Trophic Comparison of Two Species of Needlefish (Belonidae) in the Alvarado Lagoonal System, Veracruz, Mexico

We compared the diets of Atlantic needlefish, Strongylura marina, and redfin needlefish, Strongylura notata, in the Alvarado lagoonal system, Veracruz, Mexico, and analyzed diet breadth and trophic overlap between the species. All fishes were collected monthly from June 2000 to July 2001 at twelve sampling stations. A total of 74 intestinal tracts from S. marina were analyzed. The diet of S. marina consisted of 25 prey types with fish being the dominate prey. In eighty-nine digestive tracts examined from S. notata, the diet consisted of 29 prey types with the dominant prey including fishes, penaeid shrimp, polychaetes, and hymenopteran insects. There was moderate diet overlap (α = 0.4903) between S. marina and S. notata in the rainy season, while there was little diet overlap between species during the “nortes” (α = 0.1037) or dry (α = 0.1675) season. There was reduced niche breadth in both S. marina and S. notata during the “nortes” (BA = 0.175 and 0.105, respectively) and dry (BA = 0.128 and 0.173, respectively) seasons, with niche breadth values being higher for both species during the rainy season (BA = 0.254 and 0.296, respectively)