Biology subjects

Simpfendorfer, C. A.

Publications and source records attributed to Simpfendorfer, C. A..

6 recordsLinked to original sources

bioRxiv2022

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

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.

ecology↗

bioRxiv2022

High overexploitation risk and management shortfall in highly traded requiem sharks

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 Organisations (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 requires a global integrated improvement in fisheries management, supported by regulating international trade to sustainable levels.

ecology↗

bioRxiv2022

M-Risk: A framework for assessing global fisheries management efficacy of sharks, rays, and chimaeras

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. While ecological risk analyses focus on intrinsic productivity and extrinsic susceptibility, one would ideally consider the influence of fisheries management. Currently, there is no single management evaluation that can be applied to a combination of fishery types at the scale of individual country or Regional Fisheries Management Organisations (RFMOs). Here, we outline a management risk (M-Risk) framework for sharks, rays, and chimaeras used to evaluate species risk to overfishing resulting from ineffective management. We illustrate our approach with application to one country (Ecuador) and RFMO (Inter-American Tropical Tuna Commission) and illustrate the variation in scores among species. We found that while both management units assessed had similar overall scores, the scores for individual attributes varied. Ecuador scored higher in reporting-related attributes, while the IATTC scored higher in attributes related to data collection and use. We evaluated whether management of individual species was sufficient for their relative sensitivity by combining the management risk score for each species with their intrinsic sensitivity to determine a final M-Risk score. This framework can be applied to determine which species face the greatest risk of overfishing and be used by fisheries managers to identify effective management policies by replicating regulations from countries with lower risk scores.

ecology↗

bioRxiv2019

Untangling the Indonesian tangle net fishery: describing a data-poor fishery targeting large threatened rays (Order Batoidea)

O_LIShark-like rays (Order Rhinopristiformes) are among the most threatened families of marine fish. Yet little is known about their populations, as 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. C_LIO_LIMarket surveys of Muara Angke landing site in Jakarta, north-western Java (including one frozen shipment from Benoa Harbour, Bali), were conducted between 2001 and 2005, and recorded landed catch for this fishery. Recent catch data from Indonesian Capture Fisheries (2017 - 2018) were also examined to provide contemporary information about landed catch. C_LIO_LI1,559 elasmobranchs (sharks and rays) were recorded, comprised of 24 species of rays and nine species of sharks. The most abundant species landed were the pink whipray Pateobatis fai and the bottlenose wedgefish Rhynchobatus australiae, the latter being the main target species. C_LIO_LICatch composition varied based on differences in species catchability and may also be indicative of localized declines. The fishery was highly selective for larger sized individuals, however smaller size classes of target species were also caught in other Indonesian fisheries resulting in fishing pressure across all age classes. C_LIO_LIEvidence of substantial declines in global landings of wedgefish species, and the observed shift in catch composition in the Indonesian tangle net fishery, increases concerns about the status of shark-like rays and stingrays in Indonesia. C_LI

zoology↗

bioRxiv2019

The thin edge of the wedge: extremely high extinction risk in wedgefishes and giant guitarfishes

O_LIThe 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.\nC_LIO_LIThe objective of this study was to assess the extinction risk of all 10 wedgefishes and 6 giant guitarfishes by applying the International Union for Conservation of Nature (IUCN) Red List Categories and Criteria, and to summarise their biogeography and habitat, life history, exploitation, use and trade, and population status.\nC_LIO_LIWedgefishes and giant guitarfishes have overtaken sawfishes as the most imperilled marine fish families globally, with all but one of the 16 species facing an extremely high risk of extinction due to a combination of traits - limited biological productivity, presence in shallow waters overlapping with some of the most intense and increasing coastal fisheries in the world, and over-exploitation in target and bycatch fisheries driven by the need for animal protein and food security in coastal communities and trade in meat and high-value fins.\nC_LIO_LITwo species with very restricted ranges, the Clown Wedgefish (Rhynchobatus cooki) of the Indo-Malay Archipelago and the False Shark Ray (Rhynchorhina mauritaniensis) of Mauritania may be very close to extinction.\nC_LIO_LIOnly the Eyebrow Wedgefish (Rhynchobatus palpebratus) is not assessed as Critically Endangered, due to it occurring primarily in Australia where fishing pressure is low, and some management measures are in place. Australia represents a lifeboat for the three wedgefish and one giant guitarfish species occurring there.\nC_LIO_LITo conserve populations and permit recovery, a suite of measures will be required which will need to include species protection, spatial management, bycatch mitigation, and harvest and international trade management, all of which will be dependent on effective enforcement.\nC_LI

ecology↗

bioRxiv2019

Population productivity of shovelnose rays: inferring the potential for recovery

Recent evidence of widespread and rapid declines of wedgefishes, guitarfishes, and banjo ray populations (Order Rhinopristiformes), driven by a high demand for their fins in Asian markets and the quality of their flesh, raises concern about their risk of over-exploitation and extinction. Using life history theory and incorporating uncertainty into a modified Euler-Lotka model, maximum intrinsic rates of population increase (rmax) were estimated for nine species from the four families of rhinopristiforms. Estimates of median rmax varied from -0.04 to 0.60 year-1 among the nine species, but generally increased with increasing maximum size. In comparison to 115 other species of chondrichthyans for which rmax values were available, the families Rhinidae and Glaucostegidae are relatively productive, while most species from Rhinobatidae and Trygonorrhinidae had relatively low rmax values. If the demand for their high value products can be addressed, then population recovery for this species is likely possible but will vary depending on the species.

zoology↗