ORCID Profile
0000-0002-9003-2772
Current Organisation
University of Tasmania
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Publisher: Elsevier BV
Date: 07-2019
Publisher: Elsevier BV
Date: 2011
Publisher: Oxford University Press (OUP)
Date: 12-07-2017
Abstract: Ecosystem-based management (EBM) is now widely accepted as the best means of managing the complex interactions in marine systems. However, progress towards implementing and operationalizing it has been slow. We take a pragmatic approach to EBM. Our simple definition is balancing human activities and environmental stewardship in a multiple-use context. In this paper, we present case studies on the development and implementation of EBM in Australia. The case studies (Australia’s Ocean Policy, the Great Barrier Reef, New South Wales (NSW) marine estate, Gladstone Harbour, and South Australia and Spencer Gulf) span different spatial scales, from national to regional to local. They also cover different levels of governance or legislated mandate. We identify the key learnings, necessary components and future needs to support better implementation. These include requirements for clearly identified needs and objectives, stakeholder ownership, well defined governance frameworks, and scientific tools to deal with conflicts and trade-offs. Without all these components, multi-sector management will be difficult and there will be a tendency to maintain a focus on single sectors. While the need to manage in idual sectors remains important and is often challenging, this alone will not necessarily ensure sustainable management of marine systems confronted by increasing cumulative impacts.
Publisher: Wiley
Date: 30-11-2015
Publisher: Wiley
Date: 14-07-2009
Publisher: Elsevier BV
Date: 04-2002
Publisher: Inter-Research Science Center
Date: 20-03-2013
DOI: 10.3354/AEI00058
Publisher: Elsevier BV
Date: 04-2013
Publisher: Wiley
Date: 30-03-2006
Publisher: NMFS Publications Office
Date: 04-08-2021
DOI: 10.7755/FB.119.2-3.4
Publisher: Inter-Research Science Center
Date: 23-09-2011
DOI: 10.3354/ESR00353
Publisher: Elsevier BV
Date: 03-2014
Publisher: Wiley
Date: 20-07-2018
DOI: 10.1111/FOG.12383
Publisher: Elsevier BV
Date: 07-2016
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/MF08239
Abstract: Marine reserves are used widely throughout the world to conserve bio ersity, but in many instances uncertainties exist over how well these areas represent bio ersity at a regional scale (i.e. 100–1000 km). In the present study, infaunal assemblages were examined in the eastern Great Australian Bight (GAB) to evaluate the efficacy of the Benthic Protection Zone of the GAB Marine Park in representing regional bio ersity. Distributional patterns in infauna were further examined in relation to epifaunal species composition and environmental conditions to investigate structural forcing. Grab s les of infauna were collected from the same 65 sites s led in an earlier survey of epifauna. In total, 240 taxa belonging to 11 phyla were collected. Most taxa were uncommon, with 96% representing less than 2% of the total number of in iduals collected and 39% occurring at only one site. Unlike the epifauna, the infauna of the eastern GAB does not appear to be particularly erse. Sessile filter feeders dominated the infaunal communities of the inner shelf, whereas motile, deposit-feeding organisms dominated the shelf break. As was the case with the epifauna, the highest numbers of taxa and in iduals were recorded near the head of the bight and in inner-shelf waters off the western Eyre Peninsula, where productivity is enhanced by upwelling. Cluster analysis identified three community groupings, which were strongly correlated with depth. All three communities and 72% (172) of the 240 taxa collected were represented within the Benthic Protection Zone of the GAB Marine Park, confirming findings from the epifaunal survey that this protected area is well placed to represent the benthic bio ersity of the eastern GAB.
