MEPS 359:249-260 (2008)  -  DOI: https://doi.org/10.3354/meps07324

ABSTRACT: By protecting mature fishes, marine reserves are anticipated to increase local production of ichthyoplankton, a mechanism difficult to empirically demonstrate in most coastal settings. The estuarine fisheries reserve at Kennedy Space Center (KSC), Florida, is microtidal and largely isolated from public-access areas by natural shorelines and earthen causeways, conditions which help preserve spatial gradients in ichthyoplankton production. We examined the abundance of sciaenid (Pisces: Sciaenidae) sportfish larvae across the KSC Reserve boundary on 48 ichthyoplankton surveys from August 2002 to July 2004. Over 98% of the 15783 larval sportfish identified were spotted seatrout Cynoscion nebulosus, southern kingfish Menticirrhus americanus and red drum Sciaenops ocellatus, which, based on their small size (mean 2.3 to 2.6 mm) and distance from ocean inlets (typically 30 to 90 km), were all estuarine-spawned. Significantly higher concentrations of these taxa and total fish larvae occurred in public areas, contrary to study predictions. Concentrations remained higher in public areas after standardizing catch to account for habitat variables known to influence adult spawning behavior and/or ichthyoplankton survival. Further, results of an existing estuarine circulation model reaffirm that water flow across the KSC Reserve boundary is slow, impeding passive ichthyoplankton export. These findings suggest that local harvest rates of estuarine-spawning adult sciaenid sportfish (at current levels) is a poor predictor of ichthyoplankton abundance and that the KSC Reserve may do little to enhance local recruitment for these species. Nonetheless, this management area is still likely to bolster recruitment of marine-spawning taxa on a regional scale by protecting adult fish during non-reproductive periods.

KEY WORDS: Marine reserve · Fish larvae · Sciaenidae · Indian River Lagoon · Cynoscion nebulosus · Sciaenops ocellatus · Menticirrhus americanus