Can denticle morphology help identify southeastern Australian elasmobranchs?

Elasmobranchs are covered in scale-like structures called dermal denticles, comprising dentine and enameloid. These structures vary across the body of an individual and between species, and are frequently shed and preserved in marine sediments. With a good understanding of denticle morphology, current and historical elasmobranch diversity and abundance might be assessed from sediment samples.

Impacts of seasonal temperatures, ocean warming and marine heatwaves on the nutritional quality of eastern school prawns (Metapenaeus macleayi).

Ocean warming and marine heatwaves significantly alter environmental conditions in marine and estuarine environments. Despite their potential global importance for nutrient security and human health, it is not well understood how thermal impacts could alter the nutritional quality of harvested marine resources. We tested whether short-term experimental exposure to seasonal temperatures, projected ocean-warming temperatures, and marine heatwaves affected the nutritional quality of the eastern school prawn (Metapenaeus macleayi).

Investigating variability among fisheries litter accumulation on beaches in Paraná, Brazil.

Fishing activities strongly influence coastal and marine environments and are responsible for generating marine litter. In southern Brazil, there are several artisanal (small-scale) fisher settlements that potentially contribute towards regional marine litter. The present study sought to address the deficit in available information by investigating the in situ contribution of artisanal fishing communities to marine litter on adjacent beaches.

Trophic niche of Australian cownose rays (Rhinoptera neglecta) and whitespotted eagle rays (Aetobatus ocellatus) along the east coast of Australia.

Australian cownose rays (Rhinoptera neglecta) and whitespotted eagle rays (Aetobatus ocellatus) are large myliobatiform rays that co-occur off temperate eastern Australia. Here, we performed stable-isotope analyses (δ C, δ N and δ S) on fin clips of both species to gain insights into their trophic interactions and isotopic niches, and assess the effect of preservation (ethanol-stored versus frozen) on isotopic values of fin-clip tissue of R. neglecta.

Flexibility for fuelling reproduction in a pelagic ray (Mobula eregoodoo) suggested by bioenergetic modelling.

This study investigated the measurements of energy density and bioenergetic modelling for a pelagic ray, Mobula eregoodoo, to estimate its relative allocation to various bodily processes and especially reproduction. The data revealed M. eregoodoo uses up to 21.

Secondary predation constrains DNA-based diet reconstruction in two threatened shark species.

Increasing fishing effort, including bycatch and discard practices, are impacting marine biodiversity, particularly among slow-to-reproduce taxa such as elasmobranchs, and specifically sharks. While some fisheries involving sharks are sustainably managed, collateral mortalities continue, contributing towards > 35% of species being threatened with extinction. To effectively manage shark stocks, life-history information, including resource use and feeding ecologies is pivotal, especially among those species with wide-ranging distributions.

Selectivity of marine-debris ingestion by juvenile green turtles (Chelonia mydas) at a South American World Heritage Listed area.

Beaches in southern Brazil have substantial marine debris and strandings of dead juvenile green turtles (Chelonia mydas). This study investigates associations by quantifying marine debris (1) ingested among new (<40 cm curved carapace length; CCL) and older (≥40 cm CCL) juvenile C. mydas recruits; (2) concentrations on beach transects; and then (3) selective ingestion by C.

Resilience to the interactive effects of climate change and discard stress in the commercially important blue swimmer crab (Portunus armatus).

Globally, millions of people depend on nutritional benefits from seafood consumption, but few studies have tested for effects of near-future climate change on seafood health and quality. Quantitative assessments of the interactive effects of climate change and discarding of fisheries resources are also lacking, despite ~10% of global catches being discarded annually. Utilising the harvested blue swimmer crab (Portunus armatus), we experimentally tested the effects of near-future temperature and salinity treatments under simulated capture and discarding on a suite of health and nutritional quality parameters.

Short- and long-term diets of the threatened longhorned pygmy devil ray, Mobula eregoodoo determined using stable isotopes.

Most mobulids are listed as near threatened to endangered. Nonetheless, effective conservation measures are hindered by knowledge gaps in their ecology and behaviour. In particular, few studies have assessed diets and trophic ecologies that could inform methods to avoid fishing mortality.

