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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
21 - 40 of 67 results
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Spatial and temporal patterns of R. typus in the tropical fjord Golfo Dulce, Costa Rica
By Robin HannaBackground Many population parameters of the whale shark Rhincodon typus such as growth rate, survival probability and migratory routes are still unknown, but large advances in research have been achieved primarily in areas where predictable aggregations occur. Here, results from the first study on whale sharks in Costa Rica are presented. Research was prompted by anecdotal information on aggregations of 13–55 individuals in Golfo Dulce and was submitted for assessment as part of the author's Master thesis in 2007. Approach From 20 December 2006 to 3 March 2007, a total of 47 interviews were conducted in the vicinity of this tropical fjord, and a previously established sampling transect was followed to search for whale sharks and measure surface salinity and temperature. Equipment for sampling water properties in the event of a sighting was held on the research vessel, but no whale sharks were encountered. Results The maximum number of individuals sighted from 2001–2007 was Nmax=226. To reduce the probability of multiple sightings, a more conservative minimum value (Nmin=190) was calculated from the lowest number of sharks sighted in one observation and the total number of sharks in a month, respectively, and by comparing sizes. Several accounts include juveniles of very small size (2–3.5 m tl). Categorization of sizes and behaviour as well as an approximated position of a sighting enabled the integration of the data in a GIS environment. This system is available in the participating institutions and can be updated with further anecdotal information until more precise research is in place. An illustrated literature review was included to compare global whale shark research efforts with those of Costa Rica. Conclusions This preliminary and unpublished study served to investigate an unknown whale shark habitat and suggests new null hypotheses for further research. Based on the new information made available through this study, management decisions in the area of the Osa peninsula should include the annual presence of Rhincodon typus.
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Whale shark kinship and genetics: Analysis of two populations with different ecologies
Background A recent global study of whale shark population genetics has allowed for better understanding of genetic connections between aggregations in both the Indo-Pacific and Atlantic. This overview included an aggregation found within the Red Sea near Al Lith, Saudi Arabia, however the Mafia Island, Tanzania, aggregation was not part of the study. The ecological behavior of these aggregations differs with the Saudi Arabian individuals showing strong seasonality, while acoustic telemetry data revealed cryptic residency at Mafia Island. Approach Genetic analysis using 11 microsatellite markers was performed on whale sharks from both locations. A combination of primers sourced from previous studies and newly designed primers were used to compare both aggregations and the individuals within. The Red Sea population was compared between 5 seasons spanning 6 years from 2010–2015. The Tanzanian population was compared for 2 field seasons from 2012–2014. Temporal genetic diversity was examined using allelic richness on only the Saudi Arabian individuals due to a short sampling period in Tanzania. Kinship for both aggregations was tested using COLONY and KINALYZER. Results Over a 6 year period, genetic diversity in the Red Sea showed no significant change. Contrasting to other whale shark aggregations, allelic richness in the Red Sea shows no sign of reduction. Kinship analysis using COLONY found two potential sibling pairs in Tanzania. One pair had a high probability (.993) of being a full sibling dyad while the other had a lower probability (.357). There were no sibling pairs identified in the Red Sea. Conclusions The lack of significant change of genetic diversity in Al Lith, Saudi Arabia, differs from a trend at Ningaloo Reef, Australia that showed a decrease in genetic diversity. Although these differences could be driven by location, this should encourage further long term genetic sampling at aggregations to better understand whale shark population trends. The potential of sibling pairs being found within one aggregation warrants further investigation into kinship within and between aggregations throughout the Indo-Pacific.
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Association of adult female whale sharks with open ocean and coastal upwelling frontal systems in the Eastern Tropical Pacific
Authors: Alex R Hearn, Eduardo Espinoza, Jonathan R Green, David Acuña-Marrero and John P RyanBackground Although whale sharks are a mostly solitary pelagic species, most of our knowledge of their ecology is derived from around a dozen coastal feeding sites around the world where mainly immature males aggregate. Darwin Island in the Galapagos Marine Reserve is one of a few oceanic sites around the world where mostly large female whale sharks may be observed on a predictable basis. Since 2011, the Galapagos Whale Shark Project has tracked their movements from Darwin to the Equatorial Front, which is located to the north of the Galapagos Islands, extending zonally over several thousand kilometers, and is most pronounced from July through November. Towards the end of the year, the whale sharks move to the eastern boundary upwelling zone off the shelf break of Ecuador and northern Peru. Approach We placed SPOT-5 tags on 24 whale sharks in 2011 and 16 in 2012 at Darwin Island (Galapagos Marine Reserve) and tracked their seasonal movements west along the Equatorial Front then east to the eastern boundary upwelling off Ecuador and northern Peru. Using satellite data, we extracted sea surface temperature (SST) cross sections for each shark position, meridional for equatorial positions and zonal for eastern boundary positions, to emphasize habitat occupation in terms of thermal gradients relative to the sharks. We analyzed a meridional ship hydrographic section to examine habitat occupation for one shark at the EF in relation to recorded depth preferences. Results The whale sharks occupied a geographical range of 4060 km from east to west, and 2027 km from north to south. Preliminary results show that within this range, the seasonal presence of adult female whale sharks at the Equatorial Front and the eastern boundary upwelling occurs when the frontal zones are fully developed. Whale sharks were consistently located along the warm side of the Equatorial Front, occupying a narrow thermal band on average: 25–25.5 C. The depth profile of one shark in relation to in-situ vertical profiles also supports this. Similarly, they occupied the warm side of the primary coastal upwelling front, on average 21.7 C. Conclusions Although encounters with whale sharks along the coastal waters of Ecuador and Peru suggest that a larger population comprising adults and juveniles of both genders occupies the continental shelf year-round, the seasonal movements through Darwin and the Equatorial Front are mainly carried out by large, adult females. Many of these sharks display distended bellies, suggestive of pregnancy. The Equatorial Front is an important feeding ground for both planktivorous and piscivorous seabirds, while other marine filter feeders such as manta rays and southern ocean sunfish have also been tracked along the Front. We propose that Darwin is a navigational waypoint to this offshore feeding ground, which may also function as an open water pupping area.
