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The combination of highly equipped smartphones, with the increased use of social media, has offered a wide database. Given this, citizen science can be used to record and monitor non‐native fish fauna, target new samples and collaborate with monitoring occurrences in new areas. We aimed to demonstrate the efficiency of social media in citizen science as a tool to cooperate with monitoring studies of non‐native species. Consequently, we determined the occurrence points of S. brasiliensis in the Iguaçu River basin, indicating sites of greatest occurrence and analyzing the impact of the invasion on the native fauna of the basin. Files and information available on the YouTube® and Facebook® media platforms were used as data, was carried out from April 2019 to April 2020. The results were 40 records, 22 videos obtained from Youtube, and seven videos and 11 photos from Facebook, the oldest record was from April 2013, while the largest number of posts was in 2016. Fish records available from online platforms can reveal the occurrence and progressive dispersion of species, in the context of biological invasions, these tools can be of great value in studies that aim to follow the progress of introduced species, contributing by helping to direct new sampling programs and corroborating the occurrence of species in new areas in conjunction with standard monitoring programs. Based on citizen science records, it was possible to update the range of occurrence of the non‐native S. brasiliensis in the Iguaçu River basin, cooperating with scientific knowledge. Innovative monitoring and control measures are necessary to deal with invasive species, with citizen science proving to be competent for determining the occurrence of species and showing promise in the entire field of ichthyology. [ABSTRACT FROM AUTHOR]

Understanding trophic relationships of fish in estuarine ecosystem is an important element for sustainable resource management. This study examined the feeding habits of 29 dominant fish species, characterized the trophic guilds, assessed the impact of season and clarified the role of diets in structuring the fish community in the mouth region of Pattani Bay, Thailand. Samples of 5792 fishes collected monthly by gillnets from March 2019 to February 2020 were used for stomach content analyses. It was found that the number of food types and fullness index differed between fish taxa (P < 0.001). Most fishes were specialist feeders feeding on specific food components and were categorized into five trophic guilds: piscivore, shrimp‐fish feeder, polychaete feeder, zooplanktivore and planktivore. Six species were piscivorous, considered as apex predators, that fed almost entirely on fishes. High diet overlaps among some species (>0.6) were recorded. Not much variation in seasonal guilds was observed: four guilds in the dry season, three in the moderate rainy season and four in the rainy season. Some species remained in the same guild the whole year round, but some fishes changed seasonally. Two fish communities from different regions of the bay were segregated based on feeding habits. The inner bay community comprised mainly copepod and plankton feeders, but there were more piscivores in the deeper bay mouth area. Results from this study help us to understand the feeding habits and trophic guilds of dominant fish species at the mouth of this tropical estuarine bay. [ABSTRACT FROM AUTHOR]

We used the unsupervised machine learning technique to evaluate the environmental factors responsible for modulating the spatial and seasonal distribution of caridean shrimps from a southeastern region of the Brazilian coast. Samplings were collected from seven transects with an artisanal shrimp fishery boat with two double‐rig nets. Samplings occurred every month from October 2008 to September 2009. The most frequently captured species were Exhippolysmata oplophoroides, Leander paulensis, and Nematopalaemon schmitti. The highest abundance of shrimps occurred in autumn at the II, III, and V transects, which present a higher amount of coarse sediment and biodetritic fragments on the bottom. During autumn, the temperatures were the highest and salinity values were the lowest. Data evaluation indicated efficiency in the visualization of interactions of different shrimp species and environmental data. This kind of sediment may be allowing shrimps to burrow in shelters that prevent predation. The seasons with high temperatures and low salinities can offer better conditions for the establishment of the studied species, despite the fact that there is no hypothesis to prove it. Additionally, the higher abundance of such shrimps coincides with vegetal debris deposition, which could serve as food and provide protection for these shrimps. In this region, the vegetation matter deposited at the bottom of the bay comes from the Atlantic Forest. Overall, the preservation of the coastal forest strongly influences the abundance of this taxon, as it provides protection and food for these shrimps. [ABSTRACT FROM AUTHOR]

Predation from the invasive Indo‐Pacific lionfish is likely to amplify declines in marine fishes observed in multiple ocean basins. As the invasion intensifies and expands, there is an urgent need to identify species that are most at risk for extirpation—and possible extinction—from this added threat. To address this gap and inform conservation plans, we develop and apply a quantitative framework for classifying the relative vulnerability of fishes based on morphological and behavioural traits known to influence susceptibility to lionfish predation (e.g. body shape, water column position and aggregation behaviour), habitat overlap with lionfish, and degree of geographic range restriction. Applying the framework to fishes across the invaded Caribbean Sea and ahead of the invasion front in the southwestern Atlantic revealed the identity of at least 77 fishes with relatively small ranges that are likely to be most affected by lionfish predation. Trait‐based vulnerability scores significantly predict the probability of fishes appearing within the diets of lionfish across the invaded region. Spatial richness analyses reveal hotspots of vulnerable species in the Bahamas, Belize and Curaçao. Crucially, our framework identifies 29 vulnerable fishes endemic to Brazil, which has not yet been colonized by lionfish. Of these, we suggest reefs around offshore island groups occupied by a dozen highly vulnerable and range‐restricted species as priorities for intervention should lionfish spread to the region. Observations of the rate of lionfish spread across the invaded range suggest that an average of 5 years (with a median of nearly 2 years) elapses from first sighting to maximum observed densities. This lag may allow managers to mobilize plans to suppress lionfish ahead of an invasion front in priority locations. Our framework also provides a method for assessing the relative vulnerability of cryptobenthic and/or deep‐reef fishes, for which population‐monitoring data are limited. [ABSTRACT FROM AUTHOR]

