In response to increasing global interest in the utility of environmental DNA (eDNA) for non-invasively monitoring fish populations, the relationships between eDNA concentrations and electrofishing-derived relative biomasses and abundances were assessed for two ecologically distinct Australian native freshwater species: Murray cod ( Maccullochella peelii ) and bony herring ( Nematalosa erebi ). Species-specific eDNA assays tar...

Assessing the distribution and diversity of terrestrial and semi-aquatic mammals is fundamental for effective conservation efforts. Environmental DNA (eDNA) metabarcoding has emerged as a rapid and cost-effective method for surveying mammals. It has promising avenues for conducting national surveys and enabling comprehensive assessments of mammalian populations across diverse habitats. We collected eDNA samples from 60 water s...

Introduction For 87 years, gillnets have been deployed off up to 51 beaches in New South Wales, Australia, to reduce bites on humans by white ( Carcharodon carcharias ), bull ( Carcharhinus leucas ), and tiger ( Galeocerdo cuvier ) sharks. Recently, to minimise unwanted fishing mortalities, baited drumlines with electronic catch sensors, called ‘shark management alert in real time’ (SMART) have been trialled. The SMART drumlin...

Flow regimes of river ecosystems worldwide have undergone substantial changes because of water resource development, altering the way in which organic matter is generated and cycled throughout entire river catchments. Flow–ecology studies have focused on structural variables measured at small spatial scales. This creates a challenging mismatch when applying adaptive flow management for ecosystem functioning at a catchment or r...

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 13 C, δ 15 N and δ 34 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 val...

Determining the geographic range of widely dispersed or migratory marine organisms is notoriously difficult, often requiring considerable costs and typically extensive tagging or exploration programs. While these approaches are accurate and can reveal important information on the species, they are usually conducted on only a small number of individuals and can take years to produce relevant results, so alternative approaches m...

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 T ) caught as by‐catch off eastern Australia and used stable‐isotope analyses of δ 15 N, δ 13 C and δ 34 S to infer their resource use and a...

The individual and cumulative effects of increasing mesh size (from 56‐ to 75‐mm stretched mesh opening) and installing three escape gaps (36 × 120 mm) in collapsible‐netted round traps were assessed to address concerns associated with excessive discarding in an Australian portunid fishery. Compared to conventional traps comprising 56‐mm mesh throughout, those with the same mesh size and escape gaps caught significantly fewer...

During 1442 h of visual observations over 7 years throughout the World Heritage listed Paranaguá estuarine complex, Brazil, seven occurrences of interactions were observed at a single location involving breaching Manta birostris displacing schools of teleosts, which were subsequently preyed upon by Sotalia guianensis . Although the interactions were not definitively categorized as being amensal, commensal or mutual, their rest...

The maturity and reproduction of the Atlantic angel shark Squatina dumeril were assessed using 77 females (29·2–110·4 cm total length; L T ) and 269 males (58·7–108·2 cm L T ) harvested by artisanal gillnetters off Venezuela. The biased sex ratio implied segregation or sex‐specific gear selectivity. Based on the development of the reproductive tract, 50% L T at sexual maturity ( L T50 , mean ± s.e .) for females and males were...

The present study tested the hypothesis of no delayed sublethal effects of mild angling and release on the feeding, growth, somatic condition and gonadal development of golden perch Macquaria ambigua during gametogenesis. Subsamples of adult M. ambigua ( n = 17–21 of 207), originally captured from the wild and stocked into ten 0·1 ha earthen ponds, were angled and released during early and late gametogenesis. Wild samples that...

This study investigated whether the fish communities inhabiting shallow non‐vegetated habitats in two divergent bays in a subtropical World Heritage Site estuarine system differed according to wet (spring–summer) and dry (autumn–winter) seasons or polyhaline and mesohaline zones, within the broader objective of facilitating spatio‐temporal management. Species richness (total of 74 taxa; total length, L T = 11–552 mm) and abund...

The utility of varying twine diameter (0.5–0.8 mm Ø) and/or mesh area (0.5:1) in south‐eastern Australian recreational hoop nets was assessed in response to concerns over (1) impacts to discarded, undersize Scylla serrata L. and Portunus pelagicus Forskål and (2) marine debris (lost meshes). There was a negative relationship between Ø and breakage, with more in the narrowest (16.16–18.42 meshes deployment −1 ) than thickest (8...

Two otter‐board modifications designed to minimise bottom contact (and therefore habitat impacts) were compared against conventional otter boards for their relative effects on the engineering and catching efficiencies of triple‐rigged penaeid trawls. The first modification involved restricting the angle of attack ( AOA ) of a flat–rectangular otter board to ° by attaching a restraining line to an adjacent sled, while the secon...

In an attempt to improve the selectivity and engineering performances of generic penaeid trawls, three established and one novel spreading‐mechanism configurations were assessed: otter boards attached (1) with and (2) without 3.15‐m sweeps to a 7.35‐m headline trawl, and a beam rigged directly to a 9.19‐m trawl (3) with and (4) without a horizontal wire and plastic streamers. Despite more surface area (7.5 vs 6.0 m 2 ), both b...

This study assessed the effects of different retrieval depths (2, 10 or 20 m), surface intervals (none or 15 min) and release methods (untreated, vented or recompressed) on the incidence of external and internal clinical signs of barotrauma ( ECSB and ICSB ) and post‐release mortality in golden perch, Macquaria ambigua (Richardson). Fish were assessed for ECSB before and after surface intervals and either monitored for mortali...

The relationship between ecological variation and microbial genetic composition is critical to understanding microbial influence on community and ecosystem function. In glasshouse trials using nine native legume species and 40 rhizobial strains, we find that bacterial rRNA phylotype accounts for 68% of amoung isolate variability in symbiotic effectiveness and 79% of host specificity in growth response. We also find that rhizob...

This study assessed the mortality of 157 snapper Pagrus auratus (9–29 cm, total length, L T ) after being conventionally angled and then released into cages (along with 48 controls) for 4 days off south‐eastern Australia. Fatalities were restricted to 12 angled fish (7·6%) and mostly attributed to the ingestion of hooks and especially their subsequent removal, which caused substantial blood loss and immediate death. Hook inges...