll, far from bait collection areas, suggesting that local fisheries may not be the only source of food exploited by whale sharks. While the results are preliminary, the next phase of research in this potential seasonal whale shark sanctuary will focus on: establishing the frequency of fisher/shark interactions within Thaa Atoll; productivity/plankton studies inside the atoll; an increased number of whale sharks satellite-tagged; expansion of photo-identification work. This study represents the first whale shark tagging study officially recognized and permitted by the Maldivian government and it was performed under governmental supervision. It represents a milestone for the future of whale shark tracking research in the country.
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Scarring estimation in the largest whale shark aggregation
Background Ch'ooj Ajauil AC, a non-profit organization created in 2010 involving tour operator and external research collaborations, is devoted to monitoring and preserving marine pelagic life in the Mexican Caribbean. The organization explored the question, how many whale sharks are been damaged by tourism boats? Approach Six years of methodic registration of scars, injuries and abrasion on whale sharks, using video and photographs, conducted by 3 snorkelers alternating with up to 5 surface observers on board a research boat, along 150 transects, observing 1336 whale sharks, in waters off north east Isla Mujeres, México, where the largest aggregation has been reported. Results Whale shark tourism began over 15 years ago in north Quintana Roo, México on the north east coast of the Yucatan peninsula. Tour operators have been stigmatized as the ones responsible for whale shark injuries, regardless of the multiple other boats transiting the area, including commercial fishers, private yachts and huge vessels. Scars on whale sharks come from many sources including other shark bites and smack and graze, but the most conspicuous ones are propeller cuts and mutilations, mostly on the dorsal fins and body. It is hard to determine geographically where an injury happened, or when. Previous reports on the same population at a different zone, estimated between 13 – 33% of total sharks as injured. There have been statements from the public observers suggesting that up to 50% of the sharks show some kind of scars. This shark meta-population moves into other areas across a large region, including the Gulf of Mexico, the Caribbean Sea and open Atlantic waters. Actual estimations indicate that 29.64% of the whale sharks show some kind of abrasion, including healed and old scars; while less than 5% presented fresh injuries per year. Conclusions No avoidance behavior toward boats was observed from the scarred sharks or from the freshly injured, but the latter were found to be more cautious around snorkelers. Whale sharks with fresh propeller cuts did not modify their site fidelity. Boating enforcement should be improved in order to keep damage to the species at lowest rate possible. A note on healing and recovery is given to document the rapid process of this on some animals.
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Preliminary observations on whale sharks in Nosy Be, Madagascar
Background The northern Mozambique Channel is a global hotspot for whale shark sightings, based on observer records from the tuna purse-seine fleet and published literature. Nosy Be Island (NW Madagascar) hosts a flourishing marine tourism industry based on viewing whale sharks and other species. Following reports of declining sightings in other regional hotspots, such as Tofo in Mozambique, it is important to establish if these declines represent a simple shift in aggregation site, or a broader reduction. Approach Data on population structure were also collected during a preliminary field season from August to December 2015. Results Approximately 200 sightings were recorded by a single operator during 2015. Preliminary analysis indicates that the majority of whale sharks sighted were males of lengths between 3 and 10 meters. Most whale shark sightings were from October to December. Conclusions Regular whale shark sightings occur off the Nosy Be area from August to December. Limited sex and size data suggests a juvenile male-biased aggregation where whale sharks were most commonly observed traveling and feeding on copepods. New data will help to establish whether oceanographic variability has resulted in a shift in abundance to Madagascar, or whether a broad-scale decline has taken place. No species-level legislation protects whale sharks in Madagascar, and the whale shark tourism industry is presently unregulated with regard to interactions. Further work on the population ecology, movements and social importance of whale sharks in the country is justified and will inform the development of effective conservation and tourism management initiatives.
