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Currently, it is assumed that most of elasmobranchs (sharks, rays and skates) had suffered a high depletion in their populations worldwide, but there is an important lack of biological and fishing information over the bulk of the species that do not permit to determine the real status of their populations. Seven of these scarce information species are the houndsharks and dogfish shark (family Triakidae and Squalidae) found in the Canary Islands, which actual status level and contribution to the catch in the archipelago are still unknown. 136 interviews were carried out among artisanal fishers from all the islands, in which very few of them were able to distinguish all the species. Two houndshark and one dogfish shark species were frequently identified and/or caught (the common smoothhound ( Mustelus mustelus ), the tope shark ( Galeorhinus galeus ) , and the shortnose spurdog ( Squalus megalops )), and half of the fishers were not able to distinguish the sex of these fishes. The houndsharks and dogfish shark are preferentially distributed down to 200 metres depth, with higher catches off the eastern and central islands. These sharks are caught all year round with highest peaks during the summer months, probably coinciding with aggregations for mating and reproduction in shallower waters. Houndsharks and dogfish shark are generally not targeted by artisanal fisheries and, although sometimes landed, most of the catch is usually discarded. Sharks caught range from 100 to 120 cm in total length for common smoothhound and tope sharks, while the catch size for shortnose spurdog varies between 50 and 60 cm in total length. Improving taxonomic knowledge within the fishing sector is essential for sustainable management and conservation of houndshark and dogfish shark species in Canarian waters.

The identification of movement and behaviour patterns, as well as inter- and intra-population connectivity is crucial in order to implement effective and functional management and conservation measures for threatened migratory species such as tope ( Galeorhinus galeus ). Yet, previous studies struggled to elucidate clear and consistent movement and depth usage patterns of adult tope in the Northeast Atlantic, suggesting a high plasticity in the migration and behaviour. We deployed pop-up satellite archival tags on adult tope during their seasonal summer aggregations in the inner German Bight of the south-eastern North Sea and near a presumed mating site in southwest Scotland. Depth distribution and migration pathways were derived from time series data with location processing. Four individuals followed migration trajectories leaving coastal areas and crossed the European shelf slope into oceanic areas of the Northeast Atlantic, remaining fully pelagic for the rest of the deployment duration. These sharks showed far-ranging migration trajectories and undertook regular and frequent diel vertical migrations, reaching daytime depths of over 700 m. Vertical migration patterns closely overlapped with biological mesopelagic habitat structures and closely tracked the diel migration of organisms from deep scattering layers derived from hydroacoustic recordings. It is hypothesized that adult tope regularly utilize oceanic habitats, foraging on mesopelagic layers in an environment generally considered of low prey density.

Landing data are the most basic information used to manage fisheries, although they are often unavailable or incomplete. The objective of this work was to reconstruct the national database of marine commercial landings for the Brazilian industrial and artisanal fisheries, from 1950 to 2015. Total landings increased strongly from 1950 to mid-1980s and suffered sharp decline in the early 1990s, mainly associated to the collapse of sardine fisheries. After that, another period of increasing landings was observed, but at a much lower rate. Industrial landings always surpassed artisanal landings in Brazilian waters, except for the beginning of the time series, when many industrial fleets had not started yet, and in the early 2000s, when a change in the methodology for collecting landing statistics was implemented in the state of Pará leading to an overestimation of artisanal landings. Artisanal fisheries have been declining since 2005, which is worrisome due to the social impact it may have on local income and food security. Regional differences were also observed, with industrial landings being always higher than artisanal landings in southeastern-southern Brazil, while the opposite was true for the northern-northeastern regions. Higher landings were observed in the southeastern-southern regions when both artisanal and industrial fleets were combined. Sardine and demersal fishes were the main resources landed by industrial fishers. Artisanal fishers caught more species than their industrial counterpart, featuring Xiphopenaeus kroyeri , Cynoscion acoupa , and Ucides cordatus . Although the fishing of Epinephelus itajara was banned in Brazil, it continues to be landed. Yet, catches of this species and others under some threat status are still not properly registered, including: Carcharhinus longimanus , Galeorhinus galeus , Sphyrna lewini , Sphyrna mokarran , Pristis pectinata , and Pseudobatos horkelii . Fishing resources not identified in previous landing reconstruction efforts, such as sea urchins and sea cucumbers, have now been reported. The database presented here should be continuously updated and improved. It is of paramount importance to resume the collection of landing statistics, including information on fishing effort, to assess the relative impact of fisheries and environmental factors on the main Brazilian fishing stocks.

