The BoB simulations allow comparison of the trade-offs associated with different allocations of this decrease across fleets. Despite very different management contexts and objectives, viable management strategies suggest a reduction in the number of vessels in both cases.
Results suggest that under a status quo strategy both fisheries can be considered as biologically sustainable, while socio-economically (and ecologically in the NPF case) at risk. The bioeconomic models are used to investigate how the fisheries can operate within a set of constraints relating to the preservation of Spawning Stock Biomasses (BoB) or Spawning Stock Size Indices (NPF) of a set of key target species, maintenance of the economic profitability of various fleets (BoB) or the fishery as a whole (NPF), and limitation of fishing impacts on the broader biodiversity (NPF), under a range of alternative scenarios and management strategies. Economic uncertainties relating to input and output prices are also considered. A dynamic bio-economic modelling approach is used to capture the key biological and economic processes governing these fisheries, combining age- (BoB) or size- (NPF) structured models of multiple species with recruitment uncertainty, and multiple fleets (BoB) or fishing strategies (NPF). Their sustainability is therefore a major societal concern. Both fisheries entail direct and indirect impacts on mixed species communities while also generating large economic returns. This thesis proposes an application of this co-viability approach to the sustainable management of mixed fisheries, using two contrasting case studies: the French Bay of Biscay (BoB) demersal mixed fishery and the Australian Northern Prawn Fishery (NPF). The stochastic co-viability approach addresses the trade-offs associated with balancing ecological, economic and social objectives throughout time, and takes into account the complexity and uncertainty of the dynamic interactions which characterize exploited ecosystems and biodiversity.
#GEEK UNINSTALLER PRO 3.5.3 KEY DRIVERS#
These tools need to integrate (i) ecological and socio-economic drivers of changes in fisheries and ecosystems (ii) complex dynamics (iii) deal with various sources of uncertainty and (iv) incorporate multiple, rather than single objectives. Decision-support tools are increasingly required to operationalize the ecosystem-based approach to fisheries management. Empirical evidence and the theoretical literature both point to stock sustainability and the protection of marine biodiversity as important fisheries management issues.