Extinction risk and conservation of the world's sharks and rays.

The rapid expansion of human activities threatens ocean-wide biodiversity. Numerous marine animal populations have declined, yet it remains unclear whether these trends are symptomatic of a chronic accumulation of global marine extinction risk. We present the first systematic analysis of threat for a globally distributed lineage of 1,041 chondrichthyan fishes-sharks, rays, and chimaeras. We estimate that one-quarter are threatened according to IUCN Red List criteria due to overfishing (targeted and incidental). Large-bodied, shallow-water species are at greatest risk and five out of the seven most threatened families are rays. Overall chondrichthyan extinction risk is substantially higher than for most other vertebrates, and only one-third of species are considered safe. Population depletion has occurred throughout the world's ice-free waters, but is particularly prevalent in the Indo-Pacific Biodiversity Triangle and Mediterranean Sea. Improved management of fisheries and trade is urgently needed to avoid extinctions and promote population recovery. DOI: http://dx.doi.org/10.7554/eLife.00590.001.

Preparation of α- and ß-D-glucoseptanose pentaacetates.

The α- and ß-D-glucoseptanose pentaacetates have been prepared by treatment of ethyl 1-thio-ß-D-glucoseptanoside tetraacetate with mercury(II) acetate in acetic acid. The solid state structure of the ß-isomer has been determined by X-ray diffraction.

A comparison of the seasonal movements of tiger sharks and green turtles provides insight into their predator-prey relationship.

During the reproductive season, sea turtles use a restricted area in the vicinity of their nesting beaches, making them vulnerable to predation. At Raine Island (Australia), the highest density green turtle Chelonia mydas rookery in the world, tiger sharks Galeocerdo cuvier have been observed to feed on green turtles, and it has been suggested that they may specialise on such air-breathing prey. However there is little information with which to examine this hypothesis. We compared the spatial and temporal components of movement behaviour of these two potentially interacting species in order to provide insight into the predator-prey relationship. Specifically, we tested the hypothesis that tiger shark movements are more concentrated at Raine Island during the green turtle nesting season than outside the turtle nesting season when turtles are not concentrated at Raine Island. Turtles showed area-restricted search behaviour around Raine Island for ∼3-4 months during the nesting period (November-February). This was followed by direct movement (transit) to putative foraging grounds mostly in the Torres Straight where they switched to area-restricted search mode again, and remained resident for the remainder of the deployment (53-304 days). In contrast, tiger sharks displayed high spatial and temporal variation in movement behaviour which was not closely linked to the movement behaviour of green turtles or recognised turtle foraging grounds. On average, tiger sharks were concentrated around Raine Island throughout the year. While information on diet is required to determine whether tiger sharks are turtle specialists our results support the hypothesis that they target this predictable and plentiful prey during turtle nesting season, but they might not focus on this less predictable food source outside the nesting season.

Preparation and properties of the aldohexofuranose pentaacetates.

The preparation of one isomer of each of the 16 enantiomeric pairs of the aldohexofuranose pentaacetates is described together with (1)H and (13)C NMR data. Eight of the isomers have been obtained crystalline. Equilibrium values for the anomeric pairs have been determined.

Isolation of a sultone as an unusual acetolysis product.

Acetolysis of methyl 5,6-di-O-acetyl-2,3-O-isopropylidene-ß-L-gulofuranoside has yielded a sultone, 4-(1,2,5,6-tetra-O-acetyl-ß-L-gulofuranos-3-yl)-6-methyl-1,2-oxathiin 2,2-dioxide (2) whose structure was determined by X-ray diffraction. (1)H and (13)C NMR spectral properties of 2 are presented together with a rationale for its formation. Preparation and properties of the related α-d-mannofuranos-3-yl compound 4 are described.

Large scale isolation of 1,2:3,4-di-O-isopropylidene-α-D-glucoseptanose and 2,3:4,5-di-O-isopropylidene-ß-D-glucoseptanose.

Isolation of 1,2:3,4-di-O-isopropylidene-α-D-glucoseptanose and 2,3:4,5-di-O-isopropylidene-ß-D-glucoseptanose from the mother-liquors from commercial scale preparation of 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose is described.

Fine-scale movements of the Broadnose Sevengill shark and its main prey, the Gummy shark.

Information on the fine-scale movement of predators and their prey is important to interpret foraging behaviours and activity patterns. An understanding of these behaviours will help determine predator-prey relationships and their effects on community dynamics. For instance understanding a predator's movement behaviour may alter pre determined expectations of prey behaviour, as almost any aspect of the prey's decisions from foraging to mating can be influenced by the risk of predation. Acoustic telemetry was used to study the fine-scale movement patterns of the Broadnose Sevengill shark Notorynchus cepedianus and its main prey, the Gummy shark Mustelus antarcticus, in a coastal bay of southeast Tasmania. Notorynchus cepedianus displayed distinct diel differences in activity patterns. During the day they stayed close to the substrate (sea floor) and were frequently inactive. At night, however, their swimming behaviour continually oscillated through the water column from the substrate to near surface. In contrast, M. antarcticus remained close to the substrate for the entire diel cycle, and showed similar movement patterns for day and night. For both species, the possibility that movement is related to foraging behaviour is discussed. For M. antarcticus, movement may possibly be linked to a diet of predominantly slow benthic prey. On several occasions, N. cepedianus carried out a sequence of burst speed events (increased rates of movement) that could be related to chasing prey. All burst speed events during the day were across the substrate, while at night these occurred in the water column. Overall, diel differences in water column use, along with the presence of oscillatory behaviour and burst speed events suggest that N. cepedianus are nocturnal foragers, but may opportunistically attack prey they happen to encounter during the day.

Endocrine and morphological correlates of reproduction in the draughtboard shark Cephaloscyllium laticeps (Elasmobranchii: Scyliorhinidae).

This study examined the endocrine and reproductive correlates of reproduction in 636 female and 468 male draughtboard sharks (Cephaloscyllium laticeps) captured from southeastern Australia. Females were oviparous and displayed a single external-type ovary with a maximum follicle diameter of 35 mm. Vitellogenesis commenced at a follicle diameter of 10 mm. Females showed a constant overlap between follicular recruitment, ovarian growth, and egg laying. The male reproductive tract consisted of paired testes with spermatocysts undergoing diametric development. Plasma levels of the presumptive gonadal steroids, testosterone (T), 17beta-estradiol (E2), progesterone (P4), and 11-ketotestosterone (11-KT; males only) were correlated with morphological developmental stages of the gonads. In females, E2 increased as the follicle developed before declining as the follicle reached maturity. T remained low during the first stages of ovarian growth and increased as the follicle reached maturity. P4 showed a peak just before ovulation. In males, T was the only hormone that varied with maturity, increasing in adults; E2 and P4 were present at low plasma concentrations in males and did not change with stage of gonadal development. 11-KT was undetectable at all times. Endocrine changes in draughtboard sharks were consistent with hormonal correlates reported for other species and suggest roles for E2( in females) and T (in both sexes) in gametogenesis and P4 in maturational events in females.