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Atmospheric and oceanographic impacts on whale shark (Rhincodon typus) seasonality in the Bay of La Paz, Mexico
Authors: Simon T. Hilbourne, Dení Ramírez Macías and Ken CollinsBackground Whale sharks (Rhincodon typus), a highly migratory filter feeding species, aggregate in the coastal regions of the southern Bay of La Paz, Mexico every year. A growing eco-tourism industry is capitalising on the aggregations, yet very little is known about the drivers of seasonality. This investigation sought to determine the patterns of whale shark seasonality and identify the influence of oceanographic and atmospheric variables on the aggregations. Approach A 12-year (2003–2015) whale shark abundance data series, collected by the Whale Shark Mexico NGO, was analysed using generalised linear mixed effects models and generalised additive mixed models to investigate the influence of oceanographic and atmospheric variables on aggregation abundance. Sea surface temperature, wind, chlorophyll, and Oceanic Nino Index were used to investigate changes in monthly seasonality. In addition to these variables, moon illumination and tidal state were used to investigate fluctuation within seasons from 2012–2014. Results Aggregations of juvenile whale sharks are restricted to the southern-most region of the Bay of La Paz and occur in highest abundance between November and January. Sea surface temperature anomaly in the Bay of La Paz showed a positive effect on whale shark abundance. Oceanic Niño Index, conversely, showed a negative effect, potentially due to the disruption of the wind-driven upwelling corridor along the east coast of the Gulf of California. A thermal preference of ~24°C was seen to significantly increase daily whale shark sightings. Aggregations are thought to be associated with foraging on zooplankton blooms in the bay which may be detected by olfactory cues. Conclusions Effects of El Nino Southern Oscillation (ENSO) events have been associated with a number of changes in species distribution and abundance in the Gulf of California, and whale sharks appear to be no exception. Analysis of Gulf of California-wide oceanographic trends, matched with whale shark satellite tracking programmes, would help further improve the understanding of the drivers and timings of aggregations in the Bay of La Paz.
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Comparison of sex and size range of whale sharks and their sighting behaviour in relation to fishing lift nets in Borneo and Papua, Indonesia
Background The composition of sex and size of a population is important for management and conservation of marine organisms, including high mobility and global species such as the whale shark, Rhincodon typus. The presence of fish in lift nets in some Indonesian waters attracts feeding whale sharks. The objective of our study was to compare the sex, size and behaviour of whale sharks associated with lift nets in Cenderawasih Bay, Papua and Talisayan, East Kalimantan. Approach Data sampling was conducted for 52 days during April'June 2013 in Teluk Cenderawasih National Park, Papua and 60 days during August–October 2015 in Talisayan, East Kalimantan. Daily monitoring was carried out at lift nets located within the study area. Individual identification was conducted with photographic identification, sex determination was done through visual observation of the presence of reproductive organs, and size measurement was done by comparing the shark length with the observer–s height. Analysis of the fish catch was obtained by interviewing fishermen, and observation from the lift net was conducted to support the data. Results A total of 134 observations and 81 observations were recorded in Cenderawasih Bay (57 lift nets) and in Talisayan (43 lift nets), respectively. A total of 37 different whale shark individuals were identified in Cenderawasih Bay, and 30 different individuals were identified in Talisayan. More than 50% of the whale sharks in Cenderawasih Bay, and 80% in Talisayan, had scars on their bodies. In Cenderawasih Bay, scars were spread across the body: 20% of the scars were found on the fins, 20% on the main body including the gills, and 15.6% near the mouth area. In Talisayan, 70.6 % of the scars were found on the fins, 2.9% in the main body including the gills, and 17.6% near the mouth area. The scars result primarily from friction with fishing nets. The whale shark aggregations in Cenderawasih Bay and Talisayan were dominated by juvenile males. From a total of 37 individuals, only one female was found in Cenderawasih Bay, and from a total of 30 individuals, only two females were found in Talisayan. The dominant size of whale sharks in Cenderawasih Bay was in the range from 3–3.9 m total length, with the largest animals in the range of 6–6.9 m. In Talisayan, the dominant size range was 4–4.9 m total length, with the largest animals in the range of 6–6.9 m. The high abundance of smaller fishes that are caught in Cenderawasih Bay and Talisayan by lift nets could attract whale sharks to the area. The largest number of whale sharks seen in Cenderawasih Bay was 14 individuals on May 14th, 2013. The fishery catch in this area fluctuates, with the highest catch being 365 kg on May 9th, 2013. Whale shark activity in Talisayan was lower than Cenderawasih Bay, even with a greater lift net catch. The largest number of whale sharks seen in Talisayan was 8 individuals on August 25th, 2015. The lift net catch in this area also fluctuates, with the highest catch being 5,325 kg on August 25th, 2015. Conclusion The appearance and activity of whale sharks in Cenderawasih Bay and Talisayan have similar characteristics. These aggregations are dominated by males with a size range of 3–6 m, which are still categorized as juveniles. They were often present at the surface, performing feeding behaviours that correlate with lift net activity.
