Ichthyofauna of the Lower Loukkos Estuary (Morocco): Conservation Status of Endangered Species and Assessment of Invasive Fish Threats

Estuaries are transitional ecosystems of exceptional ecological value, providing an essential habitat for a wide diversity of fish species, including numerous endangered, endemic, and migratory taxa. The lower Loukkos estuary, located on the Atlantic coast of northern Morocco, represents a biodiversity hotspot of regional significance; however, its ichthyofauna remains critically understudied, leaving conservation needs largely unaddressed. This study presents a comprehensive review and meta-analysis of the existing data on the diversity, composition, and conservation status of fish species in the lower Loukkos estuary. By systematically compiling the published literature, historical records, and biological inventories, this study aims to produce an updated checklist of ichthyological assemblages, with a particular focus on species that are classified as endangered, vulnerable, or threatened under IUCN Red List criteria and national conservation frameworks. A dedicated assessment of invasive fish species was conducted to examine their origins, pathways of introduction, ecological impacts, and implications for native fish communities and broader estuarine biodiversity. This review further evaluates the compounding effects of habitat degradation, overfishing, pollution, and climate change on both endangered native species and the proliferation of invasive taxa. Expected outcomes include an evidence-based conservation baseline, the identification of high-priority species and habitats requiring urgent protection, and science-informed recommendations for controlling invasive fish species. This work aims to support biodiversity protection policies at regional and international levels, contributing directly to the objectives of the Convention on Biological Diversity and the IUCN Species Survival Commission.