Dietary niche differentiation of five sympatric species of Platycephalidae. Environmental Biology of Fishes
Barnes, L.M., Leclerc, M., Gray, C.A. and Williamson, J.E., 2011. Dietary niche differentiation of five sympatric species of Platycephalidae. Environmental Biology of Fishes, 90: 429–441.
More than 60 species of flatheads occur globally. The majority of these are found throughout the Indian and Pacific Oceans. Several flathead species including Eastern Blue-spotted flathead, Tiger flathead, Longspine flathead, Mud flathead and Freespine flathead co-occur throughout the inner continental shelf waters of south-eastern Australia, where they are targeted or caught as by-catch by commercial and recreational fishers. With the exception of Tiger flathead, little is known about the biology of these species and there has been no investigation of their diets. An understanding of what each species eats and how the different species may partition the food resources will help determine their functional role within the ecosystem and how these species coexist.
The aim of this study was to investigate the diets of Eastern Blue-spotted flathead, Tiger flathead, Longspine flathead, Mud flathead and Freespine flathead and to determine whether these five co-occurring flathead species partition prey resources. This was completed by analysing the diets of each species caught in waters adjacent to at Yamba and Newcastle.
All five species were exclusively carnivorous. Each species consumed fish and at least one other category of prey. Eastern Blue-spotted flathead, Tiger flathead, Longspine flathead and Mud flathead had the most diverse diets consisting of between four to twelve prey types and can be considered generalist carnivores. In contrast, Freespine flathead could be considered primarily piscivorous as every full stomach examined contained fish, with other prey categories contributing very little to the overall diet of this species.
Although all species consumed similar prey items and by weight fish dominated the diet of each species, there was significant variability in the importance of each prey category to the diets of the flathead species studied. Dietary overlap was observed between selected flathead species from both Newcastle and Yamba suggesting competition for food resources may be an important factor influencing how these flathead species coexist.