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...

Post-nesting movements of 12 green turtles from the Galápagos Islands (Ecuador) were tracked with satellite telemetry during the 2003 and 2005 nesting seasons. To illuminate potential environmental influences on turtle movements we compared tracks with a variety of remotely sensed oceanographic variables including sea surface temperature (SST), SST front probability, surface height anomaly, surface current, and surface chlorophyll a concentration. Three distinct post-nesting migratory strategies were observed, including oceanic migration to Central America (Type A1 movements, n = 3), residency within the Galápagos (Type A2 movements, n = 2), and movement into oceanic waters southwest of the Galápagos (Type B movements, n = 7). Two turtles migrating to Central America reached neritic foraging areas in Nicaragua and Panama that were 1500 and 1542 km, respectively, from their nesting sites, and one resident turtle established a foraging home range 75 km from its final nesting site. Oceanic movements occurred in waters with a mean SST of 26.5°C and mean surface chlorophyll a concentration of 0.18 mg m-3 , whereas neritic movements were in waters with a mean SST of 24.3°C and mean surface chlorophyll a concentration of 0.47 mg m-3. All turtles accessed SST frontal zones at a greater rate than their availability, and at least 2 turtles conducted movements in the oceanic zone that were indicative of foraging activity. This is the first report of migratory corridors for Galápagos green turtles, confirming prior flipper tagging data that show that the Galápagos is a source rookery for green turtles in coastal areas of Central America. The high proportion of green turtles departing the Galápagos (83%) indicates that marine fisheries bycatch and directed hunting on this stock outside the Galápagos may impact this population more than previously believed, and underscores the need for multinational conservation efforts that combat these threats.

Climate, behavior, ecology, and oceanography shape patterns of biodiversity in marine faunas in the absence of obvious geographic barriers. Marine turtles are an example of highly migratory creatures with deep evolutionary lineages and complex life histories that span both terrestrial and marine environments. Previous studies have focused on the deep isolation of evolutionary lineages (>3 mya) through vicariance; however, little attention has been given to the pathways of colonization of the eastern Pacific and the processes that have shaped diversity within the most recent evolutionary time. We sequenced 770 bp of the mtDNA control region to examine the stock structure and phylogeography of 545 green turtles from eight different rookeries in the central and eastern Pacific. We found significant differentiation between the geographically separated nesting populations and identified five distinct stocks (FST = 0.08–0.44, P < 0.005). Central and eastern Pacific Chelonia mydas form a monophyletic group containing 3 subclades, with Hawaii more closely related to the eastern Pacific than western Pacific populations. The split between sampled central/eastern and western Pacific haplotypes was estimated at around 0.34 mya, suggesting that the Pacific region west of Hawaii has been a more formidable barrier to gene flow in C. mydas than the East Pacific Barrier. Our results suggest that the eastern Pacific was colonized from the western Pacific via the Central North Pacific and that the Revillagigedos Islands provided a stepping-stone for radiation of green turtles from the Hawaiian Archipelago to the eastern Pacific. Our results fit with a broader paradigm that has been described for marine biodiversity, where oceanic islands, such as Hawaii and Revillagigedo, rather than being peripheral evolutionary “graveyards”, serve as sources and recipients of diversity and provide a mechanism for further radiation.

While little is known about hawksbill turtles Eretmochelys imbricata in the eastern Pacific Ocean, available information suggests that the population has declined substantially in recent decades and could be near extirpation in the region. To evaluate the current status of the population more effectively and to determine the feasibility of recovery efforts, a workshop of regional marine turtle specialists was held in June 2008 in Los Cóbanos, El Salvador. An international working group, Iniciativa Carey del Pacífico Oriental (ICAPO; Eastern Pacific Hawksbill Initiative in English), was established to consolidate information, promote conservation projects and raise awareness about the species. We present information derived from the workshop and compiled by the ICAPO working group since that time. Considering only records from 1 January 2007 to 31 May 2009 it appears that El Salvador hosts the majority of known hawksbill turtle nesting activity in the eastern Pacific, with 79.6% (n = 430) of all nesting observation records, and Mexico hosts the majority of records of hawksbill turtles at sea, with 60.3% (n = 44) of all in-water observation records. Although current abundance is very low, the pervasiveness of the species in the region suggests potential for conservation and recovery. Despite a historical paucity of research focusing on this population, the relatively large and steadily increasing number of records as a result of concerted efforts demonstrates the viability of the ICAPO network as an instrument to promote conservation of this species in the eastern Pacific.

To examine the stock composition of Hawaiian foraging populations and evaluate current life-history hypotheses, mtDNA control region sequences from immature and adult green turtles that forage around the Hawaiian Islands were compared to potential source nesting populations across the Pacific. We examined the stock composition of the feeding ground (FG) populations at 5 index sites across the Hawaiian Archipelago, as well as animals stranded in areas outside these index sites. Six haplotypes, based on mtDNA sequences, were observed among the 788 green turtles sampled around the Hawaiian Islands. Stock mixture analysis shows that the Hawaiian FG populations comprise one genetic stock derived from the nesting population at French Frigate Shoals (FFS), based on a mean estimate of 99.9% from FFS as opposed to other potential source stocks. We identified only 3 turtles with haplotypes not found at FFS, indicating that Hawaiian FGs might occasionally, albeit rarely, be visited by animals from rookeries outside the Hawaiian Archipelago, both in the eastern and western Pacific. These findings lead us to conclude that the numerous foraging aggregations around the Hawaiian Islands can be considered part of a distinct regional population for management. The finding that FGs scattered across a distance of over 2400 km belong to one genetic stock is unique among sea turtles, and allows Hawaiian green turtles to be assessed separately from other Pacific stocks with respect to risk. We explore the unique population ecology of Hawaiian green turtles with reference to the complex life history of this marine megaherbivore.

