Assessing the status of seabed habitats in 24 trawled regions of the world

HIDDINK, J. G.; PARMA, ANA M; SCIBERRAS, MARIJA; KAISER, MICHEL J; JENNINGS, SIMON; AMOROSO, RICARDO O; MCCONNAUGHEY, ROBERT A; SUURONEN, PETRI; PITCHER, C. ROLAND; COLLIE, JEREMY S; MAZOR, TESSA; RIJNSDORP, ADRIAAN D.; HILBORN, RAY

Congreso; 2019 Australian Marine Sciences Association Conference; 2019

Bottom-trawl fishing is widely considered to pose serious environmental risks to seabed habitats. We apply a new method, suitable for data-poor fisheries, to quantify the relative benthic status (RBS) of the seabed: the amount of biota present, in equilibrium with trawl depletion, as a proportion of biota present without trawling. Estimating RBS for grid cells requires parameters for trawl impact and recovery rates, and maps of trawling intensity and habitats. Regional status is summarized by the distribution of grid-cell RBS values and their mean. Regional average RBS was >0.9 for 16 regions (i.e. trawling has depleted regional biota by <0.1) whereas three (European) regions had average RBS <0.7. Where commercial trawl species were managed within accepted sustainability limits, there was 93.3% probability that regional RBS was >0.9; thus sustainable fisheries production and sustaining the environment are complementary and achievable. Within the five Australian regions, subsequent definition of 217 meso-scale eco-regions showed most had little or no exposure to trawling, but several have high trawl exposure and are priorities for detailed habitat risk assessment. These results provide sea-scape scale indicators needed for balancing production and environmental sustainability objectives and for development of best practices for ecosystem-based fishery management, reporting and certification.