Estimating reef fish reproductive productivity on artificial and natural reefs off the Atlantic coast of the southeastern United States
Danson, Bryan Lawrence
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Artificial reefs (ARs) are generally designed to increase habitat for reef fishes, especially economically important species [e.g., black sea bass (BSB; Centropristis striata)]. The three principle goals of ARs are to create reef habitat to reduce fishing pressure on natural reefs, to enhance production of reef fish species, and to provide habitat in areas that increase the convenience or efficiency of harvesting reef-associated species. No known research has attempted to assess the enhancement of reproductive productivity of reef fishes on ARs off the southeastern Atlantic coast. The present study first attempted to document spawning on four South Carolina (SC) ARs from 2008-2009 via histology in four abundant reef fishes: BSB, gray triggerfish (Balistes capriscus), red porgy (RP; Pagrus pagrus), and vermilion snapper (Rhomboplites aurorubens). The present study then investigated the eproductive production of BSB on two ARs and one natural reef (NR) off Charleston, SC, by estimating potential annual fecundity (PAF) m^-2 in the spring of 2009. An equation relating fecundity to standard length (SL) was applied to estimates of density and length to estimate PAF m^-2. The BSB fecundity assessment was conducted on fish collected by the MARMAP program at SC-NR from 2000-2009. Density estimations were collected through underwater 360 point count videos. Length estimates were obtained from fish collected via hook-and-line sampling on the ARs to document spawning. Spawning was documented on the ARs in RP and BSB. Black sea bass was found to exhibit indeterminate fecundity, spawning frequency was re-calculated, and batch fecundity was significantly related to fish length and weight. Potential annual fecundity m^-2 was 2.5-fold to four-fold greater on the ARs than on the NR, owing to the greater density and greater mean SL of BSB on the ARs compared to the NR. The methods provided here allow the comparison of reproductive productivity in fishes between ARs and NRs for the purpose of evaluating ARs as tools to enhance production.