Search results for "shark"

Ontogenetic trophic segregation between two threatened smooth-hound sharks in the Central Mediterranean Sea

2020

AbstractElasmobranchs are among the species most threatened by overfishing and a large body of evidence reports their decline around the world. As they are large predators occupying the highest levels of marine food webs, their removal can alter the trophic web dynamic through predatory release effects and trophic cascade. Suitable management of threatened shark species requires a good understanding of their behaviour and feeding ecology. In this study we provide one of the first assessments of the trophic ecology of the “vulnerable” smooth-hounds Mustelus mustelus and M. punctulatus in the Central Mediterranean Sea, based on stomach contents and stable isotope analyses. Ontogenetic diet ch…

The Pillars of Hercules as a bathymetric barrier to gene flow promoting isolation in a global deep-sea shark (Centroscymnus coelolepis).

2015

Catarino, Diana ... et. al.-- 19 pages, 5 figures, 4 tables, data accessibility http://dx.doi.org/10.5061/dryad.ss368, supporting information http://dx.doi.org/10.1111/mec.13453

Trophic position of Otodus megalodon and great white sharks through time revealed by zinc isotopes

2022

AbstractDiet is a crucial trait of an animal’s lifestyle and ecology. The trophic level of an organism indicates its functional position within an ecosystem and holds significance for its ecology and evolution. Here, we demonstrate the use of zinc isotopes (δ66Zn) to geochemically assess the trophic level in diverse extant and extinct sharks, including the Neogene megatooth shark (Otodus megalodon) and the great white shark (Carcharodon carcharias). We reveal that dietary δ66Zn signatures are preserved in fossil shark tooth enameloid over deep geologic time and are robust recorders of each species’ trophic level. We observe significant δ66Zn differences among the Otodus and Carcharodon popu…

A century of fishery data documenting the collapse of smooth-hounds (Mustelusspp.) in the Mediterranean Sea

2017

Conservation and management of shark populations is increasingly becoming important in many marine regions, since there is a growing body of evidence showing that several species are threatened and continuing to decline because of unregulated fishing. Quantifying the extent of sharks' decline, the risk of species extinction, and the consequences for marine ecosystems have been challenging and controversial, mostly due to data limitations. In this study, more than one century of multiple-sources of bibliographic records on presence and frequency of occurrence of three species of commercial sharks, the smooth-hounds Mustelus spp., in the Mediterranean Sea were compiled and analysed. Generaliz…

By-catch of cetaceans and other species of conservation concern during pair trawl fishing operations in the Adriatic Sea (Italy)

2010

By-catch is one of the main sources of anthropogenic mortality in marine species of conservation concern worldwide. Between 2006 and 2008, the Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNISMa) coordinated a monitoring programme of cetacean by-catch in Italian pelagic trawlers, funded in compliance with European Regulation 812/2004. Sixteen independent observers monitored a total of 3141 hauls. The observation coverage ranged between 0.9 and 6.3% of the regional fishing effort. Almost all by-catch events were recorded in the northern Adriatic Sea. By-catch rates of bottlenose dolphins (Tursiops truncatus) and loggerhead turtles (Caretta caretta) were 0.0006 and 0.0255 …

Past aquatic environments in the Levant inferred from stable isotope compositions of carbonate and phosphate in fish teeth

2019

Here we explore the carbon and oxygen isotope compositions of the co-existing carbonate and phosphate fractions of fish tooth enameloid as a tool to reconstruct past aquatic fish environments and harvesting grounds. The enameloid oxygen isotope compositions of the phosphate fraction (δ18OPO4) vary by as much as ~4‰ for migratory marine fish such as gilthead seabream (Sparus aurata), predominantly reflecting the different saline habitats it occupies during its life cycle. The offset in enameloid Δ18OCO3-PO4 values of modern marine Sparidae and freshwater Cyprinidae from the Southeast Mediterranean region vary between 8.1 and 11.0‰, similar to values reported for modern sharks. The mean δ13C …

Autecology, lifestyle and hydrodynamics of early vertebrates

2018

Capítulo 1. Introducción general Los vertebrados constituyen uno de los grupos de animales más exitosos, contando con más de 60000 especies distintas y ocupando la gran mayoría de ecosistemas marinos y continentales. Su origen y evolución han sido temas centrales para biólogos y paleontólogos durante décadas, pero las discusiones en este sentido se han visto obstaculizadas porque los grupos actuales (ciclóstomos, condrictios y osteíctios) constituyen solo una pequeña representación de toda la diversidad que existió en el pasado. Por lo tanto, el registro fósil es crucial para arrojar luz sobre estos aspectos permitiendo desvelar el momento y el tempo de la aparición de los diferentes caract…

Sicilian Cenozoic sharks from the collections of G. G. Gemmellaro Museum

2006

Trend of Foreign Tourist Visits in the Conservation Area of the Cenderawasih Bay National Park (TNTC) with Special Interest on Whale Shark (Rhincodon…

2021

Tourist areas have a significant role in several aspects including economic, social and environmental. The national park has a considerable potential in the aspect of tourism. In addition to having mega biodiversity, the Cenderawasih Bay National Park (TNTC) also has a strong special attraction in term of whale shark, available year-round. Therefore, foreign tourism potential at TNTC is very high and much in demand by both local and foreign tourists. By processing visitation data, we were able to obtain trend and potentials in supporting the carrying capacity of whale shark tourism areas. Through these data, the estimated number of visitors in 2020 at TNTC was also obtained. Data were perfo…

Manfaat Ekonomi Ekowisata Hiu Paus (Rhincodon typus) di Kampung Akudiomi Distrik Yaur Kabupaten Nabire

2017

Model pemanfaatan hiu paus yang memberi manfaat ekonomi sekaligus memberikan perlindungan terhadap hiu paus dapat dilakukan melalui pariwisata dengan konsep ekowisata. Kampung Akudiomi merupakan salah satu kampung di wilayah Taman Nasional Teluk Cenderawasih yang memiliki objek dan daya tarik wisata berbasis hiu paus. Meningkatnya kunjungan wisatawan ke wilayah ini telah memberi manfaat ekonomi bagi berbagai pihak. Tujuan penelitian ini yaitu mengetahui manfaat ekonomi yang diperoleh para pemangku kepentingan dan secara khusus mengetahui tingkat kesejahteraan pelaku usaha wisata lokal dari aktifitas ekowisata hiu paus. Studi dilakukan pada bulan Maret hingga Mei 2014 di Kampung Akudiomi Kab…