Payments for environmental services (PES) constitute a growing approach to achieve the sustainability of ecosystems and the benefits they provide to people. However, informal tenure and lack of capacity to enforce property rights impede implementation of PES initiatives. Such challenges are common for local communities in coastal and marine areas who overexploit Common-Pool Resources (CPR) under open access. Assigning property rights to organized users has been implemented as a solution, transforming a public good into a club good. Nevertheless, the nature of CPR makes it difficult to define and enforce use rights based on territorial criteria, which might generate equity concerns between organized users and their peers who lose rights. This paper investigates, using a choice experiment, the willingness of Ecuadorian mangrove resource users to accept a conservation policy that combines a concession for sustainable extraction and an economic incentive. Given that a collective concession for the sustainable use and management of CPR implies exclusion of other communities, we specifically analyze two different access levels: i. total exclusion, where the agreement defines that no one other than the concessionaires can access and extract the resources, and ii. discretionary exclusion, where the concessionaires can establish their own rules and conditions for allowing access and use of the resources by third parties. Our interest is to identify how externally imposed rules around exclusion prevent or motivate organized users from participating in approaches to CPR management based on allocation of property rights. We find that having the discretion to choose the level of exclusion matters to resource users when deciding whether to accept the proposed mangrove management strategy.