A Quantitative Metric to Identify Critical Elements within Seafood Supply Networks

A theoretical basis is required for comparing key features and critical elements in wild fisheries and aquaculture supply chains under a changing climate. Here we develop a new quantitative metric that is analogous to indices used to analyse food-webs and identify key species. The Supply Chain Index (SCI) identifies critical elements as those elements with large throughput rates, as well as greater connectivity. The sum of the scores for a supply chain provides a single metric that roughly captures both the resilience and connectedness of a supply chain. Standardised scores can facilitate crosscomparisons both under current conditions as well as under a changing climate. Identification of key elements along the supply chain may assist in informing adaptation strategies to reduce anticipated future risks posed by climate change. The SCI also provides information on the relative stability of different supply chains based on whether there is a fairly even spread in the individual scores of the top few key elements, compared with a more critical dependence on a few key individual supply chain elements. We use as a case study the Australian southern rock lobster Jasus edwardsii fishery, which is challenged by a number of climate change drivers such as impacts on recruitment and growth due to changes in largescale and local oceanographic features. The SCI identifies airports, processors and Chinese consumers as the key elements in the lobster supply chain that merit attention to enhance stability and potentially enable growth. We also apply the index to an additional four real-world Australian commercial fishery and two aquaculture industry supply chains to highlight the utility of a systematic method for describing supply chains. Overall, our simple methodological approach to empiricallybased supply chain research provides an objective method for comparing the resilience of supply chains and highlighting components that may be critical

Ecological impacts of non-native Pacific oysters (Crassostrea gigas) and management measures for protected areas in Europe

Pacific oysters are now one of the most ‘globalised’ marine invertebrates. They dominate bivalve aquaculture production in many regions and wild populations are increasingly becoming established, with potential to displace native species and modify habitats and ecosystems. While some fishing communities may benefit from wild populations, there is now a tension between the continued production of Pacific oysters and risk to biodiversity, which is of particular concern within protected sites. The issue of the Pacific oyster therefore locates at the intersection between two policy areas: one concerning the conservation of protected habitats, the other relating to livelihoods and the socio-economics of coastal aquaculture and fishing communities. To help provide an informed basis for management decisions, we first summarise evidence for ecological impacts of wild Pacific oysters in representative coastal habitats. At local scales, it is clear that establishment of Pacific oysters can significantly alter diversity, community structure and ecosystem processes, with effects varying among habitats and locations and with the density of oysters. Less evidence is available to evaluate regional-scale impacts. A range of management measures have been applied to mitigate negative impacts of wild Pacific oysters and we develop recommendations which are consistent with the scientific evidence and believe compatible with multiple interests. We conclude that all stakeholders must engage in regional decision making to help minimise negative environmental impacts, and promote sustainable industry development

Spatial and temporal fishery management assessment using DEA: Case study of spanner crabs in Queensland, Australia

Available online 6 July 2023The aim of this case study was to assess potential temporal and spatial differences in productivity measures of vessels operating in the Queensland spanner crab fishery. This fishery’s logbook records of catch and effort data allowed analysis of the impact of fishery management changes on productivity measures. Data envelopment analysis (DEA) with a ‘window analysis’ approach was used to derive estimates for measures of technical efficiency, capacity utilisation and scale efficiency over time for five different spanner crab fishing regions. The results suggest that average technical efficiency and capacity utilisation were relatively low over time and across fishing regions, implying a high level of technical inefficiency and the existence of excess capacity in the fishery. Scale efficiency was found to be high historically but decreased slightly since 2006 for all regions. The results suggest that this decline is likely not caused by the fishery management changes, but instead is due to other factors. Additional data (e.g., revenue, profit, costs, skipper experience) and analysis is needed to assess the causes for the low technical efficiency and capacity utilisation and reasons for the decrease in scale efficiency as a baseline for specific fishery management recommendations. The study shows that temporal and spatial efficiency and productivity analysis of fisheries can help identify potential issues that are not otherwise apparent.Peggy Schrobback, Karsten Schrobback, Sean Pascoe, Stephanie McWhinnie, Eriko Hoshin

Turning water into carbon: carbon sequestration and water flow in the Murray-Darling Basin

Large scale forest plantations in the Murray-Darling Basin are a possible carbon sequestration mechanism which may be adopted in response to the introduction of a carbon price. However, increased tree plantation will be associated with reduced inflows to river systems because of increased transpiration, interception and evaporation. This could have significant implications for regions vulnerable to drought. This study examines the interaction between carbon pricing, water pricing, and agricultural land use in the Murray-Darling Basin and its impact on water flow under current and climate change settings.Peggy Schrobback, David Adamson, John Quiggi

Turning Water into Carbon: Carbon sequestration vs. water flow in the Murray-Darling Basin

Large scale forest plantations in the Murray-Darling Basin may be embraced as a carbon sequestration mechanism under a Carbon Pollution Reduction Scheme. This paper looks at their impact. Increased tree plantations will be associated with reduced inflows to river systems because of increased transpiration, interception and evaporation. Therefore, an unregulated change in land management is most likely to have a dramatic impact on the water availability, exacerbating the impacts of climate change projected in the Garnaut Review. This paper examines the implications of unrestricted changes in land use. These results should suggest the true costs to society from carbon sequestration by determining the tradeoffs between timber production and agricultural products