Publisher: Elsevier BV
Date: 09-2010
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 11-2018
Publisher: Informa UK Limited
Date: 2009
Publisher: Public Library of Science (PLoS)
Date: 06-05-2015
Publisher: Elsevier BV
Date: 09-2006
Publisher: Oxford University Press (OUP)
Date: 08-2011
Publisher: Elsevier BV
Date: 06-2011
Publisher: Springer Science and Business Media LLC
Date: 02-08-2009
Publisher: Elsevier BV
Date: 11-2008
Publisher: Elsevier BV
Date: 06-2010
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/MF00025
Abstract: Lapemis hardwickiiand Hydrophis elegans caught by prawn trawlers reach at least 6.7 and 8.9 years of age respectively.Most L.hardwickii s led were 2—4 years of age,and most H.elegans were 3—5 years of age. Female L.hardwickii and H.elegans appear to reach sexual maturity after 2 years and minimum snout—vent lengths of approximately 76 and 120 cm respectively.The reproductive cycles of L.hardwickii and H.elegans are similar:mating occurs between early May and the end of July ovulation during August —September and gestation during September—December and September—February respectively.L.hardwickii and H.elegans produce approximately 8.5 and 12.7 offspring per clutch respectively.However,female L.hardwickii breed annually whereas female H.elegans only breed every 2—3 years.The mean annual reproductive outputs of L. hardwickii (8.4 offspring per year)and H.elegans (7.5)are thus similar. Sea snakes appear to be less fecund and more susceptible to trawler-induced effects than most by-catch taxa,and should be a focus of future strategies to ameliorate the ecological effects of prawn trawling in northern Australia.
Publisher: Oxford University Press (OUP)
Date: 21-03-2018
Abstract: Snapper (Chrysophrys auratus) in South Australia spawn over a wide range of daily times and hatch in ∼1.5 d. Traditional estimates of daily egg production (i) ide s led eggs into daily age cohorts, e.g. days 1 and 2, (ii) compute cohort ages by assuming that all spawning occurs at a fixed daily peak hour, and (iii) link the estimation of spawning egg density with egg mortality rate by regressing cohort egg densities against cohort age. We propose a method for estimating daily egg production, the number of eggs spawned per unit area per day (P0), without these assumptions. We use a range of estimates of snapper egg mortality rate obtained from prior studies to backcorrect for egg mortality to the age 0 spawning egg density for each stage of eggs in idually rather than aggregating into daily cohorts. P0 is estimated as a mean of s le tow densities rather than as a regression intercept. This stage-based P0 estimator avoids errors associated with assuming a fixed daily spawning hour and classifying eggs into day 1 or 2. It requires no regressions of s led daily cohort egg densities against age, which often provide imprecise estimates of mortality rates. Simulation testing showed 1–2% accuracy for this estimator of P0. The uncertainty of assuming egg mortality rates is moderated by the insensitivity of estimates of P0 to the input value of egg mortality rate.
Publisher: Public Library of Science (PLoS)
Date: 10-05-2017
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/MF08134
Abstract: The present study evaluates the suitability of the Daily Egg Production Method (DEPM) for stock assessment of blue mackerel, Scomber australasicus and assesses methodological options for future applications. In southern Australia, estimates of mean daily egg production were higher for Californian Vertical Egg Tow (CalVET) nets than bongo nets, and in eastern Australia, were higher in October 2003 than July 2004. Estimates of spawning area for southern Australia were three times higher for bongo nets than CalVET nets. Similar estimates of spawning area were obtained using standard (manual) gridding and natural neighbour methods. Large s les and reliable estimates of all adult parameters were obtained for southern Australia. Relatively few spawning adults were collected off eastern Australia. Preliminary best estimates of spawning biomass for southern and eastern Australia were 56 228 t and 29 578 t, respectively, with most estimates within the ranges of 45 000–68 000 t and 20 000–40 000 t respectively. The DEPM is suitable for stock assessment of S. australasicus. Several technical refinements are required to enhance future applications, including: genetic techniques for identifying early stage eggs a temperature–egg development key improved methods for s ling adults off eastern Australia and measurements of the degeneration rates of post-ovulatory follicles at several temperatures.
