Southern Fisheries Center

Deception Bay, Australia

Southern Fisheries Center

Deception Bay, Australia
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Godwin R.,University of Queensland | Brown I.,Southern Fisheries Center | Frusher S.,University of Tasmania | Green T.,University of Queensland | Ovenden J.,University of Queensland
Marine Biology | Year: 2012

Telomere length has been purported as a biomarker for age and could offer a non-lethal method for determining the age of wild-caught individuals. Molluscs, including oysters and abalone, are the basis of important fisheries globally and have been problematic to accurately age. To determine whether telomere length could provide an alternative means of ageing molluscs, we evaluated the relationship between telomere length and age using the commercially important Sydney rock oyster (Saccostrea glomerata). Telomere lengths were estimated from tissues of known age individuals from different age classes, locations and at different sampling times. Telomere length tended to decrease with age only in young oysters less than 18 months old, but no decrease was observed in older oysters aged 2-4 years. Regional and temporal differences in telomere attrition rates were also observed. The relationship between telomere length and age was weak, however, with individuals of identical age varying significantly in their telomere length making it an imprecise age biomarker in oysters. © 2011 Her Majesty the Queen in Rights of Australia.

Campbell M.J.,Bribie Island Research Center | Officer R.A.,Mayo Institute of Technology, Galway | Prosser A.J.,Southern Fisheries Center | Lawrence M.L.,Southern Fisheries Center | And 2 more authors.
Journal of Shellfish Research | Year: 2010

In the Queensland, Australia, scallop fishery, the scallop catch is graded at sea using a specially designed grading machine called a "tumbler." Experiments were conducted to determine the effect of repeated trawl capture, grading, and discarding on the survival of sublegal saucer scallops Amusium balloti. Scallops were caught within an area closed to commercial fishing and known to contain dense scallop beds. The trawled scallops were randomly divided into 2 groups, tumbled and control, and subjected to up to 4 tumbles and/or trawls before being caged for 2.5 days adjacent to the trawl grounds. Increased levels of both trawling and tumbling were found to decrease significantly the survival of sublegal scallops. Although 83% of scallops survived repeated intensive trawling (4 consecutive tows), survival fell to 64% when scallops were also graded using a commercial tumbler. Survival was high for both tumbled and control sublegal scallops after 1 trawl (97% and 98%, respectively).

Sumpton W.D.,Southern Fisheries Center | Taylor S.M.,Australian Department of Primary Industries and Fisheries | Gribble N.A.,Northern Fisheries Center | McPherson G.,Northern Fisheries Center | Ham T.,Australian Department of Primary Industries and Fisheries
African Journal of Marine Science | Year: 2011

Catches of sharks and bycatch in large-mesh nets and baited drumlines used by the Queensland Shark Control Program were examined to determine the efficacy of both gear types and assess fishing strategies that minimise their impacts. There were few significant differences in the size of both sharks and bycatch in the two gear types, apart from significantly smaller (p < 0.05) tiger sharks Galeocerdo cuvier being taken on drumlines and smaller green turtles Chelonia mydas in nets. Catch per unit effort showed orders of magnitude differences among species, even within the same family. Hammerhead sharks and rays were particularly vulnerable to net capture, whereas higher catch rates of tiger sharks were observed for drumlines. Nets caught more marine mammals, teleost fish and rays, whereas drumlines exhibited higher catch rates of the threatened loggerhead turtle Caretta caretta. Survival of most taxa (particularly obligate ram ventilators) was lower in nets than drumlines. Bycatch species (turtles and marine mammals) were able to swim to the surface to breathe when they were hooked on drumlines, enhancing their survival potential. Fishing strategies that recognise the different selectivity patterns of the gear can be developed to suit local biotic and abiotic conditions, although it is recognised that quantification of both ecological risk and risk to bathers is not a simple task. © The State of Queensland (Australia), 2011.

Benavides M.T.,Marine Conservation Institute | Feldheim K.A.,Pritzker Laboratory for Molecular Systematics and Evolution | Duffy C.A.,Aquatic and Threats Unit | Wintner S.,KwaZulu Natal Sharks Board | And 14 more authors.
Marine and Freshwater Research | Year: 2011

The copper or bronze whaler shark (Carcharhinus brachyurus) is a large, coastal top predator that is vulnerable to overexploitation. We test the null hypothesis that copper sharks are panmictic throughout the southern hemisphere. We analysed part of the mitochondrial control region (mtCR) in 120 individuals from eight sampling areas, defining 20 mtCR haplotypes (h = 0.76 ± 0.06, π = 0.016 ± 0.0007). Significant genetic structure was detected among the following three major coastal regions separated by oceanic habitat: Australia-New Zealand, South Africa-Namibia and Per (AMOVA Φ ST=0. 95, P < 0.000001). A major phylogeographic discontinuity exists across the Indian Ocean, indicating an absence of at least female-mediated gene flow for ∼3 million years. We propose that this species originated in the Atlantic, experienced vicariant isolation of Pacific and Atlantic lineages by the rise of the Isthmus of Panama and, subsequently, dispersed across the Pacific to colonise Australasia. Oceanic expanses appear to be traversed over evolutionary but not ecological timescales, which means that regional copper-shark populations should be assessed and managed independently. © CSIRO 2011.

