The Dutch mussel fishery is currently involved in a transition towards sustainable 26 practices in the Wadden Sea, a World Natural Heritage Site. During the transition period the 27 traditional but controversial method of dredging mussel seed from natural beds using trawl 28 nets will be replaced, step-by-step, by alternative methods. The main objective of the 29 transition is to allow the natural development of mussel beds ecosystems, and to 30 simultaneously achieve large scale sustainable mussel fishery. The transition is a joint 31 enterprise of state officials, environmental organizations, and the mussel sector, and requires 32 striking a balance between the different interests and identities. As such, it may be considered 33 as an example of social learning. This article explores the multiple efforts and controversies 34 that populate the transition towards a sustainable Dutch mussel culture by making use of 35 concepts such as, identities, communities and practices. What is innovative in the character of 36 this transition endeavor, the article concludes, is that new practices have brought together two 37 in principle contradictory identities in order to negotiate natural and social limits that might 38 facilitate a sustainable future in the Wadden Sea.39 40

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Sheep farmers in the Cape Midlands region of South Africa frequently sustain stock losses through predation by caracal lynx. Further losses are incurred when hyrax compete with sheep for available pasture. Hyrax constitute the natural prey for lynx with the result that culling either hyrax or lynx has complicated feedback effects. In order to investigate the spill-over problems from the natural predator-prey system on farming revenue, a differential equations model was previously formulated, comprising the sectors Hyrax, Lynx, Sheep, Pasture and Revenue and an optimization procedure was used to determine the optimal culling rate policy for farmers. The purpose of this paper is to investigate the numerical, behavioural and policy sensitivity of this model to parameter uncertainty.