Publisher: Frontiers Media SA
Date: 06-03-2020
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/MF05184
Abstract: Upwelling systems can provide ideal conditions for survival and growth of larval fishes. However, these unstable environments are highly dispersive and mortalities can be high. Anchovies (Engraulis spp.) utilise a range of behavioural strategies to increase egg and larval survival. Ontogenetic shifts in distribution have been proposed for Australian anchovy (Engraulis australis), but no supporting otolith-based age studies have been published to date. The present study used otolith increment counts to age larval, juvenile and adult Australian anchovy, which spawn throughout South Australian gulf and shelf waters. Only fish up to 1 year of age occurred in the northern Spencer Gulf, where eggs and larvae in high densities are retained in a nursery area favourable to anchovies. The southern gulf area was inhabited by 1, 2 and 3 year olds. Older anchovy were found in offshore shelf waters, where upwelling occurs and larval survivorship may be high. We hypothesise that Australian anchovy move offshore with age to utilise the wide range of environments that provide suitable spawning and nursery areas for this species.
Publisher: Springer Science and Business Media LLC
Date: 12-01-2013
Publisher: Oxford University Press (OUP)
Date: 29-03-2021
Abstract: This paper reviews application of the Daily Egg Production Method (DEPM) to sardine (Sardinops sagax) off southern Australia between 1995 and 2019. Coefficients of variation (CVs) of estimates of spawning biomass (SB) were reduced from 23–59% to 8–12% by: (i) estimating mean daily egg production (P0), spawning fraction (S), and sex ratio (R) from all historical data rather than annually and (ii) combining batch fecundity (F) and female weight (W) into a single parameter, relative fecundity (F′ = F^/W). Total daily egg production was estimated most precisely from annual estimates of spawning area (A) and estimates of P0 obtained from historical data. Both S and R were estimated most precisely from historical data. Estimating W and F from historical data did not increase precision. F′ had lower CVs than both W and F, and was stable across years and a wide range of W. Findings demonstrate that A can be converted into a precise estimates of SB using estimates of P0, S, R, and F′ obtained from historical data. However, the possibility that DEPM parameters may change in the future cannot be discounted. Future monitoring should include annual estimation of P0 and periodic (e.g. 3–5 years) re-estimation of adult parameters.
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/MF13246
Abstract: Decreases in the mean trophic level (MTL) of fishery catches have been used to infer reductions in the abundance of high trophic level species caused by fishing pressure. Previous assessments of southern Australian fisheries have been inconclusive. The objectives of the present study were to provide more accurate estimates of MTL using disaggregated taxonomic and spatial data. We applied the model of MTL to fisheries catch statistics for the state of South Australia from 1951 to 2010 and a novel set of historical market data from 1936 to 1946. Results show that from 1951 to 2010, MTL declined by 0.16 of a trophic level per decade a rate greater than the global average of 0.10 but equivalent to similar regional investigations in other areas. This change is mainly attributable to large increases in catches of sardine, rather than reductions in the catches of high trophic level species. The pattern is maintained when the historical data is included, providing a time line from 1936 to 2010. Our results show a broadening of the catch of lower trophic levels and suggest care in interpretation of MTL of catches because reductions do not necessarily reflect change in high trophic level species by fishing pressure.
Publisher: Hindawi Limited
Date: 10-2007
Publisher: Cambridge University Press (CUP)
Date: 05-2008
DOI: 10.1017/S0025315408001021
Abstract: The annual commercial catch from the Southern Zone of the South Australian rock lobster ( Jasus edwardsii ) fishery is ~1900 tonnes, representing ~50% of total landings from south-east Australia. A single minimum legal size (MLS) of 98.5 mm carapace length (CL) exists across the entire zone. Fecundity (F), size at onset of maturity (SOM) and relative reproductive potential (RRP) of female rock lobsters were investigated in two major fishing regions, i.e. the North Southern Zone (NSZ) and South Southern Zone (SSZ) with a view to providing a basis for future fine-scale spatial management of the resource. F ranged from 45,292 to 466,800 eggs per female and increased proportionally with CL according to the relationship: F = 0.0584 × CL 3.1642 . F was significantly higher in the NSZ compared to the SSZ but was attributed to differences in lobster size between regions. There was no significant difference in the number of eggs · g −1 of egg mass between areas. SOM, estimated as the size at which 50% of females reached sexual maturity (L 50 ) was higher in the NSZ (104.1 mm CL) compared to SSZ (92.3 mm CL). Approximately 20% of lobsters above the MLS in the commercial catch in the NSZ were under the L 50 estimate. RRP, as a measure of egg production, was calculated for each size-class from the product of F, SOM and population length–frequency. The modal RRP size-classes in the NSZ were 117.5–122.5 mm CL, while in the SSZ it was 97.5–102.5 mm CL. Only 6% of RRP was contributed by female rock lobsters below the MLS in the NSZ, compared to 34% in the SSZ. Regional differences in SOM and RRP in the Southern Zone of South Australia suggest that different MLSs may be beneficial, particularly if the fishery is to be effectively managed at finer spatial scales.