Kyne P.M.,University of Queensland | Kyne P.M.,Charles Darwin University | Courtney A.J.,Southern Fisheries Center | Bennett M.B.,University of Queensland
Journal of the Marine Biological Association of the United Kingdom | Year: 2011

Three species of Australian endemic catsharks (grey spotted catshark Asymbolus analis, orange spotted catshark A. rubiginosus and Australian sawtail shark Figaro boardmani) were collected from the trawl grounds of a highly seasonal commercial fishery off southern Queensland, Australia. Specimens were collected on the mid to outer continental shelf at depths between 78 and 168 m. This study provides the first information on the reproductive biology of these three poorly-known species. Mature female and male A. analis were observed from 455 mm total length (TL), mature female A. rubiginosus from 410 mm TL, mature male A. rubiginosus from 405 mm TL, mature female F. boardmani from 402 mm TL and mature male F. boardmani from 398 mm TL (although a lack of immature specimens precluded more accurate assessments of size at maturity). The reproductive mode of all species was confirmed as single oviparous (carrying only one egg case in each uterus at a time). Ovarian fecundity (the number of vitellogenic follicles) ranged from 7-20 in A. analis, 5-23 in A. rubiginosus and 9-13 in F. boardmani. Several indicators suggest that Asymbolus catsharks off southern Queensland are reproductively active year-round. The proportion of female A. rubiginosus carrying egg cases was highest in spring (60%), intermediate in autumn (50%) and lowest in winter (44%). © Copyright Marine Biological Association of the United Kingdom 2010.

Halliday I.A.,Southern Fisheries Center | Robins J.B.,Southern Fisheries Center | Mayer D.G.,Animal Research Institute | Staunton-Smith J.,Southern Fisheries Center | Sellin M.J.,Southern Fisheries Center
Proceedings of the Royal Society of Queensland | Year: 2011

The age-structure of the commercial catch of barramundi in the Fitzroy River estuary, central Queensland, was examined over fi ve consecutive years and used to estimate year-class strength (= index of recruitment). Barramundi year-class strength fl uctuated and was signifi cantly and positively correlated with freshwater flow and coastal rainfall in spring and summer. General linear models were used to identify relationships between year-class strength and freshwater variables, and explained between 85 and 90% of the variation in barramundi year-class strength. The results provide further evidence that recruitment variation in barramundi: (i) persists over time; and (ii) is signifi cantly correlated with the volume to freshwater flowing into the estuary. We reviewed the evidence in support of the three causal mechanisms currently proposed to explain the relationship between year-class strength and juvenile barramundi recruitment; and propose an additional mechanism, that of enhanced growth rates and thus increased survival of young-of-the-year. Freshwater flow is an important driver of barramundi recruitment, and reduction in flow, through water abstraction or climate change, will potentially reduce barramundi stock size available for human harvest. As such, fi shery stock assessments for barramundi should explicitly consider the impacts of variable flow on annual recruitment and stock dynamics.

Brown I.,Southern Fisheries Center | Sumpton W.,Southern Fisheries Center | McLennan M.,Southern Fisheries Center | Mayer D.,Animal Science Institute | And 9 more authors.
Journal of Experimental Marine Biology and Ecology | Year: 2010

Promotion of better procedures for releasing undersize fish, advocacy of catch-and-release angling, and changing minimum legal sizes are increasingly being used as tools for sustainable management of fish stocks. However without knowing the proportion of released fish that survive, the conservation value of any of these measures is uncertain. We developed a floating vertical enclosure to estimate short-term survival of released line-caught tropical and subtropical reef-associated species, and used it to compare the effectiveness of two barotrauma-relief procedures (venting and shotline releasing) on red emperor (Lutjanus sebae). Barotrauma signs varied with capture depth, but not with the size of the fish. Fish from the greatest depths (40-52 m) exhibited extreme signs less frequently than did those from intermediate depths (30-40 m), possibly as a result of swim bladder gas being vented externally through a rupture in the body wall. All but two fish survived the experiment, and as neither release technique significantly improved short-term survival of the red emperor over non-treatment we see little benefit in promoting either venting or shotline releasing for this comparatively resilient species. Floating vertical enclosures can improve short-term post-release mortality estimates as they overcome many problems encountered when constraining fish in submerged cages. Crown Copyright © 2010.

