Determining Blacktip Reef Shark ( Carcharhinus melanopterus ) Paternity Using Novel Microsatellite Loci for Studbook Utilization

Morotai has abundant marine biological resources, sharks being one of them. The blacktip reef shark is one of the dominant types of coral reef sharks in Morotai waters. Worldwide shark are threatened due to the demand for shark fins and over fishing, to protect sharks is important to know their distribution so protected areas can be established. This research aims to examine the distribution of blacktip reef sharks (Carcharhinus melanopterus) based on habitat characteristics in the Morotai Waters. Through surveys and observation of coral cover, using the Line Intercept Transect (PIT) method and the Baited Remote Underwater Video (BRUV) to record the blacktip reef sharks who passed by the coral reef. Water quality parameters measured include temperature, salinity, visibility, acidity, current type, tides, and moon phases. Blacktip reef sharks were found in three of the four research stations. Station 4 was the one with the most blacktip reef shark appearances, amounting to 91 individuals. This station has the lowest sloping contour and has the smallest live coral cover of only 1%. Station 4 is dominated by sand covering 40%. All water quality parameters influence blacktip reef shark occurrence. The highest appearance of the blacktip reef shark happens during the new moon phase, when the tides are loose and the currents are quite strong.

Understanding collective behaviours and interactions in sharks is still in its infancy. Although recent studies have revealed some social structures in several shark species, little is known about complex interactions and social processes such as leader-follower dynamics. Recognising the dynamics in shark populations can help to further understand population structure and the influence of specific individuals. We developed a methodological approach to detect and analyse leader-follower behavioural patterns using acoustic telemetry data. By utilising lag-time distributions from acoustic telemetry detections for pairs of individuals we infer directed relationships based on temporal patterns. We applied this method to existing datasets from grey reef sharks (Carcharhinus amblyrhynchos), blacktip reef sharks (Carcharhinus melanopterus), and tiger sharks (Galeocerdo cuvier). We found evidence of leader-follower behaviour in both reef-associated species, with half of the tagged grey reef sharks forming leader-follower networks at eight locations. Size was a significant influence on female grey reef sharks leading-following behaviour. We found similar behaviours at three locations for blacktip reef sharks, with one-third of the tagged individuals forming separate and non-overlapping networks. Size was a significant influence on male blacktip reef sharks leading-following behaviour. No species showed a significant effect of sex alone on leader-follower behaviours. Aggregating networks did not show an overall hierarchy for either species but showed that grey reef shark coordinated in smaller networks than expected with strong influences from more dominant individuals. We found no leader-follower networks for tiger sharks. Our methodology reveals leader-follower behaviours in blacktip reef sharks and grey reef sharks and corroborates findings from the literature which have previously either been described using visual observation or using a different analytical approach. We demonstrate how existing acoustic telemetry datasets are a valuable source which can be used to detect social interactions associated with leader-follower behaviours in sharks, especially when visual observations are not feasible. Our approach provides new insights into understanding the social dynamics in sharks and offers a way to be applied to many more species already acoustically tagged.

Spatial separation within predator communities can arise via territoriality but also from competitive interactions among and within species. However, linking competitive interactions to predator distribution patterns is difficult and theoretical models predict different habitat selection patterns dependent on habitat quality and how competition manifests itself. While models generally consider competitors to be either equal in ability, or for one phenotype to have a fixed advantage over the other, few studies consider that an animal may only have a competitive advantage in specific habitats. We used  10 years of telemetry data, habitat surveys and behavioral experiments, to show spatial partitioning between and within two species of reef shark (grey reef Carcharhinus amblyrhinchos and blacktip reef sharks C. melanopterus ) at an unfished Pacific atoll. Within a species, sharks remained within small ‘sub‐habitats’ with very few movements of individuals between sub‐habitats, which previous models have suggested could be caused by intra‐specific competition. Blacktip reef sharks were more broadly distributed across habitat types but a greater proportion used lagoon and backreef habitats, while grey reef sharks preferred forereef habitats. Grey reef sharks at a nearby atoll where blacktip reef sharks are absent, were distributed more broadly between habitat types than when both species were present. A series of individual‐based models predict that habitat separation would only arise if there are competitive interactions between species that are habitat‐specific, with grey reefs having a competitive advantage on the forereefs and blacktips in the lagoons and backreef. We provide compelling evidence that competition helps drive distribution patterns and spatial separation of a marine predator community, and highlight that competitive advantages may not be constant but rather dependent on habitats.