Publisher: Wiley
Date: 11-2009
DOI: 10.1111/J.1095-8649.2009.02361.X
Abstract: The spawning biomass of Australian anchovy Engraulis australis in gulf and shelf waters of South Australia was compared using the daily egg production method (DEPM). The total survey area was 128 700 km2 with recorded spawning areas in gulf and shelf waters of 4898 and 44 618 km2, respectively. High egg densities in the warm, shallow gulf waters were produced by small, young (<1 year old) E. australis that spawned relatively small batches of eggs (c. 855) approximately every 3 days. In cooler, deeper shelf waters, where larger, older E. australis are found, lower egg densities occurred despite in iduals producing much larger batches of eggs (c. 15,572) approximately every 7 days. In shelf waters, the highest densities were recorded at inshore s ling stations. Spawning appeared to peak between 0000 and 0100 hours. Females were more abundant than males in s les from both gulf and shelf waters with sex ratios of 0.61 and 0.56, respectively. The spawning biomass of E. australis in shelf waters was 101 522 t, whereas the estimate for gulf waters was 25 374 t. Due to the differences in mean size of the spawning females, however, c. 6x10(9)E. australis were present in each region. The results support the hypothesis that variability in habitat conditions may directly influence E. australis reproduction. A large reserve of young fish in the relatively stable gulf environment may increase the resilience of the E. australis population in South Australia to unfavourable interannual changes in offshore environmental conditions.
Publisher: Elsevier BV
Date: 2006
Publisher: Elsevier BV
Date: 04-2003
Publisher: Springer Science and Business Media LLC
Date: 16-10-2018
Abstract: Larval fishes are a useful metric of marine ecosystem state and change, as well as species-specific patterns in phenology. The high level of taxonomic expertise required to identify larval fishes to species level, and the considerable effort required to collect s les, make these data very valuable. Here we collate 3178 s les of larval fish assemblages, from 12 research projects from 1983-present, from temperate and subtropical Australian pelagic waters. This forms a benchmark for the larval fish assemblage for the region, and includes recent monitoring of larval fishes at coastal oceanographic reference stations. Comparing larval fishes among projects can be problematic due to differences in taxonomic resolution, and identifying all taxa to species is challenging, so this study reports a standard taxonomic resolution (of 218 taxa) for this region to help guide future research. This larval fish database serves as a data repository for surveys of larval fish assemblages in the region, and can contribute to analysis of climate-driven changes in the location and timing of the spawning of marine fishes.
Publisher: Oxford University Press (OUP)
Date: 13-07-2011
Abstract: Przeslawski, R., Currie, D. R., Sorokin, S. J., Ward. T. M., Althaus, F., and Williams, A. 2011. Utility of a spatial habitat classification system as a surrogate of marine benthic community structure for the Australian margin. – ICES Journal of Marine Science, 68: 1954–1962. This study tests whether a continental-scale classification of Australian benthic habitats (termed “seascapes”) and the interpolated environmental data from which they are derived are useful as abiotic surrogates of bio ersity at a local [tens of kilometres, Great Australian Bight (GAB)] and regional scale [hundreds of kilometres, Western Australian (WA) margin]. Benthic invertebrate community structure is moderately associated with specific seascapes in both the GAB (R = 0.418) and WA margin (excluding hard substrata, R = 0.375 all substrata, R = 0.313). Mud content, seafloor slope, and seafloor temperature are significantly correlated with invertebrate communities at both scales, with disturbance and primary production correlated with GAB communities. Seascapes are not consistently useful surrogates because the strength and significance of relationships between seascapes and community structure differs among seascapes, regions, and spatial scales. Nevertheless, a national system of seascapes is an appropriate surrogate for broad-scale benthic invertebrate community patterns when biological data are limited, provided the uncertainty is acknowledged and, where possible, an assessment made of each seascape's ability to differentiate biological communities. Further refinement of seascape derivations may include updated and additional environmental data (particularly for hard vs. soft substrata) and validation among biological datasets from a range of habitats and scales.
