According to article 87.1, “e” of UNCLOS, the High Seas is a maritime space in which States have freedom to fish. Because of that, unlike waters under national jurisdiction, in the High Seas ships have the right to carry out the activity of fishing without this being considered an invasion of other people's resources, so that, as Yoshifumi Tanaka teaches (2019, p. 188), “this is a corollary of the fact that the high seas are free from the national jurisdiction of any State” and, based on David J. Bederman (2013), true res communis (considering that no State may legitimately claim to subject any part of the High Seas to its sovereignty, according to article 89 of UNCLOS).

However, the aforementioned article is clear in stating that this freedom must be exercised in accordance with the conditions set out in article 87.2, which expressly provides that “such freedoms [such as fishing] must be exercised by all States, with due regard to the interests of other States in their exercise of freedom of the High Seas”. In this sense, it is clear that, although fishing activity is free in the High Seas region, it must be carried out in a way that does not harm the interests of other States.

It is important to explain that, according to Kuan-Hsiung Wang (2014, p. 431), Illegal, Unreported and Unregulated (IUU) fishing, which also occurs in the High Seas, has caused so much damage in recent years that an option developed by the international community was the creation of regional fishing organizations, in order to protect the sustainability of marine resources, since “combating IUU fishing has become an urgent issue in managing living resources on the High Seas”.

For Wang (2014, p. 435), these regional organizations, called Regional Fisheries Management Organizations (RFMOs), do not, a priori, have the objective of combating illegal fishing, but rather of promoting the cooperation of member States aiming at the sustainability of fishing activity, in the case of an interstate mechanism that seeks the conservation, administration and sustainable development of fisheries. It should be noted that two ideas within the aforementioned objective of RFMOs are relevant to the present study – cooperation and sustainability.

It is important to highlight that sustainability, although it is a general principle whose legal status is difficult to define (BIRNIE; BOYLE; REDGWELL, 2009, p. 115-116), is internationally accepted as being one that simultaneously promotes economic development and the protection of natural resources, in order to protect both the current and future generations, in accordance with Principle 3 of the Rio Declaration on Environment and Development, of 1992. Due to this, rampant fishing in the High Seas, under the justification that there is absolute freedom of fishing in this maritime space, is a practice contrary to the general principle of sustainability, so that the role of RFMOs is directly related to combating illegal fishing, even if it is not their primary objective.

Furthermore, the promotion of cooperation between States, as well as between States and non-governmental organizations, is aligned with the recommendations of article 118 of UNCLOS, which expressly states that “States must cooperate with each other in the conservation and management of living resources in areas of the High Seas”, in addition to the fact that, if there are zones with shared resources, “they must cooperate, when appropriate, to establish sub-regional or regional fishing organizations for this purpose”. Regarding this, Wang (2014, p. 435) explains that RFMOs work through the adoption of conservatory measures that bind their members, as well as acting in a not only decision-making manner, but also in an advisory manner, in order to coordinate the States parties towards to a fishing activity that is sustainable, which demonstrates its concern with the cooperative stance of the States.

Both sustainability and cooperation, objectives of RFMOs, are directly linked to article 87.2, given that the legal text is expressly stating that fishing freedom is limited to the interests of other States. Since illegal fishing, in conditions that could put present and future generations at risk, violates sustainable development and, therefore, harms the interests of all States involved, there must be cooperation in the international community so that this situation can be resolved, avoided and combated, an attitude that can be found in the actions of RFMOs.

However, the interference of RFMOs in the actions of flag vessels that are not part of the aforementioned organizations comes up against one of the main provisions of UNCLOS – the jurisdiction of the flag State, based on article 94. As seen, on the High Seas there is freedom of fishing, and the sovereignty of no State can be imposed on this maritime space, as well as jurisdiction over the ship's acts belongs to the flag State. If the ship flies the flag of a State that is part of the RFMO, with regard to the terms it accepted, the regional organization has jurisdiction to take the measures it deems appropriate; a situation that becomes controversial if the ship is not part of RFMO, a possibility brought about by the 1995 Agreement on the Conservation and Management of Straddling Fish Stocks and Highly Migratory Fish Stocks.