Skin color aberrations are naturally occurring abnormal pigment patterns that are generally rare among chondrichthyans. In this study, we highlight different skin color aberrations from observations of four shark species native to southern California, USA. We report the first recorded instance of apparent leucism (regional pigmentation loss), in a California horn shark Heterodontus francisci (Girard 1855) and tope shark Galeorhinus galeus (Linnaeus 1758). We also report the apparent second documented occurrence of albinism in the swell shark Cephaloscyllium ventriosum (Garman 1880) from a newly hatched captive individual with parents of normal pigmentation. Lastly, we redescribe a rare secondary color morph in the leopard shark Triakis semifasciata Girard 1855 using previous literature and new sightings/images from sharks in the wild. Color aberrations may lead to different advantages (e.g., certain color morphs may offer additional camouflage) or disadvantages (e.g., reduced pigmentation may limit camouflage and protection from ultraviolet light). Documenting these rare color aberrations augments our understanding of how color patterns can vary between individuals and taxa, and ultimately how these conditions potentially impact shark biology.

In many tropical lowland rain forests, topographic variation increases environmental heterogeneity, thus contributing to the extraordinary biodiversity of tropical lowland forests. While a growing number of studies have addressed effects of topographic differences on tropical insect communities at regional scales (e.g., along extensive elevational gradients), surprisingly little is known about topographic effects at smaller spatial scales. The present study investigates moth assemblages in a topographically heterogeneous lowland rain forest landscape, at distances of less than a few hundred meters, in the Golfo Dulce region (SW Costa Rica). Three moth lineages—Erebidae–Arctiinae (tiger and lichen moths), the bombycoid complex, and Geometridae (inchworm moths)—were examined by means of automatic light traps in three different forest types: creek forest, slope forest, and ridge forest. Altogether, 6,543 individuals of 419 species were observed. Moth assemblages differed significantly between the three forest types regarding species richness, total abundance, and species composition. Moth richness and abundance increased more than fourfold and eightfold from creek over slope to ridge forest sites. All three taxonomic units showed identical biodiversity patterns, notwithstanding their strong differences in multiple eco-morphological traits. An indicator species analysis revealed that most species identified as characteristic were associated either with the ridge forest alone or with ridge plus slope forests, but very few with the creek forest. Despite their mobility, local moth assemblages are highly differentially filtered from the same regional species pool. Hence, variation in environmental factors significantly affects assemblages of tropical moth species at small spatial scales.

Determines the population genetic structure of the Southern Hemisphere tope shark (Galeorhinus galeus) across the entire Southern Hemisphere, where the species is heavily targeted by commercial fisheries, as well as locally, along the South African coastline. Source: National Library of New Zealand Te Puna Matauranga o Aotearoa, licensed by the Department of Internal Affairs for re-use under the Creative Commons Attribution 3.0 New Zealand Licence.

Over the last century the fish community of the Dutch coastal North Sea zone has lost most its shark and skate species. Whether their disappearance has changed the trophic structure of these shallow waters has not been properly investigated. In this study historical dietary data of sharks and skates, being in the past (near)-residents, juvenile marine migrants and marine seasonal visitors of the Dutch coastal North Sea zone were analyzed for the period 1946–1954. Near-resident and juvenile marine migrant species were demersal while all marine seasonal visitors species were pelagic. Based on stomach content composition, the trophic position of four of the various shark and skate species could be reconstructed. The (near)-resident species, the lesser spotted dogfish, the marine juvenile migrant, the starry smooth hound, and the benthopelagic marine seasonal visitor, the thornback ray, had a benthic/demersal diet (polychaetes, molluscs and crustaceans), while the pelagic marine seasonal visitor, the tope shark, fed dominantly on cephalopods and fishes. Diet overlap occurred for fish (tope shark and lesser spotted dogfish), for hermit crabs (lesser spotted dogfish and starry smooth hound) and for shrimps (thornback ray and starry smooth hound). Trophic position ranged from 3.2 for thornback ray preying exclusively on crustaceans to 4.6 for the tope shark consuming higher trophic prey (crustaceans and fish). The analysis indicates that most of the shark and skate species were generalist predators. The calculated trophic positions of shark and skate species indicate that those species were not necessarily at the top of the marine ecosystem food web, but they might have been the top predators of their particular ecological assemblage.