Publisher: Oxford University Press (OUP)
Date: 30-11-2009
Abstract: McLeay, L. J., Page, B., Goldsworthy, S. D., Ward, T. M., Paton, D. C., Waterman, M., and Murray, M. D. 2009. Demographic and morphological responses to prey depletion in a crested tern (Sterna bergii) population: can fish mortality events highlight performance indicators for fisheries management? – ICES Journal of Marine Science, 66: 237–247. Disease-related mortality events in 1995 and 1998, which killed ∼70% of adult sardine (Sardinops sagax) biomass, provided an opportunity to assess whether crested tern (Sterna bergii) populations were affected by decreased prey abundance. We investigated the diet, age structure, and morphology of a population of crested terns to determine whether survival and growth were reduced for cohorts reared in years immediately following sardine mortality events. The diet of chicks and adults differed significantly. Australian anchovy (Engraulis australis) and sardine were the dominant prey in the diets of chicks, constituting an average of 36.3 and 14.6% of in idual prey items, respectively. Degens leatherjacket (Thamnoconus degeni) dominated the prey of adult terns, an average of 51.9% of in idual prey items. Age-specific information collected from banded adults indicated that the cohort reared after the first sardine mortality event in 1995 exhibited significantly lower rates of recruitment to the breeding colony than as predicted by life-table analyses, suggesting that survival was reduced in response to the absence of sardine. Females from cohorts reared year after the end of each sardine mortality event (in 1996 and 1999) were smaller than other age classes, suggesting that chick growth was reduced during periods of low sardine abundance. Future data on diet and on the survival and growth of crested tern chicks could provide performance indicators for management of sardine populations and aid in the development of conservation strategies for the populations of crested tern.
Publisher: CSIRO Publishing
Date: 2000
DOI: 10.1071/MF98134
Abstract: A total of 4378 sea snakes (14 species 5 unidentified specimens) were collected from 21 082 h of s ling effort by trawlers of the Northern Prawn Fishery. Most species (12) were collected from the southern Gulf of Carpentaria. Hydrophis elegans and Disteira major were caught frequently in all areas. The catch rates of H. elegans and Lapemis hardwickii were highest in the eastern gulf and in depths of 31–40 and m respectively. Hydrophis elegans represented % of specimens from most areas. Other species that represented ≥20% of specimens from one or more areas were: L. hardwickii, H. ornatus, D. major and Aipysurus eydouxii. Catch rates of all species of snakes combined did not differ significantly between 1984–86 and 1989–90, and were moderately high around Groote Eylandt where the fishery is centred. Most by-catch species occur in areas that are not subjected to extensive trawling, and there are no data to suggest that this fishery seriously threatens any population of sea snake. However, sea snakes may be more vulnerable to trawler-induced effects than most other by-catch species, and formal assessment of the status of populations is needed.