The Galapagos Islands are among the most important nesting areas for the green sea turtle, Chelonia mydas, in the eastern Pacific Ocean. In addition, the coastal waters of this oceanic archipelago host many important feeding areas for this species, although little is known about green turtle feeding ecology at these sites. The goal of this study was to identify and quantify the most important items in the diet of the green turtle at the foraging grounds of Bahia Elizabeth, Caleta Derek and Punta Nuñez. Our analysis was based on 65 oesophageal samples from turtles captured in 2006 and 2007. We compared spatial and seasonal composition of diet using non-metric multidimensional scaling analysis (MDS) and analysis of similarity (ANOSIM). Green turtle diet was composed mainly of the algae species Ulva lactuca, Polysiphonia sp., Hypnea sp. and Dictyota sp., and the red mangrove Rhizophora mangle. Turtles also consumed animal matter, mainly cnidarians, albeit to a lesser extent. Content of turtle diets was different among feeding grounds and seasons. The ANOSIM showed that diet composition can differ between foraging grounds using presence/absence of diet items. Even though U. lactuca was the most abundant algae consumed in both seasons, changes in species richness of algae were found between both sampling events, with diet during the warm season more varied than the cold season (χ2 = 16.84, df = 6; P < 0.05).

Abstract Patterns of genetic structure in highly mobile marine vertebrates may be accompanied by phenotypic variation. Most studies in marine turtles focused on population genetic structure have been performed at rookeries. We studied whether genetic and morphological variation of the endangered green turtle (Chelonia mydas) is consistent geographically, focusing on foraging grounds. An association between population genetic structure and body shape variation at broad (inter-lineage) and fine (foraging grounds) scales was predicted and analysed using mitochondrial DNA and geometric morphometrics. Although genetic and phenotypic differentiation patterns were congruent between lineages, no fine-scale association was found, suggesting adaptive divergence. Connectivity among Pacific foraging grounds found here suggests that temperatures of ocean surface currents may influence the genetic structure of C. mydas on a broad scale. Our results suggest that vicariance, dispersal, life-history traits and ecological conditions operating in foraging grounds have shaped the intraspecific morphology and genetic diversity of this species. Considering a range of geographic and temporal scales is useful when management strategies are required for cosmopolitan species. Integrating morphological and genetic tools at different spatial scales, conservation management is proposed based on protection of neutral and adaptive diversity. This approach opens new questions and challenges, especially regarding conservation genetics in cosmopolitan species.

The interactions of numerous abiotic and biotic factors experienced by sea turtle embryos during incubation affect their survival. In this study we determined the hatching and emergence success of green turtles Chelonia mydas from nests on 4 beaches on the Galápagos Islands, one of the most important rookeries for green turtles in the eastern Pacific Ocean. Mean (± SD) hatching and emergence success for the 1039 nests examined were 46.0 ± 33.4 and 45.6 ± 33.4%, respectively. These values are relatively low compared to other green turtle populations worldwide. We evaluated the effects of beach, year, day of oviposition, carapace length and width of female, nest position, nest habitat, and nest chamber depth on hatching and emergence success with binomial generalized additive models with fixed effects. We found variation in hatching and emergence success was significant among beaches, years, day of oviposition, and nest habitat. Predation by feral pigs and beetles and destruction of earlier nests by nesting females were the most important causes of embryo mortality. Efforts to keep threats at minimum levels, particularly controlling pigs near Isabela beaches, should be considered a major conservation objective. This study highlights important differences among beaches within a rookery and emphasizes the need to continue improving management strategies to protect green turtles and their critical habitats. Quantitative information provided here can be used as a basis for long-term studies in the Galá-pagos and for comparison to other sea turtles rookeries. KEY WORDS: Chelonia mydas · Sea turtle reproduction · Clutch success · Generalized additive models · Pacific Ocean · Predation · Feral pigs · Beetles · ReptilesResale or republication not permitted without written consent of the publisher Aquat Biol 19: 217-229, 2013 cess refer to artificial hatchery operations (Hirth 1997) or experimentally manipulated clutches of eggs (Ackerman 1980) that may not reflect natural survival rates (Wyneken et al. 1988, Abella et al. 2007).Hatching and emergence success depends upon the interaction of numerous abiotic and biotic factors and varies among species and populations of sea turtles (Hirth 1980, Van Buskirk & Crowder 1994. Temperature (Matsuzawa et al. 2002, Segura & Cajade 2010, moisture (Ackerman 1980, Mortimer 1982, sand structure and composition (Mortimer 1990), and salinity (Ackerman 1980) can affect embryonic development by altering nest conditions. Hatching success can be affected by the nest location and its microhabitat or surrounding environment (Whitmore & Dutton 1985, Bjorndal & Bolten 1992, Hays & Speak man 1993. Human activities on nesting beaches resulting in sand compaction can decrease hatching and emergence success (Kudo et al. 2003). Predation of sea turtle eggs and hatchlings by a wide taxo nomic range of predators can have major effects; both native and introduced animals can substantially reduce hatching and emergence success (Stancyk 1982).Clutches deposited earlier in the season can subs...