1. Alba Muntadas 1 *, Johanna Ballé-Béganton 2, Michel Lample 2, Silvia de Juan 1, Denis Bailly 2, Dolors Blasco 1, Montserrat Demestre 1 1 Institut de Ciències del Mar, ICM-CSIC- Barcelona; 2 Université de Bretagne Occidentale, UBO- Brest * amuntadas@icm.csic.es An ExtendSim platform to simulate the effects of trawling on benthic communities Session 5: Fisheries, Marine protected areas, population outbrusts, biodiversity shifts Symposium on Integrating New Advances in Mediterranean Oceanography and Marine Biology

2. An ExtendSim platform to simulate the effects of trawling on benthic communities BLOCKS ● SYSTEM PRESENTATION ● METHODOLOGY ● STUDY AREAS ● SIMULATION PLATFORM: SIMULATION OF TRAWLING EFFECTS ON BENTHIC COMMUNITIES AND EXPLOITED RESOURCES

3. BLOCK : SYSTEM PRESENTATION Benthos Fishing effort Commercial species Management ● Trawling affects benthic communities modifying Essential Fish Habitats  Effects on the resources. ● Platform goal  link fishing – benthos – commercial species ● This platform is meant to be a useful tool for stakeholders: managers, fishermen, scientists, politicians… Dayton et al. 1995. Aquatic Conservation. 5:205-232

4. -There are many ways to estimate fishing effort: CPUE, swept area, total length of trawl tracks.. Chosen unit: GT x days at sea/month - This information can be obtained in any area were the simulations wants to be applied BLOCK : METHODOLOGY FISHING EFFORT ESTIMATION Demestre et al. CIESM 2010

5. ● Species composition is highly influenced by local characteristics  it can mask fishing impact consequences ● SPECIES  TRAITS : - Reduces the number of variables :  Overcome regional differences  Highlights fishing effects ● For the simulation we used simple traits easily assigned to species and directly related to trawling resistance/vulnerability BLOCK : METHODOLOGY BENTHIC COMMUNITY REPRESENTATION : THE TRAITS APPROACH de Juan, S. and Demestre, M. 2012. Ecological Indicators. 18: 183–190.

6. Traits used in the simulation PositionFeedingMotilitySizeOther attributes EmergentFilter feeding Sessile (attached) Large >10 cm Fragile SurfaceDeposit feeding SedentaryMedium 5-10 cm No protection Surface burrowing PredatorsMotile (crawlers) Small <5cm Flexible Deep burrowing ScavengersHighly motile (swimmers) Strong Regeneration Vermiform Hard shell BLOCK : METHODOLOGY BENTHIC COMMUNITY REPRESENTATION : THE TRAITS APPROACH

7. BLOCK : STUDY SITES -Presentation of the data available in each study site. Community structure is presented by: ● Trait structure ● Species composition STUDY SITES

8. BLOCK : SIMULATION PRESENT FISHING EFFORT 25000 GT * days at sea/month HABITAT TYPE ● INPUTS Mud > 80% Mud 60-70% Mud 40-30% Sand DESIRED FISHING EFFORT 20000 GT * days at sea/month Sandy-mud Gravelly-mud Sand Sandy-gravel Maërl

9. BLOCK : SIMULATION -Total abundance -Percentage of trait categories within trait type PLOT RESET SIMULATION OUTPUT : PRESENT VS DESIRED EFFORT STRUCTURE Uncertainity of the simulation Actual status Structure at desired effort

10. BLOCK : SIMULATION SIMULATION OUTPUT : PRESENT VS DESIRED EFFORT STRUCTURE Scavenging Size Feeding Size Feeding Large Medium Small Filter feeding Deposit feeding Scavenging Predator PRESENT STRUCTURE STRUCTURE AT DESIRED EFFORT Large Medium Small Filter feeding Deposit feeding Predator Relationship between traits: - Possibility to show one selected trait against another trait

11. An ExtendSim platform to simulate the effects of trawling on benthic communities WORK STATUS ● DONE: -Epifauna and physical data collection -Platform structure ● IN PROGRESS: -Statistical basis to run the simulation -Building the graphical interface FUTURE CHALLENGES : - Include information on infaunal community - Include the link benthos – comercial species