An integrated methodology for assessing ecological and economic impacts for marine management: A case study for abrasion and mobile fishing gear effects

Ensuring a balance of conservation and human activities within the marine environment requires complex decisions on how to achieve conservation objectives whilst considering the likely economic and social costs and benefits of such decisions. We assessed the risk of adverse effects from abrasion caused by bottom fishing, as a case study, to demonstrate an integrated spatial management methodology. Risk was quantified in the Galway Bay, Ireland region using a 1 km grid, as the ratio between mortality and recovery of benthic infauna exposed to abrasion effects estimated from fishing data. Risk was considered high if annual mortality exceeded recovery. A Bayesian network model, incorporating ecological and economic data, compared three management scenarios: i) business as usual (BAU), ii) exclusion of fishing vessels over 18 m within 6 nautical miles (68% of study area) (Length) and iii) a network of marine protected areas (MPAs) closed to all fishing vessels (11% of study area) (MPA). The BAU scenario indicated that risk was high for 85.6% of the study area. The length scenario resulted in a 14.6% reduction in high risk cells, affecting €0.9 M of landings, €0.7 M of indirect output and 19 full time equivalent (FTE) employees. The MPA scenario resulted in a 1.7% reduction of high risk cells. This scenario affected €0.17M in landings, €0.13M in indirect outputs and 3 FTE employees. We present a method which provides a quantitative, spatial, risk and economic impact assessment of the effects of human activities and pressures on the marine environment that assesses potential costs and benefits of management options to mitigate against these pressures. Future development of a mortality-recovery ratio for defined time periods would enable application across multiple habitats, human activities and pressures.