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Coastal sharks face increasing pressure from anthropogenic impacts and environmental change. Estimated population declines in some species have created uncertainty about the effectiveness of existing management approaches. In particular, there are scarce data on the benefits of marine protected areas (MPAs) for sharks, including whether they can be used to conserve multiple sympatric species comprising diverse life histories and habitat use patterns., This study used fishery-independent longline and gill-net surveys to investigate the effects of sub-bay-sized MPAs ( c. 100-300 km2) on the abundance and community structure of tropical coastal sharks. In addition, tag-recapture data from fishery-dependent and fishery-independent sources were used to investigate the movements of individuals across MPA boundaries., Species composition varied significantly between management zones, and overall shark abundance on longlines was higher inside MPAs., Length-frequency distributions of blacktip ( Carcharhinus tilstoni/Carcharhinus limbatus) and pigeye ( Carcharhinus amboinensis) sharks inside MPAs included a greater proportion of sharks larger than c. 800 mm compared with those in open zones, although results varied between gear types for pigeye sharks., Tagging and recapture locations indicated repeated and potentially long-term use of MPAs by individuals of some species., Although the potential benefits of MPAs were not equal for all species, coastal MPAs may increase the survival of young sharks to maturity, or shelter parts of breeding stocks, and therefore do not necessarily need to be large to provide benefits., Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The distributions of three species of sea snake (olive sea snake: Aipysurus laevis, spine-bellied sea snake: Lapemis curtus, and ornate sea snake: Hydrophis ocellatus) were estimated over 14° of latitude within the Great Barrier Reef Marine Park (GBRMP) using data from baited remote underwater video stations (BRUVS). A total of 2,471 deployments of BRUVS were made in a range of locations, in sites open and closed to trawl fishing. Sightings of sea snakes were analysed alongside six spatial factors [depth, relative distance across (longitude) and along (latitude) the GBRMP, proximity to land, proximity to the nearest reef, and habitat complexity] to determine the factors that most strongly influenced the distribution and abundance of sea snakes. The results showed a strong latitudinal effect on the distribution of all three sea snake species, with the highest densities and diversities occurring in central and southern GBRMP locations, while the northern Great Barrier Reef was relatively depauperate in terms of both occurrence and diversity. Shallow inshore areas were identified as key habitats for A. laevis and L. curtus, whereas deeper offshore habitats were most important for H. ocellatus. No significant difference was found in the mean number of snakes sighted per hour between sites open and closed to trawling. There was a high degree of congruence in the distribution of sea snakes estimated from the BRUVS data and results from previous trawl and underwater visual surveys, demonstrating the utility of BRUVS to estimate distribution and relative abundance in these species of sea snake at broad spatial scales in a non-extractive manner. [ABSTRACT FROM AUTHOR]

Abstract: Global declines in shark populations have created uncertainty in the future status of many species and conservation efforts are urgently needed. Marine protected areas (MPAs) are used increasingly as conservation tools around the world, but how they benefit mobile and wide ranging species like sharks remains unclear. To evaluate the degree of protection MPAs may provide for sharks, we used an array of acoustic receivers to examine the movements and spatial use of two tropical coastal species within two MPAs in the Great Barrier Reef Marine Park, Australia. Juvenile pigeye (Carcharhinus amboinensis) and adult spottail (Carcharhinus sorrah) sharks were fitted with acoustic transmitters from 2009 to 2010. Both species displayed long-term use of MPAs, with some individuals detected for longer than 600days. The mean percentage of time C. amboinensis and C. sorrah spent inside MPAs was 22% and 32%, respectively. MPA use varied seasonally, with C. amboinensis spending a higher percentage of time inside MPAs in summer (mean=28%) and C. sorrah spending a higher percentage of time inside MPAs in winter (mean=40%). Although sharks used large areas inside MPAs, most individuals tended to use only half of the available protected space. In addition, all sharks made excursions from MPAs and individuals exited and re-entered at consistent locations along the MPA boundaries. These results demonstrate that MPAs have conservation benefits for shark populations by providing protection across different species and life stages, and tracking studies can be used to help tailor MPA design to maximize effectiveness. [Copyright &y& Elsevier]

The status of five species of commercially exploited sharks within the Great Barrier Reef Marine Park (GBRMP) and south-east Queensland was assessed using a data-limited approach. Annual harvest rate, U , estimated empirically from tagging between 2011 and 2013, was compared with an analytically-derived proxy for optimal equilibrium harvest rate, U MSY Lim . Median estimates of U for three principal retained species, Australian blacktip shark, Carcharhinus tilstoni , spot-tail shark, Carcharhinus sorrah , and spinner shark, Carcharhinus brevipinna , were 0.10, 0.06 and 0.07 year −1 , respectively. Median U for two retained, non-target species, pigeye shark, Carcharhinus amboinensis and Australian sharpnose shark, Rhizoprionodon taylori , were 0.27 and 0.01 year −1 , respectively. For all species except the Australian blacktip the median ratio of U/U MSY Lim was <1. The high vulnerability of this species to fishing combined with life history characteristics meant U MSY Lim was low (0.04–0.07 year −1 ) and that U/U MSY Lim was likely to be >1. Harvest of the Australian blacktip shark above U MSY could place this species at a greater risk of localised depletion in parts of the GBRMP. Results of the study indicated that much higher catches, and presumably higher U , during the early 2000s were likely unsustainable. The unexpectedly high level of U on the pigeye shark indicated that output-based management controls may not have been effective in reducing harvest levels on all species, particularly those caught incidentally by other fishing sectors including the recreational sector. [ABSTRACT FROM AUTHOR]