SEAwise synthetic summary report of the findings of WP4 on the ecosystem impacts of fishing for online tool

The SEAwise project works to deliver a fully operational tool that will allow fishers, managers, and policy makers to easily apply Ecosystem Based Fisheries Management. This SEAwise report identifies the appropriate findings from WP4 on ecosystem impacts of fishing that could be included in the online EBFM tool. The WP was broken down into four topics as follows:

• Mortality risk of potentially endangered and threatened species of fish, seabirds, reptiles and mammals
• Spatio-temporal benthic effects of fishing on benthic habitats relative to suggested threshold levels
• Effects of fishing on food webs and community diversity
• Pressure induced by fisheries related litter on key species groups

All four tasks were able to produce a suite of indicators of the impacts of fishing on specific indicators under each task heading. For Protected, Endangered and Threatened Species (PETS), the emphasis was on risk metrics for the bycatch calculated using Productivity Susceptibility Analysis (PSA). For benthic impact, the analysis focused on the calculation of a single metric - Relative Benthic Status, largely calculated from sensitivity epibenthic fauna survey data and fishing effort. A wide range of food web indicators could be calculated from the food web models, and empirical analyses. The final selection was for a small range of indicators that were linked to fishing pressure and were available across all case studies. For litter, the metrics of abundance (number of items and weights) were calculated with a common methodology and for a standard set of categories. It was not possible to link these directly with fishing effort.

The metrics were evaluated against five criteria, representing the desirable characteristics for use in the EBFM tool:

• Able to produce time series – was it possible to plot the indicators on an annual basis?
• Able to be mapped – were the indicators developed spatially explicit and could they be presented in maps?
• Able to have thresholds calculated – Was it possible to provide some estimation of a threshold to indicate where management action would be necessary?
• Able to be used across all, or most, case studies – were the same indicators and modelling/analysis approaches available for all case studies, where the impacts were analysed?
• Able to be disaggregated by gear – was it possible to provide gear specific evaluations of their impact to illustrate the potentially varying impacts of different fishing gears?

For three of the four topics, both time series and maps were available, and that these could be applied in a broadly consistent approach across the case studies. For food webs, maps were not available at present but can potentially be produced from survey data. Calculations for providing thresholds were more difficult. For PETS indicators, threshold values could be calculated, and compared to bycatch values available from other sources. Threshold values for RBS and litter were not available, although a quality threshold has been proposed elsewhere. No threshold values were available for litter abundance. Thresholds for food-web indicators were mainly able to be calculated within the analyses. Disaggregation by gear, i.e. providing indicators for fishing impact by gears was possible explicitly for PETS, but for a restricted range of mainly passive gears. It is possible to calculate gear specific impact metrics for RBS, and for the food-web indicators, though this has yet to be achieved. In summary, SEAwise can provide mapped and time series outputs for all the tasks and case studies for use in the EBFM online tool. Gear specific breakdown of the indicators can potentially be made for all topics.