Feeding of Arapaima sp.: integrating stomach contents and local ecological knowledge

Abstract

The giant arapaima (Arapaima sp.) has been described as a fish of change in Amazonia because of its important role in the conservation of floodplains, food security and income generation for rural communities. Nonetheless, despite the cultural, ecological and economic importance of arapaima, data on diet are scarce. Aiming to expand knowledge about arapaima diet in western Amazonia, scientific knowledge was integrated with the knowledge of local dwellers. During the low-water period (September 2018) and the falling-water period (June 2019), arapaima stomachs were collected from 11 floodplain lakes in the middle Juruá River. All fishes were measured [TL (total length)] and sexed. Food items from each stomach were categorized as fishes, invertebrates, plants and bone remains and weighed. Also, in the latter period, experienced local fishers were interviewed about arapaima feeding. This integrated approach revealed that young arapaima eat fish and invertebrates but adult arapaima eat fish of a wide range of species, which were mainly of low and intermediate trophic positions. This study reports the first case of cannibalism for arapaima and also shows that during the low-water period, many individuals had empty stomachs or only some small fish-bone remains and/or plant material. Arapaima sex and TL had no influence on the absence of prey in stomach contents. Overall, it can be concluded that local people had consistent ethnobiological knowledge of arapaima feeding ecology that could be useful within management projects in the region.

‘Taking Fishers’ Knowledge to the Lab’: An Interdisciplinary Approach to Understand Fish Trophic Relationships in the Brazilian Amazon

“…The sum may be greater than 100%, as fishers could cite more than one food item for each studied fish species. Those food interactions that agree with fish feeding relationships reported in the biological literature (Best, 1984;Silva et al, 2013;Dary et al, 2017;Jacobi et al, 2020) are marked in yellow.…”

Trophic ecology of Acestrorhynchus falcirostris Cuvier, 1819 in island lakes on the lower stretch of the Solimões River, Amazon Basin

“…The generalist strategy found in the study corroborates with the reported in the literature for predatory fish (Cardoso et al, 2019;Jacobi et al, 2020;Mérona and Rankin-de-Mérona, 2004), since, in this seasonal phase, there is a greater supply of allochthonous items of animal and vegetable origin, such as winged insects, fruits and seeds that fall from the trees (Claro-Jr et al, 2004;Goulding, 1990) and serve as food for fish. This phase also aids the fish by allowing them to store fat until the low water period, when food becomes scarce.…”

Fish, Fishing, and Conservation

“…They belong to a group of primitive bony fish known as bonytongue fish, because their tongues are used to crush prey against the roofs of their mouths. Smaller Arapaima are generalist feeders, consuming a variety of invertebrates, such as the Amazon River prawns, mayflies, and crickets, while larger Arapaima can consume larger prey, often catfish, cichlids, hatchetfish, and pacu (Watson et al 2013;Carvalho et al 2018;Jacobi et al 2020). During low water periods, many isolated lakes can become hypoxic (i.e., low in oxygen).…”