Colin A. Simpfendorfer

• PhD
• Adjunct Professor at James Cook University

Sharks, rays and chimeras (class Chondrichthyes; herein ‘sharks’) today face possibly the largest crisis of their 420 million year history. Tens of millions of sharks are caught and traded internationally each year, many populations are overfished to the point where global catch peaked in 2003, and a quarter of species have an elevated risk of exti...

Decades of overexploitation have devastated shark populations, leaving considerable doubt as to their ecological status1,2. Yet much of what is known about sharks has been inferred from catch records in industrial fisheries, whereas far less information is available about sharks that live in coastal habitats³. Here we address this knowledge gap usi...

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes—sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species...

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species-level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at...

The global shark meat trade entails diverse and tangled challenges, spanning from issues surrounding traceability and sustainability to its international dimension, involving numerous nations. This study analyzes two decades of shark product trade data using network analysis to assess the role of key trading nations. Results reveal key players in t...

The true state of ocean biodiversity is difficult to assess, and there are few global indicators to track the primary threat of overfishing. We calculated a 50-year Red List Index of extinction risk and ecological function for 1199 sharks and rays and found that since 1970, overfishing has halved their populations and their Red List Index has worse...

Context Coastal habitats function as shark nursery areas; however, coastal habitats can experience extreme variation in abiotic conditions and are susceptible to human disturbances. Aims Drivers of abundance were tested within a shark nursery-area system in two populations of reef-associated neonate sharks, namely, blacktip reef sharks (Carcharhin...

Many citizen scientists are highly motivated to help address the current extinction crisis. Their work is making valuable contributions to protecting species by raising awareness, identifying species occurrences, assessing population trends, and informing direct management actions, such as captive breeding. However, clear guidance is lacking about...

In ecosystems, sharks can be predators, competitors, facilitators, nutrient transporters, and food. However, overfishing and other threats have greatly reduced shark populations, altering their roles and effects on ecosystems. We review these changes and implications for ecosystem function and management. Macropredatory sharks are often disproporti...

Acoustic telemetry has been used to monitor the movement of aquatic animals in a broad range of aquatic environments. Despite their importance, mangrove habitats are understudied for the spatial ecology of elasmobranchs, with acoustic telemetry rarely used inside mangrove habitats. One reason for this may be a general assumption that acoustic signa...

Many shark populations are in decline around the world, with severe ecological and economic consequences. Fisheries management and marine protected areas (MPAs) have both been heralded as solutions. However, the effectiveness of MPAs alone is questionable, particularly for globally threatened sharks and rays (‘elasmobranchs’), with little known abo...

Background Acoustic telemetry has become a fundamental tool to monitor the movement of aquatic species. Advances in technology, in particular the development of batteries with lives of > 10 years, have increased our ability to track the long-term movement patterns of many species. However, logistics and financial constraints often dictate the locat...

The deep ocean is the last natural biodiversity refuge from the reach of human activities. Deepwater sharks and rays are among the most sensitive marine vertebrates to overexploitation. One-third of threatened deepwater sharks are targeted, and half the species targeted for the international liver-oil trade are threatened with extinction. Steep pop...

A wide variety of species depend on mangroves, making them essential habitats in tropical and subtropical regions. While the function of mangrove habitat is well studied for taxa such as teleost fishes, limited attention has been directed towards their value for elasmobranchs. Here, we review the available literature on how and why elasmobranchs us...

Foraging is a behavioural process and, therefore, individual behaviour and diet are theorized to covary. However, few comparisons of individual behaviour type and diet exist in the wild. We tested whether behaviour type and diet covary in a protected population of Atlantic cod, Gadus morhua. Working in a no‐take marine reserve, we could collect dat...

River sharks (Glyphis spp.) and some sawfishes (Pristidae) inhabit riverine environments, although their long‐term habitat use patterns are poorly known. We investigated the diadromous movements of the northern river shark (Glyphis garricki), speartooth shark (Glyphis glyphis), narrow sawfish (Anoxypristis cuspidata), and largetooth sawfish (Pristi...

Habitat associations and preferences of animals can be inferred from how long they remain within close proximity to a certain location. The residency index (RI) is a common metric used in acoustic telemetry studies to assess how long an individual spends in an area. However, the methods used to calculate RI can affect the interpretation of telemetr...

