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

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

Kuching

Congreso; 5th International Marine Conservation Congress; 2018

Society for Conservation Biology

The impacts of bottom trawling on seabed habitats often are con-sidered to pose serious environmental threats. Risk assessment canbe used to evaluate these threats and to guide management regard-ing interventions needed to help meet sustainability objectives. Weapply a simple quantitative method, applicable in data-limited situa-tions, to assess seabed sedimentary habitats in 24 regions worldwidewhere bottom-trawl fishing occurs. The method estimates the relativebenthic status (RBS) of the seabed: the amount of biota present, inequilibrium with bottom-trawling depletion, as a proportion of biotapresent without trawling. Estimating RBS for grid cells spanning aregion requires few parameters: rates of recovery and trawl impact,and maps of fishing intensity and habitats. The overall status of re-gions is represented by the distribution of grid-cell RBS values andtheir mean, which are sensitive to trawling exposure and impact andrecovery rates. Our assessment is currently a work-in-progress. Pre-liminary estimates indicate that most regional RBS values are greaterthan 90% (i.e. trawling has depleted regional biota by <10%) whereasfew regions had RBS <70%. This assessment places trawling impactsin regional landscape perspective and provides world-wide compar-isons for guiding management of environmental risks from trawling.A range of management interventions are possible to reduce theserisks but may require trade-offs against food security priorities. De-cisions about such trade-offs will vary among countries depending onthe relative balance of environmental, social and economic prioritiesand costs of alternative interventions. RBS can assist by quantifyingthe environmental benefits of any alternative management strategies.