Extreme climate changes during the Cenozoic Era strengthened different biogeographical barriers that decreased the connectivity among populations, triggering lineage diversification of different species worldwide.The mitochondrial DNA control region was employed to explore the phylogeography of Sphyrna zygaena, a globally distributed species threatened by unsustainable, illegal, unreported and unregulated fisheries triggered by the international shark fin trade. It is listed as 'Vulnerable' by the IUCN Red List and its trade is regulated by CITES Appendix II.Only 13 haplotypes were found with low genetic diversity levels (hd = 0.686 ± 0.014; π = 0.00206 ± 0.00004) compared with other species of the Sphyrnidae family. The species has a very strong phylogeographic population structure among the Atlantic, Indian and Pacific Oceans (ΦST = 0.79132). Worldwide, there are six distinct populations with some haplotype sharing.These populations are probably connected by a stepping‐stone dispersal of a small number of migrants per generation from the Indo‐Pacific towards the Atlantic. Modelling suggests that S. zygaena diverged into two lineages around 6.96 million years ago which have been isolated in glacial refuges in the Atlantic and Indo‐Pacific oceans; and after deglaciation, a population expansion probably permitted secondary contact.Conservation plans to establish differentiated management units should be adopted in each of the identified populations. Among these, the Eastern Central Atlantic and West Indo‐Pacific are the most important areas for the species considering the historical migration routes that act as a bridge connecting the Atlantic and Indo‐Pacific Oceans while the Gulf of Guinea connects the Atlantic populations. Still, further studies are required to know if these populations are also linked with nursery areas for the species.The results herein can help to delimit the main evolutionarily significant units to implement effective policies to establish differentiated management units as starting points to genetic monitoring programmes for Sphyrna zygaena. [ABSTRACT FROM AUTHOR]

Wildlife is an important source of nutrition and income for rural communities. The International wildlife trade of endangered species is regulated by CITES, but domestic wildlife markets are rarely subjected to this degree of scrutiny. Market surveys provide important domestic trade data but suffer limitations. Occupancy modelling, using search effort, can be applied to market surveys. To compare the availability of marine consumables from species threatened with extinction, we undertook market surveys using a 'shopping list' of threatened species. Items included turtle eggs and shark products. Turtle eggs from the Ostional Egg Project are sold under a certification scheme, but non‐certified eggs are readily available. The surveyors were local residents employed to complete the market survey. The search effort for each item was compared using an adaptation of survival analysis. Time to find each item indicated availability. We tested whether demographics and shopping habits affected surveyors' ability to find the items. Shark products were found fastest and were, therefore, the most readily available item. Non‐certified eggs were found as easily as Ostional certified eggs, implying there are few deterrents to the open sale of non‐certified eggs. The shopping habits of surveyors had no effect on their ability to find eggs. Integrating the shopping list with survival analysis can reveal valuable information on demand and supply, which would otherwise be difficult to obtain using traditional surveys. [ABSTRACT FROM AUTHOR]

The illegal sale of endangered elasmobranchs has been recorded in a number of different Brazilian states, where sharks and rays are being marketed primarily as 'cação' or 'viola'. Brazil is ranked among the top 10 nations worldwide that harvest most sharks, causing an immeasurable impact on the local elasmobranch populations.The present study applied the DNA barcoding technique, based on the cytochrome C oxidase subunit I gene, for the molecular identification of the elasmobranch species sold as processed products under the generic names of 'cação', 'mangona', 'azul', 'cambeva', 'fiuso' and 'lombo preto', in the fish market of the city of Florianópolis, capital of the state of Santa Catarina, Brazil.Nine elasmobranch species were identified in the 56 samples analysed, including six sharks and three rays, representing six families, the Carcharhinidae, Sphyrnidae, Squatinidae, Arhynchobatidae, Myliobatidae and Gymnuridae. Prionace glauca, identified in more than half (56%) of the samples analysed, is listed as Near Threatened by the International Union for the Conservation of Nature.Six species identified in the present study, Sphyrna zygaena, Sphyrna lewini, Squatina guggenheim, Carcharhinus signatus, Gymnura altavela and Rioraja agassizii, are under some level of risk of extinction, while two others (Rhizoprionodon lalandii and Myliobatis goodei) are listed as Data Deficient.Our results indicate that the commercial exploitation of endemic sharks and rays at risk of extinction is commonplace in southern Brazil. This reinforces the need for more systematic monitoring of the trade in fishery products and more effective application of the environmental legislation and conservation programmes. [ABSTRACT FROM AUTHOR]

Giant guitarfishes (Glaucostegidae) and wedgefishes (Rhinidae) are some of the most threatened marine taxa in the world, with 15 of the 16 known species exhibiting global population declines and categorized as Critically Endangered according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. The recent inclusion of all species in Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) necessitates more rigorous enforcement by regulatory authorities.Challenges in regulating the trade of giant guitarfish and wedgefish products due to difficulties in visual identification of processed products and labelling issues impede enforcement. The aim of this study is to characterize the diversity and origins of associated traded products that were commercially available in Singapore, one of the world's top importers and re‐exporters of shark and ray products.A total of 176 samples of elasmobranch products were obtained between June and December 2019 from fishery ports and various retailers in Singapore. By applying cytochrome c oxidase subunit I gene barcoding, 31 elasmobranch species were detected, with 55% of the species considered threatened (Critically Endangered, Endangered, or Vulnerable) based on the IUCN Red List and 35% of species listed in CITES Appendix II. Four species of giant guitarfishes and wedgefishes were commercially available to consumers in fresh forms of whole fish, fillet, and fin, as well as dried and cooked meats.DNA barcoding has proven to be an effective tool for identifying elasmobranch products that are impossible to recognize visually and would aid enforcement of CITES trade regulations. This work underscores the urgent need to step up enforcement of marine wildlife regulations and draw public attention to the elasmobranch trade. [ABSTRACT FROM AUTHOR]

Aim: The disjunct distributions of freshwater organisms along coastal drainages are usually explained by palaeodrainages formed during sea‐level retreats that connected currently isolated basins, or by river capture from tectonic adjustments between adjoining watersheds. We evaluate the relative importance of these events on the genetic variation of freshwater fishes inhabiting the Serra do Mar in eastern Brazil, a region with steep mountains and pronounced bays. Location: Coastal river drainages in southeastern Brazil. Taxon: Catfishes of the Trichomycterus alternatus group. Methods: We tested the effects of palaeolandscape connections (GIS‐reconstructed palaeodrainages and putative river captures) on the genetic structure (mitochondrial and nuclear markers) of T. alternatus from 15 drainages using phylogenetic reconstructions, lineage delimitation methods and analyses of molecular variance. Results: Trichomycterus alternatus is monophyletic and comprised of three main lineages: two restricted to the basin at its northernmost distribution and another broadly distributed to the south. In the latter, seven major cytb clades were geographically compatible with the eight palaeodrainages, with three incongruences matching river captures previously described for the Guanabara Bay (GB). Shared haplotypes among isolated rivers flowing into GB provide the first molecular evidence of the 'Rio de Janeiro' palaeoriver. Main conclusions: Dispersal via palaeorivers is an important process, but it is not enough to recover the most recent dispersive events. Therefore, integrating both palaeo‐riverine configuration (GIS‐based) and localized river captures (geological studies) is crucial to reveal the role of past geological and climatic events on the distribution of freshwater organisms. Taken together, these two factors significantly explained a high portion T. alternatus genetic structure along coastal drainages, revealing a palaeolandscape scenario that may have been used by other freshwater Atlantic Forest taxa. [ABSTRACT FROM AUTHOR]

