A 15‐Year Time Series Shows Major Declines in Whale Sharks in Southern Mozambique

Background 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.

Background 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.

The Mexican Caribbean is considered one of the most important sites for whale shark aggregations. Whale shark groups of over 300 individuals have been recorded frequently. There is little published information regarding the ecology of the whale shark in Mexico, and the role that the Mexican Caribbean plays as habitat for this species. This area has been recognized as important for the whale shark and therefore it is necessary to determine the environmental factors that shape the distribution of these animals. The aim of this study was to identify key environmental factors associated with whale shark feeding aggregations and to determine the patterns in habitat suitability for whale sharks in the Mexican Caribbean through the modeling approach of maximum entropy. Whale shark data obtained for this study included 250 records during April to September (2008–2012). The MaxEnt model performed better than random and produced an area under the curve (AUC) score of 0.946. Primary productivity and sea surface temperature were the variables most strongly related to whale shark sightings. The model predicted a high suitability in areas located to the north of Isla Contoy and the offshore area east of Isla Contoy named “Afuera” (>0.75), with medium suitability north of Cabo Catoche (>0.5) and lower suitability for the northeast of Cabo Catoche (<0.5). The habitat suitability maps also indicated seasonal variations, showing a higher prediction of whale shark sightings during the rainy season (June to October), when primary productivity is higher in the area.

Background The northern Mozambique Channel is a global hotspot for whale shark sightings, based on observer records from the tuna purse-seine fleet and published literature. Nosy Be Island (NW Madagascar) hosts a flourishing marine tourism industry based on viewing whale sharks and other species. Following reports of declining sightings in other regional hotspots, such as Tofo in Mozambique, it is important to establish if these declines represent a simple shift in aggregation site, or a broader reduction. Approach Data on population structure were also collected during a preliminary field season from August to December 2015. Results Approximately 200 sightings were recorded by a single operator during 2015. Preliminary analysis indicates that the majority of whale sharks sighted were males of lengths between 3 and 10 meters. Most whale shark sightings were from October to December. Conclusions Regular whale shark sightings occur off the Nosy Be area from August to December. Limited sex and size data suggests a juvenile male-biased aggregation where whale sharks were most commonly observed traveling and feeding on copepods. New data will help to establish whether oceanographic variability has resulted in a shift in abundance to Madagascar, or whether a broad-scale decline has taken place. No species-level legislation protects whale sharks in Madagascar, and the whale shark tourism industry is presently unregulated with regard to interactions. Further work on the population ecology, movements and social importance of whale sharks in the country is justified and will inform the development of effective conservation and tourism management initiatives.

Hi Reddit, My name is Pedro Afonso, and I am a senior researcher at the Institute of Marine Research and MARE - Marine and Environmental Sciences Centre, both based at the University of the Azores. I recently published a paper in PLOS ONE entitled “Dynamics of Whale Shark Occurrence at Their Fringe Oceanic Habitat”, where we investigated the patterns of occurrence of whale sharks over the mid north Atlantic ridge. Using 16 years of observational data from a pole-and-line fishery across the Azores and GAM models, we investigated the spatial and temporal patterns of whale shark occurrence in relation to oceanographic features. Our study found that whale shark sightings in this oceanic region increased sharply in 2008, and that sea surface temperature helps predict whale shark occurrence in the region. Our research also showed that the Azores are at a thermal boundary for whale sharks, which can help explain the post-2007 increase in sightings and has further implications in the face of climate change. I will be taking questions at 1pm ET – Ask Me Anything!

