Average Mutual Information and fisheries impacts Manuel Zetina Rejón
Simulation scenarios Campeche sound –Shrimp –Demersal –Pelagic –Beach seine –Octopus Terminos Lagoon –Finfish –Oyster –Blue crab All fisheries
Impact evaluation Time Relative Biomass 0 10% -10% Biomass MC TR Resilience= (R) Persistence (P) Recovery time (TR) Magnitude of change (MC) Disturbance Δ F’s
Effects of fisheries All Shrimp Demersal Pelagic Beach seine Octopus Finfish Axis 1 (49 %) Axis 2 (20 %) Persistence All Shrimp Demersal Pelagic Beach seine Octopus Finfish Axis 1 (72 %) Axis 2 (9 %) Magnitude of Change All Shrimp Demersal Pelagic Beach seine Octopus Finfish Axis 1 (70 %) Axis 2 (10 %) Recovery time All Shrimp Demersal Pelagic Beach seine Octopus Finfish Axis 1 (57 %) Axi 2 (16 %) Resilience
Resilience indicator: Area of change ( AC ) Low Impacts = Low AC High Impacts = High AC
Area of Change Years of Simulation Shrimp SC Relative Biomass Demersal SC Pelagic SC Beach seine SC Finfish LT Octopus SC Oyster LT Blue crab LT All AC=102.8 AC=43.3 AC=201.3 AC=22.8AC=37.0AC=77.9 AC=0 AC=258.4
All Pelagic Finfish Shrimp Demersal Octopus Beach seine R 2 = AC MAGNITUDE OF CHANGE All Pelagic Finfish Shrimp Demersal Octopus Beach seine R 2 = RECOVERY TIME
Information Theory (Ulanowicz, 1986) Average Mutual Information ( I ) measures the probability that a unit of energy flows to certain destination. When uncertainty of the destination is high, I is bigger, quantifies degree of articulation in network/models. Measure of organization, higher in mature and complex systems. The I is higher while more complex trophic links. I = Lower I = Higher
Hypothesis When a fishery catch or remove biomass of group of species with simple trophic links, the impact of this fishery could be more severe, making ecosystem's stability and resilience vulnerable when high biomasses are extracted from the system
Average Mutual Information ( I F )
AC vs. I F Oyster Blue crab Beach seine Octopus Demersal Shrimp Finfish Pelagic All R 2 = I F log AC
Realistic Model Simulation scenarios (changes in fishing intensity) Evaluation of Impacts Model Validation Research strategy Time series Observed data