An overview of whale shark movement ecology projects in the Red Sea Research Center

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.

Acoustic backscatter at a Red Sea whale shark aggregation site

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.

Characterization of Two Novel Whale Shark Aggregations at Shib Habil, Saudi Arabia and Mafia Island, Tanzania

The whale shark Rhincodon typus is found throughout the world's tropical and warm‐temperate ocean basins. Despite their broad physical distribution, research on the species has been concentrated at a few aggregation sites. Comparing DNA sequences from sharks at different sites can provide a demographically neutral understanding of the whale shark's global ecology. Here, we created genetic profiles for 84 whale sharks from the Saudi Arabian Red Sea and 72 individuals from the coast of Tanzania using a combination of microsatellite and mitochondrial sequences. These two sites, separated by approximately 4500 km (shortest over‐water distance), exhibit markedly different population demographics and behavioral ecologies. Eleven microsatellite DNA markers revealed that the two aggregation sites have similar levels of allelic richness and appear to be derived from the same source population. We sequenced the mitochondrial control region to produce multiple global haplotype networks (based on different alignment methodologies) that were broadly similar to each other in terms of population structure but suggested different demographic histories. Data from both microsatellite and mitochondrial markers demonstrated the stability of genetic diversity within the Saudi Arabian aggregation site throughout the sampling period. These results contrast previously measured declines in diversity at Ningaloo Reef, Western Australia. Mapping the geographic distribution of whale shark lineages provides insight into the species’ connectivity and can be used to direct management efforts at both local and global scales. Similarly, understanding historical fluctuations in whale shark abundance provides a baseline by which to assess current trends. Continued development of new sequencing methods and the incorporation of genomic data could lead to considerable advances in the scientific understanding of whale shark population ecology and corresponding improvements to conservation policy.

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.

Kwatisore waters in the Cenderawasih Bay National Park area is one of the whale sharks’ habitats in Indonesia. As shark sightings seem to occur daily there is the opportunity for ecotourism development in the area. This study aims to quantify the occurrence of whale sharks at Kwatisore, and estimate the carrying capacity of the area, together with its suitability for ecotourism based on whale shark aggregations. Primary data collection on the appearance of whale sharks was carried out every day through a census technique on 7 designated areas (Apr to Aug, 2022). Every whale shark that appears on the surface of the water is photographed and identified by an ID number based on the I3Sv2.0 and its sex determined. During the census period, 709 whale sharks’ sightings were recorded mostly in the morning. There were 15 individuals in total, all males with a total length ranging from 3-7 m. The carrying capacity of the area for whale shark ecotourism in Kwatisore waters is a maximum of 252 people per day who are allowed to interact with whale sharks, while the tourism suitability index is included in the very appropriate category for whale shark tourism.

Kwatisore waters in the Cenderawasih Bay National Park area is one of the whale sharks’ habitats in Indonesia. As shark sightings seem to occur daily there is the opportunity for ecotourism development in the area. This study aims to quantify the occurrence of whale sharks at Kwatisore, and estimate the carrying capacity of the area, together with its suitability for ecotourism based on whale shark aggregations. Primary data collection on the appearance of whale sharks was carried out every day through a census technique on 7 designated areas (Apr to Aug, 2022). Every whale shark that appears on the surface of the water is photographed and identified by an ID number based on the I3Sv2.0 and its sex determined. During the census period, 709 whale sharks’ sightings were recorded mostly in the morning. There were 15 individuals in total, all males with a total length ranging from 3-7 m. The carrying capacity of the area for whale shark ecotourism in Kwatisore waters is a maximum of 252 people per day who are allowed to interact with whale sharks, while the tourism suitability index is included in the very appropriate category for whale shark tourism.

Background 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.

Conservation efforts aimed at the whale shark, Rhincodon typus, remain limited by a lack of basic information on most aspects of its ecology, including global population structure, population sizes and movement patterns. Here we report on the movements of 47 Red Sea whale sharks fitted with three types of satellite transmitting tags from 2009–2011. Most of these sharks were tagged at a single aggregation site near Al-Lith, on the central coast of the Saudi Arabian Red Sea. Individuals encountered at this site were all juveniles based on size estimates ranging from 2.5–7 m total length with a sex ratio of approximately 1∶1. All other known aggregation sites for juvenile whale sharks are dominated by males. Results from tagging efforts showed that most individuals remained in the southern Red Sea and that some sharks returned to the same location in subsequent years. Diving data were recorded by 37 tags, revealing frequent deep dives to at least 500 m and as deep as 1360 m. The unique temperature-depth profiles of the Red Sea confirmed that several whale sharks moved out of the Red Sea while tagged. The wide-ranging horizontal movements of these individuals highlight the need for multinational, cooperative efforts to conserve R. typus populations in the Red Sea and Indian Ocean.

Background 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.

The Arabian Peninsula is one of the World’s largest dust source regions. It is also affected by natural and anthropogenic pollution of African, Asian, and European origin. As the Arabian Peninsula is highly under-sampled, we have since 2012 established and maintained aerosol monitoring sites at King Abdullah University of Science and Technology (KAUST), as well as in the North-Western part of the Arabian Peninsula, and the Red Sea coast. The sites incorporate the following instrumentation. Two CIMEL sun photometers operational since 2012 as a part of the NASA Aerosol Robotic NETwork (AERONET), providing aerosol optical depth (AOD) and aerosol parameters, reporting data to the NASA Goddard website (http://aeronet.gsfc.nasa.gov/cgi-bin/type_piece_of_map_opera_v2_new). The AOD distribution over the Red Sea is measured during KAUST Red Sea cruises using a hand-held sun photometer (Microtops II). The data are reported to the NASA Maritime Network (http://aeronet.gsfc.nasa.gov/new_web/maritime_aerosol_network.html). Vertical Distribution of aerosols is sampled using the Micro Pulse Lidar (MPL) operating as a part of the NASA MPLNET (http://kimura.gsfc.nasa.gov/site--‐page?site=Kaust). We measure aerosol deposition rates on a monthly basis using passive samplers in different several locations (KAUST, 2015-2023; Al Wajh Lagoon, 2021-2022; DUBA & Tabuk,2022 -2023) and conducted a mineralogical analysis of deposited aerosols by X-ray diffractometry (XRD) and measured particle size distributions using Mastersizer3000.Our objective in this study is to conduct an in-depth analysis of the combined effects of natural and anthropogenic pollution on air quality, climate, and application of renewable energy across the Arabian Peninsula, providing a scientific foundation for model calibration in this region. Here we report on the data sets collected in 2012- 2023:KAUST campus site: Six dust deposition samplers, AERONET, MPL Al Wajh Lagoon site: Nine dust deposition samplers Duba site: Two dust deposition samplers Tabuk site: Two dust deposition samplers In our group’s research at KAUST, these data sets, in combination with the available satellite observations, were integrated into the meteorology-chemistry-aerosol model, WRF-Chem, to quantify the aerosol environmental impacts and support environmental decision-making in the region.

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 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.

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.