Many large marine species are vulnerable to anthropogenic pressures, and substantial declines have been documented across a range of taxa. Many of these species are also long-lived, have low individual resighting rates and high levels of individual heterogeneity in capture probability, which complicates assessments of their conservation status with capture-�mark-�recapture (CMR) models. Few studies have been able to apply CMR models to whale sharks Rhincodon typus, the world’s largest fish. One of their aggregation sites off Mafia Island in Tanzania is characterised by unusually high residency of this Endangered species, making it an ideal target for CMR methods. Three different CMR models were fitted to an 8 yr photo-identification data set to estimate abundance, population trend and demographic parameters. As anticipated, resighting rates were unusually high compared to other aggregations. Different CMR models produced broadly similar parameter estimates, showing a stable population trend with high survivorship and limited recruitment. Tagging and biopsy sampling for concurrent research did not negatively affect those sharks’ apparent survival or capture probabilities. Scenario-based power analyses showed that only pronounced abundance trends (±30%) would be detectable over our study period, at a 90% level of probability, even with the relatively high precision in yearly abundance estimates achieved here. Other, more transient whale shark aggregations, with reduced precision in abundance estimates, may only be able to confidently detect a similar trend with CMR models after 15-20 yr of observations. Precautionary management and long-term monitoring will be required to assist and document the recovery of this iconic species.

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.

Background 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.

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.

Background The conservation of whale sharks, like other endangered species, requires, among others factors, an understanding of the effects that variability in habitat have on long-term species viability. In the Mexican Northern Caribbean, a Habitat Monitoring Program for the whale shark was established in 2005 to describe the spatio-temporal variability of environmental data and whale shark distribution. Approach From 2005–2014, when whale sharks were present in the region (May to September), monthly trips were made to record whale shark sightings and hydrological data (sea surface temperature, salinity and dissolved oxygen). Water samples were collected to determine nutrients (nitrite, nitrate, ammonium, silicates and phosphates), as well as chlorophyll-a (Chl-a) and zooplankton biomass. We compared the environmental variables at sites with and without whale sharks present. Maps of zooplankton biomass were produced for each year in order to explore their relationship with the distribution and abundance of whale sharks. Results Areas with high whale shark abundance have been identified inside the study region. At these sites the whale shark feeds, taking advantage of the abundance of zooplankton, as a result of two events: the intensity of the Yucatan upwelling and the presence of dense masses of fish eggs. The whale shark aggregation areas influenced by the upwelling were characterized by high Chl-a concentrations (mean±SE 0.9±0.4 mg/m3), high nutrients and mixed zooplankton in which several groups were present (usually copepods were the most abundant group). In the whale shark aggregation area called “Afuera”, the zooplankton samples were dominated by fish eggs. This area registered significantly higher zooplankton biomass (mean±SE 3356.1±1960.8 mg/m3) in comparison with that recorded in upwelling areas (mean±SE 103.5±57.2 mg/m3). Zooplankton biomass was the most influential environmental variable to determine whale shark abundance, supporting the close relationship between this species and their food availability. Spatio-temporal changes in distribution and abundance of whale sharks have been recorded in the region, as well as changes in their food availability. Conclusions The whale shark uses selected areas within the Mexican Caribbean. These areas have different hydrobiological characteristics. Changes in distribution and abundance of whale sharks inside the study area may make it more difficult to implement suitable management strategies. We need more data to understand the reason for these changes, for example increased knowledge about the ocean circulation patterns at this site and other factors that may influence and characterize spawning inside the aggregation area. The continuity of hydrobiological monitoring is key to ensure the integrity of this critical habitat.

Data from 36 whale shark (Rhincodon typus Smith, 1828) sightings off north‐east North Island, New Zealand are summarised. Sightings were concentrated over the outer shelf and shelf break in areas influenced by the East Auckland Current at sea surface temperatures (SST) of 21–24°C. Sightings occurred from late spring to early autumn (November‐April) but were most frequent in midsummer (February) when upwelling along the north‐east shelf is weakest. The data indicate whale sharks occur off north‐east New Zealand most summers, including those when SST is colder than usual. A cluster of sightings and three observations of whale sharks feeding on schools of anchovy (Engraulis australis) near Whale Island, Bay of Plenty, suggest whale sharks may aggregate seasonally in this area. Estimated total lengths (TL) of 26 whale sharks ranged from 3.5 to 15 m, with 73% between 6 and 9 m TL.

