Dietary ecology and trophic level of adults of the Chilean angel shark Squatina armata Philippi 1887 in the Central-Eastern Pacific Ocean

Abstract

As top predators, sharks play an important role in the regulation of marine ecosystems. This study provides information on the feeding ecology and trophic level of the Chilean angel shark Squatina armata in the central-eastern Pacific Ocean. A total of 320 sharks were caught by the artisanal fishery in the Ecuadorian Pacific Ocean and landed in Manta (Ecuador) between November 2003 and October 2004, in which such specimens measured 66 cm to 98.5 cm of total length (TL). The prey included bony fish, elasmobranchs, mollusks, and crustaceans. According to the Prey-Specific Index of Relative Importance (%Psiri), the kolibri shrimp Solenocera agassizii, lizardfish Synodus spp., and peanut rock shrimp Sicyonia picta were the main prey in the diet of S. armata. The sharks which belonged to size I (65–80 cm TL), consumed mostly drum Larimus spp., S. agassizi, and bignose conger Rhynchoconger nitens; while for size II (80–95 cm TL) and size III (95–109 cm TL), sharks fed mostly on S. agassizi, Synodus spp., and S. picta. The results showed that S. armata feeds on the same prey items all year round and it does not display dietary changes. This shark species is a selective predator with functions of a mesopredator (trophic level = 3.20–5.20). It could be classified as mainly piscivorous and carcinophagus, in which this shark species searches for food mainly in benthic and coastal areas. This study highlights the scarcity of knowledge regarding the biology and ecology of S. armata in the central-eastern Pacific Ocean. Additionally, it underlines the need to produce information that will allow adequate management and conservation measures to be implemented for this species by understanding their important feeding spots in coastal areas of Ecuador.