Livelihoods-based approaches are increasingly used within conservation projects in developing countries to help reduce the exploitation of species for food or income. The objective of these livelihood interventions is often to provide a more attractive substitute for that exploitation. However, the evidence for whether they do manage to achieve conservation goals is scarce, and where present, mixed. In this thesis I examine the case study of seaweed farming and fishing on Danajon Bank, central Philippines. I show that seaweed farming and declining fish catches are associated with reductions in fisher numbers in some villages, but not others. The form of income and risk profile associated with an alternative occupation such as seaweed farming can be more important than its profitability in determining its potential to substitute for fishing. The level of engagement in different occupations with different risk profiles correlates with a range of socioeconomic variables, particularly the level of existing experience in an occupation. Household livelihood portfolios vary between those self-defining as primarily fishers or seaweed farmers, as well as with wealth. Finally, seaweed farming is only associated with lower fishing income when it is perceived to be the most important occupation in the livelihood portfolio. This case study demonstrates the challenges to livelihoods-based approaches, indicating that while they may contribute to increased resilience of households faced with declining fish catches, the conservation benefits are more elusive. The results indicate that greater effort should be put into reducing the risks associated with alternative occupations, and careful consideration should be given to the frequency and timing of income obtained. They also indicate that, because of the potential for perverse incentives and the offsetting effects of increasing human populations, livelihoods-based approaches should be closely linked to direct forms of resource management, such as effort or spatial restrictions, and population, health and environment (PHE) programmes.