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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
41 - 60 of 67 results
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Inter-annual feeding ecology of resident whale sharks from Mafia Island, Tanzania
Authors: Clare E.M. Prebble, Christoph A. Rohner, Simon J. Pierce and C. TruemanBackground Mostdirectobservations of whale sharks occur at coastal feeding aggregation sites. The dominant food source in a feeding aggregation can often be quickly identified. However, there is a risk that short-term studies provide an unrepresentative snapshot of the sharks' long-term diet. Stable isotope analysis enables researchers to examine time-integrated results. Whale sharks at Mafia Island show a high degree of site fidelity. This provides a rare opportunity to study consistency, and changes over time, in individual trophic level and diet over a multi-year timescale. Approach Skinbiopsies were collected from free-swimming whale sharks between October 2011 and December 2014. Each shark was individually identified, sexed, and had their length estimated visually and/or with laser photogrammetry. Surface plankton was collected to measure the baseline isotopic signal. Additional samples from other local species from varying trophic levels were taken, including other planktivorous fishes, jellyfish, and piscivorous fishes. Targeted hand tows of the dominant food source in season, the sergestid shrimp Lucifer hanseni, were collected to investigate the longer term importance of this food source. The stable isotope composition of carbon and nitrogen were determined for all samples. Results Wewill be presenting preliminary results from this study. Throughout the sampling period we collected 223 skin biopsies from 79 individual sharks, 75% of which were male. Total lengths of all sampled sharks ranged from 4.5 to 8 m. One hundred and seventy two samples of zooplankton and other local species were collected. Overall there were no highly significant effects of the year of sampling of the sharks on δC13 (ANOVA p = 0.041) or δN15 (p > 0.05). Mean whale shark δN15 value (9.3 ± 0.07%) was similar to the other local planktivorous fishes sampled (Rastrelliger.k 10.79 ± 0.33%, and Hemiramphus sp. 10.84 ± 0.42%). There was considerable overlap of points in the δC13~δN15 biplot. The δC13 values of the sharks (–17.04 ± 0.07%) were, however, more enriched than the L. hanseni dominated surface zooplankton prey (–26.9 ± 0.38%). Whale sharks exhibited a wide range in δC13 values (–19.62 to 14.68%), and δN15 values (7.29 – 11.64%). Conclusions Thenumber of individuals sampled represents 60% of the identified population at Mafia Island, and as such this provides a unique opportunity to assess diet across a broad spectrum of the sharks that are routinely present. Initial results suggest no significant differences in feeding preference of the sharks over the three year study period. The broad range of both δC13 and δN15 is wider than seasonal changes reported in other elasmobranchs, so likely represents varied individual diets. The sharks appear to be feeding at the same trophic level as the other planktivorous fishes within this ecosystem. We will support these results by calculating an estimate of the trophic position of the sharks. The proximity and overlap of the whale shark isotope results compared to local planktivores suggests a high level of residency over the study period, which is further supported by photo-ID and acoustic telemetry. To corroborate this result we will be calculating the isotopic niche width using Bayesian ellipses framework in the SIBER package in R. Though the sharks may be highly resident, the enriched δC13 values of the sharks with respect to the surface zooplankton suggests they also have a more benthic or mesopelagic food source in their diet along with the seasonally abundant L. hansenii.
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An assessment of the past and present distribution status of the whale shark (Rhincodon typus)along the west coast of India
Authors: P.V.R. Premjothi, B.C. Choudury, Rahul Kaul, S. Subburaman, Manoj Matwal, Diresh Joshi, Jose Louise and Vivek MenonBackground Tounderstand the historical and present occurrence and distribution patterns of whale sharks along the west coast of India in the Arabian Sea, Traditional Ecological Knowledge (TEK) and Indigenous Technical Knowledge (ITK) questionnaire surveys were conducted during May 2012 to March 2013. The surveys were conducted in the maritime states of Maharashtra, Goa, Karnataka, Kerala and the union territory of Lakshadweep. Approach Thesurvey was targeted at active and non-active fisher-folk between the ages of 25 and 90 years to obtain information on historical and current presence of whale sharks in fishing territories across the West Coast. Results Atotal of 1703 fisher folk in 118 fishing villages were interviewed using an improvised structured questionnaire developed from the standard TEK and ITK questionnaires. Over 60% of the interviewed fishers reported having sighted whale sharks in the Arabian Sea along the west coast during their fishing activities 20–100 km from the shoreline. Sightings were most frequent in the Lakshadweep Sea followed by the coastal waters of Maharashtra, Karnataka and Goa. Four major whale shark aggregation locations in the Arabian Sea were identified: close to the coast of Malvan in the Sindhudurg district of Maharashtra, Netrani Island in Uttar Kannada of Karnataka, Minicoy and Kavaratti Island in Lakshadweep and along the Saurashtra coast of Gujarat. The whale shark aggregation locations that were identified as a result of this study were found to overlap with key marine resource productivity areas, such as paste shrimp (Acetes sp.) abundance zones. The incidental capture of whale sharks in fishery operations over the last few years were notably high along the Kerala coast followed by Maharashtra. The mean number of respondents (in each village) who had caught whale sharks using gill nets were significantly higher (Kruskal-Wallis x2 218.56, df 2, p <0.05) than the mean number of respondents (in each village) who had caught the species using either purse-seine or trawl nets. Conclusions Thesurvey results indicate a lack of awareness amongst the fishing community of the whale shark being a protected species and the ban on their capture and trade; it emphasizes the need tolaunch an intensive awareness campaign along the west coast of India. The respondents also mentioned that the most common human induced threats to the whale sharks are incidental catch in gill net, purse seine and trawl.