Resource use of great hammerhead sharks (Sphyrna mokarran) off eastern Australia.

Great hammerhead sharks Sphyrna mokarran are the largest member of Sphyrnidae, yet the roles of these large sharks in the food webs of coastal ecosystems are still poorly understood. Here we obtained samples of muscle, liver and vertebrae from large S. mokarran (234-383 cm total length; L ) caught as by-catch off eastern Australia and used stable-isotope analyses of δ N, δ C and δ S to infer their resource use and any associated ontogenetic patterns.

Chelonid Alphaherpesvirus 5 DNA in Fibropapillomatosis-Affected Chelonia mydas.

Fibropapillomatosis is a panzootic and chronic disease among Chelonia mydas-usually associated with anthropogenic impacts. This study contributes towards understanding fibropapillomatosis implications for C. mydas populations as a reflector of environmental quality, via prevalence and histological, molecular and blood analyses at a World Heritage site in southern Brazil.

Mother-embryo isotope fractionation in the pygmy devilray Mobula kuhlii cf. eregoodootenkee.

We determined stable-isotope ratios for replicate muscle tissues in 13 gravid Mobula kuhlii cf. eregoodootenkee (110.4-120.

Metabarcoding for stomach-content analyses of Pygmy devil ray (: Comparing tissue and ethanol preservative-derived DNA.

The application of high-throughput sequencing to retrieve multi-taxon DNA from different substrates such as water, soil, and stomach contents has enabled species identification without prior knowledge of taxon compositions. Here we used three minibarcodes designed to target mitochondrial COI in plankton, 16S in fish, and 16S in crustaceans, to compare ethanol- and tissue-derived DNA extraction methodologies for metabarcoding. The stomach contents of pygmy devilrays ( cf.

Bioaccumulation of organochlorine compounds in large, threatened elasmobranchs off northern New South Wales, Australia.

Persistent organic pollutants (POPs) include polychlorinated biphenyls (PCBs) dichlorodiphenyltrichloroethane (DDT) and hexachlorobenzene (HCB), which are resistant to biodegradation and therefore accumulate in the marine environment. In Australia, POPs occur in high concentrations primarily in costal water near farming regions and urban centres. From contaminated sediments and biota, POPs are transferred and biomagnified in larger marine organisms.

Refining a Nordmøre-grid bycatch reduction device for the Spencer Gulf penaeid-trawl fishery.

Incremental refinements were made to a generic Nordmøre-grid to minimise bycatches of blue swimmer crabs Portunus armatus and giant cuttlefish Sepia apama, while maintaining catches of western king prawns Melicertus latisulcatus in the Spencer Gulf penaeid-trawl fishery. These refinements involved varying bar spaces, escape-exit areas and guiding-panel lengths, and were compared against a conventional trawl. Catches of teleosts and M.

Climate change does not affect the seafood quality of a commonly targeted fish.

Climate change can affect marine and estuarine fish via alterations to their distributions, abundances, sizes, physiology and ecological interactions, threatening the provision of ecosystem goods and services. While we have an emerging understanding of such ecological impacts to fish, we know little about the potential influence of climate change on the provision of nutritional seafood to sustain human populations. In particular, the quantity, quality and/or taste of seafood may be altered by future environmental changes with implications for the economic viability of fisheries.

Reducing the marine debris of recreational hoop nets in south-eastern Australia.

Alternative configurations of Australian recreational portunid hoop nets were investigated to address debris and selectivity issues. Four treatment nets (all comprising 152-mm polyamide-PA mesh) were assessed that differed in their twine (conventional multifilament vs new multi-monofilament) and fishing configuration (conventional conical vs inverted shapes). The conical multifilament design lost means (±SEs) of 130.

Assessing Disease and Mortality among Small Cetaceans Stranded at a World Heritage Site in Southern Brazil.

Cetaceans are considered environmental sentinels and their health often reflects either anthropogenic or natural spatio-temporal disturbances. This study investigated the pathological findings and mortality of small cetaceans with the aim of detecting hazards and monitoring health trends in a high-biodiversity area. Between 2007 and 2012, 218 stranded cetaceans were recorded on the Paraná coast, southern Brazil.

