Ecosystem-Based Management of What? An Emerging Approach for Balancing Conflicting Objectives in Marine Resource Management

Abstract

Managing marine resources has always been challenging, but this tasklooms ever larger as society demands more seafood while also requiringthat we act as careful stewards of marine ecosystems. Evaluating,management strategies in light of the diverse and changing demands ofsociety for the goods and services the oceans provide requires that weclearly expose trade-offs among conflicting objectives In this paper, wedescribe an approach using all Atlantis ecosystem model to evaluatemanagement strategies and potential trade-oft's between economic andconservation goals in the California Current ecosystem. We Simulate arange of fishing intensities, and evaluate potential trade-offs betweenharvest maximization and the Structure of the food web. Our resultsreveal that fishing combined with life history traits will alter thecomposition of the community Such that short-lived, productive speciesreplace longer-lived, lower productivity species. From an economicperspective, sustainably fishing productive high value species(Dungeness crab, hake, and squid) while overfishing less valuable, lowproductivity species (some rockfish) may seem like it wise choice;however, from a conservation perspective Such a strategy would becompletely unacceptable. We use the ecosystem model to visualize thesetrade-offs between economic and conservation concerns. We Measureconservation and ecosystem structure by evaluating a suite of ecosystemindicators, such as ratios of the abundance of functional groups, andmean trophic level. The ratios of piscivore to planktivore, benthic topelagic fish, and scavenger to piscivore all showed Substantial shiftsill community structure as levels of harvest increased. The mean trophiclevel of biological groups in the model was not sensitive to fishingintensity, and did not capture the associated shifts in the Structure ofthe food web. Overall, we illustrate a simulation approach that canexamine trade-offs between harvest and community-level indices ofecosystem Structure. All ecosystem approach to management requires thatwe synthesize diverse physical, biological, and socioeconomic data andthink critically about the ways in which our decisions affect theecosystem services we value.The whole trend of research and education is toward specialization onparticular objects or particular organisms. These are stressed while theassemblage to which they belong is ignored or forgotten, together withthe fact that they are to be regarded as integral parts of the system ofnature. Shelford (1933)