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New records of neonatal whale sharks (Rhincodon typus) from the Arabian Sea and discovery of a possible natal ground on the Gujarat coast, India
Background To overcome the issue of accidental mortality in fishing nets, the Government of Gujarat started promoting the release of entangled whale sharks by providing adequate compensation for the gear loss incurred by the fishers during the release. The attempt to save entangled whale sharks was a great success. However, constant follow up and rescue information collection from the fishers was essential to monitor the rate of entanglement and release. The current reporting of neonatal whale sharks from the Indian coast was the result of these interactions with fishers. Approach Youngwhale sharks are rarely seen, with only 14 encounters with neonatal whale sharks reported in the scientific literature. The project sociologist is in constant touch with the fishers and collects all the information about whale shark sightings and rescue. The importance of recording the size class of whale sharks was detailed to the fishers. Results Atotal of four whale shark pups (size range 60–100 cm) were recorded during 2013. Interviews with the fishers of Sutrapada fishing village in Gujarat revealed that they found a whale shark pup entangled in a fishing net on 5th March 2013, exactly 10 km offshore of the Sutrapada headland. The length of the pup was approximately 60 cm. The second report is from 15th March 2013, approximately 10 km offshore of the Sutrapada headland. Fishermen from Sutrapada fishing village found the pup whale shark entangled in a gill net and released it. The fishermen recorded the entire event using a mobile telephone. Ocular estimation of the size of whale shark pup from the provided video by comparing with a fisherman's palm was approximately 60 cm. While intervening the fishers during the monsoon fishing ban along the Saurashtra coast (June–July), we came to know that the fishers saw one dead whale shark pup beached near the Sutrapada fishing village on 6th April, 2013. According to the fishers, the sighting of dead whale shark pups is not a common incident and it might be the first incident where fishermen come across a dead whale shark pup. The size of the pup was nearly 100 cm. The pup was found near the rocky shores of the beach and fishermen observed some scars over the head and second dorsal fin. Fishers also reported a whale shark pup swimming on the water surface 20 km off Sutrapada coast. Conclusions Neonatalwhale sharks are thought to have limited swimming abilities compared to juveniles and adults. Thus the new records of pups of size range 60–100 cm indicate that this region is a pupping ground for whale sharks.
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Mapping the path of the biggest fish: The whale shark from the Mexican Pacific side
Authors: Dení Ramírez-Macías, Abraham Vázquez-Haikini, Victor Luja, Ricardo Murillo and Roberto MataBackground Monitoring of animal populations is critical for proper management. To have a better understanding of the population dynamics and migratory pattern of the whale shark, data is required from locations close to key aggregation sites where hypothesized connections can be validated. Photo-ID is an effective marker for capture-mark-recapture studies. Underwater photographs of sharks, combined with photo-comparison software, are used to identify re-sighted sharks, which, in turn, contribute to estimations of population size, age structure, sex ratio, site fidelity, trends in abundance, and movement patterns Approach Since 2003 we have established and maintained a photographic identification research program in the Gulf of California, at Los Angeles Bay (LAB), La Paz Bay (LPB), Espiritu Santo Island (ESI) and Los Cabos (LC), and since 2010 at the Archipelago of Revillagigedo (AR, at the Mexican Pacific). Recently, we included Nayarit (Na, in the Mexican Pacific) to the study area, San Luis Gonzaga (SLG) and Coyote Bay (CB, Gulf of California) in order to address if connectivity exists in this region. Results The whale sharks appear to segregate by size. In coastal waters of LAB (n=501), LPB (n=380), SLG (n=51), Na (n=36), and CB (n=16) aggregations are exclusively juvenile sharks (<8 m). In the oceanic waters of ESI (n=20) and LC (32), pregnant adult females (>9 m) aggregate. At AR (n=11) both pregnant females and juveniles exist but are separated by time. From 2003 to 2014 we have identified 898 sharks over the course of the study; of these 841 were juveniles and 57 were adults, mainly pregnant females. Photo-identification showed the movements of 133 juvenile sharks between LAB, LPB, SLG, Na and CB and movement of 2 pregnant females between LC and AR. We found high levels of fidelity in the juveniles. For example in LPB up to 61% of the juveniles have been re-sighted between years. In contrast only one pregnant female has been re-sighted at the same locality after 7 years. Conclusions This study demonstrated the importance of a collaborative effort to have a better understanding of the population on a regional level. The connectivity data showed the necessity to generate a regional conservation strategy; of the eight localities where we study these gentle giants, currently three are protected, the other four require protection.