Some sharks and rays are subject to fisheries catch and international trade regulations. However, the Guitarfishes (family Rhinobatidae) are a highly threatened group with minimal regulations. The true volume of Guitarfishes in international trade is underestimated and masked by substantial underreporting of catch and the use of broad commodity cod...

A global survey of coral reefs reveals that overfishing is driving resident shark species toward extinction, causing diversity deficits in reef elasmobranch (shark and ray) assemblages. Our species level analysis revealed global declines of 60 to 73% for five common resident reef shark species and that individual shark species were not detected at...

Gillnets are size‐selective fishing gears commonly used by industrial and small‐scale fishers, so understanding selectivity can aid fisheries management by identifying suitable mesh sizes to optimize catches of target species while reducing bycatch. Few size selectivity parameters have been estimated for sharks, with even fewer for rays. Size selec...

Most of the international trade in fins (and likely meat too) is derived from requiem sharks (family Carcharhinidae), yet trade in only two of the 56 species is currently regulated. Here, we quantify catch, trade, and the shortfall in national and regional fisheries management (M-Risk) for all 56 requiem shark species based on 831 assessments acros...

Overfishing is the most significant threat facing sharks and rays. Given the growth in consumption of seafood, combined with the compounding effects of habitat loss, climate change, and pollution, there is a need to identify recovery paths, particularly in poorly managed and poorly monitored fisheries. Here, we document conservation through fisheri...

Sharks and rays are key functional components of coral reef ecosystems, yet many populations of a few species exhibit signs of depletion and local extinctions. The question is whether these declines forewarn of a global extinction crisis. We use IUCN Red List to quantify the status, trajectory, and threats to all coral reef sharks and rays worldwid...

The bottlenose wedgefish Rhynchobatus australiae has experienced substantial population declines throughout its range. However, there is a lack of life history information (age, growth, and maturity) available for this species to inform conservation and management efforts. A total of 48 R. australiae samples were purchased from 2 fishing ports in S...

Marine protected areas (MPAs) are key tools in addressing the global decline of sharks and rays, and marine parks and shark sanctuaries of various configurations have been established to conserve shark populations. However, assessments of their efficacy are compromised by inconsistent terminology, lack of standardized approaches to assess how MPAs...

Shark depredation is a complex social-ecological issue that affects a range of fisheries worldwide. Increasing concern about the impacts of shark depredation, and how it intersects with the broader context of fisheries management, has driven recent research in this area, especially in Australia and the United States. This review synthesises these r...

This document has been submitted by the Government of Panama * , in relation to Prop 37, 38, 39 and 40, and agenda item 65 and 87.2 Effective policy should be informed by rigorous evidence. This is particularly true for binding intergovernmental agreements like the Convention on International Trade in Endangered Species of Wild Flora and Fauna (CIT...

Unifying models have shown that the amount of space used by animals (e.g., activity space, home range) scales allometrically with body mass for terrestrial taxa; however, such relationships are far less clear for marine species. We compiled movement data from 1,596 individuals across 79 taxa collected using a continental passive acoustic telemetry...

This is an updated pre-print to include ALL members of the Carcharhinidae family. The new abstract is: Most of the international trade in fins (and likely meat too) is derived from requiem sharks (family Carcharhinidae), yet trade in only two of the 56 species is currently regulated. Here, we quantify catch, trade, and the shortfall in national an...

Some sharks and rays are subject to fisheries catch and international trade regulations. However, the Guitarfishes (family Rhinobatidae) are a highly threatened group with minimal regulations. Substantial underreporting of catch and broad commodity codes for traded products are masking the true volume of Guitarfishes included in international trade...

Area-based conservation is essential to safeguard declining biodiversity. Several approaches have been developed for identifying networks of globally important areas based on the delineation of sites or seascapes of importance for various elements of biodiversity (e.g., birds, marine mammals). Sharks, rays, and chimaeras are facing a biodiversity c...

Fisheries management is essential to guarantee sustainable capture of target species and avoid undesirable declines of incidentally captured species. A key challenge is halting and reversing declines of shark and ray species, and specifically assessing the degree to which management is sufficient to avoid declines in relatively data‐poor fisheries....

One third of chondrichthyan species (sharks, rays, and chimeras) are threatened with extinction, mainly due to unsustainable fishing. Large accessible international markets for meat and luxury products like dried fins can help drive overfishing by encouraging targeted capture or retention of high-value export species. If this is common, then specie...

