Further Evidence of Possible Skipped Spawning By Florida's Common Snook (Centropomus undecimalis)

Common Snook (Centropomus undecimalis) are euryhaline, iteroparous, and indeterminate batch spawners inhabiting coastal subtropical and tropical waters of the Americas.  On the east coast of Florida current research demonstrates females make multiple spawning migrations to and from inshore non-spawning areas and marine spawning aggregations within an annual reproductive cycle.  To address the possibility of skipped spawning we used a combination of physiological and acoustic telemetry data.  Generalized linear models were used to investigate spatial, temporal, and physiological effects on Gonadosomatic Index (GSI) of 562 females collected from 2009-2015.  The most parsimonious model included habitat type, year, month, TL, and Body Condition Index (BCI) as significant predictors of GSI.  GSI increased as TL increased, however BCI did not share the same linear relationship with GSI.  Among 280 fish monitored via telemetry from 2008-2013, smaller mature fish were less likely to migrate to a spawning site than larger fish.  These results suggest smaller mature individuals in river and estuary habitat are possibly demonstrating “younger skipping” or “delayed maturation” skipped spawning, which has also been suggested for Florida west coast common snook.