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Key elements for managing whale shark tourism in the Gulf of California
Authors: Dení Ramírez-Macías and Georgina SaadBackground There's no doubt that swimming with whale sharks is a fabulous experience. It's interesting, however, how our perception of sharks has changed and now swimming with the biggest shark can connect us to our oceans. Looking into the future, no one could have expected that this activity would contribute to local economies, like in La Paz Bay. In the late 90's you could see whale sharks around La Paz Bay on route to one of the popular islands in the area. By the 2000's some people started providing trips, offering the experience of swimming with the biggest fish on Earth. Problems occurred as a result of increased boat traffic coupled with a lack of guidelines to perform the activity. La Paz city is one of the most highly populated coastal areas in the Gulf of California and has the highest growth rate (2.6%) in the state. Whale shark tourism has also increased, from 26 authorized boats in 2006 to 109 in 2013. In contrast, the mean of the yearly abundance of sharks is 56, highlighting a capacity building issue. This is evidence that the whale sharks represent an important part of the economy of the city, and presents us with a challenge to protect it. Approach InLa Paz Bay we have maintained a whale shark monitoring program since 2004. Studies include abundance, fidelity, seasonality and injury analysis. Injury analysis from 2004–2008 showed that up to 54% (18 of 33) of sharks had been hit by boats. In 2006, with the collaboration of the Mexican government, a Code of Conduct was generated for whale shark tour operators. In order to enforce the management, each year since 2009 the tour operators are trained and a dissemination program is designed with the aim of communicating the code of conduct with a focus on private boats. The success of the management is measured by fresh injury analysis. Results Betweenseasons 2004/2005–2014/2015, 380 whale sharks were identified; of these, 49 (22.3%) returned between years. During the season, sharks spend periods of between 40–70 and up to 200 days in the area before leaving the Bay. Seasonality varied in some years but the common season runs from September to February. Without considering the extreme years, the abundance per year is estimated from 20 (95% CI =16–31) to 71 (95% CI= 65–85, 95% SS) sharks, with a mean of 56. Fresh injury analysis from 250 identified sharks, 135 (54%) had fresh injuries present. Of these, 60% were abrasions, 30% both abrasions and lacerations, and 9% had only lacerations. The trained personal from the tourism companies has increased from 33 in 2009 to 88 in 2014. From 2009–2012 careful monitoring of the whale shark population revealed that the affected sharks decreased by 26% (from 61 to 35%). Although these numbers increased again over the last two years, up to 64% (70 of 109 sharks) during the 2014/2015 season, this was perhaps because the sharks remained in the Bay for a longer period of time. Conclusions Morethan 10 years of monitoring have been key to establishing La Paz Bay as a critical habitat of the species, which needs to be protected. This study has been helping to measure the success of the management, which still needs to be enforced by the government and engaged by the community. The changes in abundance and seasonality need to be considered for a carrying capacity study. When tour operators and the community are engaged in promoting the rules it can reduce harm to whale sharks, as in 2009–2011. The increase in permits and lack of enforcement will increase negative effects on whale sharks.
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The whale shark genome project
Background The whale shark forms an interesting subject for a genome project because it represents a phenotypic extreme: the largest body size of any piscine vertebrate. Sharks are also important comparative genomics subjects because they were the first vertebrate lineage to evolve and adaptive immune response. To date, however, no shark has had its complete nuclear genome sequenced and assembled. Approach Sequencing and assembly of the whale shark genome has been underway for almost 6 years, based on tissue samples from animals in the collection at Georgia Aquarium. Initial efforts focused on 454 pyrosequencing, and later Illumina sequencing. The most recent assembly has incorporated longer-read sequence data acquired using Pacific BioSciences technology. For the genome assembly we used a de novo approach. Results We estimate the total whale shark genome size at 3.44 Gbp, 3.5x larger than that of the closest related species for which whole genome data exist, the holocephalan Callorhinchus milii (950 Mbp). The mitochondrial genome is of fundamentally similar structure to that of other elasmobranchs and whole mitogenome phylogeny affirms the accepted phylogenetic placement of this species among the Orectolobiformes. Conclusions The availability of the whale shark genome will facilitate detailed investigations of global population structure that are a necessary precursor to effective conservation management. Moreover, whale shark genome sequence should find use in comparative studies of evolution, immunology and metabolism. Those interested in collaborating on such studies should contact the authors.
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Sustaining whale shark tourism in a diminishing population
Authors: Katie E. Reeve-Arnold, Joonas Kinni, Ross Newbigging, Simon J. Pierce and Kim RoquesBackground Tofo, Mozambique has been reported as having a year-round whale shark population (Pierce et. al., 2010). An important facet of Tofo's tourism industry, which forms a large part of the area's income, has grown up around this whale shark population. Sustainable tourist interaction was investigated and a Code of Conduct voluntarily imposed. However a decline in whale shark sightings in Tofo has brought the sustainability of this population and ecotourism approach into question. Approach Commercial whale shark snorkelling trips have been routinely accompanied/participated in from 2008 to present. Photo identification records have been collected to establish residency, seasonality and other sighting trends. Whale shark encounters, tourist and whale shark behaviour and environmental information are routinely recorded. Surveys of tourists were conducted to elucidate motivation, code of conduct compliance, local economical benefit and satisfaction amongst other factors. Results Over the 8 year study period a decline in whale sharks seen on snorkelling trips in Tofo was observed. These data demonstrate a drop from 1.35 whale shark encounters per snorkelling trip, and a 65% chance of an encounter on any given trip (analysed over a 12 mth period in 2011/12) to just 0.54 whale shark encounters per snorkel trip, and just a 35% chance of an encounter on any given trip (over a 12 month period in 2015/16). For the tourism industry this literally translates as replacement of the phrase ‘you are likely to see a whale shark’ with ‘you are not likely to see a whale shark’ on any given snorkelling trip. Both numbers of new sharks seen and re-sightings have fallen. Photo ID collaboration with the international whale shark database shows no evidence that large numbers of Mozambique sharks have migrated to other aggregation sites, suggesting the ecotourism location has not simply shifted. Whale shark specific tourism has become very important to the economy of Tofo and Mozambique as a whole. Interviews of tourists currently in process, will address the satisfaction of those who participate in snorkel trips and the durability of this industry in light of the falling population. Conclusions The whale shark encounter rate in Tofo has significantly declined. However, this need not result in the abortion of this successful ecotourism approach, which has made whale shark conservation financially important in Mozambique. Whale sharks may still be used as an important attractant but tourist satisfaction should/can be maintained, despite reduction in sightings, through diversification of snorkelling goals. These findings develop new approaches to facilitate ongoing whale shark-friendly ecotourism in all locations where whale shark sightings are in decline. This study depicts a way forward which maintains the financial value of whale sharks, so continuing to encourage their conservation and study.
