Effective ocean management and conservation of highly migratory species depends onresolving overlap between animal movements and distributions, and fishing effort.However, this information is lacking at a global scale. Here we show, using a big-data approach that combines satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space-use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively), and were also associated with significant increases in fishing effort.We conclude that pelagic sharks have limited spatial refuge from current levels of fishing effort in marine areas beyond national jurisdictions (the high seas). Our results demonstrate an urgent need for conservation and management measures at high-seas hotspots of shark space use, and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real-time, dynamic management.Industrialised fishing is a major source of mortality for large marine animals (marine megafauna) 1-6 . Humans have hunted megafauna in the open ocean for at least 42,000 years 7 , but international fishing fleets targeting large, epipelagic fishes did not spread into the high seas (areas beyond national jurisdiction) until the 1950s 8 . Prior to this, the high seas constituted a spatial refuge largely free from exploitation as fishing pressure was concentrated on continental shelves 3,8 . Pelagic sharks are among the widest ranging vertebrates, with some species exhibiting annual ocean-basin-scale migrations 9 , long term trans-ocean movements 10 , and/or fine-scale site fidelity to preferred shelf and open ocean areas 5,9,11 . These behaviours could cause extensive spatial overlap with different fisheries from coastal areas to the deep ocean. On average, large pelagic sharks account for 52% of all identified shark catch worldwide in target fisheries or as bycatch 12 . 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 m...

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, the reproduction of the blue shark, Prionace glauca, in the southwestern equatorial Atlantic Ocean was studied. During this period, 88 females and 82 males were examined. Females were found in 4 different sexual stages: preovulatory (22), pregnant (47), postovulatory (non-pregnant) (7), and subadult (12). Their fork length ranged from 162 to 225 cm. Half of the females were in early pregnancy. Embryos in completely different stages of development were found in 4 of them. Oviducal glands of 44 females were examined and in 38 spermatozoa were found. These results indicate that ovulation and fertilization took place from December to July.Most of the males were adult and only 14 specimens seemed to be sexually immature. Many adult males were lacking sperm packs and had a very low volume of seminal fluid, suggesting that they were probably sexually resting. Theirfork length ranged from 156 to 228 cm.

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From February 2005 to September 2007, a total of 490 crocodile sharks Pseudocarcharias kamoharai, caught as by-catch in the swordfish and tuna longline fishery that operates in the tropical western Atlantic Ocean, was studied in regard to their reproductive biology. Maximum observed total lengths (L(T)) were 1220 and 1090 mm for females and males respectively, with a high proportion of the catch being composed of mature specimens. Sexual maturity was attained at 760-810 mm L(T) for males (L(T50) = 800 mm) and 870-980 mm L(T) for females (L(T50) = 916 mm). The size at birth was estimated at 415 mm L(T). Temporal variation in gonad morphology and mass suggests that in this region P. kamoharai, an aplacental viviparous species with oophagy, does not show a well-defined reproductive seasonality, with mating and parturition occurring possibly over an extended period of the year. Mean +/-S.D. fecundity was estimated to be 3.9 (+/- 0.6) pups per reproductive cycle.

Shark attacks on humans have prompted the implementation of shark control programs aiming at reducing local populations of potentially aggressive species using mostly gillnets. However, shark meshing produces ecological disturbances by inflicting severe mortality not only to sharks but also to several harmless, frequently endangered taxa, including cetaceans, sirenians and chelonids. A different methodological approach to mitigate shark peril off Recife combines bottom longlining and drumlines with comparably better results. This region has been experiencing an abnormally high shark attack rate since 1992, but the protective fishing strategy was developed in 2004 only. Unlike traditional shark control programs, the Shark Monitoring Program of Recife (SMPR) aims at removing dangerous sharks not from their populations but from the hazardous area instead, which is achieved by capturing, transporting and releasing sharks offshore. During 8 years, the SMPR caught fish and turtles only and showed high selectivity for sharks compared with shark meshing. Target species comprised carcharhinids and sphyrnids and accounted for 7% of total catch. The fishing mortality of abundant taxa was generally low except for Carcharhinus acronotus and Gymnothorax spp., and protected species had ∼100% survival. The shark attack rate diminished about 97% while fishing operations were being conducted (W = 1108.5, P < 0.001), whereas no-fishing periods and the period prior to the implementation of the SMPR had similar shark attack rates. Overall, the SMPR seems to be less detrimental than shark meshing strategies while clearly contributing for enhancing bather safety; thus, it may provide an effective, ecologically balanced tool for assisting in shark attack mitigation.

The blue shark (Prionace glauca) is the most frequently captured shark in pelagic oceanic fisheries, especially pelagic longlines targeting swordfish and/or tunas. As part of cooperative scientific efforts for fisheries and biological data collection, information from fishery observers, scientific projects and surveys, and from recreational fisheries from several nations in the Atlantic and Indian Oceans was compiled. Data sets included information on location, size and sex, in a total of 478,220 blue shark records collected between 1966 and 2014. Sizes ranged from 36 to 394 cm fork length.Considerable variability was observed in the size distribution by region and season in both oceans. Larger blue sharks tend to occur in equatorial and tropical regions, and