نتایج جستجو برای: sharks
تعداد نتایج: 2511 فیلتر نتایج به سال:
Shark take, driven by vast demand for meat and fins, is increasing. We set out to gain insights into the impact of small-scale longline fisheries in Peru. Onboard observers were used to document catch from 145 longline fishing trips (1668 fishing days) originating from Ilo, southern Peru. Fishing effort is divided into two seasons: targeting dolphinfish (Coryphaena hippurus; December to Februar...
This study examines the approach patterns of sharks in the vicinity of human divers, focusing on the diver’s body orientation and a shark’s distance from the sea bed when approaching the diver. A standardized video method was used to record the scenario of diver(s) kneeling in the sand while being approached by sharks. This showed that sharks had a preference to move in from outside a diver’s f...
The mouths of some bony and cartilaginous fishes are located in the anterior part of theirbodies, with a slight variation in sharks, which have theirs located in the abdominal part. Thisvariation is evolutionary over time. The force exerted by the jaws of sharks in order todismember their prey can be examined from two origins: .The determined force exerted by teethand muscles and the force as a...
Whale sharks, Rhincodon typus, are known to aggregate to feed in a small number of locations in tropical and subtropical waters. Here we document a newly discovered major aggregation site for whale sharks within the Al Shaheen oil field, 90 km off the coast of Qatar in the Arabian Gulf. Whale sharks were observed between April and September, with peak numbers observed between May and August. De...
The effects of caudal cannulation on the blood physiology of the Port Jackson shark, Heterodontus portusjacksoni, were investigated in sharks given between 4 and 72 h to recover from surgery. Neither the PaO2–PvO2 difference nor the CaO2–CvO2 difference of cannulated sharks fluctuated throughout the sampling period. The plasma acidosis exhibited 4 h after surgery was partially compensated after...
Although marine protected areas (MPAs) are a common conservation strategy, these areas are often designed with little prior knowledge of the spatial behaviour of the species they are designed to protect. Currently, the Coral Sea area and its seamounts (north-east Australia) are under review to determine if MPAs are warranted. The protection of sharks at these seamounts should be an integral com...
Understanding of species interactions within mesophotic coral ecosystems (MCEs; ~ 30-150 m) lags well behind that for shallow coral reefs. MCEs are often sites of fish spawning aggregations (FSAs) for a variety of species, including many groupers. Such reproductive fish aggregations represent temporal concentrations of potential prey that may be drivers of habitat use by predatory species, incl...
BACKGROUND In recent decades, large pelagic and coastal shark populations have declined dramatically with increased fishing; however, the status of sharks in other systems such as coral reefs remains largely unassessed despite a long history of exploitation. Here we explore the contemporary distribution and sighting frequency of sharks on reefs in the greater-Caribbean and assess the possible r...
background: brownbanded bamboo sharks (chiloscyllium punctatum) is one of the cartilaginous fish that lives in the persian gulf. objectves: the purpose of the present study is to study the effects of thyroid hormone on reproductive system of this specious. methods: in this investigation, 36 individual of brownbanded bamboo sharks (chiloscyllium punctatum) in both autumn (before reproduction) an...
The Arabian Gulf is the warmest sea in the world and is host to a globally significant population of the whale shark Rhincodon typus. To investigate regional whale shark behaviour and movements, 59 satellite-linked tags were deployed on whale sharks in the Al Shaheen area off Qatar from 2011-14. Four different models of tag were used throughout the study, each model able to collect differing da...
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