Connectivity and movements of juvenile predatory fishes between discrete restored estuaries in southern California

Establishing connectivity via fish movements among restored estuaries is important for maintaining community structure, but data on the degree to which animals efficiently move among estuaries are limited. To test estuarine connectivity potential, we translocated 5 species of juvenile predatory fishes between 2 discrete estuaries approximately 10 km apart, and using passive acoustic telemetry, measured their ability to home back to their estuary of capture. Individuals from all species except Paralabrax maculatofasciatus (spotted sand bass) moved between the sites after translocation. Feeding guild and associated foraging behavior were found to greatly influence a species’ connectivity potential, with estuarine resident ambush predators moving between sites less frequently compared to roving forager marine migrant predators. Time spent moving between sites was not significantly different among species, and 67% of homing fish completed the transit in <3 d. Fish showed no preference for one site over the other and returned to each site equally. Stable isotope analysis revealed that the availability of food (as indicated by diets) in each restored estuary could have affected Mustelus californicus (gray smoothhound) habitat use. Roving forager juvenile predatory fishes displayed high connectivity over a large scale, which suggests that newly restored estuaries should attract these species quickly. However, long-term use may depend on environmental conditions and succession of the prey community.