Recent years have seen a surge of interest in the problem of plastics pollution in the environment, and especially in the ocean. It is part of a larger trend where it has become clear that the economic linear status quo and its related activities are unsustainable. Circular Economy is presented as a possible solution to mitigate the negative externalities of economic activity. The purpose of this master thesis is to explore the concept of circular economy, as well as its potential application in a context of extended producer responsibility for fishing gear and its implementation potential and possible benefits in a fishing gear case company and supply chain. We have found that while the current circular maturity in the studied case company is basic, there is willingness to implement circular principles at the company level, but that it depends on overcoming economic and organizational barriers. There seems to be unexploited business opportunities relating to fishing gear circularity, and a lack of infrastructure or applicable technology makes capturing this potential difficult. We also found that external intervention may be necessary for implementation throughout the supply chain, or across the domestic industry. The idea of closed loops for materials is an ideal within Circular Economy thinking, but in the examined company and industry, technical and organizational barriers exist which make closed loops impossible at present.