The purpose of this research is to analyze the dialoguesand the absence of communicationbetween the regimes of the Law of the Sea and Trade in conflicts about fisheries. Part I discusses the concepts and theoretical assumptions. The debate on the fragmentation of international law and the proliferation of international Courts is reviwed as the argument over the existence of self-contained regimes. The definitions of regimes are discussed and it is explained why the Law of the Sea and Trade should be understood as regimes. Subsequently, the toolbox of principles developed by the International Law Comission to deal with normative conflicts is analyzed, as will be other approaches developed by international lawyers. Special attention will be addressed toward the cooperation between courts and the mainstreaming interaction, which is a form of cooptation. Parte II is split in two sections. In chapter 2, a study is carried out on the regimes of the Law of the Sea and Trade law, emphasizing the vocabulary and the ethos of each one, as well as the main normative instruments applicable on cases about fisheries and the structure of their dispute settlement mechanisms. In chapter 3, the theoretical insights developed in Part I will be applied to a specific research study on case law surrounding fisheries, a study that includes some parallel judicial proceedings. The methodological approach adopted to analyze the interactions between regimes is based on three levels of dialogue: the direct quotation of one tribunal to another; the interaction between cases informed by the doctrine; and the cross-application of the terms precautionary principle, sustainable development and ecosystem approach. In the end, it is concluded that the regime of the law of the sea fails to provide a vocabulary or an ethos in and of itself. In this sense, although many elements of the environmental vocabulary have been assimilated, the International Tribunal for the Law of the Sea remains attached to the orthodox legal positions held by International Court of Justice and Permanente Court of International Justice, serving the general international law audience in which the mare liberum principle and the trade ethos prevails. The Trade law regime, in turn, is very self-centered and has a strong vocabulary and an efficient Dispute Settlement Understanding. In this context, its mainly concern is to attend to the regime's internal audience. As such, arguments that seek the conservation of fish stocks are, for the most party placed in a compliant position towards free trade. It is understood that disclosing the political interests surrounding the activity of each regime is essential to promote transparent, plural and counter-hegemonic dialogues among them.