Demographic Effects On Reproductive Potential of Red Drum

Older and larger marine teleosts with indeterminate fecundity can produce the majority of eggs in a population through increased batch fecundity and extended spawning seasons. Maintaining these females in the spawning population has been hypothesized to increase resilience. Two studies (1996-98 and 2006-09) targeting spawning aggregations of adult red drum in Tampa Bay coastal waters provide an opportunity to examine the demographic effects on reproductive potential by comparison of age, length, and batch fecundity data. Strict management actions enacted in the mid 1980s dramatically reduced fishing pressure and fish collected in these two studies (10 and 20 years following the moratorium) reflect rebuilding of the spawning population following fishing-induced age truncation. The size and age structure of adult red drum significantly changed between the two studies with fish collected in the 2006-09 having a larger size range, an older average age and more fish over the age of 12. Batch fecundity estimates also increased between the two studies, with the maximum eggs per females increasing from 2.3 million in 1996-98 (n=77) to 4.9 million in 2006-09 (n=167). Additionally, average batch fecundity in 2006-09 (2.6 million) exceeded the maximum fecundity (2.3 million) in the initial study.