Animal dietary information provides the foundation for understanding trophic relationships, which is essential for ecosystem management. Yet, in marine systems, high‐resolution diet reconstruction tools are currently under‐developed. This is particularly pertinent for large marine vertebrates, for which direct foraging behaviour is difficult or impossible to observe and, due to their conservation status, the collection of stomach contents at adequate sample sizes is frequently impossible. Consequently, the diets of many groups, such as sharks, have largely remained unresolved. To address this knowledge gap, we applied metabarcoding to prey DNA in faecal residues (fDNA) collected on cotton swabs from the inside of a shark's cloaca. We used a previously published primer set targeting a small section of the 12S rRNA mitochondrial gene to amplify teleost prey species DNA. We tested the utility of this method in a controlled feeding experiment with captive juvenile lemon sharks (Negaprion brevirostris) and on free‐ranging juvenile bull sharks (Carcharhinus leucas). In the captive trial, we successfully isolated and correctly identified teleost prey DNA without incurring environmental DNA contamination from the surrounding seawater. In the field, we were able to reconstruct high‐resolution teleost dietary information from juvenile C. leucas fDNA that was generally consistent with expectations based on published diet studies of this species. While further investigation is needed to validate the method for larger sharks and other species, it is expected to be broadly applicable to aquatic vertebrates and provides an opportunity to advance our understanding of trophic interactions in marine and freshwater systems. [ABSTRACT FROM AUTHOR]

Resource use by organisms is mainly influenced by factors such as the morphology of individuals and the diversity and abundance of resources. For omnivores, the influence of these factors is more complex, as they have a morphology adapted to access different trophic levels, and any change in the environment can affect the quality or availability of resources. The aim of this study was to evaluate the effect of biotic and abiotic factors on the use of resources by omnivorous fish. We analysed the diet of 107 individuals of Astyanax lineatus in headwater streams in the Pantanal plateau, Brazil. We analysed the influence of body size and the characteristics of streams on the dietary composition, proportion of allochthonous items, trophic niche width and trophic position of individuals. These alimentary parameters were mainly influenced by body size and environmental variables, such as stream vegetation cover, flow, dissolved oxygen and conductivity. Allochthonous resources were more important to the diet of our model fish. We observed that larger individuals are more specialists than medium‐sized individuals and the trophic position decreases with increasing body size. Basically, three factors may have contributed to these results: large supply of carbon‐rich resources; morphology adapted for the consumption of larger, harder and carbon‐rich foods; and the interaction of increased body size and the high temperatures in the Neotropical region that can increase the demand for carbon for energy production. [ABSTRACT FROM AUTHOR]

As environmental change persists, understanding resource use patterns is of value to predict the consequences of shifting trophic structures. While many sharks are opportunistic predators, some exhibit prey selectivity, putting them at higher risk compared to species with greater trophic plasticity. In the Gulf of Mexico (GOM), Clupeids and Sciaenids comprise 69% of blacktip shark (Carcharhinus limbatus) diets, which is consequential considering potential responses of these prey groups to disturbance and over harvesting. We assessed if blacktips exhibit selectivity for Clupeids and Sciaenids in the western GOM based on stomach contents from sharks in coastal Texas. Clupeids comprised <2% of diets, while striped mullet (Mugil cephalus) and red drum (Sciaenops ocellatus) comprised >70% of identifiable prey. Ontogenetic shifts from smaller (Clupeids, small Sciaenids) to larger, higher trophic level (Ariidae, Elasmobranchii) prey fits our understanding of foraging among coastal sharks, and suggests our regional understanding of blacktip trophic ecology may be limited by the sizes of sampled sharks. Observed increases in blacktip densities coupled with declines in prey (Mugilids, Sciaenids) is concerning if blacktips have limited diet plasticity. Yet GOM blacktips may be more generalized than previously thought, which is promising for conservation and management. [ABSTRACT FROM AUTHOR]

A species is considered native to a region if its presence is the result of natural processes or if its colonisation of a new geographical region occurs naturally, while non-native species are defined as those living outside their natural range, even if introduced from other basins or regions within the same country (Guo & Ricklefs, 2010; Vitule et al., 2019). Such differences in regulations may motivate fishermen to move from states where the species is protected to states where the species occurs naturally but where there is no such protection. In south-eastern Brazil (Doce River), this species negatively affects other species ( I e.g i . crustacean and fish communities) (Ruschi, 1965). However, the way in which legal regulations are being drafted compromises the maintenance and conservation of native species by protecting species outside of their region of origin (Ota et al., 2018). [Extracted from the article]

Rays (superorder Batoidea) are the most diverse group of elasmobranchs, and many are threatened with extinction. However, there remain areas where research on the ecology of this group is lacking, from trophic interactions to their importance to ecosystem structure and function. Such ecological insights are critical for predicting the potential consequences of changes in their population sizes. Our aim was to synthesize the existing ray ecology literature and identify key knowledge gaps in order to provide a framework for future research. Numerous studies describe ray diets, and the number of studies using biochemical methods to address ray trophic interactions is increasing. The implications of ray predator–prey interactions on population dynamics of prey and how ray foraging might influence ecosystem dynamics through bioturbation remain relatively unexplored, despite claims that rays are ecologically important because they are bioturbators and because of their potential to deplete stocks of commercially important bivalves. Therefore, to better integrate rays in our understanding of marine community dynamics, there is a need to: (i) combine behavioural data with dietary information to describe predator–prey interactions; (ii) understand how ray bioturbation affects biogeochemical cycles and infaunal communities; (iii) elucidate conditions under which rays might initiate or transmit trophic cascades through consumptive and non‐consumptive pathways; and (iv) consider anthropogenic influences on the ecological roles and importance of rays. [ABSTRACT FROM AUTHOR]

