MEPS 633:181-196 (2020)  -  DOI: https://doi.org/10.3354/meps13183

ABSTRACT: Although stock structure is based on reproductive isolation and recruitment to the adult stock is an important parameter for stock assessments, data on the ecological process as individuals move from nursery to adult habitat is rare. As red drum Sciaenops ocellatus show delineated estuarine nursery grounds and coastal spawning habitat, we acoustically implanted and monitored subadults in neighboring southwest Florida estuaries Tampa Bay (2012, n = 20) and Charlotte Harbor (2013, n = 20) over 3 yr to evaluate if recruitment and consequent spawning site selection differed between estuaries. To assess estuarine presence, we used a mobile hydrophone survey (Tampa Bay) and estuarine receivers (Charlotte Harbor); recruitment to adult habitat was monitored with nearshore receiver arrays off both estuaries. Tagged fish were of similar size and age but reproductive development, recruitment timing, and spawning habitat post-recruitment varied significantly. Although Charlotte Harbor fish exhibited significantly more advanced gonadal maturity indicators compared to Tampa Bay fish, only 24% were detected in adult habitat the year tagged, with 65% following the next reproductive year. By contrast, 74% of fish from Tampa Bay moved to adult habitat within the same year tagged. Natal homing—returning to the nearshore adult habitat off their estuarine nursery for subsequent reproductive periods—was observed in fish from both estuaries. Differences in recruitment timing and movement patterns of red drum between the 2 estuaries indicates natal estuary drives spawning site selection and consequent movement ecology in ways not previously understood, with potential recreational fishery implications as this species is managed by escapement rates.

KEY WORDS: Red drum · Sciaenops ocellatus · Acoustic telemetry · Spatial ecology · Ontogeny · Maturation · Recruitment · Spawning · Natal homing · Tampa Bay · Charlotte Harbor · Florida