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Pitman L.R.,CSIRO | Haddy J.A.,National Center for Marine Conservation and Resource Sustainability | Kloser R.J.,CSIRO
Fisheries Research | Year: 2013

To assess the impact of exploitation on the fecundity and reproductive potential of orange roughy, historic biological data from when exploitation began (1987-1992) is compared with a current day assessment (2010) of the eastern Tasmanian stock. Findings highlight that fecundity was negatively related to stock size (r2=0.95, F=80.11, P<0.05), with length standardised fecundity increasing from 41,145±1363 in 1992 to 59,236±1047 eggs in 2010. This density dependent increase suggests that from the onset of the fishery (1987) length standardised fecundity has increased by 73%. Modelling this increase based on the 2006 stock assessment showed that the female spawning stock biomass was at 19% of virgin levels, whereas the total reproductive potential was markedly higher and estimated to be at 32% of virgin levels. The biological mechanisms of this compensatory effect were also investigated and showed fecundity was not related to ovarian atresia levels but was positively related to body condition, liver condition and ovarian lipid levels. The implications of these findings for stock recovery and management are discussed and suggest that the stock is in a better position to recover from overexploitation than would be expected if only spawning stock biomass were considered. © 2013 Elsevier B.V. Source


Shanthanagouda A.H.,RMIT University | Patil J.G.,Inland Fisheries Service Tasmania | Patil J.G.,National Center for Marine Conservation and Resource Sustainability | Nugegoda D.,RMIT University
Comparative Biochemistry and Physiology - A Molecular and Integrative Physiology | Year: 2012

To investigate the role of cytochrome P450 aromatase, we isolated cyp19 isoforms in the Murray River rainbowfish, M. fluviatilis. The cloned cDNA for cyp19a1a and cyp19a1b had an open reading frame (ORF) of 492 and 499 amino acid residues, with shared identity of up to 83% and 87% with the corresponding homologues of other teleosts respectively. In contrast, the cyp19a1a and cyp19a1b of the Murray River rainbowfish had a shared identity of only 61%. Not surprisingly, the phylogenetic analysis clustered the M. fluviatilis cyp19 isoforms with the corresponding isoforms of other teleosts, suggesting a shared evolutionary ancestry of the respective isoforms. We also studied the expression of cyp19 isoforms during ontogeny and in adult fish using quantitative Real-Time PCR (qPCR). Results suggest that uniquely only cyp19a1b transcripts are maternally inherited, suggesting its role in early development and growth in the species. In contrast to reports in many teleosts, the cyp19a1a was exclusively expressed in the ovarian tissue and completely absent in other tissues examined, including testis. The cyp19a1b like in most teleosts was predominantly expressed in the brain of both males and females with low level of expression in other tissues including gonads of both sexes. © 2011 Elsevier Inc. Source


Cliff N.,National Center for Marine Conservation and Resource Sustainability | Campbell M.L.,National Center for Marine Conservation and Resource Sustainability | Campbell M.L.,Central Queensland University
Aquatic Invasions | Year: 2012

We set out to explore whether the inclusion of perceptions into risk assessment might be a key to unlocking the human factor in the vectoring of aquatic non-indigenous species. To this end, we developed a risk assessment model that used people's perception of concern and stated behavioural intentions to measure consequence. We trialled this risk model using a test scenario of the non-indigenous species Didymosphenia geminata (a freshwater diatom) being introduced to Tasmania, Australia: a location where it is currently not present. Likelihood was determined by calculating the probability of Didymosphenia entering the test region based on exposure to D. geminata (travel history of arriving air passengers and the passenger's participation in freshwater recreational activities) and mitigation activities (whether their recreational equipment had been washed). The likelihood of a Didymosphenia incursion into Tasmania was determined to be rare. Consequence was determined by targeting three recreational user groups that participate in activities related to the movement of this species in other countries: trout anglers, hikers, and kayakers. Consequence was measured as respondent's level of concern and stated behavioural intentions if the respondent was confronted with an incursion of Didymosphenia. The consequence of a Didymosphenia incursion ranged from moderate to catastrophic. Thus, the total derived risk was determined to be low-medium. The use of perception to inform the consequence component of the risk assessment proved useful as individuals behaviours are often attributable to the introduction of species, and thus are an important consideration for risk management and education. At a local level these outcomes provide direction to biosecurity of unregulated pathways. At a global level, this risk assessment is a useful tool to assess the potential vectoring of a nonindigenous aquatic species, and potential human actions that might impede the management of a non-indigenous species once it crosses a border. © 2012 The Author(s). Source


Trenouth A.L.,National Center for Marine Conservation and Resource Sustainability | Trenouth A.L.,Central Queensland University | Harte C.,National Center for Marine Conservation and Resource Sustainability | de Heer C.P.,National Center for Marine Conservation and Resource Sustainability | And 7 more authors.
Ocean and Coastal Management | Year: 2012

Marine and coastal protected areas (MCPAs) are a key conservation strategy implemented globally to reduce impacts in these environments. The involvement of stakeholders in the design and management of MCPAs is considered integral to MCPA success. As such, knowledge of how stakeholders perceive the risks of hazards and their perception of management importance should be an integral management and planning component of MCPAs. This study aimed to explore the relationship between stakeholder perceptions of the importance and management of MCPAs with regards to a selection of natural and anthropogenic environmental hazards.Data was gathered using a questionnaire that was implemented by face to face interviews that were conducted at two locations: Strahan and St. Helens, Tasmania. Sewerage and ship groundings were perceived as the most important hazards when considering MCPAs in Tasmania. These perceptions were significantly correlated with the management and importance of MCPAs, and with the hazards. The outcomes have the potential to enhance Tasmanian MCPA management and thus improve success of management goals, if it is afforded sufficient weight in management planning and decisions. © 2012 Elsevier Ltd. Source

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