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Where the whale sharks are: An innovative satellite tagging programme to track the movements of whale sharks from Ningaloo Reef, Western Australia
Background Coastal aggregations of whale sharks, typically dominated by juvenile males and occurring seasonally, are now documented in many places around the world, including Ningaloo Reef, Western Australia (WA). This aggregation occurs during the Austral autumn and winter and supports a lucrative tourism industry which operates during the whale shark “season” (generally April – July). Despite being one of the most highly studied aggregations of whale sharks in the world, their location and movements outside this period remain poorly understood, but are critical for understanding long term population dynamics and for effective management and conservation. An earlier study by ECOCEAN, combining satellite tracking and citizen science sightings of whale sharks outside the “season” at Ningaloo Reef and elsewhere along the WA coast, indicates that whale sharks may move north and south along the coast throughout the year, and/or make relatively short migrations, rather than undertaking long, trans-oceanic migrations. To test this further, a novel satellite tagging programme, supported by The Western Australian Department of Education (The Department), aims to discover where the whale sharks are when they are not at Ningaloo Reef and determine whether there are other unidentified “hotspots” for foraging and/or migration, i.e. areas of habitat critical for whale sharks. This programme also aims to provide innovative learning opportunities for school children, to make them more aware of the biology and ecology of WA's marine emblem and the marine environment, as well as to encourage engagement with STEM (Science, Technology, Engineering and Maths) learning. Approach Satellite tags (Wildlife Computers SPOT tags) were deployed on 12 whale sharks (identified using photo-identification through the Wildbook for Whale Sharks) at Ningaloo Reef in July 2015 using a custom-made clamp attachment on the first dorsal fin, designed to have minimal impact on the animals. Tags were funded by 16 schools from around WA participating in a joint ECOCEAN - Western Australian Department of Education science learning programme. Tracks of the sharks are displayed publically on the ZoaTrack website (www.zoatrack.org/projects/243/ analysis) and were used by participating schools in an eight week teaching programme. Results Data from satellite tags deployed in 2015 are still being collected and will be analysed as part of an Honours project in 2016, however, the teaching programme proved highly successful: The Department developed a comprehensive suite of resources addressing science, technology, engineering, mathematics and arts subjects to support students to engage in authentic learning experiences, and classes from pre-primary through to senior high school were involved. Preliminary results from the tags show that all have successfully reported positional data, for periods ranging from 15 to 156 days (mean 93.4 ± 13.1 SE) (as at 31/12/15). Homing migrations, to the southern part of Ningaloo Reef, have been recorded for 50% of all the sharks tagged, within periods ranging from 44 to 93 days (mean 65.7 ± 7.8 SE). These data show sharks making short forays away from Ningaloo Reef, and reveal areas important for commuting and foraging. Conclusions This innovative approach to funding allowed the satellite tracking programme to proceed and not only provided new information on the movements of whale sharks from Ningaloo Reef that can be used for conservation planning and management, but also provided novel learning experiences for school children and raised awareness for whale shark conservation and the marine environment. The data gathered support the hypothesis that whale sharks from the Ningaloo Reef aggregation do not typically undertake ocean basin scale migrations, rather they make shorter forays, perhaps to exploit food resources that vary spatially and temporally, and could be used to benchmark conservation outcomes for WA whale sharks and to provide pathways for more effective protection.
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Managing the impacts of tourism on the Ningaloo whale shark aggregation – asking the right people the right questions
Authors: Dani Rob and Peter BarnesBackground The Department of Parks and Wildlife manages the whale shark tourism industry within the Ningaloo Coast World Heritage Area, Western Australia. Guided by the Wildlife Management Program no. 57, Whale shark management with particular reference to Ningaloo Marine Park, the Department licences and monitors the activity of 15 commercial tour operators. A key strategy in the Management Program is to continue to research and monitor the impacts of whale shark interaction tourism on whale sharks in Ningaloo Marine Park, providing an on-going challenge. Approach This presentation will discuss the utility of the various approaches taken by both the Department and researcher activity licensed by the Department. These include the use of electronic monitoring systems on board the commercial tour operators' vessels which document encounter duration, photo identification of whale sharks, aerial behavioural monitoring and archival, acoustic and satellite tagging. Results As a management agency, the Department has identified a number of questions as outlined in the Management Program that aim to determine the level of impact on whale sharks. Potential impacts on whale sharks can arise from a number of anthropogenic sources including tourist vessels, recreational vessels and research activity. Finding the appropriate methodology to answer these questions is the key. Encounter duration is useful for determining short-term intra-season impacts. Photo identification catalogues combined with satellite tagging have been useful for determining longer-term inter-season return rates. Acoustic tagging will reveal patterns of residency while archival tagging has the potential to allow detailed behavioural studies. Photo identification also allows the analysis of scarring and potential impact on survival of the whale sharks visiting Ningaloo Marine Park and where possible can attribute scars to anthropogenic sources. Aerial monitoring of whale shark behaviour allows us to study whale shark swimming behaviours and direction in the presence and absence of vessels and swimmers. Conclusions Understanding and managing the impacts on whale sharks is a complex, challenging task. A single method cannot determine disturbance level on whale sharks. Determining which approach is appropriate to the given question and drawing upon the expertise of others to make informed management decisions is paramount and we will continue to take a multidisciplinary approach.