Publisher: Springer Science and Business Media LLC
Date: 18-05-2009
Publisher: Elsevier BV
Date: 03-2006
Publisher: Informa UK Limited
Date: 20-11-2011
Publisher: American Geophysical Union (AGU)
Date: 08-2006
DOI: 10.1029/2004JC002699
Publisher: Springer Science and Business Media LLC
Date: 27-01-2017
Publisher: Elsevier BV
Date: 03-2023
Publisher: American Meteorological Society
Date: 10-2007
DOI: 10.1175/JPO3119.1
Abstract: To determine the possible importance of ENSO events along the coast of South Australia, an exploratory analysis is made of meteorological and oceanographic data and output from a global ocean model. Long time series of coastal sea level and wind stress are used to show that while upwelling favorable winds have been more persistent since 1982, ENSO events (i) are largely driven by signals from the west Pacific Ocean shelf/slope waveguide and not local meteorological conditions, (ii) can account for 10-cm changes in sea level, and (iii) together with wind stress, explain 62% of the variance of annual-averaged sea level. Thus, both local winds and remote forcing from the west Pacific are likely important to the low-frequency shelf edge circulation. Evidence also suggests that, since 1983, wintertime downwelling during the onset of an El Niño is reduced and the following summertime upwelling is enhanced. In situ data show that during the 1998 and 2003 El Niño events anomalously cold (10.5°–11.5°C) water is found at depths of 60–120 m and is more than two standard deviations cooler than the mean. A regression showed that averaged sea level can provide a statistically significant proxy for these subsurface temperature changes and indicates a 2.2°C decrease in temperature for the 10-cm decrease in sea level that was driven by the 1998 El Niño event. Limited current- meter observations, long sea level records, and output from a global ocean model were also examined and provide support for the hypothesis that El Niño events substantially reduce wintertime (but not summertime) shelf-edge currents. Further research to confirm this asymmetric response and its cause is required.
Publisher: Wiley
Date: 26-08-2004
Publisher: EDP Sciences
Date: 04-2008
DOI: 10.1051/ALR:2008034
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/MF07158
Abstract: The present study investigated the reproductive biology of blue mackerel (Scomber australasicus) off southern and eastern Australia and assessed the suitability of the Daily Egg Production Method (DEPM) for future stock assessment. This analysis revealed that S. australasicus is a serial spawner with asynchronous oocyte development and indeterminate fecundity. S. australasicus spawns between November and April off southern Australia and between July and October off eastern Australia. In southern Australia, ~50% of males and females were mature at 236.5 and 286.8 mm fork length (FL), respectively. Size at ~50% maturity could not be estimated reliably for eastern Australia owing to the smaller proportion of mature fish in s les. Mean spawning frequencies ranged from 2 to 11 days off southern Australia. Batch fecundity was related to fish size and mean batch size was 69 894 ± 4361 oocytes per batch and 134 oocytes per g of weight. The timing and duration of the spawning season, size at maturity, spawning frequency and batch fecundity of S. australasicus off southern Australia were consistent with those of S. japonicus in the northern Pacific Ocean. The present study’s estimates of adult reproductive parameters of S. australasicus off southern Australia were suitable for the application of the DEPM for estimating spawning biomass. Collecting representative s les of mature fish from waters off eastern Australia during the spawning season is a high priority for future stock assessment of this species.
Publisher: Wiley
Date: 18-03-2019
DOI: 10.1002/AQC.3045
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/MF06061
Abstract: The effectiveness of two monitoring programs, designed to describe and quantify the bycatch from commercial pots, was examined in the South Australian rock lobster (Jasus edwardsii) fishery (SARLF). The first, logbook s ling, relied on information collected and recorded by fishers in logbooks. The second, bycatch s ling, required fishers to collect bycatch specimens on a nominated day for later scientific analysis. A total of 40 bycatch species were recorded during the study. Finfish, mainly blue-throat wrasse (Notolabrus tetricus) and leather jacket species (Meuschenia hippocrepis and Meushenia australis), were the major component ( % by number). Data from the logbook program were appropriate for monitoring spatio-temporal trends in bycatch, whereas the bycatch s ling provided more accurate information on bycatch species. Each program was subject to bias when estimating total bycatch numbers and, as a result, a combination of both methods indicated a cost-effective and appropriate way with which to monitor bycatch from the fishery. In comparison with other fisheries, bycatch from the SARLF was relatively low however, because bycatch was dominated by relatively few species, ongoing monitoring and risk assessment of these populations is needed to ensure long-term sustainability of bycatch levels.
