Summer Movements of the Gulf Killifish (Fundulus grandis) in a Northern Gulf of Mexico Salt Marsh

The Gulf Killifish (Fundulus grandis) is one of the most abundant nekton species in the US Gulf of Mexico (GOM) salt marshes, providing an important trophic link in these systems. Recently, the use of F. grandis as an indicator species of salt marsh health in the region has been suggested because its Atlantic coast congener, the Mummichog (Fundulus heteroclitus) has filled such a role due to its demonstrated high site fidelity and small-scale movements. Given the similar life histories between species, F. grandis was assumed to exhibit the same type of small-scale movements, although this has not been documented. During summer 2013, we collected and marked 1,719 fish from a northern Gulf of Mexico estuary, recapturing 959 (56 % recapture rate). Of these recaptured fish, only 31 moved from their original tagging location, and of these, 29 moved only 100 m between sites connected by salt marsh. Based on these results, F. grandis appears to exhibit high site fidelity and make only small-scale movements, similar to F. heteroclitus, supporting its role as an indicator species.