Transboundary movements, unmonitored fishing mortality, and ineffective international fisheries management pose risks for pelagic sharks in the Northwest Atlantic

Abstract

Abstract:The shortfin mako (Isurus oxyrinchus), porbeagle (Lamna nasus), and blue shark (Prionace glauca) are three frequently caught shark species in the northwestern Atlantic Ocean. Satellite tagging studies show that all three species range widely across many national boundaries but spend up to 92% of their time on the high seas, where they are largely unregulated and unmonitored. All are caught in large numbers by swordfish and tuna fishing fleets from a large number of nations, usually unintentionally, and all are unproductive by fish standards, which makes them particularly sensitive to fishing pressure. Landing statistics that grossly underrepresent actual catches, unreported discards that often exceed landings, and high discard mortality rates are threats to the populations and roadblocks to useful population monitoring. The influence of these threats is greatly magnified by inattention and ineffective management from the responsible management agency, the International Commission for the Conservation of Atlantic Tunas (ICCAT), whose prime focus is the more valuable swordfish and tuna stocks. Although practical management options are available, none will be possible if organizations like ICCAT continue to treat sharks like pests.Résumé : Le requin-taupe bleu (Isurus oxyrinchus), le requin-taupe commun (Lamna nasus) et le requin bleu (Prionace glauca) sont trois espèces de requin fréquemment capturées dans le nord-ouest de l'océan Atlantique. Des études reposant sur les étiquettes satellites montrent que les trois espèces sont réparties sur de vastes territoires chevauchant de nombreuses frontières nationales, mais qu'elles passent jusqu'à 92 % de leur temps en haute mer, où elles ne font l'objet de presque aucune réglementation ni surveillance. Toutes ces espèces sont capturées en grand nombre par des flottes de pêche à l'espadon et aux thonidés de nombreux pays, généralement de manière non intentionnelle, et il s'agit dans les trois cas d'espèces de poissons non productives, ce qui les rend particulièrement sensibles à la pression de la pêche. Des statistiques sur les débarquements qui sousreprésentent nettement les prises réelles, des rejets non signalés qui dépassent souvent les débarquements et des taux élevés de mortalité par rejet sont autant de menaces pour les populations et d'obstacles à la surveillance efficace de ces dernières. L'influence de ces menaces est grandement amplifiée par l'inattention et une gestion inefficace de l'agence de gestion compé-tente, la Commission internationale pour la conservation des thonidés de l'Atlantiques (CICTA), dont les efforts sont principalement axés sur les stocks d'espadons et de thonidés de plus grande valeur économique. Si des options de gestion pratiques existent, aucune ne sera possible si des organismes comme la CICTA continuent de considérer les requins comme étant des animaux nuisibles. [Traduit par la Rédaction]

Global spatial risk assessment of sharks under the footprint of fisheries

“…Conservation of pelagic sharkswhich currently have limited high seas management 12,15,16 -would benefit greatly from a clearer understanding of the spatial relationships between sharks' habitats and active fishing zones. However, obtaining unbiased estimates of shark and fisher distributions is complicated by the fact that most data on pelagic sharks come from catch records and other fishery-dependent sources 4,15,16 .…”

“…All these species face some level of fishing pressure in coastal, shelf and/or high-seas fisheries, with the International Union for the Conservation of Nature (IUCN) Red List assessing almost two thirds as being Endangered (26%) or Vulnerable (39%), and a further quarter as Near Threatened (26%) (Supplementary Table 2). Regional fisheries management organizations (RFMOs) are tasked with the management of sharks in high seas areas, yet little or no management is in place for most species 3,5,[12][13][14][15][16][17][18] .…”

“…Regional declines in abundance of pelagic sharks have been reported 13,14 , but it is unclear whether exposure to high fishing effort extends across ocean-wide population ranges and overlaps areas in the high seas where sharks are most abundant 5,13 .Conservation of pelagic sharkswhich currently have limited high seas management 12,15,16would benefit greatly from a clearer understanding of the spatial relationships between sharks' habitats and active fishing zones. However, obtaining unbiased estimates of shark and fisher distributions is complicated by the fact that most data on pelagic sharks come from catch records and other fishery-dependent sources 4,15,16 .Here, we provide the first global estimate of the extent of space use overlap of sharks with industrial fisheries. This is based on the analysis of the movements of pelagic sharks tagged with satellite transmitters in the Atlantic, Indian and Pacific oceans, together with fishing vessel movements monitored globally by the Automatic Identification System (AIS), developed as a vessel safety and anti-collision system (see Methods).…”

Fisheries Bycatch of Chondrichthyes

“…In addition, these species are the most encountered in reliable commercial landings and a large portion of these is a result of indirect fishing removal [52,53]. While, in Mexico and Caribbean waters, sharks and rays are usually fished by artisanal fishermen, and juveniles of large species are often taken as bycatch [117]. However, regional management and conservation measures have been implemented in some fisheries.…”

“…In addition, other measures including the reduction of fishing effort targeting sharks, time/area closure in certain seasons and gear restrictions have been adopted in the North Atlantic [116,[118][119][120]. Notably, many large pelagic sharks are overfished or in overexploitation and are often removed as bycatch in longline fisheries targeting tuna and swordfish in the North Atlantic as a whole [11,54,117]. Given their wide distribution and their high ability to migrate, large pelagic sharks have been usually exploited by different nations in the North Atlantic.…”