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Habitat conditions and potential food items during the appearance of whale sharks (Rhincodon typus) in Probolinggo waters, Madura Strait, Indonesia
Authors: Mohammad M. Kamal, Yusli Wardiatno and Nenden S. NoviyantiBackground In Probolinggo coastal waters, part of the Madura Strait, the appearance of whale sharks (Rhincodon typus) is a common sight especially during late December to March. The aggregation of these large vertebrates in this area have become highly attractive for local coastal tourism. Yet there has been limited scientific information regarding their population, from which better conservation management might result. The present study partly dealt with an exploration of whale shark habitat conditions at their arrival in this region. Approach Twelve days of whale shark sightings were made on board a wooden fishing boat (8 m length), coupled with weather data based on Beaufort's scale and plankton sampling at the time of shark surfacing. Observations were performed from early morning to late afternoon (7 am to 4 pm). The animals were counted and their length estimated by placing the boat and a whale shark in parallel positions. Zooplankton was sampled by filtering 100 L seawater using a 250 ìm mesh-size plankton net. Site marking was done at each sight using GPS. The combination of primary data and secondary supporting information was combined to understand why whale sharks are present in the area. Results There were 72 individual whale sharks recorded during 12 d of observation, of which 94% appeared between morning to late morning. The highest number of sharks was found on day 6 with 14 individuals. Shark size ranged between 2 – 8 m, with most animals between 3 – 6 m, indicating the population might by dominated by immature individuals. During observation, there was no preferred temperature for whale shark sightings, with temperatures ranging between 28.5 – 30.0°C. Instead, whale shark presence coincided with relatively calm weather (1 – 3 Beauforts' scale). Whale sharks were absent on days 3, 7, and 12, when weather conditions were between 4 – 5 Beauforts' scale. The sharks swim as close as 1 nm to shore, in 5 – 10 m water depths. Among potential food items, there were 5 dominating zooplankton groups, i.e. crustaceans, sagittoideans, urochordatans, hydrozoans, and scyphozoans. In addition, fish eggs and larvae were also found. Regarding crustaceans, the copepods were the dominant group, especially genera Lucifer, Mysis, Sergia, and nauplii larvae forms. Conclusion The aggregation of whale sharks in Madura Strait is likely feeding-based in this area where wind-driven oceanographic conditions cause food to be in high abundance. Research on ID-based population structure of this whale shark aggregation is required.
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A Whale Shark Virtual Reality Underwater Environment
Authors: AbdelGhani Karkar, Osama Halabi and Jihad JaamBackground Virtual Reality (VR) can provide an immersive experience and enables users to live in different worlds. The technology becomes affordable with the recent development in VR technology and the release of many consumers VR Head Mounted Display (HMD). VR provides a unique and efficient way of exploration and learning. The available VR systems, so far, provides seated experience where the user uses gamepad or joystick to navigate and interact. In this work, we are proposing a walking VR immersive experience where the user will be able to walk naturally and interact in the virtual world. This achieved by using cameras to track user movements. As a result, the participant will be able to lively experience the underwater live and be able to have an enjoyable learning space. Approach Recently, we developed a bilingual animal domain knowledge base (ontology) where information are stored in a hierarchical structure based on the classifications of the animals (e.g., mammal, aquatic, etc.). The knowledge base defines the relationship between the classifications (concepts). Each concept can have different properties which describe all viable facts that can be associated with. Each property can have specific settings (e.g., multiplicity, restriction, etc.). For instance, the animal cannot have two different blood types (i.e., this can be restricted using multiplicity). In this work, we propose a VR whale shark educational system that presents whale sharks and diverse kind of aquatic animals. The system extracts informative facts from the knowledge base and attaches them to the generated 3D models. The VR simulation provides the ability to walk in the world by tracking the movements of the user using cameras. The result is fully immersive VR-based simulation. The aim of the proposed system is to improve the educational skills about whale sharks and underwater environment which includes comprehension, realization, and deduction. Results Previous mobile based educational system have been developed and showed significant improvements for learners. The features of the proposed educational system include: 1) presentation of illustrations for natural text, 2) knowledge extraction from an animal domain knowledge base, 3) getting illustrations (i.e., 2D and 3D images) from a multimedia repository; and 4) querying online search engine to get new images. Our ongoing system development includes the development of a VR system for Whale shark and underwater environment. Conclusions The study presents a virtual reality educational system for whale sharks and underwater environment. An animal domain knowledge base will be used to extract semantic information about aquatic animals. The proposed system provides immersive VR with ability to walk and navigate.
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Studying spatial distribution of the whale shark in the Gulf of Tadjora, Djibouti
Authors: Savinien T. R. Leblond and David R. L. RowatBackground The Marine Conservation Society Seychelles, in partnership with Dolphin Excursions and NGOs Decan and Megaptera, have been monitoring the whale shark population off Djibouti during the peak aggregation season since 2006. The first formal scientific study found a substantial aggregation of very small juvenile whale sharks off the Arta coastline and in subsequent years a significant number of photo-identified individuals were resighted and appeared to be preferentially using certain areas. Approach This study explored the spatial utilization of the site during the annual two week monitoring trip in January 2014. Monitoring was done on two surveys each day for two six-day periods. We focused mainly on the known aggregation areas around Arta and Acacia coastlines, with a one-day survey to Ghoubet al Kharab (20 km to the West) each week. A GPS waypoint was recorded for every shark encountered which was identified by the spot pattern using the I3S Photo Identification software. Geographic Information System pattern analyses (Getis Ord Gi* tool, with a 10 m nearest neighbour band) were carried out to assess whether there was any significant clustering or over-dispersion in the spatial distribution of sharks during the morning and afternoon. The encounter data were further analysed using SOCPROG to define movements between the areas and any tendency for individual associations. Results During the two week study, 782 encounters were recorded with 127 individual whale sharks. These sharks were seen along the 3 km of Arta and 4 km of Acacia coastline in the survey area. During the morning 13% of sharks clustered in significant “hot spots' off Acacia and 32% of Arta, while 13% and 1% were found to be over-dispersed in “cold spots' in both Acacia and Arta respectively (95%C.I.). When examining the spatial distribution in the afternoon no significant cold spots areas of overdispersion were found, while 33% of sharks where found in hot spot clusters off Acacia and 28% in Arta (95%C.I.). Morning aggregations at Acacia spanned a length of 3 km along each coast of Acacia and Arta while afternoon aggregations were more compact only spanning 2 km at Acacia and 1.5 km at Arta. Clusters were located up to 500 m off the shore lines in the mornings compared to 200 m in the afternoons. Movement models indicated transitions both between Acacia and Arta and also into and out of the study area. 17 sharks associated with another specific individual 6 or more times (max 46) during the study period with a Coefficient of Variation of 1.23 between sampling periods. A hierarchical cluster analysis defined 6 clusters with a Cophenetic Correlation Coefficient of 0.79. Conclusion The juvenile whale shark aggregation in the Gulf of Tadjora occurs mainly along the coastlines of Acacia and Arta with sharks forming more significant/dense clusters in the afternoons. The hot spots occur over areas of healthy coral reef with many branching and tabulate acropora corals while the cold spots form near the 45 degree rubble slopes with little or no coral cover. The westerly winds in the gulf drive plankton into the coves of Acacia and Arta which accumulate around coral reefs intensifying whale shark feeding behavior in these areas. While associations between individuals were identified between daily sampling periods this was found for only a small number of individuals over a relatively short time period; further studies are needed to see if these associations remain stable over longer periods.