The Neotropics harbour the greatest diversity of freshwater fish on Earth. Despite recent advances in characterizing the fish fauna, the total number of species, distributional range, evolution and ecological traits remain uncertain. Thus, we quantify shortfalls in the knowledge of taxonomy (Linnean shortfall), geographic distribution (Wallacean shortfall), evolutionary relationships (Darwinian shortfall) and feeding habits (Raunkiæran shortfall) of Auchenipteridae driftwood catfishes, one of the most representative groups of the Siluriformes family in the Neotropics. We find a steep increase in the historical accumulation of valid species over time, suggesting that 45% of the total number predicted remains to be described. Auchenipterids also remain under‐collected; only 45% of the ecoregions and less than 3% of the one‐degree grid cells covering the Neotropics are reasonably sampled. The topologies of recent phylogenies are more similar to each other than former ones, showing a tendency towards a robust phylogenetic hypothesis for this family. Current knowledge on feeding habits is biased towards a few genera and species and is still expanding with every new published study. Our study highlights specific knowledge gaps that need to be addressed: a considerable number of Auchenipteridae species remain to be described; and most of valid species lack reliable information on their geographic distribution and feeding habitat. It implies that research on fish systematic biology needs to advance and it will require a concerted effort of taxonomists, ecologists and biogeographers to reduce these gaps. [ABSTRACT FROM AUTHOR]

Sharks and rays caught by a small-scale fisheries in the western equatorial Atlantic Keywords: artisanal fisheries; Chondrichthyes; conservation; elasmobranch; endangered species EN artisanal fisheries Chondrichthyes conservation elasmobranch endangered species 830 833 4 12/21/20 20201201 NES 201201 INTRODUCTION The more than 1,100 known species of sharks and rays (Weigmann, 2016) are important trophic components of marine ecosystems. DISCUSSION This is the first study to use systematic monitoring of fisheries landings to describe the coastal fauna of elasmobranchs for the Ceará state and one of few for northeastern Brazil. The most captured and landed elasmobranch species at the Mucuripe embayment, I H. americanus i and I R. porosus i , are currently considered Data Deficient in Brazil (ICMBio, 2016). [Extracted from the article]

Public aquaria globally display numerous threatened fish species captured from wild populations. Potential impacts of harvests are rarely evaluated despite the need for improved management and conservation practices.Sawfishes (Family Pristiidae) are one of the world's most at‐risk fish families. Most commonly displayed (30+ wild caught individuals) is the Critically Endangered largetooth sawfish, Pristis pristis.Two Australian aquaria release captive P. pristis to the wild as they outgrow displays, intending to offset impacts of the original harvests. The fate of released sawfish is unknown.Using acoustic telemetry, the behaviour (rates of movement, patterns of habitat use) and survival of aquarium released sawfish (n = 5) were compared to a control group of wild sawfish (n = 5).Aquarium sawfish had reduced rates of movement, were more sedentary, and occupied smaller activity spaces than wild sawfish; but diel activity and habitat use patterns were similar.Collectively, mortality was high. Two aquarium sawfish survived to the end of the monitoring period (391 days and 117 days, respectively), and no wild sawfish survived. The mean duration of survival for aquarium and wild sawfish was 157 and 58 days, respectively.Whilst captivity affected behaviours, the lower mortality rates of aquarium sawfish indicates that releases may partially offset the impact of the original harvest. Further data are required to investigate potential long‐term ecological impacts.If P. pristis are to be used for aquarium displays, the best conservation outcomes could be achieved by harvesting in the first year of life when natural mortality is highest, followed by release into the freshwater reaches of the natal river where predation risk may be minimized. Size on release should be less than ~2,800 mm total length to allow for migration from the river system as part of their natural life cycle. [ABSTRACT FROM AUTHOR]

Indirect interactions mediated by shared enemies or mutualists (i.e. apparent competition) can influence whether invasive plants harm or benefit co‐occurring species. However, studies to date have largely examined single pairwise interactions, limiting our understanding of the interplay among different types of interactions and whether indirect impacts systematically favour native or exotic species. Predicting indirect interaction strength has also proven challenging, and it remains unclear whether the strengths of different indirect interactions are correlated.We conducted a field experiment in a grassland invaded by Scotch broom Cytisus scoparius to compare the strength of its indirect impacts, via both soil fungi and herbivores, on 21 native and exotic legume species growing in pots buried in the ground. Direct interactions of plants with soil fungi were controlled using nylon mesh pot windows of differing porosity (1 or 38 µm) to prevent or allow soil fungi hyphal growth. Arthropod herbivores were controlled through spraying pyrethrum pesticide. To assess indirect impacts, interactions were compared between plants adjacent to or 50 m away from an extensive Scotch broom invasion. We measured plant performance (survival, height and biomass), arthropod and hare herbivory, and rhizobia nodulation.Despite increasing arthropod herbivory of both native and exotic plant species, Scotch broom had a net positive impact on their survival and growth, through sheltering them from abiotic stress, and indirectly via beneficial soil fungi and release from hare browsing. Soil fungi also increased arthropod herbivory, decreased rhizobia nodulation and disproportionately promoted the growth of exotic plants. Overall, exotic plants experienced stronger interactions, which favoured them with beneficial soil fungi and rhizobia but not hare browsing. Finally, indirect interaction strength was not correlated among indirect interactions mediated by different interaction partners.Synthesis. We demonstrate that invaders affect their competitors through multiple interacting indirect pathways that were stronger than direct 'nurse plant' effects, emphasizing the importance of a community‐level approach to studying biological invasions. Exotic species experienced stronger positive and negative impacts than natives, but were facilitated overall, potentially contributing to exotic dominance in communities. [ABSTRACT FROM AUTHOR]

Isopisthus parvipinnis, commonly known as "bigtooth corvina", is a marine estuarine‐dependent fish captured in the southeast and south Brazilian coast as bycatch of the shrimp fishery. This work used the sagittae morphology as a tool to primarily study the population structure of I. parvipinnis between São Paulo and Santa Catarina states (23ºS to 26.9ºS) in Brazil. Secondly, it intended to verify the existence of morphological alterations over time, by comparing otoliths of fish captured in 1975 and 2018/2019. Otolith shape analyses were performed in individuals ranging from 66 to 139 mm of total length, obtained from historical (1975) and present catches (2018/2019) in the shallow coastal areas off North of São Paulo (NSP), Centre of São Paulo (CSP), South of São Paulo (SSP), Paraná (PR) and Santa Catarina (SC). Otoliths were analyzed using shape indices (SIs), elliptical Fourier descriptors (EFDs) and both tools combined. Morphological variations among locations and between years were tested using uni and multivariate statistics. Data showed regional differences in the otolith shape analysis over the years. Samples from 1975 presented an overall low reclassification rate (43%), with a high overlap of individuals among locations, suggesting the existence of a single group. Differently, samples from 2018/2019 discriminated four distinct spatial units with a good overall reclassification (74%): group 1 ‐ NSP; group 2 ‐ CSP; group 3 ‐ SSP + PR; and group 4 ‐ SC. The hereby data suggests regional changes at long term in the population dynamics of I. parvipinnis, from a single panmictic population in the past to a metapopulation structure in the present days, with consequences for the rational and sustainable management of the fishery. However, once it was the first evaluation of the population structure of I. parvipinnis, it is highly recommended to use complimentary phenotypic and/or genetic approaches to corroborate the hereby observed findings. [ABSTRACT FROM AUTHOR]

