Comparative Diets and Prey Resource Competition between Early-juvenile Common Snook Centropomus undecimalis and Non-native Pike Killifish Belonesox belizanus.

Pike killifish is an established non-native fish species in Florida, USA, that was first documented in south Florida in 1957 and secondarily in Tampa Bay tributaries in 1994. Decreases in small-bodied fish abundances have been linked to the introduction of pike killifish in both of these regions. Increases in the range and abundance of pike killifish in the Tampa Bay area and overlap in habitat usage has led to concerns about potential competition with, and predation on, early-juvenile C. undecimalis (≤100 mm standard length (SL)). Stomach contents of pike killifish (N = 422; 14 -127 mm SL) and early-juvenile C. undecimalis (N = 1132; 5-119 mm SL) were collected to examine the dietary overlap of these two species and potential differences in the diet of early-juvenile C. undecimalis from locations with and without pike killifish co-occurring. Prey resources were collected by seine to assess prey resource limitation and prey selectivity. Stomach content analysis indicated that there was low overlap in the diet of early-juvenile C. undecimalis and pike killifish (C ≤ 0.40). Early-juvenile C. undecimalis had a wider diet breadth, consuming many organisms that are not consumed by pike killifish and which make up a large portion of the early-juvenile C. undecimalis diet. Analysis of prey resources indicated that some prey groups may have lower abundances in locations where pike killifish are present, with some of these differences reflected in the diet of early-juvenile C. undecimalis. Despite these differences, there was minimal difference in the diet overlap of early-juvenile C. undecimalis from locations with and without pike killifish co-occurring. Currently pike killifish appear to be competing minimally with early-juvenile C. undecimalis for prey resources, with no substantial impacts being detected. This article is protected by copyright. All rights reserved.