RESUMEN
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 population declines cannot be easily reversed owing to long generation lengths, low recovery potentials, and the near absence of management. Depth and spatial limits to fishing activity could improve conservation when implemented alongside catch regulations, bycatch mitigation, and international trade regulation. Deepwater sharks and rays require immediate trade and fishing regulations to prevent irreversible defaunation and promote recovery of this threatened megafauna group.
Asunto(s)
Conservación de los Recursos Naturales , Extinción Biológica , Caza , Tiburones , Rajidae , Animales , Humanos , Internacionalidad , Carne , Aceites de Pescado , Biodiversidad , Océanos y Mares , RiesgoRESUMEN
The deep-sea spiny eels of the genus Notacanthus Bloch 1788 are currently represented by six valid species, of which only one, Notacanthus indicus, has been described so far from the Arabian Sea, part of the Western Indian Ocean. This paper reports the discovery of a new species, described herein as Notacanthus laccadiviensis, from the outer reef drop-off, off the Kavaratti Island, Lakshadweep Archipelago, Arabian Sea. The new species differs from its congeners in the shape of the head; morphology of dorsal, pectoral and anal fins; number of gill rakers; number of vertebrae; and body colour, and specifically from N. indicus (the only known congener from the Indian Ocean) in the unusual morphology of the dorsal fin, and number of rays in the dorsal and pectoral fins.
Asunto(s)
Peces , Perciformes , Animales , Océano Índico , Branquias , Anguilas , Perciformes/anatomía & histologíaRESUMEN
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.
Asunto(s)
Arrecifes de Coral , Tiburones , Animales , Ecosistema , Conservación de los Recursos Naturales , Explotaciones Pesqueras , MamíferosRESUMEN
Pomfrets (Genus Pampus) are commercially important fish in the Indo-Pacific region. The systematics of this genus is complicated because of morphological similarities between species. The silver pomfret from Indian waters has long been considered to be Pampus argenteus. Morphological and molecular examination of specimens from the Arabian Sea and Bay of Bengal regions suggested the silver pomfret from the region represents two species that are distinct both from each other and from P. argenteus from the South China Sea. Based on detailed morphological, meristic and molecular examinations, the most common species from the Indian Ocean was found to correspond with the descriptions of Stromateus candidus (Cuvier), which is resurrected from the synonymy of P. argenteus and redescribed here as Pampus candidus (new combination). The second species, which has restricted distribution in Indian waters needs further studies to arrive at taxonomic conclusions and is hence not described in the current study. Lectotypes are also designated for Pampus candidus.