Background: The Northern Gulf of Mexico Whale Shark Research Program was initiated in 2003 to increase our knowledge of whale shark occurrence and distribution within the region. A primary goal was to obtain sightings data from “citizen scientists” to guide directed research. Whale sharks are typically solitary animals, but are known to aggregate in areas of high prey abundance. Methods: Whale shark sightings data reported from 2003 to present were compiled. Aggregations were defined as more than one whale shark, and large aggregations were defined as 10 or more sharks, observed at a specific location at the same time. Efforts were made to encounter aggregations to determine size and sex assemblage of the sharks, and to collect plankton samples to identify potential prey. Results: To date we have over 600 whale shark sightings reports and four research encounters of large aggregations. Whale shark aggregations represented 31% of reported sightings, 25% of which were large aggregations between 10-150 individuals. All of thereported large aggregations occurred during summer, almost exclusively along the continental shelf edge, with 41% occurring at Ewing Bank. Three out of the four scientific encounters occurred at Ewing Bank (2009, 2010, 2013). Aggregations were dominated by immature males that were primarily feeding on Euthynnus alletteratus eggs. Conclusions: The use of sightings data provided by “citizen scientists” has proven to bean inexpensive and effective technique for identifying whale shark aggregation locations in the northern Gulf of Mexico. Aggregation assemblages appear to consist of largely juvenile males that were feeding on tuna eggs. Similar to other regions, it is unknown if whale sharks in the northern Gulf of Mexico primarily consist of juveniles or if juveniles simply dominate these large feeding aggregations.

Background 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.

Sightings of planktivorous elasmobranchs at their coastal aggregation sites are often linked to biological, environmental and temporal variables. Many large planktivorous elasmobranchs are also globally threatened species, so it is necessary to try and separate population trends from environmentally driven, short-term fluctuations. We investigated the influence of environmental variables on sightings of 3 species of planktivorous elasmobranchs off Praia do Tofo, Mozambique: the reef manta ray Manta alfredi, giant manta ray M. birostris and whale shark Rhincodon typus. We used 8- (2003 to 2011) and 6-yr (2005 to 2011) logbook data for manta rays and whale sharks, respectively, and constructed a generalised linear model with animal sightings as the response. Predictors included temporal (year, month, time of day), biological (plankton categories), oceanographic (water temperature, time from high tide, current direction and strength and wave height) and celestial (moon illumination) indices. These predictors best fitted reef manta ray sightings, a coastal species with high residency, but less so for the wider-ranging giant manta rays and whale sharks. We found a significant decline in the standardised sightings time series for the reef manta ray (88%) and whale shark (79%), but not for the giant manta ray.

A study on whale sharks have been carried out in Teluk Cenderawasih National Park (TCNP) on May-June 2014. The objectives of this study were to analysis bioecological of whale shark, the perceptions of local communities and tourists on whale shark ecotourism development and to formulate the ecotourism development strategy in TCNP. Data were collected through observations and and counting the number of whale sharks, gender identification and age categories, and estimation of body length; measurement of some environmental variables (sea surface temperature, salinity, sea brightness); and regarding their perception of whale sharks as objects of tourist attraction. The result showed that the generally the whale sharks come to the surface in waters that there are many bagan fisheries that many fish in the net. Whale sharks feed and come to the surface in the fishing platform in the morning until noon with a duration of 15-30 minutes. Physical enviroment conditions of sea in TCNP were temperatures 28-31°C; salinity 33-34‰ and sea brightness 7-12 m. The total number of the emergence of the whale sharks was 30 times and identified as 15 animals, all young males, measuring between 3 and 6 m, generally do not have injuries. The perseptions of local communities about development of whale shark ecotourism were positive and will be supported this program. Generally, most tourists, of which 87,88% of them were foreigners, gave positive perceptions on whale shark attractions in TCTN, from attractive to very attractive, although there are some aspects of travel managements that need to be improved, such as the availability of information services, tourist guides, and the comfort level. Some development strategies must be done, i.e. continuous monitoring of whale shark, human resource capacity building, provision of tourist support infrastructure, coordination and synergy with stakeholders, and increase public awareness and the development of cultural tourism attractions as an integrated ecotuorism program. Keywords: bioecological, ecotourism, development strategy, Teluk Cenderwasih National Park, whale shark