publications

2023

1. High overexploitation risk due to management shortfall in highly traded requiem sharks

   C. Samantha Sherman, Eric D. Digel, Patrick Zubick, and 6 more authors

   Conservation Letters, Feb 2023

   _eprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/conl.12940

   Abs

   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 across 30 countries and four Regional Fisheries Management Organizations (RFMOs). Requiem sharks comprise over half (60%) of the annual reported global Chondrichthyan catch with most species (86%) identified in the international fin trade. Requiem sharks are inadequately managed by fisheries, with an average M-Risk of half (50%) of an ideal score, consequently 70% of species are threatened globally. The high catch and trade volume and shortfall in management of these iconic species require worldwide fisheries management for sustainable catch, supported by full implementation of CITES regulations for international trade of this newly listed family.

2. Conservation successes and challenges for wide-ranging sharks and rays

   Nathan Pacoureau, John Carlson, Holly Kindsvater, and 14 more authors

   Proceedings of the National Academy of Sciences, Jan 2023

   Abs

   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 fisheries management success for 11 coastal sharks in US waters by comparing population trends through a Bayesian state-space model before and after the implementation of the 1993 Fisheries Management Plan for Sharks. We took advantage of the spatial and temporal gradients in fishing exposure and fisheries management in the Western Atlantic to analyze the effect on the Red List status of all 26 wide-ranging coastal sharks and rays. We show that extinction risk was greater where fishing pressure was higher, but this was offset by the strength of management engagement (indicated by strength of National and Regional Plan of Action for sharks and rays). The regional Red List Index (which tracks changes in extinction risk through time) declined in all regions until the 1980s but then improved in the North and Central Atlantic such that the average extinction risk is currently half that in the Southwest. Many sharks and rays are wide-ranging, and successful fisheries management in one country can be undone by poorly regulated or unregulated fishing elsewhere. Our study underscores that well-enforced, science-based management of carefully monitored fisheries can achieve conservation success, even for slow-growing species.

3. Half a century of rising extinction risk of coral reef sharks and rays

   Samantha Sherman, Colin Simpfendorfer, Nathan Pacoureau, and 17 more authors

   Nature Communications, Jan 2023

   Abs

   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 worldwide. Here, we show that nearly two-thirds (59%) of the 134 coral-reef associated shark and ray species are threatened with extinction. Alongside marine mammals, sharks and rays are among the most threatened groups found on coral reefs. Overfishing is the main cause of elevated extinction risk, compounded by climate change and habitat degradation. Risk is greatest for species that are larger-bodied (less resilient and higher trophic level), widely distributed across several national jurisdictions (subject to a patchwork of management), and in nations with greater fishing pressure and weaker governance. Population declines have occurred over more than half a century, with greatest declines prior to 2005. Immediate action through local protections, combined with broad-scale fisheries management and Marine Protected Areas, is required to avoid extinctions and the loss of critical ecosystem function condemning reefs to a loss of shark and ray biodiversity and ecosystem services, limiting livelihoods and food security.

2022

1. Guitarfishes are plucked: undermanaged in global fisheries despite declining populations and high volume of unreported international trade

   Samantha Sherman, Colin Simpfendorfer, Alifa Haque, and 6 more authors

   Oct 2022

   Abs

   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. Here, we collate international trade information for Guitarfishes that have not readily been documented in trade, possibly due to poor resolution of molecular genetic markers, to begin to document the extent of trade. We assess the shortfall in fisheries management (M-Risk) for all species of Guitarfish based on 99 assessments across 28 countries. Globally, Guitarfishes are inadequately managed, with an average M-Risk of 45% of an ideal score, resulting in 76% of species being threatened globally. The high and unregulated catch and trade volume, paired with the management shortfalls, require global integrated improvement in fisheries management, supported by regulating international trade to sustainable levels.

2021

1. Overfishing drives over one-third of all sharks and rays toward a global extinction crisis

   Nicholas K. Dulvy, Nathan Pacoureau, Cassandra L. Rigby, and 21 more authors

   Current Biology, Nov 2021

   Publisher: Elsevier