O'Neill M.F.,Maroochy Research Station | O'Neill M.F.,University of Queensland | Campbell A.B.,Southern Fisheries Center | Brown I.W.,Southern Fisheries Center | Johnstone R.,University of Queensland
ICES Journal of Marine Science | Year: 2010

For many fisheries, there is a need to develop appropriate indicators, methodologies, and rules for sustainably harvesting marine resources. Complexities of scientific and financial factors often prevent addressing these, but new methodologies offer significant improvements on current and historical approaches. The Australian spanner crab fishery is used to demonstrate this. Between 1999 and 2006, an empirical management procedure using linear regression of fishery catch rates was used to set the annual total allowable catch (quota). A 6-year increasing trend in catch rates revealed shortcomings in the methodology, with a 68 increase in quota calculated for the 2007 fishing year. This large quota increase was prevented by management decision rules. A revised empirical management procedure was developed subsequently, and it achieved a better balance between responsiveness and stability. Simulations identified precautionary harvest and catch rate baselines to set quotas that ensured sustainable crab biomass and favourable performance for management and industry. The management procedure was simple to follow, cost-effective, robust to strong trends and changes in catch rates, and adaptable for use in many fisheries. Application of such "tried-and-tested" empirical systems will allow improved management of both data-limited and data-rich fisheries. © 2010 International Council for the Exploration of the Sea.

Werry J.M.,Griffith University | Werry J.M.,Ocean and Coast Research | Lee S.Y.,Griffith University | Otway N.M.,Port Stephens Fisheries Institute | And 2 more authors.
Marine and Freshwater Research | Year: 2011

Understanding the ontogenetic habitat linkages of sharks is important for conservation and managing human interactions. We used acoustic telemetry, catch data, elemental and stable isotope signatures and dietary analyses to investigate ontogenetic habitat use in south-east Queensland, Australia, by the bull shark Carcharhinus leucas, a IUCN 'near-threatened' species that is implicated in many shark attacks on humans in urban estuaries. Sequential analyses for 15N and 13C of vertebrae from five adult C. leucas and laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) for elemental composition from 23 C. leucas, including a pregnant female, were also used to trace ontogenetic habitat dependence. Acoustic telemetry indicated large juvenile and subadult C. leucas remained in estuarine habitats. 15N values across shark vertebrae showed an ontogenetic shift in diet with total length (TL), confirmed by stomach contents. LA-ICPMS data reflected the ontogenetic movements of C. leucas from natal habitats. Differences among adults were gender related. Shifts in habitat use by subadults were correlated with a sigmoidal 13C relationship with TL. C. leucas have a multipartite, stage-specific dependency in their transition between habitats along the freshwaterestuarinemarine continuum, making them particularly susceptible to the habitat alteration that is occurring globally. © 2011 CSIRO.

Dichmont C.M.,CSIRO | Brown I.W.,Southern Fisheries Center
Marine and Coastal Fisheries | Year: 2010

The Queensland spanner crab Ranina ranina is the target of a relatively data-poor, low-value fishery that has been managed for the last decade by using total allowable catches (TACs) in an individual transferable quota system. Despite the fact that this management system is usually applied to data-rich fisheries, it has been successfully used on this data-poor fishery. The key factor has been the use of harvest strategies that consisted only of simple decision rules that were appropriate given the size of the fishery and knowledge of the resource. These strategies were tested in a management strategy evaluation framework; however, it was not traditional in that (1) the operating model (or "true" resource to be managed) was not conditioned to data but rather was set to parameter ranges seen as appropriate for the resource and (2) the TAC was not set by using a stock assessment model, so the magnitude of the stock biomass was unknown. The important test was whether one could develop harvest strategies that were robust to this large uncertainty in knowledge by using only commercial catch rates. The management system had to be adaptive over time as more was learned about the biology of the species and how the harvest strategies affected the management of the fishery. This meant that the TAC was almost always set using the harvest strategies, but modifications to the decision rules were made on several occasions as more was learned about the fishery. The transparency and simplicity of the rules mean that the industry was empowered to make significant contributions to fine tuning the harvest strategies. As a result, the process does not rely solely on scientific advances but on the pooled knowledge of scientists, industry, and managers in a cooperative environment. © American Fisheries Society 2010.

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