Importance of a large, free-flowing river for snook in the southern Gulf of Mexico

ABSTRACT Objective Populations of snook Centropomus spp. often include catadromous contingents that move inland into river habitats to forage, with some moving long distances upstream and some remaining in freshwater habitats for multiple years. Expansive connectivity from estuaries, up into rivers, and laterally onto floodplains may enhance population growth and productivity by providing snook access to freshwater feeding habitats. Little is known about their ecology in freshwater habitats, however, particularly below the northern edge of their range, where snook have been most extensively studied. Our objective was to present what is known about river habitat use by snook in the Usumacinta River in southern Mexico. Methods We review available information on river habitat use by snook species in the Usumacinta River, one of the largest remaining free-flowing Neotropical rivers, where riverine prey resources are plentiful and snook are highly valued culturally and economically. We interpret the importance of intact river corridors for snook in the context of the extensive research from systems in Florida and available studies from other regions, highlighting unique conservation issues affecting snook that enter tropical rivers. Results Snook frequently move >300 km inland in the Usumacinta River, which provides an exceptionally large migratory domain due to the lack of main-stem dams. For catadromous snook in this system, accessing habitats such as highly productive floodplains with periodically inundated lagoons offers feeding opportunities that likely fuel growth. Our literature review showed that most studies of river habitat use by snook have focused on Common Snook C. undecimalis and have been carried out in the United States ≤50 km from the coast. Conclusions In general, more research is needed on movement, resource use, and growth of snook in the Usumacinta River and in other rivers in the Neotropics, a region with relatively few studies, despite making up a large part of their latitudinal distribution.