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Satellite tracking of whale sharks from Al Shaheen
Authors: David P. Robinson, Steffen S. Bach, Ali A. Abdulrahman and Mohammad Al-JaidahBackground The Qatar Whale Shark Research Project is a collaboration of government, industry and academia founded in 2012 to investigate anecdotal reports by Maersk Oil-platform workers of large numbers of whale sharks seen in the Al Shaheen field, Qatar. Approach The Qatar Whale Shark Research Project is a collaboration of government, industry and academia founded in 2012 to investigate anecdotal reports by Maersk Oil-platform workers of large numbers of whale sharks seen in the Al Shaheen field, Qatar. Results Satellite tracking of whale sharks tagged in Al Shaheen showed that they prefer depths in excess of 40 m and rarely made dives deeper than 100 m. Temperature preferences were between 27 °C and 33 °C but the sharks were shown to regularly feed in temperatures in excess of 35 °C. Sharks were seen to aggregate in the Al Shaheen region in the summer and disperse widely throughout the region in the winter months outside of the tuna spawning season. The majority of sharks stayed within the Arabian Gulf and Gulf of Oman. Only one shark ventured southwards and left the study area where the tag popped off between Somalia and Socotra. This exceptional and large-scale horizontal movement was made by a visibly pregnant 9 m female whale shark. A previously unknown area of interest was discovered in Saudi Arabian waters 126 km North-West of Al Shaheen and 100 km offshore off Al Jubail, which could possibly be a new aggregation site for whale sharks in the Arabian Gulf. Conclusions Whale sharks tagged in Al Shaheen distributed throughout the Arabian Gulf and Gulf of Oman outside of the Al Shaheen tuna-spawning season and only one large female left the area entirely. The size of whale sharks tagged in Al Shaheen was defined by occurrence and ranged from 4–10 m. The absence of smaller or larger sharks suggest that these animals demonstrate a different movement strategy, and that this region may be a staging post for sub-adult and recently mature individuals. When not feeding in Al Shaheen, whale sharks spend little to no time at the surface. No notable difference in habitat preference was noted between male and female or juvenile and mature animals. Individual sharks display different behaviour and movements patterns, assessment of individuals and their unique behaviour is necessary to help determine the behaviour of the species. Areas of interest identified through the satellite tagging initiative warrant further investigation, especially the site of Al Jubail in Saudi Arabia that appears to be another significant aggregation site.
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Caught in the net: A small, resident group of whale sharks feeding among fishing boats
Background Off Mafia Island, Tanzania, whale sharks are seen in a small bay that also boasts one of the country's largest coastal fisheries. We set out to determine the population structure of whale sharks here, examine their feeding behaviour and residency, and investigate the interaction between the sharks and fishers. Approach We conducted 261 boat-based surveys at Mafia Island between Oct 2012 and Dec 2015, recording all whale shark sightings as well as counting the numbers of tourist and fishing boats in the survey area during each trip. We estimated shark size visually and with laser photogrammetry and recorded sex, scars and behaviour of each shark. To examine residency, we deployed 67 acoustic tags on whale sharks and 19 receiver stations within the bay, and analysed recapture probability (both visual- and acoustic-based) with generalised additive mixing models. To investigate feeding plankton biomass and community structure, we collected 20 plankton samples when whale sharks were feeding and 202 background samples for comparison. We interviewed fishers and they recorded their fishing locations using a GPS. Results We identified 129 different whale sharks at Mafia Island, 54% of which were resighted in two or more years. Tagged sharks were acoustically detected throughout the year even though sightings were largely limited to Oct-Mar. Sharks ranged in total length from 2.5–9.7 m, were mostly male (87%), and were usually seen feeding (75%) at or near the surface. Dense patches (25 mg m–3) of large sergestids Lucifer hanseni prompted feeding, while background plankton tows were dominated by small copepods (2.5 mg m–3). Small and medium-sized planktivorous fishes also fed on the same patches of sergestids, often together with whale sharks. These smaller species were the main target of the local fishers. Fishing boats operated in the survey area on 90% of the time, but also made catches further afield. Fishers reported a conflict between whale sharks and their fishing operations on 36% of the time, although sharks were usually released from the nets without injury. A mean of 2.6 tourist boats per day searched the same survey area for whale sharks. Conclusions This small, resident group of whale sharks is routinely exposed to tourists, boat traffic and high fishing pressure. Whale sharks are commonly encircled in fishing nets and released, but scars indicate that they do occasionally get injured during this process. Mortalities are rare, based on interviews with fishers and long-term observers. Whale sharks at Mafia Island are unusually resident and face clear local threats. No defined management measures are currently in place, but we present some potential strategies for mitigating threats to whale sharks here.
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Djibouti – a kindergarten for whale sharks?
Background An aggregation of juvenile whale sharks were first reported off Arta, Djibouti, in 2003 and formally investigated in 2006. Standardised monitoring started in 2009 to establish the demographics of this aggregation and how it relates to the broader Red Sea and Indian Ocean whale shark population. Approach Photo-identification images have been collected from 2003 to present. Satellite relayed archival tags have been deployed to show longer term movements and tissue samples have been collected for DNA. Plankton and environmental information are routinely recorded. For the last two years digital Photo-IDs were collected by volunteers at the local dive operation to enable a longer annual study period to help establish seasonality and sighting trends. Results During 2003–2015, a total of 503 individual sharks were identified by photo-identification from more than 6300 in-water encounters; a maximum of 181 individuals were recorded in a single year. Overall 85% of sharks identified were males and mean body total length ranged from 3.5–4.3 m among years, with no significant difference between sexes. Sharks which were sighted in more than one year had a mean period of inter-annual residency of 4 years (maximum 11 years, n=3). Using data from 2003–2015, mark and recapture models estimated a gross population of 660–777 with 53–78% of individuals being re-sighted in any one year. Satellite tag data showed tagged individuals left the immediate area and travelled into the Red Sea and Northern Indian Ocean; however, 2 of the 3 PAT tagged sharks were seen off Djibouti in subsequent years. Diving depth data showed all sharks made short duration dives to depths greater than 400 m (maximum 832 m) but that all spent at least 45% of the time within 10 m of the surface and an average of 73% of the time shallower than 40 m. Comparison with plankton and environmental data showed that sharks were associated primarily with high plankton concentrations and swimming crab (possibly Charybdis erythrodactyla) spawning events. Conclusions The Arta area off Djibouti is host to a regular and significant aggregation of whale sharks. The average size of the sharks is smaller than those found in other Indian Ocean coastal aggregations suggesting that this may be an intermediate or kindergarten group from which the sharks will leave as they grow to join other juvenile aggregations. Satellite tracking and photo ID support the movement of sharks into Red Sea aggregations.