Prior to COVID-19 pandemic, Morotai waters was well known as one of the favorite destination for shark watching tourism in Indonesia. Similar to other animal sighting tourism in Indonesia, shark diving has been hit hard by the pandemic of COVID-19 and has been banned since April 2020. However, the absence of tourist or diver on the shark dive site brings opportunity to investigate the impact of prolonged absence of diver-shark interaction on the blacktip reef shark’s agonistic behavior. The researches on blacktip reef shark’s agonistic behavior were conducted using diver operated video technique in monthly basis from May to October 2020. These data were compared with the previous diver-shark interaction videos from January 2013 to February 2020. Comparison of both pre-COVID-19 pandemic and during COVID-19 pandemic found that the blacktip reef shark’s agonistic behavior toward diver were not affected significantly by the absence of diver.

The study was conducted during April, 2006 to March, 2014 on the status of shark fishery (shark and ray) resources in the Bay of Bengal of Bangladesh region; data were collected from Fishery ghat fish landing center, Chittagong and BFDC fish harbor, Cox’s Bazar. A total 11 species of sharks belonging to 3 families (under Carcharhinidae-8 species, Sphyrnidae-2 species and Hemiscyllidae-1 species) and 24 species of rays belonging to 7 families (under Dasyatidae-14 species, Rhinobatidae-2 species, Rhynchobatidae-1 species, Gymnuridae-1 species, Myliobatidae-2 species, Rhinopteridae-2 species and Mobulidae-2 species) were recorded. The elasmobranch species, such as sharks were Grey sharp nose shark (Rhizoprionodon oligolinx-Springer, 1964), Graceful shark (Carcharhinus amblyrhynchoides -Whitley, 1934), Bull shark (Carcharhinus leucas -Valenciennes in Muller and Henle, 1839), Black tip reef shark (Carcharhinus melanopterus -Quoy and Gaimard, 1824), Soft tail shark (Carcharhinus sorrah- Valenciennes, in Muller and Henle,1839), Milk shark (Rhizoprionodon acutus -Rupell,1837), Spade nose shark (Scoliodon laticaudus -Cuvier 1829), Tiger shark (Galeocerdo cuvier -Peron and LeSueur, in LeSueur, 1822), Scalloped hammerhead shark (Sphyrna lewini -Griffith and Smith, 1834), Great hammerhead shark (Sphyrna mokarran- Ruppell, 1837) and Slender bamboo shark (Chiloscyllum indicum -Gmelin, 1789). And the ray’s species were- Pink whip ray (Himantura fai -Jordan and Seale, 1906), Tube mouth whip ray (Himantura lobistoma -Manjaji- Matsumoto & Last, 2006), Leopard whip ray (Himantura undulata -Bleeker,1852), White spotted whip ray(Himantura gerrardi- Person and Lesucur,1822), Reticulate whip ray (Himantura uarnak -Forsskal,1775), Brown whip ray (Himantura uarnacoides -Bleeker, 1852),Scaly whip ray (Himantura imbricata -Bloch and Schneider, 1801), Dwarf whip ray (Himantura walga -Muller and Henle, 1841),Chinese sting ray (Dasyatis sinensis -Steindachner, 1892),Sharp nose sting ray (Dasyatis zugei -Miiller and Henle, 1841), Blue spotted sting ray (Dasyatis kuhlii -Muller and Henle,1841), Banana leaf -tail ray (Pastinachus sephen -Forsskal, 1775), Blotched fantail ray (Taeniura meyeni -Miiller and Henle, 1841), Porcupine ray (Urogymnus asperrimus -Bloch and Schneider,1801), Giant shovelnose ray (Rhinobatos typus -Bennett, 1830),Club nose guitar fish (Rhinobatos thouin -Anonymous, in Lacepede,1798), Bowmouth guitar fish (Rhina ancylostoma -Bloch and Schneider,1801), Japanese butterfly ray (Gymnura japonica -Schlegal, 1850), Banded eagle ray (Aetomylaeus nichofii -Blyth, 1860),White spotted eagle ray (Aetobatus narinari -Euphrasen, 1790), Rough cow nose ray (Rhinoptera adspersa -Valenciennes in Muller and Henle, 1841), Javanese cow nose ray (Rhinoptera javanica -Muller and Henle, 1841), Lesser devil ray (Mobula kuhlii- Valenciennes, in Muller and Henle,1841) and Japanese devil ray (Mobula japonica -Miiller and Henle, 1841). Among the shark species, Milk shark (Rhizoprionodon acutus), Spade nose shark (Scoliodon laticaudus) & Scalloped hammerhead shark (Sphyrna lewini) were dominantly exploited and Grey sharp nose shark (Rhizoprionodon oligolinx) & Soft tail shark (Carcharhinus sorrah) are rarely exploited. And belong to ray species Brown whip ray(Himantura uarnacoides), Leopard whip(Himantura undulata), Giant shovelnose ray(Rhinobatos typus), Japanese devil ray(Mobula japonica), Japanese butterfly ray(Gymnura japonica), Rough cow nose ray(Rhinoptera adspersa), Banded eagle ray Aetomylaeus nichofii) & Dwarf whip ray(Himantura walga) were prominently landed and Pink whip ray (Himantura fai), Tube mouth whip ray (Himantura lobistoma), White spotted eagle ray (Aetobatus narinari) & Club nose guitar fish (Rhinobatos thouin ) were rarely found. Key Words: Sharks, rays, species, landing volumes, artisanal and industrial fishing

