Differences in diet and feeding ecology of similar-sized spotted (Lepisosteus oculatus) and shortnose (Lepisosteus platostomus) gars during flooding of a south-eastern US river


Correspondence: Reid Adams, PhD, Department of Biology, University of Central Arkansas, 201 Donaghey Avenue, Conway, AR 72035, USA. Tel.: 1 501 450 5933; Fax: 1 501 450 5914; E-mail: radams@uca.edu


Connection events between rivers and their adjacent floodplains can alter availability of resources. Riverine fishes opportunistically exploit seasonally available resources during periods of high water. Gars are known to utilize floodplain habitats throughout different life stages for spawning and feeding. Food habits of gars have been the focus of many studies; however, less is known regarding the partitioning of food resources between syntopic species overlapping in body size. Further, little information exists on food resources of shortnose gar, Lepisosteus platostomus. We report results of diet analysis of spotted, Lepisosteus oculatus, and shortnose gar from the Fourche LaFave River in central Arkansas. Stomachs were examined from 74 adult spotted gar (46–81 cm TL) and 91 adult shortnose gar (49–76 cm TL) collected between May and July 2007 during flooding. Forty-seven (64%) spotted and 54 (59%) shortnose gar contained identifiable prey items. Spotted and shortnose gars had low diet overlap (33.0%), indicating these two species partition food resources. Considering percent composition by weight (%Cw), spotted and shortnose gar appear to partition available food resources during summer flooding. Percent composition by weight of fishes and crustaceans was significantly greater in the diet of spotted gar than shortnose gar (Table 2). Shortnose gar had significantly greater %Cw of amphibians and terrestrial invertebrates compared to spotted gar. It is likely that the seasonal and consistent annual availability of terrestrial subsidies to the system holds a unique importance for the shortnose gar population.