Alba Muntadas1*, Johanna Ballé-Béganton2, Michel Lample2, Silvia de Juan1, Denis Bailly2, Dolors Blasco1, Montserrat Demestre1

1Institut de Ciències del Mar, ICM-CSIC- Barcelona; 2Université 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

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

BLOCK : SYSTEM PRESENTATION

Benthos

Fishing effort

Commercial species Management

THE SYSTEM

[ Find out more ...]

This platform is meant to be a tool

to estimate the status of a community

subjected to a provided fishing

effort

● 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

-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 : METHODOLOGYMETHOD

[ Find out more ...]

FISHING EFFORT ESTIMATION

Demestre et al. CIESM 2010

● 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 : METHODOLOGYMETHOD

[ Find out more ...]

BENTHIC COMMUNITY REPRESENTATION : THE TRAITS APPROACH

de Juan, S. and Demestre, M. 2012. Ecological Indicators. 18: 183–190.

Traits used in the simulation

Position Feeding Motility Size Other attributes

Emergent Filter feeding

Sessile (attached)

Large>10 cm

Fragile

Surface Deposit feeding

Sedentary Medium5-10 cm

No protection

Surface burrowing

Predators Motile (crawlers)

Small<5cm

Flexible

Deep burrowing

Scavengers Highly motile (swimmers)

Strong

Regeneration

Vermiform

Hard shell

Legend

Very resistant*

Resistant*

Vulnerable*

Very vulnerable*

* Vulnerability regarding to trawling

BLOCK : METHODOLOGYMETHOD

[ Find out more ...]

BENTHIC COMMUNITY REPRESENTATION : THE TRAITS APPROACH

BLOCK : STUDY SITES

-Presentation of the data available in each study site.

Community structure is presented by:

● Trait structure

● Species composition

STUDY AREAS

[ Find out more ...]

STUDY SITES

BLOCK : SIMULATION[ Find out more ...]

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

BLOCK : SIMULATION

-Total abundance-Percentage of trait categories within trait type

PLOTPLOT

RESET

[ Find out more ...]

SIMULATION

SIMULATION OUTPUT : PRESENT VS DESIRED EFFORT STRUCTURE

Uncertainity of

the simulation

Actual status

Structure at desired effort

BLOCK : SIMULATION[ Find out more ...]

SIMULATION

SIMULATION OUTPUT : PRESENT VS DESIRED EFFORT STRUCTURE

Scav

engi

ng

Size

Feeding

Size

Feeding

Large

Medium

Small

Filte

rfe

edin

g

Dep

osit

feed

ing

Scav

engi

ng

Pred

ator

PRESENT STRUCTURE STRUCTURE AT DESIRED EFFORT

Large

Medium

Small

Filte

rfe

edin

g

Dep

osit

feed

ing

Pred

ator

Relationship between traits: - Possibility to show one selected trait against another trait

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