As part of conservation means, ecotourism on shark watching activities has been popular for the last 10 – 25 years. Achieving rank fourth in the shark tourism world, shark watching tourism in Indonesia begins to play as an economically important for gross national products (GDPs). Morotai, as one of the prominent shark diving and shark research site in Indonesia is became popular in recent years. However, the precise number of blacktip reef shark living in Morotai’s most famous dive site, blacktip point is unknown. The knowledge of shark individual marking and their number is important for developing ecological assessment, shark diving carrying capacity, and shark behavior observation. DOV (Diver Operated Video) is employed to visually identify the blacktip reef shark’s fin marking, its patterns and its changes over time. Analysis of hundreds of photographs and video of the Carcharhinus melanopterus during SCUBA diving – from February 2015 to March 2019 – reveals the precise number of these blacktip reef shark living in the proximity of blacktip point area. Study also shows that the photo identification shark fin’s natural marking can be used effectively to recognize unique individual of blacktip reef shark.As part of conservation means, ecotourism on shark watching activities has been popular for the last 10 – 25 years. Achieving rank fourth in the shark tourism world, shark watching tourism in Indonesia begins to play as an economically important for gross national products (GDPs). Morotai, as one of the prominent shark diving and shark research site in Indonesia is became popular in recent years. However, the precise number of blacktip reef shark living in Morotai’s most famous dive site, blacktip point is unknown. The knowledge of shark individual marking and their number is important for developing ecological assessment, shark diving carrying capacity, and shark behavior observation. DOV (Diver Operated Video) is employed to visually identify the blacktip reef shark’s fin marking, its patterns and its changes over time. Analysis of hundreds of photographs and video of the Carcharhinus melanopterus during SCUBA diving – from February 2015 to March 2019 – reveals the precise number of these blacktip reef ...

Short-term shifts of stable isotope (δ13C, δ15N) values in juvenile sharks within nursery areas suggest rapid shifts in energy pathways

Wound healing is important for sharks from the earliest life stages, for example, as the 'umbilical scar' in viviparous species heals, and throughout adulthood, when sharks can incur a range of external injuries from natural and anthropogenic sources. Despite anecdotal accounts of rapid healing in elasmobranchs, data regarding recovery and survival of individuals from different wound or injury types has not been systematically collected. The present study documented: (i) 'umbilical scar' healing in wild-caught, neonatal blacktip reef sharks while being reared for 30 days in flow-through laboratory aquaria in French Polynesia; (ii) survival and recovery of free-swimming blacktip reef sharks in Australia and French Polynesia following a range of injuries; and (iii) long-term survival following suspected shark-finning activities. Laboratory monitoring, tag-recapture records, telemetry data and photo-identification records suggest that blacktip reef sharks have a high capacity to survive and recover from small or even large and severe wounds. Healing rates, recovery and survival are important factors to consider when assessing impacts of habitat degradation and fishing stress on shark populations. The present study suggests that individual survival may depend more on handling practices and physiological stress rather than the extent of physical injury. These observations also contribute to discussions regarding the ethics of tagging practices used in elasmobranch research and provide baseline healing rates that may increase the accuracy in estimating reproductive timing inferred from mating scars and birth dates for neonatal sharks based on umbilical scar healing status.