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Update on the use of an open source tri-axial accelerometer tag for monitoring whale shark (Rhincodon typus) behavioral disturbance
Background The rapidly decreasing cost of electronic components has enabled access to better tools for monitoring the behavior of whale sharks on a fine scale never before achieved. We use the new Kinematic tag (Oceans Forward) and the OpenTag (Loggerhead Instruments) as a novel approach to visualizing behavior of whale sharks. Fine scale habitat use and baseline behaviors are fundamental for understanding potential anthropogenic impacts of disturbance. Approach Each tag is an Arduino compatible open-source inertial measurement unit for recording motion sensor data to a solid state memory card. A three dimensional gyroscope, accelerometer and magnetometer allow for calculating pitch, yaw, and heading, while depth and temperature sample continuously. The rechargeable lithium battery allows for deployments up to 14 days sampling at 100 Hz. The Open Tag is placed in a hydrodynamic syntactic foam float, and banded around the dorsal fin. A galvanic release incorporated into the tag allows for a release time to be programmed and a VHF tag (Animal Telemetry Systems) aids in recovery. Trackplot (University of New Hampshire) was used to visualize behavior. Further analysis was conducted using Humu signal processing suite (Humu.io). Results Five tags were successfully deployed in the waters offshore of Cancun, Mexico between 2013 and 2015. Behaviors noted included frequent surface intervals, even during the night when previously believed whale sharks were normally in deeper waters. A maximum depth of 62.2 m was observed, with mean depth of 17.2 m. We were able to identify possible harassment at the surface and visualize possible defecation events. Conclusion Both the k-tag and Open Tags fill a unique niche in whale shark studies as a useful tool to better understanding of fine scale habitat use and behavior. By incorporating these data into Trackplot with data from potentially harassing activities such as vessel traffic, we can visualize behavior and investigate potential erratic changes in depth, heading and lateral movement amplitude indicative of harassment.
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Close genetic relatedness of whale sharks (Rhincodon typus) in the Indo-Pacific region
Background The whale shark (Rhincodon typus) is a prominent species in Cenderawasih Bay. Its recent association with moored lift-net fisheries there has led to an increase in tourism that facilitates encounters for human snorkelers and SCUBA divers with the sharks. This association has also supported opportunities for research to discover various elements of their biology, ecology, movements and genetics. An understanding of the genetic composition of the sharks in Cenderawasih Bay and their relationships with whale sharks elsewhere in the Indian Ocean and Western Pacific Ocean is important for their conservation and to help design marine protected areas. Approach Skin samples from whale sharks in Cenderawasih Bay were collected with modified hog ear notch pliers and small biopsy tips. The samples were preserved in 96% ethanol and stored at 4°C in the laboratory until DNA extraction. The DNA template was amplified for the cytochrome oxidase I (COI) gene. The nucleotide composition and genetic diversity (polymorphisms, haplotypes, and nucleotides) were analyzed. The results from whale sharks in Cenderawasih Bay were compared with those available in Genbank for nearby areas of the Indian and Western Pacific oceans with the neighbor-joining method. Evolutionary distances and haplotype networks were calculated. Results Seven haplotypes were detected among the 31 whale sharks sampled in Cenderawasih Bay, for a haplotype diversity (Hd) of 0.1871 (variance = 0.00859, s.d. = 0.093). The nucleotide diversity (Φ) was 0.00244 (±0.0013) and the values for theta were 0.75094 per shark and 0.00722 per site. The neighbour-joining tree for individual whale sharks from Cenderawasih Bay and other regions appeared to be closely related to each other. They also appeared to be closely related to whale sharks sampled elsewhere in the Indian and Western Pacific oceans (Chi-square, Chi2: 3.620, df: 5, p: 0.605). Haplotype one has highest frequency (37 individuals), one haplotype has two individuals, and six other haplotypes each have one individual. The three last haplotypes have just one individual, respectively. The whale sharks that we sampled in Cenderawasih Bay had low genetic diversity (haplotype, nucleotide and polymorphic). Conclusion 31 whale sharks in Cenderawasih Bay were very closely related, and these sharks were closely related to whale sharks elsewhere in the Indian and Western Pacific oceans. The extent of movements among reproductive sharks in this large region is unknown as is the frequency and magnitude of mating among sharks from these different areas. Further research is needed to monitor the long-term movements of sharks within and among regions, particularly reproductively mature males and females, to help design conservation plans for whale sharks and the habitats that they might depend on for feeding andreproducing.