Regarding this, Maria Gavouneli (2007, p. 109-111) teaches that, unlike the exclusive jurisdiction of the flag State brought by UNCLOS, the aforementioned 1995 Agreement provides that States parties to regional organizations can board and inspect ships in High Sea suspected of practicing IUU fishing, who are signatories to the Agreement, but not necessarily members of RFMOs, in order to allow States not participating in the regional organization to be inspected by it. The aforementioned author understands that the 1995 Agreement is more aimed at the primacy of action of the RFMOs than at the jurisdiction of the flag State (GAVOUNELI, 2009, p. 112-113), being a system that prioritizes the interstate cooperation envisaged in articles 117 and 118 of UNCLOS, which is why it allows interference by regional organizations in non-member States.

Despite being intricate, this situation has not yet been taken to any international court to be resolved, so the reflections remain at a doctrinal level, not jurisprudential. It is important to emphasize, as already mentioned, that overfishing has become a serious problem faced by the fishing community, harming developing countries, which depend on the aforementioned economic activity, and developed countries, whose economy is also strongly related to this industry. This situation is precisely what Article 87.2 of UNCLOS predicted – an unlimited freedom that would put the interests of other States at risk.

Not enough, UNCLOS itself also brings the solution, which is shown in the mechanism of interstate cooperation provided for in article 118, making it necessary for States to promote the management of resources for the benefit of all interested parties, taking the necessary measures for conservation and development sustainable fishing cooperatively (BIRNIE; BOYLE; REDGWELL, 2009, p. 710). In this sense, although not perfect, the action of RFMOs is an international resource that can, through joint and coordinated action by interested States, promote sustainable fishing. In theory, despite violating the exclusive jurisdiction of the flag State and freedom on the High Seas, the possibility of boarding and inspecting even vessels from States that are not part of the organization enables more efficient control of IUU fishing, allowing the principles of UNCLOS to be fulfilled.

Furthermore, Gavouneli (2009, p. 111) highlights that, even though it can inspect vessels that are not members of RFMO, the organization does not have jurisdiction to prosecute the ship, and must inform the flag State of what happened, so that it can conduct the process. The aforementioned author also teaches that, even if the flag State does not take the appropriate procedural measures, the State that has inspected the ship cannot prosecute it and can, at most, send it to the nearest port, pending the flag State exercises its jurisdiction (GAVOUNELI, 2009, p. 112), in accordance with UNCLOS. Because of this, the 1995 Agreement aims to make the fight against overfishing more effective, without ignoring the provisions of UNCLOS.

When talking about regional fishing organizations, André de Paiva Toledo and Marcos Edmar da Silva (2020, p. 36-37) express that, aiming to control the consequences of excessive actions at sea, they suggest, in International Law, attempts at “programmed structuring between States, through coordinated plans for rapprochement for the purposes of mutual association", and "institutes of integration, cooperation and solidarity are examples of these initiatives", citing the Central American Fisheries and Aquaculture Organization - OSPESCA as being "one of the organizations with transnational dialogue that seek, through coordinated actions, to advance inclusive policies of cooperation, integration and international solidarity”.

In view of the above, it is understood that the operation of RFMOs on flag ships whose State is not part of the regional organization is not in disagreement with UNCLOS. It is evident that UNCLOS itself establishes the interests of States as being a clear limit to fishing freedom in the High Seas, and determines that they must act with cooperation, in order to protect the objectives of all, prescriptions related to the sustainability sought by RFMOs. Furthermore, according to Gavouneli, the 1995 Agreement does not contravene UNCLOS, and leaves it up to the flag State to exercise its jurisdiction over the inspected vessel at a procedural level, so that, although not perfect, regional fishing organizations allow for more efficient control of the IUU fishing.