While some sharks are subject to trade regulations, much of the international trade in fins (and likely meat too) is derived from requiem sharks (Carcharhinus spp). Here, we quantify catch, trade, and the shortfall in fisheries management (M-Risk) for 18 requiem shark species based on 230 assessments across 27 countries and four Regional Fisheries...

Fisheries management is essential to guarantee sustainable capture of target species and avoid undesirable declines of incidentally captured species. A key challenge is halting and reversing declines of shark and ray species, and specifically assessing the degree to which management is sufficient to avoid declines in relatively data-poor fisheries....

The repeated evolution of the same traits in distantly related groups (convergent evolution) raises a key question in evolutionary biology: do the same genes underpin convergent phenotypes? Here we explore one such trait, viviparity (live birth), which qualitative studies suggest may indeed have evolved via genetic convergence. There are >150 indep...

Abstract Environmental DNA (eDNA) methods are increasingly applied in the marine environment to identify species and community structure. To establish widely applicable eDNA techniques for elasmobranchs, we used the Critically Endangered largetooth sawfish (Pristis pristis Linnaeus, 1758) as a model species for: (1) assessing eDNA particle size dis...

Shark placentae are derived from modifications to the fetal yolk sac and the maternal uterine mucosa. In almost all placental sharks, embryonic development occurs in an egg capsule that remains intact for the entire pregnancy, separating the fetal tissues from the maternal tissues at the placental interface. Here, we investigate the structure and p...

Over the past 4 decades there has been a growing concern for the conservation status of elasmobranchs (sharks and rays). In 2002, the first elasmobranch species were added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Less than 20 yr later, there were 39 species on Appendix II and 5 o...

Nursery areas are crucial for many elasmobranch species, providing advantages such as increased access to prey and reduced predation risk. This study investigated the trophic interactions of two juvenile stingray species within a coastal communal nursery using stable isotope analysis. Muscle, plasma and red blood cells samples were taken from the m...

Assessing the feeding patterns of sharks provides insight into ecological interactions. Three coastal sharks are common by-catch in the Gulf of Papua prawn fishery in Papua New Guinea. The diets of Carcharhinus coatesi (n = 122), Rhizoprionodon acutus (n = 83) and Rhizoprionodon taylori (n = 177) were assessed using stomach content analysis. Teleos...

• Shark-like rays (Order Rhinopristiformes) are among the most threatened families of marine fish, yet little is known about their populations. These rays are normally taken as opportunistic catch in fisheries targeting other species and are thus poorly reported. One exception is the Indonesian tangle net fishery, which targets shark-like rays. • M...

The scale and drivers of marine biodiversity loss are being revealed by the International Union for Conservation of Nature (IUCN) Red List assessment process. We present the first global reassessment of 1,199 species in Class Chondrichthyes—sharks, rays, and chimeras. The first global assessment (in 2014) concluded that one-quarter (24%) of species...

The conservation of threatened elasmobranchs in tropical regions is challenging due to high local reliance on aquatic and marine resources. Due primarily to fishing pressure, river sharks (Glyphis) and sawfishes (Pristidae) have experienced large population declines in the Indo-Pacific. Papua New Guinea (PNG) may offer a refuge for these species, a...

Blue sharks (Prionace glauca) are recognised as one of five key pelagic shark species in the Western Central Pacific Ocean (WCPO) due to their frequent incidental catch in tuna and billfish longline fisheries. Given their importance in the region, the aim of this study was to investigate the life history of this species for use in future population...

• One-third of all elasmobranch species currently known to occur in Papua New Guinea are taken as bycatch in the Gulf of Papua trawl fishery. An ecological risk assessment was conducted on the 16 species of sharks and 23 species of rays caught by the fishery. • Eight species were classified to be at low risk, 28 species were at medium risk while th...

Acoustic telemetry (AT) is a rapidly evolving technique used to track the movements of aquatic animals. As the capacity of AT research expands it is important to optimize its relevance to management while still pursuing key ecological questions. A global review of AT literature revealed region-specific research priorities underscoring the breadth o...

• Sawfish (Pristidae) are considered to be among the most threatened families of elasmobranch (sharks and rays). There is a need to gather information on the status of poorly known sawfish populations to assist in global recovery initiatives. • This study used interviews with local fishers to investigate the presence of sawfish in southern Papua Ne...