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Unveiling a new foraging area for the threatened whale shark
Background Whale sharks usually form aggregations by gender and age in many nearshore waters, but they can be as well solitary wanderers. In the Eastern Pacific, there are regular sightings of whale sharks in the Gulf of California and the Galapagos Islands. Tracking studies indicated movement of individuals from Galapagos to the edge of the continental shelf off northern Peru. Although the presence of whale sharks off the Peruvian coast has been reported since 1955, no proper research has been conducted so far. Therefore, there is a critical information gap on their biology, ecology and population status, fundamental information to plan local and international conservation actions. In Peru, no direct fishing occurs, but incidental captures had been reported and many individuals retained. In spite of being a member of international conventions, Peru does not have any local or national protection laws for whale sharks. We started a program; the first one conducted in Peru, to generate knowledge about whale sharks in the region. Approach Our monitoring program includes two components: interviews and boat surveys. Interviews were conducted with fishermen, on-board observers, captains and diving companies in fishing ports located in northern Peru. Interviews included questions about whale shark presence, their behavior, body metrics, dates, times and areas of sightings, as well as an explanation with images for the correct identification of species. Boat surveys for whale shark sightings were planned based on the interview information. During each survey, we recorded whale shark biological data like size, gender, behavior, scars, geo-position, date, time, besides water temperature. Pictures taken were compared with the database from Mexico and submitted to the Wildbook of Whale Sharks. Results We conducted 185 interviews that provided information on 272 whale shark observations. Interviews suggest that there are two marked seasons for whale shark aggregations in Peru, one in the austral summer and one in the spring, with the highest densities observed in the summer. The whale sharks were seen mostly as solitary animals, and within 50 miles off the coast. The individual size was estimated between 10 and 49 feet. The juveniles showed a mode of 16 feet and most of them were observed while feeding. Adults (>29 feet) were usually seen in the open ocean with a size mode of 32 feet. From October 2014 to March 2015 we conducted 17 boat surveys. Four more were conducted in the summer 2015–2016. Surveys resulted in twelve whale shark encounters, ten of which were observed while feeding, half as solitary animals and the rest in groups. The size of these sharks was estimated between 13 and 17 feet, which classifies them as juvenile sharks. The twelve observations resulted in ten unique individuals without a match in any of the photoID databases. From this, we were only able to determine the gender of eight of them resulting in 100% males. Conclusions Interviews and boat surveys indicate a prevalent presence of whale sharks in Peru, which is influenced by seasons. Individuals are more common during the austral spring and summer. There seems to be spatial segregation with larger whale sharks, likely adults, seen in the open ocean, while juveniles are seen closer to the coast. The northern coast of Peru seems to be used by juvenile males during the summer for feeding purposes in shallow waters. Our study has photo-identified ten new individual whale sharks for the Eastern Pacific. This represents a unique opportunity to conduct more research in the region to elucidate connectivity with other areas and to involve stakeholders in future whale shark management and conservation.
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Body measurements and size estimation of whale sharks in Okinawa Churaumi Aquarium
Authors: Rui Matsumoto and Keiichi SatoBackground Okinawa Churaumi Aquarium (formerly Okinawa Expo Aquarium) has been conducting research on the whale shark, both in captivity and in the wild since 1975. Proportional measurements, including total length, girth, and weight, are essential to examine the growth, maturity, and physical condition of the animal, as well as to estimate the required quantity of food and drug dose for medical treatment. However, measurement of the precise length of large aquatic animals is very difficult and often results in errors. We formulated an allometric equation used to estimate the total length (TL) and body weight (BW) by measuring appropriate smaller body parts. Approach We used morphometric data from 33 individuals stranded or accidentally caught by commercial fishery off Okinawa Island between 1979 and 2010. We examined 66 measured characters of each whale shark. Furthermore, we applied the conventional allometric function, and modified the function to be logarithmic to use a liner approximation. The reduced major axis (RMA) test was applied to all logarithmic morphometric data, and we chose to measure characters that were highly correlated with TL. Some of the characters showing high correlation with TL according to the RMA test were further analyzed for sex-based differences using the t-test. The most suitable morphometric characters that were measurable in free-swimming sharks were chosen from the set of characters that passed those tests. In addition, we analyzed weight data from 8 specimens (7 male and 1 female) that were considered to be in an almost normal condition. We applied the conventional allometric function to an estimation equation. Girth measurement at the posterior margin of the pectoral fins was directly performed on the free-swimming individuals. Results A high coefficient of determination (R2) was obtained for 8 morphometric characters: pre-first dorsal length (PD1), pre-second dorsal length (PD2), pre-caudal length (PRC), pre-pelvic length (PP2), pre-anal length (PAL), length of dorsal caudal margin (CDM), mouth width (MOW), and interorbital space (INO). We considered that the equation formulated using PD1 was the most suitable based on sex-based differences and the animal's swimming properties. The following equation estimates the TL in centimeters:
log TL = 0.964 log PD1 + 0.443 (R2 = 0.930, n = 33)
For BW estimation, the sex-based differences could not be tested because of the small sample size. The following equation estimates BW in kilograms:
BW = 4.510 TL3.280 (R2 = 0.958, n = 8)
The data of girth measurements was collected from captive (n = 3) and wild (n = 6) sharks. Conclusions Data on proportional measurements is useful as an index of growth condition. Our focus is to monitor the size of our females and track the physiological indicators of maturation to achieve the first captive reproduction of whale sharks.
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Will the world's biggest fish get any bigger? Limits to the size of filter-feeding fishes over the last 160 million years
More LessBackground Many taxa of marine animals have increased in size through time, with some of the largest that have ever existed being vertebrate filter-feeders targeting plankton. Present day ecological studies show that the size and body structure of whale sharks is likely to reflect a strategy for gigantothermy that conserves heat while foraging in cool deep waters. However, the temperature of the oceans has changed through time, as has the composition of the guild of large, filterfeeding fishes. What do these changes reveal about the evolution and ecology of whale sharks? Approach I synthesise the results of new analyses of the fossils of filter-feeding fishes that were the largest representatives of their guild over the last 160 million years with ecological studies of whale sharks and filter-feeding whales. This analysis offers an opportunity to examine the evolutionary forces that have shaped the biology of whale sharks. Results Throughout time, bony fishes, sharks and whales that were obligate ram filter-feeders attained similar maximum lengths of around 16–20 m and in the case of the whale shark, body masses equal to, or even greater than, many baleen whales today. This shows that ecological niche and mode of feeding are more important drivers of limits to the body size of fishes than phylogeny. Conclusions The relatively small variation in maximum sizes of the largest ram filter-feeders over the last 165 million years suggests that animals within this guild will not continue to increase insize through evolutionary time, but have already attained sizes constrained by their environment and mode of feeding.