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New insights into the South Ari atoll whale shark, Rhincodon typus, aggregation
Background Examples of aggregations of large Chondrichthyes are well known worldwide and occur mostly in response to seasonal increases in prey abundance. In the Maldives, whale sharks, Rhincodon typus, are thought to have a semi-annual residency pattern, moving west from December to April and east from May to November. However, an important aggregation of predominantly immature male whale sharks seems to be persistent all year round throughout the South Ari atoll region. Understanding residency patterns of this aggregation as well as inter-atoll movements is fundamental to determine the drivers of aggregation, and to design effective conservation management plans at a regional and national scale. Approach The present study used mark-recapture photo identification of whale sharks sightings collected from 2006 to 2015 in the Republic of Maldives. For the aggregation analysis, the Maldives Whale Shark Research Programme (MWSRP) in collaboration with 52 stakeholders and citizen scientists, members of the Big Fish Network (BFN), provided over 3000 sightings, across the South Ari Marine Protected Area (S.A.MPA). Generalised linear models were used to determine seasonality patterns and the effect of environmental variables. Maximum likelihood population models were fitted to establish the size and residency patterns of the aggregation. Results Through the close collaboration between MWSRP and the BFN, 271 individual whale sharks were successfully identified. At a regional scale, as in most whale shark aggregations worldwide, the South Ari aggregation is mainly composed of immature males (86% of the sexed individuals). However, despite a large seasonal variation in sea surface temperature, primary productivity, wind speed and direction, the lag identification rate did not show any significant seasonal pattern. Population models revealed that the aggregation could be characterised as an open population, with an average of 15 sharks present at any given time. Our findings also imply that whale sharks visit the aggregation for a mean of four years and during that time stay for around two of every six weeks. Conclusions South Ari atoll aggregation shows unprecedented levels of residency and site fidelity. Despite showing size and gender structures similar to other aggregations around the world, this aggregation is remarkable because there is no seasonal peak in sightings. It remains to be investigated if this is a due to aperiodic ocean climate phenomena (as in Tofo, Mozambique) or if sharks are aggregating in response to drivers different than feeding. For instance, exploitation of an undetected food source in adjacent deep waters, and subsequent thermoregulation might account for the observed residency patterns. In conclusion, our findings have important implications for the improvement of the conservation management of this symbolic species in the Republic of Maldives, where it is largely targeted by an unregulated tourism industry.
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Whale sharks, tunas and Azorean fisherman, BFF?
Authors: Jorge Fontes, Niall McGinty, Miguel Machete and Pedro AfonsoBackground The Azores archipelago lies at the limit of whale shark (WS) distribution in the North Atlantic, where sporadic sightings of “pintado” (local name) date back to the early tuna fishing operation from the mid XX century. From 1998 and 2008, only nine adult whale shark sightings had been confirmed by the Azores Fisheries Observer Program. However, from 2008 onwards there has been a dramatic increase in the numbers of reported adult individuals around the most southern island of Santa Maria. A recent study found that this increase in sighting frequency was related to an increase in local SST (above 22.5°C), and decrease in chlorophyll-a, with local variation around the large seamounts in the area. While whale sharks and tuna have long been known to associate, the nature and motivation of these associations remains unclear. Moreover the WS-tuna associations in the region remain to be characterized as well as the potential impact of fishing these associations. Approach In this study, we analysed a 13-year observer dataset (1998–2011) from the pole-and-line tuna fisheries from the Azores EEZ to investigate the regional behaviour (distribution in catch abundance and composition) of three tuna species, skipjack, bigeye and albacore during this period. We also examined how these patterns have responded to the environmental drivers, the distribution and abundance of whale sharks and compared whale shark associated fishing events and events targeting free swimming schools. We also detailed an elaborate protocol to guide future research to investigate the impact of fishing the WS-tuna associations and test the “functional bycatch” theory by combining state of the art electronic tracking and behaviour technology with physiological proxies of stress and condition of both whale shark and tuna. Results Changes in the distribution the tuna species were evident with the centre of gravity found closest to the whale shark aggregations in the latter years (2008 in particular) and was independent of fishing effort. Between 2008 and 2011 for the areas where whale sharks have been found we find the associated whale shark fishing events have significantly more individuals of skipjack and bigeye tuna and the area surrounding the eastern islands (Santa Maria etc.) also yielded the highest catches per fishing event. The albacore did not show any significant variation in CPUE for either predictor. Overall, catch rates of tuna were higher and multi-species aggregations were more likely when associated with whale sharks. Conclusions Preliminary results suggest that the presence of WS during the tuna fishing season may have an effect on fishing yields and tuna species composition of catches. It is also apparent that the fishing fleet behaviour could be responding to WS distribution and abundance. Our results support the need to investigate the potential detrimental effects that fishing WS-tuna associations may have on both the WS and tuna.
