ORCID Profile
0000-0001-5642-5372
Current Organisations
University of Tasmania
,
CSIRO
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Oxford University Press (OUP)
Date: 09-2022
Abstract: Multispecies, multigear fisheries occur in most ecosystems in the world, but are typical in tropical ecosystems and especially in emerging economies. However, much of fishery science has been developed from a single-species perspective. Management schemes based on single-species reference points often ignore the trophic link among species and the technical interaction between gears, essentially disconnecting management objectives from the context of an ecosystem—or socioecological system—where fisheries operate. Using the Gulf of Thailand fishery as an ex le, we demonstrate how aggregate production models can be used to estimate system-level fishery reference points for multispecies fisheries. Our results show that the multispecies maximum sustainable yield changes with ecosystem state—the systemic productivity level due to species composition and ecological (trophic/habitat, etc.) structure—under various development levels of fishing and varies with management objectives such as bio ersity, system resilience, total catch, total value, and employment. Aggregate approaches are a tractable way of estimating sustainable ecosystem-scale extraction for multispecies fisheries, avoiding the dilemma of facing conflicting advice derived from single-species methods and providing a practical, operational step toward ecosystem-based management. However, these methods are sensitive to the ecosystem states over time and decision makers need to make informed decisions on which state they want to maintain (or recover) and thus which system-level reference points to use. Consequently, management of multispecies fisheries must be clear on their system-level fisheries policy objectives.
Publisher: Elsevier BV
Date: 12-2013
Publisher: Elsevier BV
Date: 09-2023
Publisher: Springer Science and Business Media LLC
Date: 06-06-2023
Publisher: PeerJ
Date: 19-07-2021
DOI: 10.7717/PEERJ.11712
Abstract: The Tasman and Golden Bays (TBGB) are a semi-enclosed embayment system in New Zealand that supports numerous commercial and recreational activities. We present three ecosystem models of the TBGB ecosystem with varying levels of complexity, aimed at contributing as tools to aid in understanding this ecosystem and its responses to anthropogenic and natural pressures. We describe the process of data compilation through to model validation and analyse the importance of knowledge gaps with respect to model dynamics and results. We compare responses in all three models to historical fishing, and analyse similarities and differences in the dynamics of the three models. We assessed the most complex of the models against initialisation uncertainty and sensitivity to oceanographic variability and found it most sensitive to the latter. We recommend that scenarios relating to ecosystem dynamics of the TBGB ecosystem include sensitivities, especially oceanographic uncertainty, and compare responses across all three models where it is possible to do so.
Publisher: Oxford University Press (OUP)
Date: 18-05-2017
Abstract: Juvenile jack mackerel were found in 2009 in the Challenger break and the East Pacific ridge (CHAEPR). This seamount region is ∼3500 km from the coastal historic jack mackerel nursery grounds off Chile (north of 30°S). We reviewed historic evidence of juveniles around this seamount and data on several local environmental conditions: sea surface temperature, chlorophyll-a, wind, turbulence levels, and Eddy kinetic energy (EKE). A Lagrangian model for the early life stages of jack mackerel in the eastern South Pacific was used to assess the potential of the seamount region as a permanent nursery ground. Transport/retention mechanisms were assessed by releasing virtual particles coupled to a growth model into the flow simulated by an eddy-resolving ocean model. Model simulations showed high inter-annual variability for particle retention in the seamount region high retention levels were associated with low EKE such that the particles were retained for several months. Satellite altimetry has shown a local minimum in eddy activity in the region where the juveniles were observed this minimum was consistent with the above temporal relationship. The inclusion of the CHAEPR oceanic seamount region as a potential nursery ground for jack mackerel expands the current conceptual framework for the spatial population structure of this species in the South Pacific off central Chile proposed by Arcos et al. (The jack mackerel fishery and El Niño 1997–98 effects off Chile. Progress in Oceanography 49: 597–617, 2001). Finally, we discuss the relevance of seamounts playing a double role (spawning and nursery grounds) from the standpoint of conservation and bio ersity.
Publisher: Wiley
Date: 21-08-2019
Publisher: Wiley
Date: 08-12-2022
Abstract: Ecosystem‐based fisheries management aims to ensure ecologically sustainable fishing while maximising socio‐economic benefits. Achieving this goal for mixed fisheries requires better understanding of the effects of competing fishing fleets on shared resources and economic performance. Proposed management strategies that promote either specialisation or ersification of catches may result in unintended consequences for ecosystem‐based management. Here, we ask the following questions: does increased or decreased competition among fleets lead to better ecological and socio‐economic fishery outcomes? How effective are currently proposed management strategies for achieving these outcomes? We integrated fleet dynamics into a multispecies size‐spectrum model and parameterised this model to represent Australian Southern and Eastern Scalefish and Shark Mixed Fishery. We compared the fishery status quo to two extreme scenarios: no competition , where each species is fished only by one fleet (specialisation) and maximal competition , where all fleets catch all species ( ersification). To answer our second question, we considered three more plausible scenarios resulting from proposed management strategies: decreased competition due to reduced bycatch, and increased competition due to increased catches of under‐utilised or valuable species. We used indicators to explore scenarios' outcomes. Our model reproduced observed trends in fishing effort and yield. Extreme scenarios showed that a fishery dependent on single species management structures is more likely to achieve ecosystem‐based management objectives if fleets do not compete, while maximal competition can lead to socio‐economic loss as management buffers the ecological impact of ersifying. The more plausible scenarios showed little improvement over the status quo , with mixed ecological and negative economic effects. Synthesis and applications . Our model can be applied to assess mixed fisheries ecosystem‐based management strategies. Our results show that, under single species management approaches, greatest outcomes can be achieved when fleets are specialised, whereas managing fleets that catch similar species is unlikely to be successful. They question the effectiveness of these management approaches in providing resilience for mixed fisheries facing changes and highlight the need to account for fleet interactions in the evaluation of management strategies to avert unintended risks.
Publisher: Public Library of Science (PLoS)
Date: 22-02-2019
Publisher: Elsevier BV
Date: 11-2019
Publisher: Oxford University Press (OUP)
Date: 21-01-2013
Abstract: The genetic structure of present-day populations has been highly affected by glacial periods and physical oceanographic forcing, particularly with respect to species distributions and population gene-flow patterns. We assessed the current genetic composition of the Jasus frontalis population in the southeastern Pacific Islands off the coast of Chile to evaluate their connectivity modulated by contemporary and historic oceanographic processes. Population structure and demographical history for this species were assessed based on classic and Bayesian approaches using 84 sequences of cytochrome oxidase subunit I. In addition, we estimated the time of origin of J. frontalis in the different geographic zones. The analyses show a panmictic population with high gene flow between subcomponents and a lack of genetic structure (F (ST) < 0.008). This high gene flow is mainly modulated by mesoscale oceanographic factors such as eddies and meanders. In a historical spatial context, the most probable common ancestor of J. frontalis could have colonized the region around 0.258 million years before present (MYBP), first becoming established in the Juan Fernández Archipelago and then expanding toward the Desventuradas Islands. The demographic history shows a consistent increase in the effective population size (N ( e )) starting approximately 0.130 MYBP, which is highly correlated with sea-level changes during the last glacial maximum.
Publisher: Elsevier BV
Date: 11-2018
Location: Australia
No related grants have been discovered for Javier Porobic.