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Democratic tourism service directory maps to help the whale shark
Authors: Frederick D. Michna, Bradley D. Santos and Bradley M. NormanBackground Through travel, people discover whale sharks. They also come to know about the problem of the animals safety. Different things may be more or less strong at hurting or helping the sharks. Tourism may move other things that hurt sharks more than tourism away. Not all tourism is the same. Some tourism hurts sharks more. Not all places with sharks are the same. Some places are safer. A tourism service directory map gathers some services that help travellers. It shows different services for different things that different people may want to do. It can gather only the best services. It can show people the best services for their money and other needs. Good tourism helps sharks most where it is least safe for them. A service directory may show those services because they help the least safe sharks. If no services are where sharks are not safe, the directory can help make new services by sending travellers or giving help. If a bad thing happens to the people who give services at a place then the directory may help by sending more people to those services or giving help. People who run the directory must choose which services are good or in need. They must choose which places are safe and not safe for whale sharks. They must choose what services to show other people. Approach We look at two approaches that explain helping the whale shark with a tourism service directory. The first approach is ‘citizen participation’. All people who use the directory are its citizens. They participate by:
- Letting it help them chose services
- Learning about the whale shark and how services hurt or help them
- Knowing about this when they decide which services to use
- Gathering information about the whale shark and the things that hurt or help them when they use services,
- Asking other people to join the service directory
- Deciding which services the directory should help create to help the whale shark
- Deciding which services the directory should help when bad things hurt the people who make the services
- Deciding which tourism services are not good and should not be in the directory.
- A larger law that all other controls must follow. This helps stop the controls going too far and hurting people who serve the whale shark. It is the constitution and design stage.
- Laws of how the service directory is controlled. Where tourists and money should be put. People who create these laws should work for the good of the worst off sharks and people and not their own reasons. This is the legislation and development stage.
- People who decide on whether each service should be in the directory, whether it should be created or helped. They should act as though they are the law and are answerable to the laws of the directory. This is the enacting stage.
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Tourist satisfaction with whale shark watching and swimming tours in the Mexican Caribbean
More LessBackground In the Mexican Caribbean, tourism around the whale shark has become one of the most important sources of income for the local communities. It was estimated that during 2014 more than 100,000 tourists went on whale shark watching and swimming tours. In addition, the proximity of the tourist corridor of the Riviera Maya could further increase whale shark tourism. The vulnerability of the specie and the increased volume of tourism could become an ecological and economic problem for sustainable management of the whale shark in this region. Approach In 2014 and 2015, from June to August, a survey formed by 20 closed, reflective questions, and a Likert scale section, was applied to obtain information about perception and satisfaction of tourists during the whale shark watching and swimming activity. Questionnaires were applied to tourists who took the whale shark tour in Holbox-Chiquilá and Isla Mujeres-Cancun, in Mexico. The application method was direct, pollsters asked participants at the arrival docks about their experience during the whale shark tour. Results A total of 486 surveys were applied, and the presence of tourists from 31 different nations was recorded. The mean age was 35 years old, with a mode 27 years old (range: 9–71). From the total of tourists surveyed, 61.5% mentioned that they visited the localities solely for swimming with whale sharks. 37.7% of respondents mentioned that they had received information about the whale shark tour by person to person or word of mouth, while 30.9% did so by media, mainly Internet. It should be mentioned that 30.7% of users said they had not received information about the rules for the development of the activity, and of those who received it, 43.9% did so after boarding the boat. In our results, 70% of people qualified the experience as excellent, however, some factors that could influence public satisfaction were identified. First, 68.5% of tourists reported having seen many whale sharks, indicating values between 20 and 50 individuals. The care provided aboard the boat was another important factor for the tourist, and 72% of respondents qualified it from good to excellent, compared with the treatment received at the point of sale, where only 57% considered it as good. On the other hand, 46.7% of the tourists said that there were many boats when they participated in the swimming and watching activity, observing between 30 and 59 boats. Finally, 45.2% of respondents felt that there were only a few people who swam at the same time with a single whale shark, while 24.6% said it was many or too many people, noting up to 30 swimmers at the same time. Conclusions This activity has an “innate” guarantee: seeing an animal of this size in the wild, however, there are several factors that could affect the user experience. The presence of a large number of vessels and/or swimmers may decrease the quality of service, resulting in some level of discomfort and dissatisfaction, and consequently cause the participant to be less likely to recommend or repeat the activity. Management strategies must be designed to promote successful experiences for the visitors without altering the natural conditions around which they are developed.
