Habitat distribution, size and quality are recognized as important drivers of fish productivity and fisheries yields. The Sustainable Fisheries Act recognizes the importance of habitats, and emphasizes on the importance of habitats related to critical life stages, such as nursery habitats. However, there is a lack of evidence that directly relates nursery habitats to the economic benefits derived from fisheries. This limits our ability to implement policies that protect habitats that maximize fisheries benefits. We collected underwater biomass and annual total landings data from two of the most important artisanal fisheries in the Gulf of California (yellow snapper (Lutjanus argentiventris) and leopard grouper (Mycteroperca rosacea)) and on the size and distribution of their nursery habitats (mangroves and sargassum beds). To explore the relationships between habitat and biomass/fisheries yields, we generated spatial layers for all our datasets on a grid of 407 cells across the coastal area (depth < 200 m) of the Gulf of California, separated into ecologically distinct geographic regions.
Nonlinear regressions showed that there was a significant logarithmic relationship between nursery habitat size, underwater biomass and total landings for both species. In the case of the yellow snapper we found that the influence of mangroves as nursery habitats was related to the total fringe area. For leopard grouper, we found that the influence of the sargassum beds as nursery habitats could be explained by the total sargassum biomass. By using null models to randomize the distribution of nursery habitats, we tested that for both species, the current specific distribution of habitats significantly explains the current spatial patterns of both, underwater biomass and total annual landings. For the first time, our results show evidence of the influence of both, size and location of nursery habitats, to enhance underwater fish biomass and total fisheries landings. These results may be used to promote the protection of habitats as a tool to enhance fisheries productivity.