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Increasing numbers of whale sharks along the Andhra Pradesh coast, India – the conservation and management initiatives taken by EGREE Foundation
Authors: P. Sathiyaselvam, P. Prashanthi, Tarun Kathula, M. Ravi Kumar, Ramesh G. Kalghatgi and S.B.L. MishraBackground The whale shark conservation programme along the East Godavari River Estuarine Ecosystem (EGREE) region, of Andhra Pradesh, east-coast of India, was started in June 2012 under the direction of the Government of India, the United Nations Development Programme, the Global Environment Facility and the Government of Andhra Pradesh Godavari Project. It was started for the conservation and management of globally threatened species protected under the Indian Wildlife (Protection) Act of 1972, and employing cross sectoral mechanisms among various stakeholders, namely enforcement departments (state and central governments), production sectors (industries), fishermen and the public. Approach Questionnaire surveys are conducted to learn the present status of whale sharks along the Andhra Pradesh Coast, and literature surveys are done to understand the past and present whale shark distribution along the east coast of India. Major fish landing centres are monitored to record whale sharks landings, including seasonality, size and sex ratio. Massive awareness programmes and campaigns are conducted to improve the knowledge levels of various stakeholders. A whale shark conservation action plan is being prepared for the Andhra Pradesh coast by cross sectoral mechanisms. Results Fishery experts, researchers and local fishermen opined that until late 2007, the whale shark was a rare visitor to the EGREE region, but the number of sharks has increased in recent years. According to fishermen, whale sharks are seen at a depth of 20–40 m and sometimes come close to shore where they become entangled in shore seine nets. The fishermen revealed that whale sharks are seen mostly solitary or in small groups of 3 to 5 individuals, but sometimes over 200–300 individuals will aggregate in the open sea near the EGREE Region. As per the available literature, the total number of whale sharks killed as bycatch was 20 along the Andhra Pradesh coast between 1889 and 1998 (110 years). But surveys by the EGREE Foundation that between June 2013 and January 2016, 79 individual whale sharks were killed. The whale shark landings happened in all months except during the fishing ban from 16th April to 15th June. In September of 2014, 22 whale sharks were brought to the landing center. Of these 22 sharks, four were alive after being caught in a shore-seine fishing net. Both questionnaire and field surveys revealed that coastal and marine areas of the EGREE region have become a hot spot for whale sharks in recent years. The size of the whale sharks brought to the landing centers ranged between 2.1–6.68 m (mean 3.71±SD 1.04, n=44), and males (58%) outnumbered females. Based on the study, conservation and management measures are being taken by the EGREE Foundation through 1) massive awareness programmes to sensitize the fishermen and local public, 2) education and awareness applied to students and elected representatives of state and central governments, and 3) training of enforcement staff such as the Indian Coast Guard, Marine Police, Fisheries, Forest and Customs and Central Excise. A whale shark conservation action plan is being prepared for the Andhra Pradesh Coast by involving various state and central government departments, production sectors like oil & gas operators, and private port operators, local fishermen and policy makers. Conclusions This study indicated that whale shark numbers have increased and a globally significant aggregation of whale sharks is happening in the coastal and marine areas of EGREE region. Long-term research and monitoring is needed in this region.
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Long-term husbandry and physical observation of the whale sharks in Okinawa Churaumi Aquarium
Authors: Keiichi Sato, Rui Matsumoto, Kiyomi Murakumo and Kiyoshi AsahinaBackground Okinawa Churaumi Aquarium has established a long-term husbandry program for whale sharks since 1980. Currently, three individuals (1 male and 2 female) are housed in the 7,500 m3 capacity main exhibit tank. The male shark was caught by a set-net on March 11, 1995, and it measured a total length (TL) of 460 cm; a subsequent measurement in December 2015 revealed the TL had increased to 865 cm. The corresponding TLs of the female sharks that have been housed in this facility for nine and eight years were 762 cm and 787 cm, respectively. The growth rate, hormonal trends, quantity of food ingested, behaviors, and other physical changes along with maturation of these sharks are presently monitored. Approach The total length of each whale shark was estimated by measuring the length between the snout tip and the first dorsal fin using an equation formulated by us. Periodic measurements of the girth at the posterior margin of the pectoral fin have been recorded since May 2014. For measuring hormonal levels, blood was collected underwater from free-swimming individuals and plasma samples were extracted. The plasma concentration of steroid hormone was measured using time-resolved fluorescent antibody analysis. This data has been collected since May 2008. The quantity of food consumed and the feeding behavior of the whale sharks are recorded each day. Results The TL of the male whale shark increased from 460 cm to 744 cm by March 2005, at an average annual growth rate of 28 cm/year. Since 2005, there has been a decrease in the growth rate, to 12.5 cm/year. The two females have been growing at an annual rate of 33 cm/year (TL = 762 cm) and 37 cm/year (TL = 787 cm). Our data shows that the rate of change of girth appears to be associated with calorie intake. The plasma concentration of steroid hormone of the male shark increased from June 2011 to June 2012 (21.49 ng/ml; TL: 850 cm). This appears to be in synchrony with the rapid elongation of the claspers. Additionally, since April 2012, we have been observing the male shark rotating its entire body laterally crossing both claspers, which is a behavioral indication that the male has reached maturity. Conclusions From our long-term study on captive whale sharks, details on direct observations on the maturity process, growth rate, required food consumption, behavioral patterns, and proportional measurement changes are available. Based on these details, we expect that future attempts for reproduction in captivity would be successful and would allow us to unravel many mysteries of whale shark reproduction.