Human-wildlife conflicts are a growing phenomenon globally as human populations expand and wildlife interactions become more commonplace. While these conflicts have been well-defined in terrestrial systems, marine forms are less well-understood. As concerns grow for the future of many shark species it is becoming clear that a key to conservation su...

Understanding movement patterns underlies effective management and conservation measures. The current study summarises the main findings from a tagging program of Western Australian sharks to provide insights into the movement patterns of the main commercial shark species: dusky (Carcharhinus obscurus), sandbar (C. plumbeus), gummy (Mustelus antarc...

Few studies have considered linkages of mobile predators across large spatial scales despite their significant and often critical role in maintaining ecosystem function and health. The bull shark (Carcharhinus leucas) is a large, widespread coastal predator capable of undertaking long-range movement, but there is still limited understanding of intr...

The eastern shovelnose ray (Aptychotrema rostrata) is a medium-sized coastal batoid endemic to the eastern coast of Australia. It is the most common elasmobranch incidentally caught in the Queensland east coast otter trawl fishery, Australia’s largest penaeid-trawl fishery. Despite this, age and growth studies on this species are lacking. The prese...

Delineation of population structure (i.e. stocks) is crucial to successfully manage exploited species and to address conservation concerns for threatened species. Fish migration and associated movements are key mechanisms through which discrete populations mix and are thus important determinants of population structure. Detailed information on fish...

Temperature and oxygen limit the distribution of marine ectotherms. Haematological traits underlying blood-oxygen carrying capacity are thought to be correlated with thermal tolerance in certain fishes, and this relationship is hypothesised to be explained by oxygen supply capacity. We tested this hypothesis using reef shark neonates as experimenta...

• Pressures on coastal ecosystems are increasing and aquatic species that are restricted to these habitats are facing the threat of extinction. However, the true extent of many threatened and rare aquatic species, especially elasmobranchs, remains unclear due to high levels of data deficiency and poor efficacy of traditional survey methods. Sawfish...

Introduction Viviparity (live-birth) has evolved from oviparity (egg-laying) multiple times in sharks. While most transitions from oviparity to viviparity have resulted in non-placental forms of viviparity, some sharks develop a yolk sac placenta during pregnancy. The Australian sharpnose shark (Rhizoprionodon taylori) is a placental species that s...

The tiger shark (Galeocerdo cuvier) is believed to be a fast-growing shark that has shown regional variation in growth. Vertebrae samples were taken from 124 tiger sharks (60 females, 38 males, 26 of unknown sex) caught in Western Australia (WA) from 1994 to 1998. Samples were aged using standard vertebral ageing techniques, and the data were used...

Proximity and size of the nearest market (‘market gravity’) have been shown to have strong negative effects on coral reef fish communities that can be mitigated by the establishment of closed areas. However, moray eels are functionally unique predators that are generally not subject to targeted fishing and should therefore not directly be affected...

Overfishing is the primary cause of marine defaunation, yet declines in and increasing extinction risks of individual species are difficult to measure, particularly for the largest predators found in the high seas. Here we calculate two well-established indicators to track progress towards Aichi Biodiversity Targets and Sustainable Development Goal...

Coastal sharks can use shallow, nearshore habitats as nursery areas, which is a behaviour that may increase fitness. The ecological benefits of shark nursery areas are well studied; yet the physiological mechanisms that enable sharks to exploit coastal habitats, especially those that experience extreme and dynamic temperatures, remain understudied....

Baited remote underwater video stations (BRUVS) are increasingly being used to evaluate and monitor reef communities. Many BRUVS studies compare multiple sites sampled at single time points that may differ from the sampling time of another site. As BRUVS use grows in its application to provide data relevant to sustainable management, marine protect...

Abstract Ocean warming and acidification act concurrently on marine ectotherms with the potential for detrimental, synergistic effects; yet, effects of these stressors remain understudied in large predatory fishes, including sharks. We tested for behavioural and physiological responses of blacktip reef shark (Carcharhinus melanopterus) neonates to...

Achieving fisheries compliance is challenging in contexts where enforcement capacity is limited and the incentives for rule-breaking are strong. This challenge is exemplified in Myanmar, where an active shark fishery exists despite a nationwide ban on targeted shark fishing. We used the Kipling method (5W1H) to gather a complete story of non-compli...

