Fishery resources are in principle renewable, but modern fisheries are typically characterised by excessive fishing effort, fleet overcapacity, illegal, unregulated and unreported (IUU) fishing along with deficient governance. This has led to growing trends of unsustainability. Fisheries management is a social and political process which aims to regulate human activities within the constraints of the biological ecosystem in which it operates. But the incorporation of sustainability into fishery practices around the world has to date generally failed. In this thesis I explore the relationship between science and politics in several different spheres of marine resource management.
Analysis of the extent to which European politicians have adhered to scientific recommendations on annual total allowable catches (TACs) from 1987 to 2011 for 11 stocks revealed that in 68% of decisions TACs were set higher than recommendations. Politically-adjusted TACs averaged 33-37% above scientifically advised levels. A simple stochastic model indicated that such politically-driven decision-making dramatically reduces stock sustainability. With 88% of European fish stocks overexploited relative to maximum sustainable yield targets, I conclude that political mismanagement must bear a considerable share of the responsibility for this decline.
Whilst the practice of political adjustment of scientific advice reveals the negative political impact on management and its failure to integrate science into management, the establishment of marine protected areas (MPAs) shows the relationship between science and politics in a more positive light. MPAs are increasingly being established to protect and rebuild coastal and marine ecosystems. However, the process of establishing these areas is not simple, particularly in areas beyond national jurisdiction (ABNJ) where few MPAs currently exist. Nevertheless, in 2010 the OSPAR Commission successfully established six MPAs forming the world's first network of MPAs in ABNJ. I summarise how this network was created, identify the main challenges, and offer a series of key lessons learned, highlighting approaches that may also be effective for similar efforts in the future. This success story was driven by strong political commitment and based on the best available science, and serves as an example of the positive integration of science into management by politicians.
The difficult relationship between science and politics is illustrated clearly by the story of the Atlantic bluefin tuna (Thunnus thynnus). This species has become the quintessential example of overfishing and general mismanagement of the world’s fisheries. An age-structured spatial model of the two stocks of Atlantic bluefin tuna highlighted the importance of taking area and stock movement into consideration when determining total allowable catches for the Atlantic bluefin tuna fisheries. The western bluefin stock was found to be more sensitive to assumptions of stock movement and mixing than the eastern populations, corroborating previous research. My results also indicated that to maximise the total catches of bluefin in perpetuity, it may be better to cease fishing in the western Atlantic and to only target individuals in the eastern Atlantic. The estimated timeframes for recovery are found to be medium to long term if fishing were halted today (within 20 years for both stocks to attain their BMSY) and it is estimated that a 34% reduction in fishing mortality on both stocks is the minimum required decrease to ensure recovery. The aim of this model is to further research on the integration of science into a political management system in order to create a sustainable fishery.
In this thesis I identify several important requirements for sustainable fisheries management, namely: the need for a sound scientific basis, stakeholder engagement and cooperation, and strong political commitment and willingness.
