Abstract Berger, Morten M. (2015). "Don't get sick at sea": An Ecological Study of the Fishermen of Pulau Tuba, Langkawi, Malaysia. Master's thesis in Social Anthropology. Department of Anthropology, University of Oslo. This study is a project based on a fieldwork of 6-months duration at the island of Pulau Tuba in the Langkawi archipelago outside the north-western coast of Malaysia. I've been using anthropological research methods like participant observation and informal interviews for data-collection. My approach to establish my field was the following: Firstly to investigate prior literature from the region or discussing similar themes as what I wanted to investigate further. Secondly to establish the following research theme, namely how Pulau Tuba can be seen as an ecosystem on a smaller scale within which the inhabitants are conducting multiple activities and how the products from such activities are flowing out of the Tuban ecosystem through the interaction between people, as well as how external influence impinge on the lives of the inhabitants. Using the methods above and going along people during their activities, resulted in a bulk of raw data, carefully registered in several notebooks. After reading these notes I started looking for theories useful for analyzing my data. I elected to use an ecological approach in combination with the idea of a generative model from Barth's "Models of Social organization" in order to produce my own conception of how the flow of the Tuban ecosystem could be charted. However I also investigated structures and systems existing at Pulau Tuba. Through multiple observations of people involved in religion, kinship and politics I determined that these should be viewed as important parts of social organization at the island and which should be presented in detail. Prior regional literature was also important for enabling comparison and showing how some things have changed in the field. It is important to note that my main focus has been on activities within the primary sector of the economy like fishing, agriculture and animal husbandry as well as less practiced activities like hunting and gathering. I've been closely investigating the inhabitant's ecological adaption to particular niches within different habitats in their ecosystem. The Tubans are however also engaged in service activities within the tertiary sector like tourism and hospitality, transport and recently waste management. It could actually be argued that the inhabitants of Pulau engaged within the primary sector also are active in the tertiary sector, as they sell some of the goods they have produced themselves directly to fellow villagers, which can be viewed as consumers. The majority of the produce is however sold to middlemen and is something that I investigate through making a generative model. Significant components of this model includes possibilities and limitations within ecological conditions and social relations, which together with cultural values and existing assets influence an individual's choice of whether to engage in activity or not. In order for a transaction to take place there must also be an agreement on the definition of a transactional situation and a shared system of evaluation must be proposed. Through a successful interaction between two parties, activity patterns and social patterns become evident which subsequently influences what was termed significant components through positive and negative feedback loops.