Site Fidelity and Reproductive Timing At a Spotted Seatrout Spawning Aggregation Site: Individual Versus Population Scale Behavior

We evaluated spotted seatrout spawning site fidelity and reproductive timing at both the population and individual level at a resident spawning aggregation site.  Because males make sounds associated with courtship, we were able to use aggregation sound as an indicator of population spawning activity, monitoring sound at this site with passive acoustics.  To assess individuals, we acoustically tagged and released 32 fish and monitored the spatio-temporal patterns of their movements with a receiver array.  Both aggregation sound and detections of tagged fish indicated a truncated spawning season in 2005, apparently due to a persistent red tide event.  Individuals exhibited strong intra-seasonal site fidelity, with most fish spawning at this site drawn from the estuary and returning to the estuary within a 24 h cycle.  Aggregation sound indicated daily spawning at this site, but it was not by the same individuals.  Individual estimates of spawning indicated males spawned more frequently than females, with an average spawning interval of 2.2 d compared to 9.3 d for females.  The probability of an individual spawning at this site was significantly affected by sex and lunar phase (spawning increased on dates near the full moon) but not by current speed or direction.