Elasmobranchs are particularly vulnerable to overexploitation and population depletion, especially due to their life‐history traits, such as low reproductive output and slow growth. Given that capture‐induced parturition (abortion or premature birth) is a common consequence of fisheries in elasmobranchs, but still little studied, we investigated how the abortion/premature birth process varies in response to reproductive traits in a freshwater stingray, Potamotrygon amandae. Our results revealed that capture‐induced parturition was affected by reproductive traits, such as litter size (one to seven) and gestation stage. The event occurred faster in pregnant females with high litter size during late pregnancy. Also, as found in other elasmobranchs, litter size was positively correlated with maternal size. These findings indicate that larger pregnant females in late pregnancy are more vulnerable to capture‐induced parturition. This study improves our understanding of the capture‐induced parturition process in stingrays, and provides useful information for management strategies and future recommendations for elasmobranch conservation. [ABSTRACT FROM AUTHOR]

In the southern Gulf of Mexico, the bonnethead shark, Sphyrna tiburo, is one of the most frequently captured species in landings of small‐scale fisheries. Based on the analysis of two fishery‐dependent sampling periods (1993–1994 and 2007–2014), this study aimed to determine reproductive parameters and identify temporal differences between the two time periods. In the first sampling period, 776 males and 352 females with a size range of 28.0–120.0 cm total stretched length (LT) were analysed, and in the second sampling period, 387 males and 432 females with a size range of 28.0–122.0 cm LT were analysed. The size at 50% maturity in the second sampling period was significantly different between sexes, 82.6 cm LT for females and 73.8 cm LT for males (no estimation was possible for the first sampling period). The size at 50% maternity was not different between sampling periods, 97.3 cm LT for the first sampling period and 99.0 cm LT for the second sampling period. Litter size varied from 3 to 19 embryos and the average was not statistically different in both periods, 10.1 (S.D. = 3.8) for the first sampling period and 11.3 (S.D. = 3.5) for the second sampling period. The female reproductive cycle is asynchronous, and it seems to be annual, with a gestation period of 5–6 months, and a consecutive ovarian cycle and gestation period. Temporal (between sampling periods) and latitudinal (southern Gulf versus northern regions) variations occur in the synchronicity of the reproductive cycle, temporal variation in the relationship between maternal length and litter size, and latitudinal variation in average size of mature sharks. [ABSTRACT FROM AUTHOR]

The U.S. Congress is currently discussing the Shark Fin Sales Elimination Act to eliminate shark fin trade at the federal level. This bill was introduced in 2017 and has been proceeding very slowly in Congress because of mixed reviews from the scientific community. Debate exists on whether shark conservation and management are effectively addressed with tightened trade controls for imported shark products or blanket bans that outright end U.S. participation in the shark fin trade. Here we contribute to this debate with a review and analysis of economic, nutritional, ethical, and legal arguments, as well as of the shark fisheries status and shark fin trade. We show that the United States has a limited commercial interest in shark fisheries and contributes to the shark fin trade mainly as a facilitator. A fin trade ban has few tangible economic drawbacks but would have a considerable conservation impact. While making all shark fisheries sustainable is the ultimate goal, in practice this objective is far from achievable everywhere in the world. Conversely, banning shark fin trade is an interim measure that nations like the United States can take with negligible cost and can truly impact the biggest driver of shark exploitation globally. [ABSTRACT FROM AUTHOR]

During their evolutionary history, modern sharks developed different tooth mineralization patterns that resulted in very distinct histological patterns of the tooth crown (histotypes). To date, three different tooth histotypes have been distinguished: (i) orthodont teeth, which have a central hollow pulp cavity in the crown, encapsulated by a prominent layer of dentine (orthodentine); (ii) pseudoosteodont teeth, which have their pulp cavities secondarily replaced by a dentinal core of porous dentine (osteodentine), encased by orthodentine; and (iii) osteodont teeth, which lack orthodentine and the whole tooth crown of which consists of osteodentine. The aim of the present study was to trace evolutionary trends of tooth mineralization patterns in modern sharks and to find evidence for the presence of phylogenetic or functional signals. High resolution micro‐computed tomography images were generated for the teeth of members of all nine extant shark orders and the putative stem group †Synechodontiformes, represented here by three taxa, to examine the tooth histology non‐destructively. Pseudoosteodonty is the predominant state among modern sharks and represents unambiguously the plesiomorphic condition. Orthodonty evolved several times independently in modern sharks, while the osteodont tooth histotype is only developed in lamniform sharks. The two shark orders Heterodontiformes and Pristiophoriformes showed highly modified tooth histologies, with Pristiophorus exhibiting a histology only known from batomorphs (i.e. rays and skates), and Heterodontus showing a histological difference between anterior and posterior teeth, indicating a link between its tooth morphology, histology and durophagous lifestyle. The tooth histotype concept has proven to be a useful tool to reflect links between histology, function and its taxonomic value for distinct taxa; however, a high degree of variation, especially in the pseudoosteodont tooth histotype, demonstrates that the current histotype concept is too simplistic to fully resolve these relationships. The vascularization pattern of the dentine might offer new future research pathways for better understanding functional and phylogenetic signals in the tooth histology of modern sharks. [ABSTRACT FROM AUTHOR]

The international fin trade is a major source of mortality for many threatened shark species but most of what it is known about this trade comes from assessments of large fins commanding high prices in trade hubs. There is growing international trade in 'small, low‐value' fins in Southeast Asia, which are used for inexpensive shark fin soup products. These fins could be derived from small species, juveniles of large species, or a combination of both. Resolving the species identification of these small fins has important conservation implications, because large sharks tend to be more vulnerable (VU) to overexploitation than small ones. Here we describe the first species‐specific assessment of the small, low‐value fins in the shark fin retail markets of Hong Kong. A total of 475 randomly collected samples were genetically identified using a portion of the cytochrome oxidase I, revealing at least 29 species. Around a third (34.5%) of the species found are in threatened International Union for the Conservation of Nature Red List categories, and 21.2% of the samples were from four species listed on Appendix II of the Convention on International Trade in Endangered Species (CITES). The size of the analyzed fins and the species composition found suggests that small fins come from a combination of small (62.9 %) and large (37.1%) species, with the majority of small fins coming from suspected juveniles of large species. We suggest the sources of most of these fins are likely to be multi‐species fisheries in shallow, coastal habitats used by large species and also occupied by small species. Our results represent the first step to better understand the trade in small shark fins on a species‐specific basis and highlight the need for market surveys and increased inspection of this fin category at border control check points for CITES‐listed species. [ABSTRACT FROM AUTHOR]