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First ecotoxicological investigation in whale sharks of the Gulf of California (Mexico) using skin biopsy
Background The impact that pollutants have on whale sharks (Rhincodon typus) is a question that remains largely unexplored. Whale sharks (WSs) are known to aggregate seasonally in different areas in the Gulf of California. Although this species is protected in Mexico since 2001, habitats for most of these aggregations are not protected. Out of the 7 localities were they aggregate, 3 are protected whereas the other 4 need to have some protection. Urban and touristic developments are major threats to their habitats because they lead to mangrove and estuary damage, both being important areas for their food resources. Moreover, due to poor fishery regulations, whale sharks often die as by-catch in fishing nets. The growth of tourism in the area of La Paz and Los Cabos represents an increase in maritime traffic and, thereby an increase in the number of collisions of WSs with boats. Finally, the increasing human activity in WS grounds is the cause of chemical pollution from urban waste waters, vessels, agriculture and solid waste (it is common to see WSs feeding while surrounded by marine litter). Approach In this work, we perform the first ecotoxicological investigation, using skin biopsy, of whale sharks sampled in the Gulf of California. In order to evaluate the potential impact of anthropogenic activities on this species, 13 skin biopsy samples were collected in January 2014 from 12 males and 1 female whale shark in La Paz Bay. PCBs (twenty-one ortho PCB congeners), DDTs (six o,p'- and p,p'- DDE, DDD and DDT isomers), PBDEs (fourteen congeners from tri- to deca-substituted) and HCB were analyzed on freeze-dried blubber biopsy samples by GC-qMS. Biomarker responses (cytochrome P450 1A, CYP1A1) were detected, using western-blotting (WB) techniques, in integument biopsies (skin tissue samples) of this vulnerable (IUCN) species. Semi-quantitative analysis was performed for each WB using Quantity One software (Bio-Rad, 1-D Analysis Software). Results The average abundance pattern for the target contaminants was PCBs >DDTs > PBDEs >HCB. Mean concentration values (and ranges) of 8.42 (0.720–41.40) ng/g w.w. were found for PCBs, 1.31 (0.20–6.36) ng/g w.w. for DDTs, 0.294 (0.02–1.14) ng/g w.w. for PBDEs and finally 0.192 (0.01–0.66) for HCB. The detected values are lower than in other planktivorous shark species (e.g. basking shark) in other areas (e.g. Mediterranean Sea). Cytochrome P450 1A (CYP1A1) was also detected for the first time, using western-blotting techniques, in the skin samples of this species. The potential impact of microplastic (plastic fragments smaller than 5 mm) and related contaminants (such as plastic additives) has also been explored in this large filter feeding species. Preliminary data on the average density of microplastics in the superficial zooplankton/microplastic samples collected from the Sea of Cortez (La Paz Bay) showed that the values ranged from 0.00 items/m3 to 0.14 items/m3; furthermore, concentrations of mono-(2-ethylhexyl) phthalate (MEHP), used as a tracer of plastic additives, ranged from 13.08 ng/g to 13.69 ng/g. Conclusions Further ecotoxicological investigation on whale shark skin biopsies will be carried out in order to support the idea of the usefulness of non-lethal approaches in the worldwide ecotoxicological risk assessment of this vulnerable species.
