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Stomach contents of 175 Brazilian sharpnose sharks, Rhizoprionodon lalandii, were examined to assess their feeding habits. Caught by artisanal fishers between June 2006 and July of 2007 at Ipanema Beach, on the central coast of the state of Paraná, southern Brazil, R. lalandii appears to be piscivorous (89.7% IRI), feeding mainly on families of Clupeidae (5.1% IRI) and Sciaenidae (3.7% IRI) and secondarily on squid Lolliguncula brevis (8.6% IRI). Diets were similar between sexes and seasons. However, there were ontogenetic changes in their diets. The major items for neonates were Penaeidae crustaceans (%IRI = 56.4) and Engraulidae fishes (%IRI = 29.3); for the juveniles, Sciaenidae (%IRI = 62.5) and Clupeidae (%IRI = 19.7), and for adults Clupeidae (%IRI = 45.8) and Sciaenidae (%IRI = 15.9). Only neonate sharks consumed crustaceans, whereas all size classes consumed cephalopods and teleosts. Neonates had the lowest trophic level (TR = 3.8), with the diet of juveniles and adults the highest (TR = 4.2). Given its abundance and diet, R. lalandii may be an important predator of demersal and pelagic prey in coastal waters of Brazil. [ABSTRACT FROM AUTHOR]

Research on the feeding habits of batoids provides information of intra and interspecific interactions of this taxon in marine ecosystems. We analyzed 832 stomachs of nine ray species collected from the artisanal fishery on the Northwest coast of Baja California Sur (NBCS). We identified 79 prey items assembled in five trophic groups (crustaceans, fish, mollusks, polychaetes, and sipunculidae). Results indicated that the red crab Pleuroncodes planipes was the most important prey in the diet of the seven batoid species. A low dietary similarity of the rays was observed, which evidenced different feeding strategies. In this regard, we identified four well‐separated trophic guilds. Each guild was characterized by the consumption of specific prey: (1) Hypanus dipterurus and Narcine entemedor that fed mostly on polychaetes; (2) Rostroraja velezi and Gymnura marmorata fed mostly on fishes (Clupeidae and Batrachoididae); (3) Hypanus longus, Myliobatis californica, and Platyrhinoidis triseriata fed on crustaceans (Munnidae) and Sipunculus worms; and (4) Pseudobatos productus and Zapteryx exasperata fed on crustaceans (Portunidae) and fishes (Synodontidae and Batrachoididae). We concluded that batoids off the NBCS show prey sharing between the different species. [ABSTRACT FROM AUTHOR]

Increasing fishing pressure has negatively impacted elasmobranch populations globally. Despite high levels of historical and current fishing pressure, the Bay of Bengal region remains data‐poor. Focusing on Bangladesh, we conducted a socio‐ecological study to characterize elasmobranch fisheries and evaluate their impact on threatened species. The results demonstrate that several globally threatened elasmobranch species are frequently captured, and some of them have experienced substantial population declines (e.g., wedgefishes, sawfishes, large carcharhinid sharks) over the past decade. A decrease in elasmobranch diversity, abundance, and size of caught specimens was also reported, which was attributed to increased fishing intensity, destructive practices (e.g., bottom trawling), and an accessible elasmobranch market. While catch and trade of more than 90 elasmobranchs are regulated under Bangladesh's law, non‐compliance is widespread. Likely causes include a dearth of awareness, practical alternative livelihoods, and technical facilities, and the complex nature of the fisheries. Encouraging and facilitating the engagement of fishers in science (data collection), local governance (policy‐making), and field implementation (bycatch mitigation) is vital. These interventions must be rooted in sustainable approaches and co‐designed with fishers, with appropriate training available. Development of this work through enhanced engagement with fishers has the potential to transform the elasmobranch fishery situation in Bangladesh and could be used as a model for data‐poor regions. [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]

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]

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]

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]

The diets of the milk shark, Rhizoprionodon acutus, and the slit-eye shark, Loxodon macrorhinus, landed from the artisanal fishery in the Arabian Gulf waters of the United Arab Emirates were investigated to determine their dietary preferences. Stomach contents from 57 milk sharks and 53 slit eye sharks were collected from Abu Dhabi ( R. acutus, n = 23), Dubai ( R. acutus, n = 5; L. macrorhinus, n = 15) and Ras Al Khaimah ( R. acutus, n = 29; L. macrorhinus, n = 38) during fishery surveys from January to May 2012. Prey items were identified to the lowest possible taxonomic level, grouped into five categories including 'teleost fish', 'cephalopods', 'crustaceans', 'invertebrates', and 'other'. The diets of both species were described using the numeric, frequency and weight methods, and the index of relative importance ( IRI). The majority of stomachs for both species had food, with 66.6% of milk shark stomachs and 90.5% of slit-eye shark stomachs containing prey items, both dominated by small teleosts. Rhizoprionodon acutus fed on a wide variety of teleost species, primarily Engraulidae (anchovies) (28%), Gerreidae (mojarras) (5.6%) and Carangidae (jacks) (1.6%) with occasional crustacean and cephalopod prey (8%). On the other hand, L. macrorhinus seemed to have a preference for one species in terms of teleosts (anchovies) (35.1%) and fed on a wider variety of crustaceans and cephalopods (22.6%). There was little overlap in the diets of these two species, suggesting that they may either be using different habitats or that in these waters, the milk shark is a generalist species while the slit-eye is a specialist feeder. [ABSTRACT FROM AUTHOR]

Based on the knowledge of local artisanal fishermen and on direct observations, this study presents evidence that the giant manta ray Manta birostris uses the Paranaguá estuarine complex in south Brazil, south-western Atlantic Ocean, in a predictable seasonal pattern. Behavioural observations suggest that the estuary can act as a nursery ground for M. birostris during the summer. [ABSTRACT FROM AUTHOR]