Spatio-temporal changes of Mycteroperca spp in the Gulf of California, Mexico

The Gulf of California (GC) is the most important fishing area in Mexico and small-scale reef fisheries play an important socio-economic role for the region. The genus Mycteroperca (Epinephelidae) includes four large-sized species which represent a major component of reef fisheries in the GC: M. jordani, M. rosacea, M. prionura and M. xenarcha. Assessing the spatio-temporal pattern of their distribution is a fundamental step to adopt efficient conservation policies. Some of these species are known to have declined in the last decades (e.g. M.jordani endangered status in the IUCN Red list), while data are insufficient to evaluate the status of others (M.xenarcha and M.prionura). Mycteroperca rosacea is the most caught species in the region, and although it is the most studied, large spatial and temporal studies of its distribution are still lacking. Here, we studied the spatio-temporal changes in Mycteroperca spp biomass in the GC thanks to data gathered over the period 2010-2022 by diverse monitoring programs in the GC and along 8 degrees of latitude, encompassing 151 reefs. We observed a latitudinal gradient in Mycteroperca spp biomass, with the Midriff Islands and San Pedro Martir Island (center-north of the GC) as a hotspot of M.rosacea biomass. No clear temporal changes of M.rosacea biomass were detected over the studied period. The endangered species M.jordani is also observed in the center-north of the GC, while almost absent in the southern GC except in the marine park of Cabo Pulmo. M.prionura is rarely observed and is undetected in the southern GC for a decade, while M.xenarcha is almost absent in all data collected. These data reveal biomass hotspots for commercially important species, highlight concerns about trends in endangered species and confirm the rarity of certain species. This suggests therefore that specific studies on these species are needed to assess their status.