Across their North American range, grizzly bears (Ursus arctos) occupy a special place in human imagination, as icons of nature's rugged and raw power, to representations of safety risks and economic costs of living with carnivores. Different bear representations can also be found across news media, from controversial and sensational descriptions of attacks, tragic events and conflicts, to scientific accounts of conservation research. News media certainly has the power to pique curiosity, spark debate, or elicit emotional responses through framing and repetition of content. In turn, news stories can influence how people might interpret and internalize information about grizzly bears. Using media content analysis, we examined newsprint stories on grizzly bears across their North American range between 2000 and 2016, to understand message framing and attention cycle, as well as attitudinal expression and representative anecdote conveyed to the readership. We found that human–bear conflict stories are over‐reported compared to other narratives, where a single incidence garners more attention than a story about new scientific findings. We also found articles that included hunting frames largely originated in Alberta, likely due to the threatened species listing and hunting moratorium. Attitudinal expressions included ecological, negative or neutral, and moral sentiments toward bears. The most common representative anecdote conveyed to the readership reflected the dire state faced by grizzly bears. The bear eco‐gossip expressed in the articles we reviewed, which included clear protagonists and antagonists and the occasional man‐bites‐bear surprise, appears to be the diet of manufactured information fed to the public. Results of our study can help scientists and conservationists understand how news media portrays grizzly bears to the public and how this might influence public sentiment toward their conservation, but also identifies the roles that scientists, conservationists and journalists together can play in crafting effective, factual and engaging news stories about bears. [ABSTRACT FROM AUTHOR]

Copyright of Biotropica is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Largemouth Bass (Micropterus salmoides) have been introduced on a global scale for sport fishing but represent a conservation concern given their documented negative impacts on native faunal diversity and abundance. Recent research using molecular data to characterize invasive Largemouth Bass populations elsewhere has demonstrated that populations are typically characterized by limited genetic diversity, or represent a combination of Largemouth Bass and Florida Bass (Micropterus floridanus). To test whether these traits were consistent with invasive populations in Brazil, we generated mitochondrial sequence data from four established populations of Largemouth Bass collected in southern Brazil as well as a local aquaculture facility to confirm species identity and quantify levels of genetic diversity. We identified the exclusive presence of Largemouth Bass in the region and observed limited levels of haplotype (haplotype diversity = 0.0684, SE = 0.038) and nucleotide diversity (0.0003, SE = 0.0002) which suggested the presence of a founder effect associated with introduction. Each of the four populations were dominated by a single haplotype that was identical to one recovered from a nearby aquaculture facility, which identified this facility as a potential introduction source. [ABSTRACT FROM AUTHOR]

Statistical fisheries data are usually obtained during landings, through rapid fish classification and their categorization under the trade names given to species or groups of species. However, species classification is often difficult, particularly concerning elasmobranchs whose fins and heads have been removed, leading to labelling errors.The aim of this paper is to identify the ray species composition landed in south‐east Brazil, providing identification strategies to support a plan for more efficient labelling and management.Samples were obtained from artisanal fleet landings, between November 2012 and May 2014. For taxonomic identification of whole or processed animals (n = 279, belonging to 10 species), morphological, metric, and molecular techniques were employed. The common name used by fishermen was more related to the location where they lived than the fishing gear used.Morphometric analyses resulted in pectoral fin to length and weight conversion equations of whole individuals for each species, and 10 variables were found to be diagnostic of each genus.A genetic identification, based on sequencing of the mitochondrial genes cytochrome b and cytochrome oxidase I, was applied to verify morphological identification. A dichotomous key that allowed ray identification at the species level from pectoral fin morphology was developed. The approach was field tested and deemed adequate, leading to a robust monitoring strategy for estimating the biomass of specific landed rays. [ABSTRACT FROM AUTHOR]

Sagitta otoliths are usually formed of calcium carbonate polymorphs as aragonite. The objective of this study was to verify which carbonate polymorph is predominant in the sagitta otolith of Menticirrhus americanus and check whether this pattern remains in otoliths with morphological alterations. Otoliths of M. americanus were obtained from five sites on the southeast‐south coast of Brazil (São Sebastião (SS) 23°45′S–45°24′O, n = 29; Cananéia‐Iguape Estuarine Complex (CI) 25°02′S–47°54′O, n = 30; Paranaguá Estuarine Complex (PEC) 25°28′S–48°20′O, n = 35; Itapoá (IT) 26°07′S–48°36′O, n = 31; Laguna (LA) 28°28′S–48°46′O, n = 13). The characterization of carbonate polymorphs of otoliths was performed through Raman spectroscopy, a photonic and non‐destructive technique that analyzes molecular vibrations induced by laser. We analyzed 138 pairs of M. americanus otoliths, of which eight otoliths from different pairs presented morphological alterations (SS n = 1, CEP n = 5, IT n = 1, LA n = 1). The Raman spectra show that normal otoliths, that is, without morphological alterations, presented only aragonite in their structure. Among the otoliths that presented morphological alterations, the Raman spectra allowed to identify in six otoliths the deposition of aragonite and in only two otoliths the deposition of vaterite (one specimen of the PEC and one of SS). [ABSTRACT FROM AUTHOR]

We reported the genus Parasphyraenops (Perciformes: Serranidae) in the Brazilian Biogeographic Province. Four Parasphyraenops incisus specimens were identified based in body shape and color pattern through underwater remote video records, on shallow coral reefs in the Bahia state, Brazil. In the video frames P. incisus was observed swimming close to the pomacentrid Chromis multilineata at 14 m depth, being this the shallowest record for this species. The present record expands on 6.500 km the southern limit of distribution of P. incisus in the Western Atlantic. [ABSTRACT FROM AUTHOR]

