Spawning Site Fidelity, Catchment, and Dispersal of Common Snook along the East Coast of Florida

Abstract

AbstractA population's fidelity to spawning sites and variation in the strength of site fidelity among individuals are influential components of fish population dynamics. The literature on fidelity to aggregation sites is dominated by studies on marine species, whereas less is known about the fidelity of euryhaline species to spawning aggregation sites. We used passive acoustic telemetry to quantify intra‐annual and interannual site fidelity and resident habitat associated with spawning sites (inlets) for 280 sexually mature Common Snook Centropomus undecimalis through an array of more than 200 receivers deployed in rivers, estuaries, inlets, and nearshore waters along 320 km of Florida's Atlantic coast. Fish were detected four times as often at and made twice as many trips to a primary spawning inlet than to secondary inlet sites. Fish displayed interannual site fidelity, returning to the primary inlet for as many as five consecutive reproductive seasons. Overall, individuals returned to their primary inlet (return rate [RR] = 0.54) more often than they changed sites between years (straying rate [SR] = 0.29), but variation in RRs and SRs between inlets suggested a spatial effect on interannual site fidelity. During the nonspawning season, fish generally resided less than 40 km to the northwest of their primary inlet. The 95% kernel density estimates (KDEs) for catchment area and dispersal area averaged 220 km2 and overlapped greatly for five out of six inlets. The 50% KDE did not overlap between inlets, suggesting that each spawning site had a corresponding winter resident habitat supporting a group of fish that were primarily associated with that inlet. The inclusion of telemetry data in traditional measures of site fidelity allowed for the identification and accurate description of behavioral polymorphism and may be applied to other fish species when spatial substructuring is suspected.Received June 9, 2015; accepted December 3, 2015