The Port-Cros National Park (PCNP) was established in 1963. It encompassed the Island of Port-Cros and the neighbouring island and islets (the Port-Cros Archipelago). Progressively, the PCNP has been entrusted with the management of an increasing number of territories outside the initial territory of 1963. Between 2012 and 2016, the PCNP was engaged in a major redefinition and extension of its territory; the new Port-Cros National Park (N-PCNP), established in 2016, includes the Port-Cros and Porquerolles Archipelagos as core areas (both terrestrial and marine), a vast Adjacent Marine Area (AMA) including the Gulf of Hyères and extending seawards to the edge of the continental shelf, and a discontinuous continental area (Adhesion Area, AA) including five municipalities. The management of the marine area of the Port-Cros Archipelago MPA (Marine Protected Area) can clearly be referred to the MUM type (Multi-Use Management) characterized by a complex zoning of the marine part of the MPA, based upon the uses, the goals of conservation of the habitats and the ecosystems and priorities clearly displayed (artisanal fishing rather than recreational fishing). MUM management strongly contrasts with NTZ (No-Take Zone) management, where any form of human activity is prohibited. In addition to the ban on spear fishing, angling and trawling, the Port-Cros Archipelago MPA has its own artisanal fishing regulations, enshrined in a fishing charter; those regarding maximum vessel length, soak time, mesh size, net length, number of hooks and traps, are more restrictive than outside the MPA; these regulations are strictly enforced, in contrast with a number of Mediterranean MPAs which are actually 'paper parks'. It is worth noting that, as far as the conservation of the natural heritage is concerned, MUM management, as practiced in the Port-Cros Archipelago MPA, is at least as efficient as NTZ management. In addition, it is compatible with sustainable fisheries in particular, sustainable development in general, and fits well with the concept of the socio-ecosystem. We have seized the opportunity of having at our disposal one of the oldest Mediterranean MPAs, with exemplary protection and an exceptional level of scientific knowledge, to assess the species diversity (point diversity and alpha diversity), the biomass and the trophic structure of fish (teleosts) assemblages in 5 habitats,-shallow rocky reefs (RS, 0-3 m depth), deep rocky reefs (RD, 5-15 m), relatively shallow Posidonia oceanica seagrass meadows (PS, 10