Studies on the feeding ecology of fish are essential for exploring and contrasting trophic interactions and population and community dynamics within and among aquatic ecosystems. In this respect, many different methods have been adopted for the analysis of fish stomach contents. No consensus has, however, been reached for a standardised methodology despite that for several decades there has been an ongoing debate about which methodical approaches that should be preferred. Here, we critically review and scrutinise methods, addressing their strengths and weaknesses and emphasising inherent problems and possible pitfalls in their use. Although our critical assessment reveals that no completely ideal approach exists, appropriate and reliable procedures can be adopted through careful considerations and implementation. In particular, we advocate that different objectives require different methodical approaches and the choice of method should therefore be closely linked to the research questions that are addressed. For a standardisation of methods, we recommend a combination of the relative‐fullness and presence–absence methods as the optimal approach for the commonly applied feeding studies addressing relative dietary composition in terms of prey diversity and abundance. Additionally, we recommend the gravimetric method for objectives related to the quantification of food consumption rates and the numerical method for prey selection studies. DNA‐based dietary analysis provides a new and promising complementary approach to visual examination of stomach contents, although some technical challenges still exist. The suggested method standardisation facilitates comparisons across species, ecosystems and time and will enhance the applicability and benefits of fish feeding studies in trophic ecology research. [ABSTRACT FROM AUTHOR]

The age and growth of three endemic threatened guitarfish species were analysed using vertebrae of Pseudobatos horkelii, P. percellens and Zapteryx brevirostris. Edge and marginal‐increment analyses were used to evaluate the periodicity of the formation of the band‐pairs, suggesting deposition of one band‐pair per year, from late winter to late spring. The von Bertalanffy growth model was used to describe the growth of these species with the following parameters, for pooled sexes: P. horkeliiL∞ = 126.93, k = 0.19 and t0 = −1.51; P. percellensL∞ = 109.31, k = 0.16 and t0 = −1.78; Z. brevirostrisL∞ = 60.37, k = 0.24 and t0 = −1.42. Our results are essential to understanding the resilience and vulnerability of these species to harvest, which can contribute to management and conservation actions of these species. [ABSTRACT FROM AUTHOR]

Morphometric measurements, meristic counts and DNA barcoding identified the presence of a biglip grunt Plectorhinchus macrolepis in the western Atlantic Ocean. As the species is endemic to the tropical eastern Atlantic Ocean and has not previously been reported in the western Atlantic Ocean, we discuss the possible means by which it might have dispersed to the western Atlantic Ocean. Even though this species is not considered established in Paranaguá Bay, we advocate monitoring of possible new individuals and other exotic fish species. [ABSTRACT FROM AUTHOR]

On 20 December 2017, a mature Triaenodon obesus was observed at Hanga Roa Bay, Rapa Nui (Easter Island) at c.18 m depth. This observation increases both the range of T. obesus in the Pacific Ocean and the number of elasmobranch species at Rapa Nui. In combination with other recent sightings further extending the southern range of this species during the Austral summer, sea surface temperature is suggested as key to southern dispersal. [ABSTRACT FROM AUTHOR]

Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

While environmental alterations have made Homo sapiens the hyperkeystone species of the globe, biotic homogenization initiated a new era, the "Homogenocene." Still, some terrestrial and aquatic ecosystems in South America are considered pristine and wild, which can lead to a general faith that economic progress is consistent with conservation strategies, even without scientific support. We compiled anthropogenic threats to fish biodiversity in a hierarchical meta‐analysis, along with an evidence synthesis of threats related to biological invasions, based on peer‐reviewed research with the aim to represent the actual conservation status of the South American ichthyofauna. We highlighted human‐related threats and synergistic effects of biological invasions, climate change, environmental alterations (e.g., pollution, aquaculture and damming) and fisheries. Considering measures that reinforce novel alien fish (e.g., artificial hybrids or genetically modified) introductions, it became clear why an eventual increase in local or regional species richness is not always beneficial to aquaculture, biodiversity, human well‐being or nature. In fact, citizens in all societal roles, including scientists, should revise their concepts about threats to fish biodiversity. Environmental policies require more than taxonomic diagnostics to achieve conservation goals under an incompatible scenario of a multiplying number of fish species and biotic homogenization. We advocate for countries in South America using science‐based strategies useful to maintain their social and economic growth along with their "remaining nature." We live a crucial moment when the government overlooks threats to biodiversity and uses agribusiness as the most acceptable manner of fuelling the economy. [ABSTRACT FROM AUTHOR]

Robust assessments of the effects of fishing require accounting for components of fishing mortality, including post‐release fishing mortality (Fr). Random‐effects meta‐analysis synthesized Fr in seven pelagic shark species captured, tagged and released with 401 pop‐up satellite archival tags compiled from 33 studies and three gears (longline, purse‐seine, rod & reel). The majority of Fr outcomes occurred within days of release, and the summary effect size for Fr was 0.27 [95% CI: 0.19–0.36], ranging from a low pooled effect size of 0.17 for blue shark (Prionace glauca, Carcharhinidae) to 0.38 (silky shark, Carcharhinus falciformis, Carcharhinidae). Fr rates in blue shark were consistent over dissimilar spatial and temporal scales, and results from earlier meta‐analysis were replicated, which is the most powerful way to authenticate results. Condition at tagging was a strong predictor, and dichotomized survival outcomes in silky shark and no sex‐, size‐, location‐ or gear‐specific Fr rates were demonstrated. Meta‐analyses and sensitivity analyses indicated exposure to risk factors and conditions whilst caught on the gear probably had the largest explanatory effect on Fr, rather than stressors incurred during handling and release. Records from 549 tagged istiophorid billfishes (six species, three gears, 43 studies) demonstrated they are more robust to stressors sustained during capture, handling and release than pelagic sharks. Findings from previous meta‐analysis on Fr rates in white marlin (Kajikia albida, Istiophoridae) were replicated. Synthesized Fr rates enable prioritizing approaches to mitigate by‐catch fishing mortality, to improve the quality of stock and ecological risk assessments and to expand our knowledge of factors influencing trophic structure. [ABSTRACT FROM AUTHOR]

Specialised predators foraging in the boundaries of adjacent ecosystems can control or redirect the flow of subsidies through trophic interception. Ecologically diverse predators can capture terrestrial invertebrates that fall on the water surface and, consequently, influence the flow of energy to aquatic environments. In this study, we show that the movement of prey triggers ripples on the surface of the water, and these stimuli are detected by bulldog bats (Noctilio albiventris, Noctilionidae) during foraging. Thus, the bats located live crickets (Gryllus assimilis, Gryllidae) on average of 15 times faster when compared to the location of dead or artificial crickets (i.e. without movements or ripples on the water surface). The bats also inspected (i.e. touched with their feet) all floating objects on the water surface. During this behaviour, the characteristics of the object (i.e. texture) were critical for bats to distinguish between debris (e.g. leaves and sticks) and the resource (i.e. insect carcasses) that floated on the water surface. In addition, when we compare the efficiency of predators (i.e. bats and fishes) in capturing this resource, our findings suggest that bats are extremely effective (i.e. consumed 100% of the available prey), since the fishes consumed only 40% of the available crickets on the surface of the water over a 60‐s period. These results bring novel information about the influence of prey‐based stimuli on the behaviour of its predators and, consequently, on the flow of nutrients between terrestrial and aquatic ecosystems. [ABSTRACT FROM AUTHOR]

