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Movement of Bigmouth Sleeper, Gobiomorus dormitor, in the Río Cañas, Puerto Rico, revealed by radio telemetry, and a discussion of the species’ amphidromous characterization

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Bigmouth Sleeper, Gobiomorus dormitor, are tropical fish native to rivers of Puerto Rico. They are popular sport fish targeted by local anglers. They are considered as diadromous, but this characterization is controversial. The displacement of Bigmouth Sleepers in the Río Cañas, Puerto Rico, was examined using radio telemetry. Twenty fish were radio-tagged and monitored from January to November 2008. Fish were in the Río Cañas 69%, 62%, and 59% of the time before (January-May), during (June-August), and after (September-November) the spawning season, respectively. Average detected linear home range (within the river) for all tracking periods was 2.3 km, but varied from less than 0.1 km to 8.1 km. Detected linear home range was not related to weight class or sex. They may remain in freshwater as juveniles and adults, only spending their larval stage in estuarine or marine habitats (i.e. amphidromous diadromy). However, they can complete their larval stage in freshwater but appear to make periodic migrations to the marine environment as adults, as suggested by this study. The best descriptor of Bigmouth Sleeper is that of a facultative amphidromous euryhaline species. Fishery and habitat management for this fish should take into consideration their general migratory behavior and their plasticity with respect to this life history strategy.

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