Fidelity to spawning grounds by a catadromous fish, Centropomus undecimalis

Abstract

There is increasing recognition that many traditionally managed marine fish stocks have metapopulation structure resulting from fidelity to spawning grounds. Such fidelity may result in population segregation, even if this segregation is not evident through genetic testing. Homing to spawning grounds is well documented for anadromous salmonids, but less so for broadcast-spawning marine fishes. This study used tag-recapture (external dart tags and internal PIT tags) and tracking (sonic transmitters and stationary receivers) to examine the potential site fidelity of mature common snook Centropomus undecimalis to coastal spawning grounds (barrier islands) of the Gulf of Mexico coast of Florida, USA, in 2 consecutive spawning seasons. Of the 63 fish (3.5% of tagged fish) recap- tured within and between years, all occurred at the same island where the fish was tagged. Of the sonic-tagged snook with sufficient detections to determine movement patterns, 88.3% were detected only at the island where they were tagged. The low average distance between tag and recapture locations, and the high individual residence times at few receiver locations, suggest that fidelity may occur at an even smaller scale than the barrier island. Since spawning ground fidelity may mean that different spawning groups are subject to different conditions, and the ability of a stock to respond to anthropogenic or natural stressors may be influenced by such segregation, additional research is needed to determine the implications of spawning ground fidelity by common snook.