In this study we tested the use of mucus from five species of Neotropical marine batoid elasmobranchs to extract genomic DNA for barcoding and phylogenetic analysis. The DNA from all individuals sampled was successfully amplified and sequenced for molecular barcode, allowing 99–100% accuracy to the species level. This method proved to provide reliable and good‐quality DNA for barcoding and phylogenetic analysis of Neotropical elasmobranchs, through rapid handling and with low disturbance to animals. [ABSTRACT FROM AUTHOR]

Pay to conserve: what we have achieved in 10 years of compensatory releases of threatened with extinction guitarfishes Three guitarfishes are found in the region; two of them are listed as threatened with extinction (the Brazilian guitarfish, I Psedobatos horkelli i - Critically Endangered; and, the Shortnose guitarfish, I Zapteryx brevirostris i - Vulnerable), and one is listed as Near Threatened (the Southern guitarfish, I Pseudobatos percellens i ). Guitarfishes are of particular concern for marine conservationists, as their populations are declining at alarming rates, and more than 70% of these species is listed under some threat category or as data deficient. [Extracted from the article]

This study aimed to characterize morphological aspects related to abortion through a non‐lethal approach in the shortnose guitarfish Zapteryx brevirostris, an endemic and threatened species commonly caught by artisanal fisheries. Two females with signs of abortion and one female exhibiting external signs of pregnancy were purchased alive at a fish market during the period when this species has developing embryos in southern Brazil. Scans were conducted using a portable ultrasound. Females with signs of abortion revealed an absence of embryos despite having a similar morphology of the uterus when compared to the pregnant female. Examination of the pregnant female revealed the presence of two embryos, measuring c. 100 mm, each detected through their midline. This study presents new data on uterine macromorphology following successive abortive events in a viviparous elasmobranch species and validates ultrasonography as a diagnostic tool for the species. Ultrasonography is an effective, non‐lethal and less‐invasive methodology that is recommended for use in future studies of abortion and other reproductive events in elasmobranchs. [ABSTRACT FROM AUTHOR]

A single Pomacanthus maculosus was filmed during a scuba diving survey on a rocky reef from southern Brazil. The body shape and coloration pattern confirmed the species identification. The biological and ecological characteristics of P. maculosus and the long distance of Brazil from its original distribution strongly suggest of an anthropogenic pathway of dispersion. [ABSTRACT FROM AUTHOR]

Summary: This contribution presents a brief morphometric description of adult females and embryos of the ray Gymnura altavela. Two females, pregnant with a total of five embryos, were captured in Rio de Janeiro, southeastern Brazil, and their morphometry was compared to their respective embryos. The embryos showed higher body proportions (%DW) than adults, regardless of sex, which may be an effect of ontogeny. [ABSTRACT FROM AUTHOR]

Egg cases of the narrowmouthed catshark Schroederichthys bivius were recorded entangled with sponges, corals and tubeworms at different sites in the south-west Atlantic Ocean. This work sheds light on the importance of benthic invertebrates in the life cycle of oviparous chondrichthyan species. [ABSTRACT FROM AUTHOR]

Neotropical freshwater fishes are the most diverse on the planet (>5,500 species), although nations in Latin America have been negligent regarding their conservation. National policies have historically encouraged unsustainable practices, and recent decades have witnessed a sharp increase in harmful activities. Our aim with this review was to expose this situation and illustrate how national policies constitute the main threat to freshwater fish biodiversity. We explain that the most devastating, pervasive and systemic threats are rooted in official policies, particularly unsustainable activities (e.g. hydropower, water diversion, mining, aquaculture, agriculture and fishing), poor management/conservation (e.g. fish stocking and passages) and harmful legislation (e.g. poor licensing, non-native species). We provide a broad portrait of the Neotropical scenario, where unsustainable policies have caused considerable damage to freshwater ecosystems, and focus on major examples from Brazil, where development projects have caused large-scale losses to fish biodiversity. Such modus operandi of human development is incompatible with the persistence of biodiversity, and no simple solution is available to correct or minimize its effects. The current situation demands a profound behavioural shift towards better practices and policies, or these multiple high-impact activities will continue eroding freshwater fish biodiversity and impairing essential ecosystem services. [ABSTRACT FROM AUTHOR]

Elasmobranchii shows particular characteristics that make them susceptible to the impacts caused by fishing pressure, especially bottom trawling, which mostly affect rays, as they have demersal habits. Based on food availability and feeding ability, Polychaeta and Sipunculiforme are the bases of Brazilian electric ray Narcine brasiliensis diet. Morphologically, the digestion starts in the oesophagus with acid mucines action. The existence of acid and neutral mucines in the posterior intestine prevents lesions in the mucosa and favours the passage of faeces and shell residues. Thus, this study shows the interaction between their habitat, the organisms and their morphophysiology. [ABSTRACT FROM AUTHOR]

Knowing the trophic level of marine organisms is essential to understanding their ecological role in the ecosystem and for quantifying the ecosystem effects of fishing to establish effective management of fishing resources. In comparison to other systems, information about the trophic level of marine organisms in the Persian Gulf and Oman Sea is very scarce. Here, the main aim was to estimate trophic level in these areas using all available diet information from different marine species using TrophLab software. The trophic level of 32 fish species was estimated with the available diet data. The trophic level ranged from 2.28 to 4.50. High trophic levels were found for Chorocentrus nudus ( TL = 4.7), Saurida tumbil ( TL = 4.6), Rhizoprionodon acutus ( TL = 4.5), Torpedo sinuspersici ( TL=4.5), Gymnura poecilura ( TL = 4.5), Sphyraena putnamae ( TL = 4.5) and Euthynnus affinis ( TL = 4.5). In contrast, lower trophic levels were estimated for Tenualosa ilisha ( TL = 2.28) and Sardinella sindensis ( TL = 2.92). As expected, a positive correlation was found between the trophic level and body size, indicating changes in the diet due to variations in predatory capacities. The results of this study may be useful in the formulation of trophic indicators and modelling of the ecosystems. [ABSTRACT FROM AUTHOR]