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Distribution, abundance and mortality of whale sharks (Rhincodon typus) in coastal and offshore waters of Pakistan (Northern Arabian Sea): Review of a ten year study with information on the successful release of whale sharks entangled in fishing gear
Authors: Muhammad Moazzam, Hamid B. Osmany, Rab Nawaz and Saba AyubBackground Whale sharks are frequently found in the coastal and offshore waters of Pakistan, however, no information on whale shark distribution (seasonal and spatial) was available from this area. Approach A study to investigate the interaction of whale sharks with commercial fisheries gear was initiated. Data on various parameters of dead and live animals observed during 2005 through December 2014 was collected from the coastal and offshore waters of Pakistan. Additionally fishermen were trained to release entangled whale sharks from the fishing gears. Results Whale sharks are commonly found throughout the year all along the coast of Pakistan, however, the area between Ras Malan and Churna Island and the offshore Indus Delta (between Khajar and off Ghora Bari) seem to be two main hotspots for whale sharks. Sharks were mainly abundant during May to June and October to December. Newborn pups were observed during October and November, whereas juveniles were seen during December through March. Data about morphometry and other parameters was collected from a total of 76 dead specimens which were landed mainly at the Karachi Fish Harbour since 2005. In addition, information from 24 live specimens was recorded between 2013 and 2015. It was observed that the main cause of mortality of whale sharks in Pakistan is their entanglement in gillnet fishing gear deployed in coastal and neritic waters. In addition, a few specimens died from entrapment in trawl nets, but very rarely in line gears. In order to conserve the population of whale sharks in Pakistan an awareness programme was started, and fishermen were trained to safely release entangled whale sharks. Through this initiative, a total of 17 whale sharks were safely released from gillnets between October 2013 and December 2015. Conclusion Whale sharks are found throughout the year along the Pakistan coast. They are facing serious threats from fishing operations. Among these, gillnets are the main gear responsible for shark mortality. Through an awareness programme and training, 17 entangled whale sharks were released by fishermen in a span of 27 months.
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Understanding constellations: The use of ‘citizen science’ to elucidate the global biology of a threatened marine mega-vertebrate
Authors: Bradley M. Norman, Jason A. Holmberg, Zaven Arzoumanian, Samantha Reynolds, Rory P. Wilson, Adrian C. Gleiss, Dani Rob, Simon Pierce, Rafael de la Parra, Beatriz Galvan, Deni Ramirez-Macias, David Robinson, Steve Fox, Rachel Graham, David Rowat, Matthew Potenski, Marie Levine, Jennifer A. McKinney, Eric Hoffmayer, Alistair Dove, Robert Hueter, Alessandro Ponzo, Gonzalo Araujo, Elson Aca, David David, Richard Rees, Alan Duncan, Christoph A. Rohner, Alex Hearn, David Acuna, Michael L. Berumen, Abraham Vázquez, Jonathan Green, Steffen S. Bach, Jennifer V. Schmidt and David L. MorganBackground Gathering data on the life of enigmatic animals remains a challenge, despite its important role in biodiversity conservation and management. For many species, biogeographic investigations are largely the result of information that is generated from multiple sources, often over long time-scales, because measuring biogeographic and biological data over large geographic areas is simply not feasible by a single team of researchers. But in the current age of a well-educated public and accessible and mobile digital technology, scientists are now able to harness the observations of many, thus infinitely increasing their power of observation. Despite its status as the world's largest fish, there remains a paucity of information on the biology and ecology of whale sharks (Rhincodon typus). This species is however a prime target for ‘citizen science’ monitoring because of its charismatic nature, presence at many coastal aggregation sites and the growth of ecotourism around this species. Approach Information on whale shark sightings worldwide can be gathered by various stakeholders and stored in the Wildbook for Whale Sharks (www.whaleshark.org) database. Whale shark identification images are collected when a swimmer photographs the individual's unique spot pattern immediately behind the gill slits, which is distinct and long-lasting, and this image (with associated sighting data and information on shark size and sex) is then submitted to the online database. Computer-assisted scanning technology is then employed to determine whether the individual whale shark in question is a ‘new’ shark or a ‘resight’ of a previously reported whale shark within the database. Wildbook can then be queried to gain insights on various aspects of whale shark biology and ecology from data available at the various global hotspots. Results Members of the public and researchers alike contributed in this collaborative citizen science project enabling (as of 31 December 2014) almost 30000 whale shark encounter reports, comprising 6300+ individuals from 54 countries, to be identified. The number of recognized global aggregation sites (constellations) has increased from 13 to 20. The majority of these (14 out of 20) show a marked sex-ratio bias towards males (>66%). Site fidelity is relatively high, with an overall mean percentage of sharks returning to the 20 hotspots in two or more years of 35.7% (to a maximum of 21 years). Despite photo-identification revealing movements of sharks between a number of neighbouring countries/regions, there are no records confirming large, ocean basin-scale migrations. Strong seasonality in sightings is evident at many locations, suggesting that in general, that these aggregations are frequently exploiting known coastal feeding opportunities. Conclusions This study demonstrates the utility of citizen science in amassing large datasets and their utility in elucidating key aspects of whale shark life-history and demographics.
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Are we losing the battle to save the biggest fish in the sea – and can we turn it around?
More LessBackground Prior to 1999, the conservation status of the biggest fish in the sea was listed by the World Conservation Union (IUCN) as ‘Indeterminate – Data Deficient’ in its Red List of Threatened Species publication. A Species Report was commissioned in 1999 and the Whale Shark's status was subsequently upgraded to ‘Vulnerable’ in 2000. Much attention has been afforded this species since 2000, with various protective measures implemented at the local, national and international scale. But has it had any effect? Approach Literature Review and discussions with stakeholders from across the globe was used to investigate the current state of play. A recent updated IUCN Red List Report was also consulted. Areas of concern are highlighted and suggested ways forward discussed. Results Whale Sharks are listed under many international conventions e.g. the United Nations Convention on the Law of the Sea (UNCLOS); the Bonn Convention for the Conservation of Migratory Species of Wild Animals (CMS); the Convention on International Trade in Endangered Species (CITES). There is however little evidence of actions under these Conventions. The Whale Shark is known to occur in the waters of more than 100 countries – yet it receives protection in less than 50% of these. One country that lists protection for this species is China – the location of the largest active commercial whale shark fishery. Yet enforcement of existing laws is lacking. A review of the conservation status for the Whale Shark was undertaken in 2015 resulting in no change to its ‘Vulnerable’ assessment in the IUCN's 2016 Red List. The main threats are fisheries catches, bycatch in nets, vessel strikes, whale shark tourism, marine pollution, and the inability for implementation/actions under current laws and Conventions. Conclusions Where are we failing – and what needs to be done? For a start, we need better information, starting with regional and global population assessments to establish population trends globally (at present ‘unknown’ in the latest Red List Assessment). We need improved monitoring of threats and the means to implement adjustments as required (including tourism activities) to minimise impacts. We must have an increased level of data sharing: greater collaboration between researchers, especially to maximise the use of limited available resources to achieve tangible outcomes (which can then be reviewed by relevant authorities when implementing conservation measures). And then an increased level of public education on a local, national and global scale – to help minimise threats (esp. fin trade/habitat destruction e.g. various marine industries; development etc.). Perhaps consumer-driven pressure to make it unviable for stocking/sourcing of whale shark products? And then could it be possible to have a fisheries quota – and benefit the global conservation of this species? Discussions need to be had.
