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In International Law of Sharks, the authors critically analyse current legal frameworks for this important group of species. They explore obstacles, options and opportunities to improve the conservation status of sharks and draw out broader lessons for marine species.

The silky shark (Carcharhinus falciformis) is the most common shark landed in Indonesian waters, including in the Indian Ocean. However, even though they are frequently caught, there is a lack of information on the population and abundance of silky sharks in the Indian Ocean. Cilacap and Tanjung Luar are two of Indonesia’s shark fishery hotspots, both located on the edge of the Indian Ocean, which is a part of the Indonesian Fisheries Management Area (FMA) 573. The fishers from both places usually have fishing grounds in that particular fisheries management area. This research aims to update the abundance, and to investigate the factors, which influence catches of silky shark in the FMA 573 based on monthly enumeration during 2015–2016. This study found that standardized catch-per-unit-effort (CPUE) or abundance indices of silky shark in the Indonesian FMA 573 increased from 2015 to 2016. We suggested that fish immigration and decreasing fishing pressure may affect the fish abundance. Fisheries management is required to regulate the fishing pressure, such as controlling the number of boats/licenses and the number of trips or fishing gear, as well as initializing spatial and temporal fishing closure.

The Australian gummy shark Mustelus antarcticus is distributed across southern and eastern Australian waters and is the main target of a large shark fishery. Commercial harvest of the species is considered sustainable based on biomass estimates that show recovery from past overexploitation. However, the effective population size and genetic-based assessments of stock structure remain unresolved. We evaluated the genetic structure and effective population size (Nₑ) of the gummy shark using genome-wide single nucleotide polymorphisms. We found genetic divergence between individuals from the east coast and those along the south coast, resulting in 2 discrete populations with signatures of adaptive divergence. Spatial analyses revealed widespread gene flow within each of these populations, with some evidence for mild isolation-by-distance observed using individual-based tests. Demographic modelling of each population showed a comparatively rapid decline of Nₑ in the most recent past compared to more historical projections, with evidence that such declines have occurred to the point where genetic variation could be at risk. The identification of 2 divergent populations of gummy shark suggests that management should consider each individually to ensure the long-term sustainability of the species.

The expanding shark fin market has resulted in intensive global shark fishing and with 90% of teleost fish stocks over-exploited, sharks have become the most lucrative target. As predators, they have high ecological value, are sensitive to fishing pressure, and are in decline, but the secretive nature of the fin trade and difficulties obtaining relevant data, obscure their true status. In consumer countries, shark fin is a luxury item and rich consumers pay high prices with little interest in sustainability or legal trade. Thus, market demand will continue to fuel the shark hunt and those accessible to fishing fleets are increasingly endangered. Current legal protections are not working, as exemplified by the case of the shortfin mako shark, and claims that sharks can be sustainably fished under these circumstances are shown to be misguided. In the interests of averting a catastrophic collapse across the planet’s aquatic ecosystems, sharks and their habitats must be given effective protection. We recommend that all sharks, chimaeras, manta rays, devil rays, and rhino rays be protected from international trade through an immediate CITES Appendix I listing. However, a binding international agreement for the protection of biodiversity in general is what is needed.

The relationship between humans and sharks has existed for a long time, especially in shark utilization. Tanjung Luar is the largest shark and ray fishery in West Nusa Tenggara. The community’s dependence on shark and ray resources is very high in this location. This study aims to look closely at the performance of shark target fishing and utilization and to measure the acceptance of shark fishers to regulation. Data were collected in November 2021 using questionnaires, in-depth interviews, and snowball techniques. There were 15 respondents: eight fishers who caught sharks, three collectors that bought whole sharks directly from the fishers, and four processors who processed shark bodies into products. The results showed that the most extensive fishing grounds were the Southern Nusa Tenggara (60%), followed by Kangean (20%), Sulawesi (13%, and Savu Sea (7%).) The fishing gear used is drift longlines, with an average fishing duration of 15 days. The largest catch is usually obtained from June to September. There are 21 shark-targeting vessels, five collectors, and several shark body processors. Sharks provide a protein source and livelihood. This study revealed the history behind shark fishing by Tanjung Luar community, shark utilizations and fishers’ responses to the local government regulation on shark fishing management.

Information on broad-scale movements is required for spatial management and improved conservation of large marine predators. We studied the mobility of the 4 most commercially important shark species of Western Australia (WA) using a network of acoustic receivers. Dusky sharks Carcharhinus obscurus showed very high mobility across WA. Sandbar C. plumbeus, gummy Mustelus antarcticus and particularly whiskery Furgaleus macki sharks were less mobile but can still move over long distances. The proportion of monitored time within different fisheries management zones varied among species. Dusky sharks showed the highest interconnectivity among these zones, reflecting the high mobility and complex movement patterns of this species. Sandbar, gummy and whiskery sharks followed, showing less movement among zones. Our study demonstrates how acoustic telemetry can be used to determine the movement patterns of species at the scale of fisheries management and therefore contribute to improved management and sustainability.