Knowledge of reproductive movements and sources of recruitment in highly mobile species is important to understand population-level resilience and to manage recovery in populations depleted by human interference. Management of the school shark Galeorhinus galeus (Linnaeus, 1758), a Conservation Dependent species in Australia subject to a national recovery strategy after stock collapse from overfishing, has long assumed obligate female migration to pupping areas in the southeast of their range. We used post-natal elemental signatures of individuals from 3 cohorts born in 1996 to 1998 as a proxy to test whether females use common pupping areas. Environmental or biological factors that differ among pupping areas can give rise to unique trace element signatures in shark vertebrae that act as natural tags and can be used to assess relative contributions from recruitment sources to adult populations. We compared post-natal signatures from sharks caught in 2 regions, South Australia in the northwest of the species’ range and Bass Strait in the southeast, using laser ablation inductively coupled mass spectrometry. Signatures were similar between regions for 1 cohort, suggesting high use of shared or similar pupping areas, but differed for the 2 remaining cohorts. Region of capture could also be accurately predicted (>75%) based on post-natal signatures, refuting the long-held view that all females use common pupping areas. We conclude that female movements and reproductive strategies are likely more plastic than previously assumed, highlighting the need to clarify them and their potential effects on resilience and conservation.

In karst aquifers, groundwater flow is often turbulent and occurs in variably saturated conduits. This implies a nonlinear response to recharge events which cannot be reproduced with the tools commonly used for groundwater flow modeling. Recent studies have shown the usefulness of using conduit flow models to simulate flow in karst systems. However existing models are built on abstract representations of the actual conduit network or at a rather coarse resolution. Such models cannot provide information on local flow conditions in the conduits or be used to simulate mass transport. In the catchment of the Milandre Cave, in the Jura Mountains of Switzerland, a good portion of the active drainage network is accessible by caving, which opens the possibility for a distributed fine-scale numerical model. This report presents the development of a hydraulic model of the downstream part of this system (1.5 km × 0.5 km) using EPA SWMM 5. The network geometry is based on a detailed cave survey. Calibration is achieved by fitting the observed hydraulic head vs. flow-rate curves. The model performs well when compared against the hydraulic heads that were monitored throughout the system. Simulated transit times are also in line with tracer test results. This confirms that the model reproduces well the physics of flow in this karst system, while being spatially distributed at a fine scale (median element size of 6 m). It can thus provide information on local flow conditions in the conduits at various water stages and be used to address mass transport problems.

Fishing represents a major problem for conservation of chondrichthyans, with a quarter of all species being overexploited. School sharks, Galeorhinus galeus, are targeted by commercial fisheries in Australia and New Zealand. The Australian stock has been depleted to below 20% of its virgin biomass, and the species is recorded as Conservation Dependent within Australia. Individuals are known to move between both countries, but it is disputed whether the stocks are reproductively linked. Accurate and unbiased determination of stock and population connectivity is crucial to inform effective management. In this study, we assess the genetic composition and population connectivity between Australian and New Zealand school sharks using genome‐wide SNPs, while accounting for non‐random kin sampling. Between 2009 and 2013, 88 neonate and juvenile individuals from Tasmanian and New Zealand nurseries were collected and genotyped. Neutral loci were analyzed to detect fine‐scale signals of reproductive connectivity. Seven full‐sibling groups were identified and removed for unbiased analysis. Based on 6,587 neutral SNPs, pairwise genetic differentiation from Tasmanian and New Zealand neonates was non‐significant (FST = 0.0003, CI95 = [−0.0002, 0.0009], p = 0.1163; Dest = 0.0006 ± 0.0002). This pattern was supported by clustering results. In conclusion, we show a significant effect of non‐random sampling of kin and identify fine‐scale reproductive connectivity between Australian and New Zealand school sharks. OPEN RESEARCH BADGES This article has earned an Open Data Badge for making publicly available the digitally‐shareable data necessary to reproduce the reported results. The data is available at https://doi.org/10.5061/dryad.pd8612j. Fishing represents a major problem for conservation of chondrichthyans, such as school sharks. Accurate information on population boundaries is needed for effective management. However, nonrandom kin sampling leads to false‐positive signals of structure in Tasmanian and New Zealand school sharks.