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Fine-scale behaviour of whale sharks off Mafia Island, Tanzania
Background Mafia Island off the Tanzanian coast features a year-round resident whale shark population. Many of the sharks are seen regularly, making this a great natural laboratory to study their behaviour in detail. At the same time, whale sharks here also face threats locally from net entanglement and boat strike. We therefore set out to determine their fine-scale behaviour using novel telemetry methods in order to establish a profound baseline. Approach We conducted field work at Mafia Island from November–December 2015 and used 3D tags (Open Tags) and satellite tags (Desert Star SeaTagMODs) to examine whale shark behaviour. 3D tags recorded depth, temperature, acceleration as well as gyrometer and magnetometer readings at 200 data points per second. Satellite tags recorded depth, temperature, acceleration and geolocation. We attached 3D behavioural tags to the first dorsal fin using a padded clamp, and double-tagged some of the sharks with satellite tags attached with a titanium dart anchor and short tether. We manually retrieved both types of tags. A total of 117 hours of 3D tag data and 53 days of satellite tag data were recorded. Data were analysed in R. Results The attachment method using a padded clamp kept the tags in a stable position throughout their deployment period, although minor scarring of the fin was evident. We suggest some further improvements to the clamp to reduce scarring. Preliminary dive depth analysis of 3D tag data indicates that whale sharks largely stayed in shallow water, with an average swimming depth of just 4.7 m, SE: ± 0.008. The sharks also spent 10.4 hours, SD: ± 2.2 or 44.4% of the day swimming near or at the surface (depth < 2 m), indicating extensive surface feeding behaviour or surface swimming. We will clarify which behaviours were exhibited following further analysis of acceleration and gyrometer data. A simple one-way ANOVA revealed a significant difference between dive depth during the day and night (p < 0.005). During daytime, the deepest dive was to 18.8 m, with an overall mean depth of 3 m ± 0.007. The deepest recorded dive (29.8 m) occurred at night. Mean dive depth at night was two times higher, at 6.4 m ± 0.012. Time spent above 2 m was twofold higher during the day with 6.9 h ± 1.9 than at night with 3.5 h ± 1.2, indicating that a diel behavioural shift occurred. Conclusion 3D telemetry is an emerging technique that provides unprecedented insight into whale shark behaviour. Here, we show some initial results that indicate the potential applications for this technology. We will continue analysing gyrometer and acceleration data that allow us to further distinguish and quantify behaviours, such as feeding and search behaviour.
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Solving the whale shark mystery: How do we save the fish we can't find?
More LessBackground Whale sharks have received significant research attention in recent years, yet key questions on their biology and ecology remain unanswered. This continues to hamper the conservation assessment of the species. The critical mass of whale shark researchers at IWSC4 presents an opportunity to collaboratively develop strategic research initiatives to close these knowledge gaps. Approach Thispresentation is intended to promote discussion, and eventual consensus, on key research questions and approaches. Accompanying this presentation will be a discussion document. My aim is to publish a multi-author manuscript outlining a framework for achieving medium-term (the next five years, to 2020) applied research objectives for whale sharks. Results Mykey questions are: (1) How many whale sharks are there? Movement models applied at single sites consistently point to transience, with a degree of site fidelity in some individuals. Some mark-recapture models are better-suited than others to modelling this reality. A more existential challenge is that, at most aggregations, we are disproportionately sampling juvenile male sharks. We need to understand habitat use of other life stages and incorporate them into population models. (2) Are regional populations present? Two major genetic subpopulations exist, in the Atlantic and Indo-Pacific, respectively. Further genetic/genomic studies, along with the expansion of photo-ID studies and medium- to long-term electronic tag deployments, will be vital in clarifying smaller-scale divisions. Biochemical studies are also showing promise. This work is vital, as the human threat profile differs between regions. (3) Are regional populations, if they exist, increasing or decreasing? Whale sharks are highly mobile. Even studies that have attempted to control for biophysical variation, such as in Mozambique, have documented declines in sightings that are steeper than can be explained by known human pressures. On the other hand, in at least some areas where whale shark sightings are on the increase, such as in the Azores, changes in the long-term ocean climate is a likely contributor. An improvement in our ability to relate local sighting trends to broader abundance is necessary. More data on whale shark demographic parameters, such as age at maturity and reproductive periodicity, are also required to understand the potential timeframe for recovery. (4) How can human impacts be mitigated? Some clear threats to large whale shark aggregations remain, such as the active whale shark fishery in southern China, ship strikes off the Quintana Roo coast in Mexico and in the Arabian Gulf, and the inadequate management of purse-seine bycatch. These examples, and others, require specific examination. (5) What is the best overall strategy for ensuring population recovery? Broadly, large juvenile and adult females are the most important individuals to the species' rebound potential. Identifying human threats to these life stages, and mitigating them, will be the most efficient means of reversing population decline. Regionally, identifying high-priority threats (i.e. the most significant impact on the largest number of sharks) will help with the development of practical mitigation strategies. Conclusions Effectivemanagement requires good data. I hope that the discussions we start at IWSC4 will go a long way towards aligning our regional research objectives towards answering these global questions in the shortest possible timeframe.
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