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Whale shark genetics: Where are we now and where should we be going?
More LessBackground Classic ecological approaches can reveal only glimpses of the behavioral spectrum of a longlived migratory species. Genetic analysis has the potential to inform the migratory behavior and reproductive habits of animals that are difficult or impossible to observe in the wild. Although studied primarily as juveniles at seasonal feeding aggregations, whale sharks are believed to be capable of extensive migrations. The frequency and magnitude of these movements is unknown, as is the degree to which they mediate gene flow between populations. Recent studies have asked whether the sharks observed at different aggregation sites show evidence of genetic structure, or whether they constitute a single breeding population. We published a preliminary study in 2009, based on microsatellite analysis of animals from numerous globally distributed aggregation sites, with a finding of minimal genetic differentiation. Approach Our genetic study is ongoing, and now encompasses hundreds of whale sharks representing all major aggregations worldwide. Other groups have also performed genetic analyses of whale shark population structure, focusing on both regional and global scales. Particularly for studies using microsatellite markers, direct comparisons across laboratories and platforms are not possible. Synthesizing the overall conclusions from aggregate genetic studies, however, provides additional power to understand species behaviors. Results Initial analysis of broadly distributed whale sharks found only low levels of genetic differentiation across geographically distinct populations. While sharks from the Western Atlantic Ocean showed slightly greater differentiation from Pacific/Indian Ocean animals than these populations did from each other, this result was not statistically significant. An expanded data set has now provided stronger analytical resolution between populations, revealing subtle yet statistically significant levels of genetic differentiation of Atlantic sharks. Conclusions Our previous analysis suggested gene flow between whale shark populations at a level sufficient to normalize genetic differentiation. Combined with satellite tracking and other data, these results confirmed that whale sharks can and do migrate between oceans. An expanded study, however, along with data published by other groups, now indicates reduced mixing between Western Atlantic and Indian/Pacific sharks. A significant body of evidence therefore indicates that whale sharks do not have strong population structure, nor do they represent a single panmictic population. Rather they occupy a more biologically realistic intermediate, with varying degrees of isolation by distance and by ecological features. Future genetic characterization should focus on the addition of yet unstudied whale shark populations, on building a robust mitochondrial haplotype dataset with broad applicability, and on technical standardization that could allow comparisons between microsatellite data sets across laboratories and platforms.
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Global shark protection
More LessBackground Sharks have been exploited over decades with very little or no management at all. This had devastating effects on many shark populations around the world. A recent report published by the IUCN Shark Specialist Group in 2014 showed that globally close to 25% of sharks and rays are threatened with extinction. They face more threats today then ever before in history. Primary drivers for this overfishing, as well as much of the bycatch related mortality, is the demand for shark fins used in shark fin soup, the demand for cheap shark meat and other traditional products, as well as the lack of management control along the whole trade chain. Approach In this respect CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) is a good instrument to help in achieving a more sustainable use of sharks and a more species specific management. Another global convention to adress this issue is the Convention on the Conservation of Migratory Species (CMS) and the associated “Sharks MoU.” However, one of the arguments used against further listing of shark species in these conventions is the difficulty of implementation and enforcement. To address this issue, many governments were approached with the offer to do implementation workshops by different NGO's. An important aspect of these workshops is the training of the participants to identify protected species or parts, especially fins, of these animals. Results Whale sharks were among the first two species which got some international protection through their listing on App 2 in CITES in 2002. This has been followed by a rising awareness and additional protection in CMS, different regional fishery regulations or national regulations. This was supported by a whole series of workshops organized by different NGOs, governments and CITES. This has led to a better understanding of the issue and subsequently to additional listings of sharks and manta rays during the last CITES conference in 2013 in Bangkok. Conclusions Since then, aditional workshops have been held and will hopefully lead to better data collection, a more species specific management and ultimately enhanced protection of sharks. They will hopefully help officials in fishery and customs to implement and enforce these new regulations to better manage sharks. First results show positive effects especially in the Middle East and aditional species are proposed to be listed in the above mentioned conventions. This talk informs about international protection of whale sharks and about the recent new CITES and CMS listings of sharks – what they mean and the efforts and global cooperation between NGOs and governments to get there.
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Vertical movement patterns of juvenile whale sharks Rhincodon typus at a seasonal aggregation in Saudi Arabian Red Sea
Background Large marine species have been a focus of scientists and public for their unique role in the ecosystem as well as in conservation. To study the behaviors of large marine species, electrical tagging is a direct and reliable method. Researchers have been utilizing technology advances in biologging tags on multiple spatiotemporal scales. This study provides a detailed insight into the vertical movement of whale sharks in a newly described seasonal aggregation off the coast of Al Lith, Saudi Arabia. Approach In the aggregation season of 2015, two biologging tags were fitted on two juvenile whale sharks and lasted over a period of 22 hours each. Fine-scaled diving behavior was recorded with a sampling rate of 10 Hz and energy consumption was generated from acceleration sensory data. Results Tagged whale sharks exhibited intensive and consistent diving behaviors throughout the day except a prolonged surface swimming in the morning and a brief surfacing around sunset. Deep dives from the two tagged sharks reached 80 meters, which is the depth of this aggregation habitat. In multiple stages of the diel cycle, whale sharks utilized different depths in the water column. Diving speeds also varied among diel stages and between two individuals, most possibly as a strategy of optimizing energy consumption from forage efforts. Combining with previous study on horizontal movement of whale sharks in this aggregation, this study portrays movement behaviors of juvenile whale sharks comprehensively. Conclusions Whale sharks in this aggregation showed a distinct diel vertical movement pattern which also effectively utilizes energy. We hope this study will benefit the management of this hot spot of whale sharks and even larger scale ecosystems, revealing potential excessive human activities (e.g. ecotourism, aquaculture) and global climate issues.