Stingrays are a diverse and widespread group of elasmobranchs. Despite their ecological and economical importance, many aspects of stingray ecology remain poorly understood. Few studies have examined fine-scale movements of juvenile stingrays within nursery areas. This study aimed to examine diel movement patterns in juvenile mangrove whiprays (Uro...

An Amendment to this paper has been published and can be accessed via a link at the top of the paper.

There is increasing concern about the conservation and sustainable use of hammerhead sharks nationally and globally, with documented declines in many parts of their range. Several hammerhead species have been recently added to international conventions such as the Convention on International Trade in Endangered Species (CITES), and the Convention o...

Animal movement has direct applications in spatial management and conservation planning, yet it is rarely taken into account for the design of natural protected areas. For instance, reef shark species are thought to benefit from marine protected area networks, even though their movement behaviour remains poorly characterized. Poor understanding of...

Size limits are a common fisheries management strategy that are applied to many fisheries and species. Most size limits use a minimum legal size to protect adult fish as per the ‘reproduce at least once’ paradigm, where stock collapse becomes impossible if every adult can produce one spawner prior to harvest. These approaches can be useful in fishe...

Thermal dependence of growth and metabolism can influence thermal preference and tolerance in marine ectotherms, including threatened and data-deficient species. Here, we quantified the thermal dependence of physiological performance in neonates of a tropical shark species (blacktip reef shark, Carcharhinus melanopterus) from shallow, nearshore hab...

Effective sampling of marine communities is essential to provide robust estimates of species richness and abundance. Baited Remote Underwater Video Stations (BRUVS) are a useful tool in assessment of fish assemblages, but research on the optimal sampling period required to record common and rare elasmobranch species is limited. An appropriate ‘soak...

Shark abundances are decreasing on many coral reefs, but the ecosystem effects of this loss are poorly understood. Rays are a prevalent mesopredator in tropical coral reef ecosystems that are preyed upon by top predators like sharks. Studies have suggested reduced predator abundances lead to increases in mesopredator abundance (mesopredator release...

Marine Protected Areas (MPAs) have the potential to support small-scale fishers in managing their resources. However, a general failure to consider the varying levels of vulnerability of fishers has resulted in MPAs that, often unintentionally, adversely impact small-scale fishers. Furthermore, when fishers lack the capacity to adapt to MPA-related...

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 shor...

• The process of understanding the rapid global decline of sawfishes (Pristidae) has revealed great concern for their relatives, the wedgefishes (Rhinidae) and giant guitarfishes (Glaucostegidae), not least because all three families are targeted for their high‐value and internationally traded ‘white’ fins. • The objective of this study was to asse...

The use of turtle excluder devices (TEDs) has resulted in fewer elasmobranchs (i.e. sharks and rays) caught in tropical penaeid-trawl fisheries. However, very few studies in the primary literature have quantified the effects of various TED design aspects affecting the escape of elasmobranchs. Data collected by observers on board commercial trawlers...

Risks to deepwater chondrichthyans (sharks, rays, and chimaeras) from fishing are poorly understood, particularly in areas beyond national jurisdiction. We adapted productivity-susceptibility analysis (PSA) and sustainability assessment for fishing effects (SAFE) to assess the vulnerability of 173 deepwater chondrichthyans to various demersal fishi...

Elasmobranchs play an important role in the functioning of marine ecosystems and top-down control in food webs. However, overexploitation threatens elasmobranch populations worldwide. Indonesia is currently the leading elasmobranch fishing nation, yet elasmobranch management in Indonesia is challenging because of the paucity of data on elasmobranch...

Stingrays are thought to play important ecological roles in coral reef ecosystems. However, little is known about juvenile stingray movement patterns and habitat use in coral reefs. This study used active acoustic telemetry to determine fine-scale diel movement patterns and habitat use of juvenile cowtail stingrays (Pastinachus ater) in a coral ree...

Embryos of the viviparous dwarf ornate wobbegong shark (Orectolobus ornatus) develop without a placenta, unattached to the uterine wall of their mother. Here, we present the first light microscopy study of the uterus of O. ornatus throughout pregnancy. At the beginning of pregnancy, the uterine luminal epithelium and underlying connective tissue be...

No-take marine protected areas (MPAs) are a commonly applied tool to reduce human fishing impacts on marine and coastal ecosystems. However, conservation outcomes of MPAs for mobile and long-lived predators such as sharks are highly variable. Here, we use empirical animal tracking data from 459 individual sharks and baited remote underwater video s...