The coexistence of ecologically and morphologically similar species is often facilitated by the partitioning of ecological niches. While subordinate species can reduce competition with dominant competitors through spatial and/or trophic segregation, empirical support from wild settings, particularly those involving large-bodied taxa in marine ecosystems, are rare. Shark nursery areas provide an opportunity to investigate the mechanisms of coexistence. We used experimental and field studies of sympatric juvenile sharks (blacktip reef shark, Carcharhinus melanopterus; sicklefin lemon shark, Negaprion acutidens) to investigate how competitive ability influenced realized niches at St. Joseph Atoll, Seychelles. Captive trials revealed that sicklefin lemon sharks were dominant over blacktip reef sharks, consistently taking food rewards. In the field, blacktip reef sharks were captured over a broader area than sicklefin lemon sharks, but daily space use of actively tracked sharks showed a high degree of overlap across microhabitats. While stomach contents analysis revealed that blacktip reef shark diets included a broader range of prey items, stable isotope analysis demonstrated significantly higher mean δ13C values for sicklefin lemon sharks, suggesting diverging dietary preferences. Overall, our results matched theoretical predictions of subordinate competitors using a greater range of habitats and displaying broader feeding niches than competitively dominant species. While separating the realized and fundamental niche of marine predators is complicated, we provide evidence that resource partitioning is at least partially driven by interspecific competition.

As a matter of fact, Araucaria angustifolia populations occur predominately in small and isolated stands; only a minor number of continuous natural forests of this dioecious wind-pollinated coniferous tree species remain. To implement reasonable conservation, breeding and restorations program it is necessary to have the knowledge of pollen dispersal distance and fine-scale genetic structure. In this paper, levels and dispersion distance of pollen and spatial genetic structure of A. angustifolia were investigated in a 14 ha transect in a continuous forest in Parana State, Brazil. Analyses have been performed by the use of eight microsatellite loci, paternity and TwoGener approaches, and spatial autocorrelation analysis. In transect, 52 male and 56 female adult trees were mapped and genotyped, together with 190 seeds. In the present transect, A. angustifolia show spatial genetic structure at distances up to 75 m. Paternity analysis indicated that 54% of seeds were fertilized by pollen from trees outside the transect. The calculated average pollination distance within transect was 102 and 98 m based on the paternity analysis and TwoGener analysis, respectively. We found a significant pollen gene pool structure across seed-trees ( \(\widehat\Phi _{ft} = 0.078\), P 100 m) inside the continuous forest. However, the high proportion occurs in short-distance producing biparental and correlated mating as well as reducing the variance effective size.