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Photo ID-based assessment of the whale shark (Rhincodon typus) population in Kwatisore, Wondama Bay, West Papua, Indonesia
Authors: Sampari Suruan, Bayu Pranata, Casandra Tania and Mohammad M. KamalBackground The presence of whale sharks (Rhincodon typus) in Wondama Bay has long been known and the species is an icon of this region. In addition to their enormous size, these sharks are not dangerous to or fearful of humans, so there has been growing interest in utilizing this animal for eco-tourism. Within Wondama Bay, whale sharks distribute in several regions, including Kwatisore waters. Since biological information on this species is lacking, the present study aimed to investigate the whale shark population using photo identification, frequency of appearance, sex, and scars on the body. The information obtained from this study is important for species conservation and management. Approach The research was performed in Kwatisore waters of Wondama Bay during 2010–2013, and continued from April to June 2014. Whale shark identification was based on photos taken by divers by plotting three reference points, i.e. the top of the fifth gill slit, the posterior-most point where the pectoral fin meets the body, and the bottom of the fifth gill slit (Brooks et al., 2010). During each encounter, the animals were length measured, sex was identified through the presence or absence of claspers, and the position of scars and wounds were determined on the body. Results The total number of whale sharks encountered in Kwatisore waters were 120 and 19 animals for the period of 2010–2013 and 2014, respectively. Based on ID pictures, the population was composed of 126 sharks consisting of 122 males and 4 females. With regard to 2014 observations, the animals were all males and were immature, as the average body length was 4 m. The greatest number of sharks was observed between 0600–1200 hours, during which time 80 individuals were seen on the surface. It was found that 58% of the population had scars and wounds, of which 34% were on the lips and 25% on the fins. Conclusions Data on IDs and body length of each individual, as well as sex composition, are important information for understanding whale shark population structure, and will benefit the conservation and management of these animals.
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Characteristics of whale sharks (Rhincodon typus) in Teluk Cenderawasih National Park, Indonesia
Background The whale shark (Rhincodon typus) is an iconic species for Teluk Cenderawasih National Park (TCNP), West Papua and Papua. They appear regularly near lift-net fisheries (bagans) year round in some areas, especially near Kwatisore in West Papua, resulting in the development of limited tourism since 2009. The objective of our study was to document the characteristics (i.e., number, size, sex) of whale sharks that occur in TCNP. Approach We used photographs to identify whale sharks from natural patterns and other body markings that periodically appeared near operational bagans in southern Cenderawasih Bay. The photo ID technique was used to identify each individual based on the white body spot pattern. We also made subjective estimates of the relative sizes of each shark and determined whether they were male or female from the presence or absence of claspers. Results We obtained 8,530 photos of sharks from February 2010 through June 2015. From that database we tentatively identified 126 sharks, 83% of them male, 14% female and 3% undetermined. The estimated length of the sharks averaged 4.4 m (± 1.25 m, range = 2 m to 8 m). Around 40% of the individuals had scars, mostly around their mouths and fins. Most (59%) of the sharks were seen in one year, while only 3% were seen over more than one year during the five year study. Some exceptions were one shark that was seen 32 times over four years, and another that was seen 29 times over five years. Conclusions Juvenile male whale sharks appear to be transient and highly mobile in Cenderawasih Bay. Whether adult males or adult females occur here is not known, as they may not be attracted to the fishing bagans or do not otherwise approach the sea surface where they can be observed. Because of the increased tourism for whale sharks and the interactions of whale sharks with the fishing bagans, we recommend continued systematic observations of whale sharks and vigilant surveillance for understanding the dynamics of interactions among tourist activities, fishing operations, and whale sharks.
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Whale shark behavior with swimmers and boats present during tourism activities in the northern Mexican Caribbean
More LessBackground Whale shark watching and swimming are two of the most popular activities for tourists in the northern Mexican Caribbean. Each year since 2002, these activities have had an exponential growth, which could represent a hazard for whale sharks. It is important to monitor the tourism effect on whale shark behavior to take sustainable management measures concerning the use of this natural resource. Approach Whale shark behavior monitoring was conducted from June to September in 2014 and 2015. In order to know the effects of tourism activities and their influence on feeding behaviors and diving paths shown by whale sharks, we conducted surveys to observe whale shark behavior with and without tourism activities (swimmers and boats). Results The monitoring effort in 2014 and 2015 for whale shark surface behavior includes 571 minutes on video, of which 414 minutes include whale shark behavior during tourism activities, and 157 minutes without tourists present. In 2014, 26 whale sharks were observed without tourism activity, and 56% of these sharks showed ram feeding behavior near the surface from the beginning to the end of the observation. 42 whale sharks were observed with tourism; at the beginning of the observation 48% of these sharks presented ram feeding behavior near the surface, but this behavior decreased to 29% to the end of the observation. In 2015, only 7 whale sharks were observed without tourism interactions; 57% had ram feeding behavior from the beginning to the end of the observations. 51 whale sharks were observed with tourism interactions, where 31% of these sharks had ram feeding behavior at the beginning of the survey, but it decreased to 27% by the end of the survey. For 2014, the main behavior was ram feeding behavior. In 2015, the main behavior showed by whale sharks during tourism interactions was diving path behavior (37%). Conclusions Tourism activity might have an effect on whale shark behavior and on surface sightings, indicating a decrease in the surface feeding time in one of the most important feeding aggregations for whale sharks in the northern Mexican Caribbean. Precautionary measures are necessary for adaptive management of tourism activities and the whale sharks in this area.
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