Fisheries are complex social-ecological systems, where managers struggle to balance the socio-economic interests of fishing communities with the biology and ecology of fisheries species. Spatial closures are a popular measure to address conservation and fisheries management goals, including the protection of shark populations. However, very little research has been published on the effectiveness of shark-specific closures to protect sharks, or their impacts on fisher behavior. Situated within the global center of tropical marine biodiversity, Indonesia’s shark fishery contributes more to the international shark fin trade than any other nation. Here we evaluate the effect of shark-specific closures on sharks and other species of interest, as well as shark fishers’ responses to losing access to their former fishing grounds. We assessed shark diversity and abundance in an open access zone (OAZ) and two No-Take Zones (NTZs) of a Marine Protected Area within the recently established shark sanctuary in Raja Ampat, Indonesia, where sharks have high monetary value as a tourism attraction. Shark abundance was significantly higher in the privately managed NTZs than in the OAZ. Across all management zones, neither zone size, depth nor reef complexity explained variations in shark abundance, suggesting that governance is the main driver of successful shark conservation areas. These trends were also reflected in species targeted by small-scale reef fisheries, including snappers, emperor, groupers, tunas, mackerels, and large-bodied wrasse and parrotfish. Interviews with shark fishers who lost access to their primary fishing grounds when the shark sanctuary was established showed that while most fishers (88%) knew that sharks were protected in Raja Ampat, many were unsure about the purpose of the sanctuary. Few fishers felt that the agencies implementing fishing bans understood their livelihood needs. We found that shark fishers adapted to the loss of former fishing grounds by shifting fishing effort to other locations or diversifying their livelihoods, including illegal petrol transport. While conserving sharks for tourism can be effective, it may inadvertently result in displacing fishing effort to unprotected regions. We propose that effective shark conservation in Indonesia will need to combine strategic spatial protection with efforts to support livelihood security and diversification.

Prior to burning down in 1906 CE, Point Alones in the Monterey Bay region of Central California was home to one of the largest Chinese fishing communities in the United States of America. Both historical records and the recovery of numerous cartilaginous fish (Chondrichthyes) vertebrae during archaeological excavations of the village indicate sharks were among the taxonomic groups being regularly harvested by its inhabitants. However, as shark vertebrae are difficult to identify past the family-level using conventional morphology-based approaches, our understanding of the Point Alones shark fishery remains incomplete. In this study, we address this issue by using ancient DNA analysis to assign species-level identifications to a sample of 54 shark vertebrae from the site. We successfully amplified a 173 bp fragment of the mitochondrial cytochrome c oxidase I gene from 47 of the 54 analyzed specimens (87.03%). Our results indicate that Tope Shark ( Galeorhinus galeus ; n  = 39) was the primary focus of the site’s shark fishery, with Brown Smooth-Hound ( Mustelus henlei ; n  = 7) and Leopard Shark ( Triakis semifasciata ; n  = 1) also harvested to a lesser extent. All three of these species are found locally in the waters overlying the continental shelf, suggesting Chinese fishers were harvesting sharks from these coastal environments. While some of the sharks caught by fishers from Point Alones were likely being consumed at the village, historical records suggest a significant number of fins from harvested Tope Sharks were also likely being exported to China and other diaspora communities.

As a hotspot of species diversity and fishing pressure, Indonesia is a global priority for the conservation of sharks, rays and their cartilaginous relatives (herein ‘sharks’). The high value marine tourism industry in Indonesia can create economic incentives for protecting and sustainably managing marine ecosystems and species, including sharks. This study estimates the economic value of shark and ray tourism in Indonesia and explores tourist preferences and local community perceptions of the tourism industry to understand the current and potential future role of this industry in shark and ray conservation. We identified 24 shark tourism hotspots across 14 provinces, with primary data collected from 365 tourists and 84 local community members over six case study sites. We use Purchasing Power Parity and travel efforts to extrapolate expenditures to other tourism sites. We estimate that at least 188,931 dedicated or partially dedicated shark tourists visit Indonesia each year. The median annual expenditures of these shark tourists is estimated at USD 22 million (for 2017), accounting for at least 7% of the total USD 1 billion marine tourism revenue in Indonesia in 2017 and 1.45x the value of annual shark exports in the country (inflation-adjusted to 2017 values). If sharks were absent from the surveyed sites, Indonesia’s tourism industry could lose ~ 25% of these dive tourist expenditures. Despite this considerable value, our study indicates a mismatch between the absolute economic value of shark and ray tourism and its role in providing an incentive for conservation. Results from interviews with local communities in or near shark and ray tourism sites indicate that shark fishers are not well placed to receive direct economic benefits from shark and ray tourism. Since overfishing is the primary threat to shark populations, failure to engage with and appropriately incentivise these stakeholders will be detrimental to the success of Indonesia’s shark conservation efforts. If shark populations continue to decline due to insufficient conservation actions, the tourism industry could suffer economic losses from shark and ray tourism of more than USD 121 million per annum by 2027, as well as detrimental impacts on species, marine ecosystems, fisheries and people.

We compared life-history traits and extinction risk of chondrichthyans (sharks, rays and chimaeras), a group of high conservation concern, from the three major marine habitats (continental shelves, open ocean and deep sea), controlling for phylogenetic correlation. Deep-water chondrichthyans had a higher age at maturity and longevity, and a lower growth completion rate than shallow-water species. The average fishing mortality needed to drive a deep-water chondrichthyan species to extinction (