Refining the ecological role of stingrays in coral reef ecosystems

Commercial and recreational fisheries around the world typically target specific catch species, but often capture other species incidentally, some of which are retained (byproduct) and others are discarded (bycatch). This incidental fisheries capture is a major threat to global elasmobranch (shark and ray) populations because bycaught animals can die during capture or post-release. Furthermore, their life history traits of slow growth, late maturity, and low fecundity put elasmobranchs at generally greater ecological risk of overexploitation than bony fish species. Although the potentially deleterious effects of incidental capture are raising conservation and sustainability concerns, factors influencing the immediate and post-release mortality rates of elasmobranch discards are not fully understood. Accordingly, a greater understanding of the factors affecting these mortality rates is necessary to develop fisheries management strategies that reduce the detrimental effects of fisheries capture on elasmobranch bycatch. This study aimed to address these knowledge gaps by investigating environmental, operational, and physiological factors contributing to immediate and post-release mortality in elasmobranchs. This was achieved by a combination of meta-analysis, field sampling, laboratory analysis, and modelling of capture data. Species-specific analyses were conducted on log-book and empirical data and revealed that several factors influenced immediate mortality rates in longline-caught sharks, including capture duration (bronze whalers), sea surface temperature (blue sharks), fishing location(blue sharks, tiger sharks), regulatory period (blue sharks, tiger sharks), target catch (blue sharks, tiger sharks), and an interaction effect between regulatory period and fishing location(blue sharks). Following gillnet capture, total length was the only factor examined that affected immediate mortality rates (blacktip reef sharks). To determine how contrasting respiratory strategies and fishing gear types can influence mortality, I conducted a multi-species meta-analysis on published elasmobranch immediate and post-release mortality rates. This meta-analysis revealed that elasmobranch immediate and post-release mortality are more likely during trawl and gillnet capture than longline capture, and that obligate ram-ventilating species are particularly susceptible to mortality. Hematological analyses showed that high concentrations of plasma lactate and potassium were correlated with poor capture condition in bronze whalers. As high plasma lactate and potassium concentrations are associated with struggling and insufficient oxygen intake during capture, this result further demonstrated the vulnerability of obligate ram-ventilating sharks to immediate mortality caused by fisheries capture. My results suggest that fisheries management strategies such as reductions in allowable soak times and the mandatory use of circle hooks can effectively reduce immediate mortality rates in several shark species, such as bronze whalers and blue sharks. Following a reduction in immediate mortality rates, fisheries management strategies that promote the rapid release of bycatch can be effective. However, several elasmobranch species and groups have inherently high immediate mortality rates following capture (e.g. nervous sharks and juvenile blacktip reef sharks). Given the high immediate mortality rates of these species, catch and release is not a viable conservation strategy. Fisheries regulations designed to protect species with high immediate and post-release mortality rates should instead minimize the likelihood of interactions with fishing gear (e.g. gear modifications such as changing minimum allowable gillnet mesh size or spatio-temporal closures). The strategies recommended can be implemented to reduce the pressures global fisheries exert on elasmobranch bycatch populations.

Information on the spatial ecology of reef sharks is critical to understanding life-history patterns, yet gaps remain in our knowledge of how these species move and occupy space. Previous studies have focused on offshore reefs and atolls with little information available on the movement and space use of sharks utilising reef habitats closer to shore. Cross-shelf differences in physical and biological properties of reefs can alter regional ecosystem processes resulting in different movement patterns for resident sharks. Passive acoustic telemetry was used to examine residency, space use and depth use of 40 blacktip reef sharks, Carcharhinus melanopterus, on an inshore reef in Queensland, Australia, and assess temporal or biological influences. All sharks showed strong site-attachment to inshore reefs with residency highest among adult females. Sharks exhibited a sex-based, seasonal pattern in space use where males moved more, occupied more space and explored new areas during the reproductive season, while females utilised the same amount of space throughout the year, but shifted the location of the space used. A positive relationship was also observed between space use and size. There was evidence of seasonal site fidelity and long-distance movement with the coordinated, annual migration of two adult males to the study site during the mating season. Depth use was segregated with some small sharks occupying shallower depths than adults throughout the day and year, most likely as refuge from predation. Results highlight the importance of inshore reef habitats to blacktip reef sharks and provide evidence of connectivity with offshore reefs, at least for adult males.

Identification of a ghrelin-like peptide in two species of shark, Sphyrna lewini and Carcharhinus melanopterus

Sharks play important functional roles in coral reef ecosystems. Studying reef shark populations’ spatial ecology also contributes important data for effective conservation planning. The purpose of this study was to define the home range of neonatal blacktip reef sharks (Carcharhinus melanopterus) around Moorea, French Polynesia, and compare estimates using both mark-recapture surveys and active acoustic telemetry. Mark-recapture surveys produced a minimum convex polygon (MCP) of 0.07 km2 that was significantly larger than the MCP derived from acoustic telemetry (0.02 km2). Acoustic telemetry produced 50 and 95% kernel utilization densities that were smaller (0.02 km2) and larger (0.14 km2) than home range estimates from mark-recapture surveys, respectively. Home range estimates from this study are the smallest that have been documented for neonatal blacktip reef sharks, possibly owing to the study sites’ proximity to deep channels. Mark-recapture and active acoustic telemetry are complementary approaches worthy of consideration where passive telemetry is impractical.