Feeding biology and age structure of Atlantic batfishes (Lophiiformes: Ogcocephalidae)

Batfishes (Ogcocephalidae) are a poorly known group of demersal fishes in the order Lophiiformes. This study provided the first comprehensive work on batfish biology that investigated how these fishes have further evolved and diverged from other Lophiiformes. The feeding biology and population age structure of batfishes were investigated by analyzing stomach contents, feeding kinematics, chemical luring, and age - length relationships. Specimens were collected from trawl surveys in the Gulf of Mexico, Rookery Bay in southwest Florida, intake screens of the Progress Energy Crystal River electric generation power plant north of Tampa, and from the ornamental aquarium trade.; Stomach content analyses were performed on four species of batfishes: Halieutichthys aculeatus, Ogcocephalus cubifrons, Ogcocephalus declivirostris, and Ogcocephalus pantostictus and gonadal analysis indicated that females comprised 61-100% of all collections of all species. Batfishes were found to prey on a variety of benthic invertebrates, particularly gastropods, polychaete worms, and xanthid crabs. Schoener's dietary overlap indices indicated that different batfish species preyed upon different assemblages of prey and that most species exhibited temporal variation in diet. O. cubifrons also showed significant variation in diet from two sites along the Florida coastline. Relationships between gape and prey size were analyzed for one collection of O. declivirostris. Prey were generally 2-5 mm in maximal prey cross sectional dimension. Linear regressions showed only a very minimal trend toward larger prey consumed by fish with greater gape size.; Because the invertebrate prey of batfish are unlikely to respond to the visual lures of the modified first dorsal spine utilized by other species of Lophiiform fishes, the hypothesis that the lure emitted chemical attractants was tested for O. cubifrons. Water samples collected from the anterior region of actively luring batfish quickly elicited an emergence response from buried gastropods (Nassarius vibex), a common prey item that emerges from the substrate to scavenge. A one way ANOVA and post-hoc Tukey test revealed significant (p<0.001) differences between positive and negative control and luring treatments.; Descriptive kinematics of the feeding strike for Ogcocephalus nasutus and Halieutichthys aculeatus were obtained using a Redlake Motionscope 2000 camera and computer program to record feeding events. Batfish used their pectoral and pelvic fins to slowly move along the bottom to get within 10-20 mm of the prey before initiating a feeding strike. Both species used a combination of ram and suction feeding methods with the premaxilla being fully protruded before suction was initiated by depressing the hyoid. Strikes were generally completed within 58 ms for H. aculeatus and 122 ms for O. nasutus.; Age analyses were conducted on four species of batfishes H. aculeatus , O. cubifrons, O. declivirostris, and O. pantostictus using sectioned sagittal otoliths. Otoliths were embedded in resin, sectioned with an isomet saw, and read under a dissecting microscope. Maximum ages ranged from 2 years for H. aculeatus to 16 years for O. cubifrons. The von Bertalanffy growth models calculated for each species comprise an initial step in an evaluation of the impact of trawling activities that take batfish as bycatch.