Presentation on theme: "Indicators for ecosystem based management: Methods and applications Verena Trenkel, Anik BrindAmour, Pascal Lorance, Stéphanie Mahevas, Marie-Joëlle Rochet."— Presentation transcript:
Indicators for ecosystem based management: Methods and applications Verena Trenkel, Anik BrindAmour, Pascal Lorance, Stéphanie Mahevas, Marie-Joëlle Rochet Ecology and Models for Fisheries Science Ifremer, Nantes, France
Definition An indicator is a variable which quantifies how well a human activity is managed, in relation to specified objectives. A structured suite of indicators will reveal important system changes.
Reduce quota Fishing mortality Demand for food & wealth Less fish Fish biomass Ecosystem based fisheries management
Example: Developing food web indicators Has the food web structure changed in the Mediterranean? Morphometrics = diet & habitat Food web Position in water column 1 Species type 7 Functional groups
Temporal changes in food webs Golf of Lions Ionian Sea Aegean Sea Example: Developing food web indicators
10 Ecological objective: Maintain pelagic food supply for higher trophic levels Knowledge Few top predators & piscivores have strong pelagic prey dependance Operational objectives Maintain herring and sprat in the Baltic Sea as prey for cod Maintain total forage fish biomass in North Sea State & impact indicators Prey biomass in critical area Proxy: predator condition/growth/productivity Reference level >x tons of prey species Pressure management TAC, effort control, escapement rules Example: Selecting indicators for pelagic ecosystems
Is occupancy a sensitive indicator for population abundance? In certain cases only: occupancy can change much less than abundance uncertainty in catches or effort can mask changes Example: Simulation testing population indicators Demographic rates Depth r, K Demographic rates 1 Spatial population dynamics 2 Spatiotemporal catch & effort distribution Spatiotemporal abundance distribution Observations 4 Time Occupancy 5 Indicator calculation Fishery dynamics Effort 3 Density Trenkel et al In Press, Testing CPUE-derived spatial occupancy as an indicator for stock abundance: application to deep-sea stocks. Aquatic Living Resources DOI: 10.1051/alr/2013060
Which management indicators are sensitive and robust to uncertainty? Example: Simulation testing management indicators Model Management scenarios + Uncertainties Indicators SENSITIVE to management? ROBUST to uncertainty?
Which management indicators are sensitive and robust to uncertainty? Example: Simulation testing management indicators Huret et al. 2010. Spatialized recruitment and natural mortality ECOMARS IBM Larvaire Mahévas et al. 2011 Vermard et al 2008 Spatial and seasonal distribution of populations Pelletier et al 2009 Assessing indicator performance for management Spatial and seasonal distribution of fleets and economic behavior Spatial modelling of fisheries dynamics Lehuta et al 2010. IJMS & 2012. FR Lehuta et al 2013.
Do fishing pressure differences affect differentially fish community states? Example: Developing fishing pressure indicators InputFishing intensityFishing selectivity Fishing mortality Average F across species SD(F) across species or size- classes Catch Total catch per unit areaCV(catch) across species; No species => 85%; % piscivores
Do fishing pressure differences affect differentially fish community states? Example: Developing fishing pressure indicators Fishing pressure varies in space & time, but differential impacts are difficult to detect High & selective removals Diverse catch Piscivores preferred
For more information on our work on indicators Come and see me Read our publications http://wwz.ifremer.fr/emh/Publications-EMH