Browsing by Author "Norman-Lopez, Anna"

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    Assessing the adequacy of current fisheries management under changing climate: a southern synopsis
    (Oxford University Press, 2011) Plagányi, Éva E; Weeks, Scala J; Skewes, Tim D; Gibbs, Mark T; Blamey, Laura K; Soares, Muri; Robinson, William M L; Poloczanska, Elvira S; Norman-Lopez, Anna
    Climate change is likely to have a significant impact on both target and non-target marine stocks worldwide, with the concomitant need for management strategies capable of sustaining fishing in future. We use several southern hemisphere fisheries to highlight the likely impacts of climate change at a range of levels, from individual to population responses, as well as ecosystem ramifications. Examples span polar (Antarctic krill fishery), temperate (west coast pelagic fishery, abalone and rock lobster), and tropical (Torres Strait rock lobster) commercially important fisheries. Responses of these fisheries to either past observed environmental changes or projected future changes are used to deduce some anticipated implications of climate change for fisheries management, including economic impacts and governance considerations. We evaluate the effectiveness of current single-species assessment models, management strategy evaluation approaches and multispecies assessment models as future management tools to cope with likely climaterelated changes. Non-spatial stock assessment models will have limited ability to separate fishery effects from the impacts of climate change. Anthropogenic climate change is occurring at a time-scale relevant to current fisheries management strategic planning and testing. Adaptive management frameworks (with their feedback loops) are ideal for detecting and adapting to changes in target stocks
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    Assessing the adequacy of current fisheries management under changing climate:a southern synopsis
    (ICES Journal of Marine Science, 2012) Plagányi, Éva E; Weeks, Scala J; Skewes, Tim D; Gibbs, Mark T; Blamey, Laura K; Soares, Muri; Robinson, William M L; Norman-Lopez, Anna
    Climate change is likely to have a significant impact on both target and non-target marine stocks worldwide, with the concomitant need for management strategies capable of sustaining fishing in future. We use several southern hemisphere fisheries to highlight the likely impacts of climate change at a range of levels, from individual to population responses, as well as ecosystem ramifications. Examples span polar (Antarctic krill fishery), temperate (west coast pelagic fishery, abalone and rock lobster), and tropical (Torres Strait rock lobster) commercially important fisheries. Responses of these fisheries to either past observed environmental changes or projected future changes are used to deduce some anticipated implications of climate change for fisheries management, including economic impacts and governance considerations. We evaluate the effectiveness of current single-species assessment models, management strategy evaluation approaches and multispecies assessment models as future management tools to cope with likely climaterelated changes. Non-spatial stock assessment models will have limited ability to separate fishery effects from the impacts of climate change. Anthropogenic climate change is occurring at a time-scale relevant to current fisheries management strategic planning and testing. Adaptive management frameworks (with their feedback loops) are ideal for detecting and adapting to changes in target stocks
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    Ecosystem modelling provides clues to understanding ecological tipping points
    (Inter Research, 2014) Plagányi, Éva E; Ellis, Nick; Blamey, Laura K; Morello, Elisabetta B; Norman-Lopez, Anna; Robinson, William M L; Sporic, Miriana; Sweatman, Hugh
    Ecological thresholds, associated with abrupt changes in the state and organisation of ecosystems, challenge both scientists and managers. Adaptive response to such changes, and planning for their occurrence, requires an understanding of the underlying drivers and system responses as well as appropriate monitoring. In addition to field studies, modelling can advance our ability to anticipate or deal with such major ecosystem shifts. Here, we used an existing multispecies model with smooth continuous functions that were modified to include thresholds representing 3 alternative scenarios of predator responses when prey numbers drop below a critical threshold: (I) no threshold-like response; (II) an abrupt decrease in breeding success by 90%, and (III) an abrupt halving of adult survival. Second, we analysed field observations from 3 independent marine case studies (abalone, starfish, penguins) for evidence of abrupt non-linear responses of predators to changes in abundance of principal prey. Third, we compared the model output with empirical results and tested (using both a statistical method and by fitting multispecies models) the 3 alternative response scenarios. With this approach, we found evidence for nonlinear changes in population parameters (such as survival rate) of predators as prey numbers declined below critical thresholds. As an example of the potential for this approach to inform management, we found that abundances of a range of marine predators become more variable as prey numbers decline, which may be a useful indicator that a system is approaching a tipping point.