Effects of Modified Handling on the Physiological Stress of Trawled-and-Discarded Yellowfin Bream (Acanthopagrus australis).

Modified handling is often claimed to reduce (sub-)lethal impacts among organisms caught-and-released in fisheries. Improving welfare of discarded fish warrants investigation, when their survival is of both economic and ecological importance. In this study, juvenile yellowfin bream (Acanthopagrus australis) were trawled in an Australian penaeid fishery and then discarded after on-board sorting in either dry or water-filled (modified) trays and with delays in starting sorting of either 2 or 15 mins.

A 'simple anterior fish excluder' (SAFE) for mitigating penaeid-trawl bycatch.

Various plastic strips and sheets (termed 'simple anterior fish excluders'-SAFEs) were positioned across the openings of penaeid trawls in attempts at reducing the unwanted bycatches of small teleosts. Initially, three SAFEs (a single wire without, and with small and large plastic panels) were compared against a control (no SAFE) on paired beam trawls. All SAFEs maintained targeted Metapenaeus macleayi catches, while the largest plastic SAFE significantly reduced total bycatch by 51% and the numbers of Pomatomus saltatrix, Mugil cephalus and Herklotsichthys castelnaui by up to 58%.

Angling-induced barotrauma in snapper Chrysophrys auratus: are there consequences for reproduction?

In response to concerns regarding the potential for sub-lethal impacts of barotrauma on reproductively active Chrysophrys auratus during catch and release, 90 males and 90 females representing five reproductive stages (immature or resting--28%, developing--8%, developed--7%, ripe or spawning--23% and spent--34%) were angled from 8-70 m and macroscopically assessed (on-board and then in a laboratory). Irrespective of sex, all fish exhibited various clinical signs of barotrauma, including a prolapsed cloaca (60% of fish); gastric herniation (46%); ruptured swim bladder (73%); organ displacement (48%); and kidney (3%), liver (73%) and coloemic-cavity haemorrhaging (33%); with the frequency of nearly all positively associated with capture depth. Reproductive stage was also an important barotrauma predictor (reflecting related morphological changes) with a general trend towards spent fish least likely to incur the various clinical signs--especially for a prolapsed cloaca (also common among immature or resting fish and significantly affected by food in the digestive tract) and a ruptured swim bladder (common among ripe or spawning fish).

Marine debris in a World Heritage Listed Brazilian estuary.

Using monthly otter-trawl deployments, spatial and temporal variability among the relative densities of marine debris were assessed in the Paranaguá estuarine complex; a subtropical World Heritage Listed area in southern Brazil. During 432 deployments over 12 months, 291 marine debris items were identified; of which most (92%) were plastic, and more specifically shopping bags, food packages, candy wrappers and cups typically >21 mm long. The most contaminated sectors were those closest to Paranaguá city and the adjacent port, and had up to 23.

Effects of mesh size and escape gaps on discarding in an Australian giant mud crab (Scylla serrata) trap fishery.

In response to concerns over excessive discarding from Australian recreational round traps (with four funnel entrances) used to target giant mud crabs, Scylla serrata, an experiment was done to assess the independent and cumulative utility of paired, bottom-located horizontal escape gaps (46×120 mm) and increasing mesh size (from 51 to 101 mm). Compared to conventional traps comprising 51-mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer (by 95%) undersize (<85 mm carapace length--CL) crabs while maintaining legal catches. Traps made from 101-mm mesh (but with the same funnel entrances as conventional designs) and with and without escape gaps similarly retained fewer undersize crabs and also yellowfin bream Acanthopagrus australis (the key bycatch species) by up to 94%, but there were concomitant reductions in fishing power for legal sizes of S.

Configuring the mesh size, side taper and wing depth of penaeid trawls to reduce environmental impacts.

The effects of reducing mesh size while concomitantly varying the side taper and wing depth of a generic penaeid-trawl body were investigated to improve engineering performance and minimize bycatch. Five trawl bodies (with the same codends) were tested across various environmental (e.g.