Diet, trophic interactions and possible ecological role of commercial sharks and batoids in northern Peruvian waters

Abstract

The Peruvian sea represents one of the most productive ocean ecosystems and possesses one of the largest elasmobranch fisheries in the Pacific Ocean. Ecosystembased management of these fisheries will require information on the trophic ecology of elasmobranchs. This study aimed to understand the diet, trophic interactions and the role of nine commercial elasmobranch species in northern Peru through the analysis of stomach contents. A total of 865 non-empty stomachs were analysed. Off northern Peru, elasmobranchs function as upper-trophic-level species consuming 78 prey items, predominantly teleosts and cephalopods. Two distinctive trophic assemblages were identified: (a) sharks (smooth hammerhead shark Sphyrna zygaena, thresher shark Alopias spp. and blue shark Prionace glauca) that feed mainly on cephalopods in the pelagic ecosystem; and (b) sharks and batoids (Chilean eagle ray Myliobatis chilensis, humpback smooth-hound Mustelus whitneyi, spotted houndshark Triakis maculata, Pacific guitarfish Pseudobatos planiceps, copper shark Carcharhinus brachyurus and school shark Galeorhinus galeus) that feed mainly on teleosts and invertebrates in the benthonic and pelagic coastal ecosystem. This study reveals for the first time the diet of T. maculata and the importance of elasmobranchs as predators of abundant and commercial species (i.e., jumbo squid Dosidicus gigas and Peruvian anchovy Engraulis ringens). The results of this study can assist in the design of an ecosystem-based management for the northern Peruvian sea and the conservation of these highly exploited, threatened or poorly understood group of predators in one of the most productive marine ecosystems.

Improving sustainable practices in tuna purse seine fish aggregating device (FAD) fisheries worldwide through continued collaboration with fishers

“…Note that Portugal and Croatia do not have a tropical tuna purse seine fleet per se, but many fishers from these countries have been working on vessels of the Pacific Ocean since the 1960s. Meanwhile countries like Peru are rebuilding their tuna fishery (i.e., 14 purse seiners as of 2022) and raising bycatch mitigation awareness in this fleet is especially critical due to their rich waters being among the most important hotspots for sharks and rays worldwide (Lezama-Ochoa et al, 2019;Gonzalez-Pestana et al, 2021). Additional to the ISSF Skipper Workshops other parallel sustainability initiatives (e.g., observer training programs, deck crew trainings, biodegradable FAD projects) coordinated by other scientific teams have complemented mitigation training needs in several regions.…”

Trophic ecology of three stingrays (Myliobatoidei: Dasyatidae) off the Brazilian north‐eastern coast: Habitat use and resource partitioning

“…When considering the ecological role of batoids, species have been shown to alter habitat, restructure invertebrate and algae communities, and promote resuspension of nutrients in the benthic environment through their feeding mode (Aguiar, 2010; Flowers et al ., 2020; Gonzalez‐Pestana et al ., 2021; Sasko et al ., 2006). The balance and health of ecosystems is therefore partially dependent on the integrity of local elasmobranch populations (Aguiar & Valentin, 2010), with batoids acknowledged as possessing key functional roles, but for which limited comparative data exist.…”

“…When considering the ecological role of batoids, species have been shown to alter habitat, restructure invertebrate and algae communities, and promote resuspension of nutrients in the benthic environment through their feeding mode (Aguiar, 2010;Flowers et al, 2020;Gonzalez-Pestana et al, 2021;Sasko et al, 2006).…”