Nonnative Pike Killifish Do Not Exert Predatory Pressure on Juvenile Common Snook

The Pike Killifish Belonesox belizanus is an established nonnative fish species that was first documented in south Florida, USA, in 1957 and secondarily in Tampa Bay tidal tributaries in 1994. Decreased abundance and altered size structure in small-bodied fish populations have been linked to Pike Killifish introductions in both of these regions. Increases in the range and abundance of Pike Killifish in Tampa Bay waters and overlap in habitat usage with juvenile Common Snook Centropomus undecimalis have led to concerns about potential predation on early juvenile (<= 125 mm TL) Common Snook. We investigated predation of Pike Killifish on early juvenile Common Snook through experimental predation trials and stomach content analysis of Pike Killifish from field sampling. During predation trials, fasted, large adult (>= 104 mm TL) Pike Killifish were presented with one of three prey taxa: Common Snook (N = 139), Pike Killifish conspecifics (N = 68), and Eastern Mosquitofish Gambusia holbrooki (N = 68); the fate of the prey was recorded after 48 h. Common Snook with both intact (N = 70) and clipped (N = 69) anal spines were used as prey to investigate whether this structure deterred predation by Pike Killifish. Predation trials indicated that Pike Killifish were capable of consuming early juvenile Common Snook up to 60 mm TL and that the anal spine did not deter predation by Pike Killifish. Stomach content analysis was performed on 422 wild-caught Pike Killifish from Tampa Bay tidal tributaries where early juvenile Common Snook co-occurred, but no Common Snook remains were found in their diets. Combined, these studies indicate that despite being able to consume relatively large early juvenile Common Snook, Pike Killifish do not exert predatory pressure on early juvenile Common Snook in the wild and therefore do not appear to be a factor contributing to population-level effects or delayed recovery in Common Snook populations.