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Tourist management of the whale shark in the Mexican Caribbean
Background The whale shark population in the Mexican Caribbean is one of the largest in the world. Its touristic exploitation began in 2002, with 200 visitors and 25 licensees, and by 2012 its popularity had risen to 30,000 visitors. In 2013 a load capacity study for the visitors was launched, and it was determined that no more than 160 boats should visit the aggregation each day. However, given the social pressure to give access to more service providers, in 2015 up to 234 boats were allowed per day, but not simultaneously so that the load capacity was not exceeded. The service providers were allowed to work according to this management plan with one condition, they had to work only every other day. This condition was not submitted for public consultation because the service providers did not agree to it, but chose other alternatives to avoid exceeding the load capacity of the aggregation site. The objective of this study is to determine the compliance with this plan and the ease of its supervision. Approach Supervision of boat traffic at the aggregation was performed by the staff of the Whale Shark Biosphere Reserve from June 1 to September 17, 2015, on land from the boarding sites and on tours around the area on board official and touristic boats. The supervisors recorded all boats and tourist who did not obey the regulations. Moreover, surveys were applied to the service providers. Results Supervision was performed for 52 days from the docks and for 12 days on board touristic boats, and 19 supervisions were performed from boats inside the reserve. Conclusions The conclusion was that the management program was not met by 43% of tourist boats. The supervisors found it difficult to monitor the boats, as boats do not carry any visual flags to show if they are operating or not. It was found that the visible presence of park rangers in the area is fundamental for the service providers to abide by the rules. It was determined that the daily boat load capacity was not being exceeded, but other conditions of the permits were not being respected. All the service providers manifested their disagreement with this condition of the management plan, and proposed a rotation system that does not exceed 100 boats per day, along with one day a week in which no boats visit the aggregation, to reduce disturbance to the sharks.
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The “Big Fish Network”: Using new technology to incentivise citizen science engagement in the Maldives
Background The use of citizen scientist contributions is a cost-effective approach that can provide valuable information, usually at scales larger than those attainable by individual researchers. The challenge, however, is to motivate contributors to continuously supply data when doing so can be time consuming and monotonous and where the results of the contributions they make are part of long term studies with infrequent outputs. When studying a highly mobile animal in a geographically disparate location such as the Maldives, a widely spread network of contributors submitting encounter information on whale shark (Rhincodon typus) sightings is vital to providing information on spatial movements and residency patterns. Approach The Maldives Whale Shark Research Programme created a prototype of a mobile device friendly version of the identification software I3S and linked it to an established, custom made interactive online portal called the Big Fish Network, designed to provide a platform for data exchange. Tour operators were invited to submit standardised data logs from their excursions. In return, operators were openly provided access to a photo-identification database of whale shark individuals and 8 years of corresponding encounter data. Outputs from the portal for the operators include an interactive map, a customised trip report, social-media bulletins and a mobile app. These features were designed to aid tour guides in planning and marketing their excursions and informing and engaging tourists, during and after the excursion. Results Since the launch of the Big Fish Network in July 2013, 834 stakeholder data submissions were received from external contributors; equivalent to 59.8% of the total encounters recorded in the same period, as compared to 23.4% between April 2006 and July 2013. In addition, utilising this network produced evidence for 5 instances of inter-atoll movements using sightings submitted from locations that are outside the main survey areas. Conclusions We believe that this example of using appealing technology and open data as tools to produce carefully tailored incentives may strengthen stakeholder commitment to citizen science initiatives and increase the catchment of data from a wider range of stakeholders. Employing similar models at a regional level in whale shark hotspots around the world may improve data flow to global databases for this species.
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