Capturing Ecosystem Services, Stakeholders' Preferences and Trade-Offs in Coastal Aquaculture Decisions : A Bayesian Belief Network Application

Aquaculture activities are embedded in complex social-ecological systems. However, aquaculture development decisions have tended to be driven by revenue generation, failing to account for interactions with the environment and the full value of the benefits derived from services provided by local ecosystems. Trade-offs resulting from changes in ecosystem services provision and associated impacts on livelihoods are also often overlooked. This paper proposes an innovative application of Bayesian belief networks - influence diagrams - as a decision support system for mediating trade-offs arising from the development of shrimp aquaculture in Thailand. Senior experts were consulted (n = 12) and primary farm data on the economics of shrimp farming (n = 20) were collected alongside secondary information on ecosystem services, in order to construct and populate the network. Trade-offs were quantitatively assessed through the generation of a probabilistic impact matrix. This matrix captures nonlinearity and uncertainty and describes the relative performance and impacts of shrimp farming management scenarios on local livelihoods. It also incorporates export revenues and provision and value of ecosystem services such as coastal protection and biodiversity. This research shows that Bayesian belief modeling can support complex decision-making on pathways for sustainable coastal aquaculture development and thus contributes to the debate on the role of aquaculture in social-ecological resilience and economic development

North American Journal of Fisheries Management 23 1 297 306 Bethesda, USA: American Fisheries Society.

Conserving genetic diversity within and among populations of northern pike Esox lucius is important for maintaining their short-term fitness and long-term evolutionary potential. Northern pike have consistently shown low within-population variation, as detected by allozymes, mitochondrial DNA, and randomly amplified polymorphic DNA. Microsatellite DNA loci reveal considerably greater variation in northern pike, yet microsatellite variation tends to be less than that in other fish species. Low genetic variation within populations may result from compounding factors of low effective population size and bottlenecks. Allozyme, randomly amplified polymorphic DNA, and microsatellite markers have revealed significant differentiation of populations located in different continents and major drainages, but only microsatellites have differentiated populations on finer geographic scales. Within the north-central United States, analyses with microsatellites have detected genetic differences among most populations but have inconsistently detected structure, or genetic relationships, among populations. Microsatellites did reveal fine-scale structure between freshwater and brackish-water populations in Finland, showing that population structure does develop in this species. The lack of structure in the north-central United States may be the result of repopulation from a common glacial refugium, but stock transfers also may have played a role in obscuring past structure. Allozyme studies indicated that western North American populations might have recolonized from a second glacial refugium. Northern pike biologists should consider how management actions affect within- and among-population variation. Stock transfers are the most common means by which genetically differentiated populations are mixed. Genetic data support avoiding transfers of northern pike across continents and between populations in western and central North America. Management actions such as harvest and habitat manipulations can also reduce genetic variation within populations by altering demographic factors that determine effective population size.

Risk Assessment of Transgenic Fish: Synthesis and Conclusions

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