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Cronulla, Australia

Kennelly S.J.,IC Independent Consulting | Broadhurst M.K.,Australian Department of Primary Industries and Fisheries
Endangered Species Research | Year: 2014

Trawlers in Spencer Gulf, Australia, target western king prawns Melicertus latisulcatus, with nearly all other species discarded; two of the latter have evoked significant, although quite different, concerns. The first is the giant cuttlefish Sepia apama, which has undergone a drastic decline in numbers in Spencer Gulf in recent years, and is listed as 'Near Threatened' by the International Union for the Conservation of Nature. S. apama are susceptible to trawling during their annual spawning migration through Spencer Gulf. The other bycatch problem involves large quantities of blue swimmer crabs Portunus armatus, which currently are separated inside the trawl using a large-meshed liner. Due to the additional handling required and the physical damage caused by the crabs' exoskeletons on the soft-bodied M. latisulcatus and Sepia spp., P. armatus would ideally be able to escape of their own accord during towing. This study examined the utility of mechanical-separating bycatch reduction devices (BRDs) for reducing unwanted bycatches of Sepia spp. and P. armatus. We compared (against conventional codends) the smallest and largest practical sizes of Nordmøre-grids (the latter to maximise sorting area), with correspondingly large and low grid angles. The large Nordmøre-grid significantly reduced Sepia spp., P. armatus and total bycatch (by 33-50%), but had no effect on catches of M. latisulcatus. Whilst additional research is required, a modified Nordmøre-grid should help to resolve the bycatch of P. armatus and S. apama in this fishery, with minimal commercial impacts. © The authors 2014. Source

Dorner H.,European Commission - Joint Research Center Ispra | Graham N.,Marine Institute of Ireland | Bianchi G.,Food and Agriculture Organization | Bjordal A.,Norwegian Institute of Marine Research | And 7 more authors.
ICES Journal of Marine Science | Year: 2015

In this paper, we synthesize information presented at the 2nd Fishery Dependent Information (FDI) Conference, held in Rome, Italy, from 2 to 6 March 2014. We review current issues and advances in the collection, interpretation and application of fishery-dependent data, and highlight emergent findings in the field. Key issues include (i) the design and collection of data associated with commercial and recreational fisheries and the use of these data to support conventional and novel approaches to fisheries science and management and (ii) the role of fishers in co-management and policy setting. We noted that since the 2010 FDI conference a paradigm shift towards full engagement of key stakeholders started to take place. It also became evident that trust between stakeholders, managers, and scientists is necessary to develop efficient fishery monitoring programmes. While building such trust among key players often begins in informal settings, eventually one must evolve structured, formalized, and agreed processes for such interactions. We also conclude that because of the diversity of fisheries any determination of "best practices" may be difficult. Instead, we provide a list of "best principles" emerged from the conference. © International Council for the Exploration of the Sea 2014. Source

Smoothey A.F.,Australian Department of Primary Industries and Fisheries | Gray C.A.,WildFish Research | Kennelly S.J.,IC Independent Consulting | Masens O.J.,Australian Department of Primary Industries and Fisheries | And 2 more authors.
PLoS ONE | Year: 2016

Information about spatial and temporal variability in the distribution and abundance of shark-populations are required for their conservation, management and to update measures designed to mitigate human-shark interactions. However, because some species of sharks are mobile, migratory and occur in relatively small numbers, estimating their patterns of distribution and abundance can be very difficult. In this study, we used a hierarchical sampling design to examine differences in the composition of species, size- and sex-structures of sharks sampled with bottom-set longlines in three different areas with increasing distance from the entrance of Sydney Harbour, a large urbanised estuary. During two years of sampling, we obtained data for four species of sharks (Port Jackson, Heterodontus portusjacksoni; wobbegong, Orectolobus maculatus; dusky whaler, Carcharhinus obscurus and bull shark, Carcharhinus leucas). Only a few O. maculatus and C. obscurus were caught, all in the area closest to the entrance of the Harbour. O. maculatus were caught in all seasons, except summer, while C. obscurus was only caught in summer. Heterodontus portusjacksoni were the most abundant species, caught in the entrance location mostly between July to November, when water temperature was below 21.5°C. This pattern was consistent across both years. C. leucas, the second most abundant species, were captured in all areas of Sydney Harbour but only in summer and autumn when water temperatures were above 23°C. This study quantified, for this first time, how different species utilise different areas of Sydney Harbour, at different times of the year. This information has implications for the management of human-shark interactions, by enabling creation of education programs to modify human behaviour in times of increased risk of potentially dangerous sharks. © 2016 Smoothey et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

McHugh M.J.,University of Queensland | Broadhurst M.J.,University of Queensland | Sterling D.J.,Australian Department of Primary Industries and Fisheries | Millar R.B.,Sterling | And 2 more authors.
ICES Journal of Marine Science | Year: 2015

Reducing otter-board angle of attack (AOA) has been proposed as a way to limit the habitat impacts of demersal trawls, but there are few quantitative assessments. This study tested the hypothesis that a novel otter-board design, termed the "batwing" (comprising a 0.1-m wide sled with an offset sail at 208 AOA) would have relatively fewer bottom impacts than a conventional flat-rectangular otter board (358 AOA, with a similar hydrodynamic spreading force). Pairs of each otter board were suspended beneath a purpose-built rig comprising a beam and posterior semi-pelagic collection net and repeatedly deployed across established trawl grounds in an Australian estuary. Compared with the conventional otter boards, the batwings displaced significantly fewer empty shells (Anadara trapezia and Spisula trigonella) by 89% and school prawns (Metapenaeus macleayi) by up to 78%. These rates were similar to the difference in base-plate bottom contact (87%). Further, the batwing damaged proportionally fewer damaged shells, attributed to their displacement away from the board's surface area. Other debris (lighter pieces of wood) and benthic fish (bridled gobies, Arenigobius bifrenatus) were not as greatly mobilised (i.e. reduced by 50 and 25%, respectively); possibly due to their position on or slightly off the bottom, and a similar influence of hydrodynamic displacement by the hydro-vane surface areas. Although the consequences of reducing otter-board bottom contact largely remain unknown, low AOA designs like the batwing may represent a practical option for fisheries where trawling is perceived to be hazardous to sensitive habitats. © 2015 International Council for the Exploration of the Sea All rights reserved. Source

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