Publisher: Wiley
Date: 05-01-2011
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/MF06181
Abstract: Like many pelagic fish, sardine Sardinops sagax is difficult to age by counting structures in otoliths. Of 12968 whole otoliths analysed in the present study, % could be counted with accuracies of greater than ±1 zone. Estimates of average percentage error (APE) were high (11.37%). We used a ‘case building approach’ to corroborate a method for estimating age. Regressions of otolith weight–age from otoliths with high readabilities were used to estimate the age of fish with lower or unreadable otoliths. Growth rates determined from daily increments ranged from 0.36 to 0.75 mm day–1 for larvae and from 0.22 to 0.47 mm day–1 for juveniles. Estimates of von Bertalanffy growth coefficients were k = 0.32–1.07 year–1 and L∞ = 166.96–195.68 mm. Growth parameters estimated during the present study support previous assertions that levels of pelagic production in South Australian (SA) waters lie between those recorded in the predominantly oligotrophic waters off Western Australia (WA) and the productive waters off southern California and South Africa. Disparities in the age distributions of inshore and offshore s les suggest that age data from commercial catch s les may not be representative of the population. This finding has implications for the use of age-structured models to assess of stocks of S. sagax and other small pelagic fishes.
Publisher: Elsevier BV
Date: 12-2010
Publisher: American Geophysical Union (AGU)
Date: 11-05-2004
DOI: 10.1029/2003GL019221
Publisher: Springer Science and Business Media LLC
Date: 13-11-2014
Publisher: Elsevier BV
Date: 02-2017
Publisher: Inter-Research Science Center
Date: 29-07-2010
DOI: 10.3354/MEPS08606
Publisher: Springer Science and Business Media LLC
Date: 23-01-2018
DOI: 10.1038/S41598-018-19354-6
Abstract: Understanding the spatial distribution of human impacts on marine environments is necessary for maintaining healthy ecosystems and supporting ‘blue economies’. Realistic assessments of impact must consider the cumulative impacts of multiple, coincident threats and the differing vulnerabilities of ecosystems to these threats. Expert knowledge is often used to assess impact in marine ecosystems because empirical data are lacking however, this introduces uncertainty into the results. As part of a spatial cumulative impact assessment for Spencer Gulf, South Australia, we asked experts to estimate score ranges (best-case, most-likely and worst-case), which accounted for their uncertainty about the effect of 32 threats on eight ecosystems. Expert scores were combined with data on the spatial pattern and intensity of threats to generate cumulative impact maps based on each of the three scoring scenarios, as well as simulations and maps of uncertainty. We compared our method, which explicitly accounts for the experts’ knowledge-based uncertainty, with other approaches and found that it provides smaller uncertainty bounds, leading to more constrained assessment results. Collecting these additional data on experts’ knowledge-based uncertainty provides transparency and simplifies interpretation of the outputs from spatial cumulative impact assessments, facilitating their application for sustainable resource management and conservation.
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/MF14081
Abstract: Little is known about the population trajectory and dynamics of many marine invertebrates because of a lack of robust observational data. The giant Australian cuttlefish (Sepia apama) is IUCN-listed as Near Threatened because the largest known breeding aggregation of this species in northern Spencer Gulf, South Australia, has declined markedly since the turn of the century. We used by-catch records from long-term trawl surveys to derive abundance data for S. apama and commercial cuttlefish harvest data as a measure of exploitation. Using Bayesian hierarchical models to account for zero-inflation and spatial dependence in these abundance counts, we demonstrated a high probability of broad-scale declines in the density of S. apama, particularly surrounding the primary aggregation site, which supports the recent closure of the entire S. apama fishery in northern Spencer Gulf. Historical harvest data were positively correlated with S. apama density estimated from the trawl surveys, suggesting that the commercial cuttlefish catch tracks the species abundance. Our results also indicated the possibility that the known S. apama breeding grounds might be supplemented by in iduals that were spawned elsewhere in northern Spencer Gulf.
Location: Australia
Start Date: 2020
End Date: End date not available
Funder: Fisheries Research and Development Corporation
View Funded ActivityStart Date: 2019
End Date: End date not available
Funder: Fisheries Research and Development Corporation
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