Ontogenetic diet shifts of rough scad Trachurus lathami in the North Patagonian shelf (south‐west Atlantic Ocean)

Abstract

Rough scad Trachurus lathami is a key pelagic fish in the Argentinean continental shelf (ACS, south‐west Atlantic Ocean), with recent increases in abundance. It is a main prey of fishes and marine mammals, and shares the environment with commercially relevant pelagic species (Engraulis anchoita and Scomber colias), playing an important role linking lower and upper trophic levels in the ecosystem. This study aims to determine the ontogenetic changes in the diet composition, feeding strategy, trophic niche breadth and trophic level of T. lathami in the North Patagonian Shelf (43°–45°30′S). The stomach contents of adult fish (n = 238) were analysed. The results suggest a clear ontogenetic shift in the diet at a size of ~190 mm. Smaller individuals (160–190 mm) were specialized on misidaceans, and showed the highest trophic level, while larger T. lathami (221–230 mm) consumed decapods (Peisos petrunkevitchi) and teleosts (eggs and larvae). Trophic niche breadth was higher at the medium‐sized class (191–220 mm), which mainly preyed on copepods (Calanoides carinatus) and chaetognaths (Sagitta spp.), evidencing a more diverse diet and a rather generalist strategy. Updated information on the trophic ecology of T. lathami evidences its extremely plastic feeding behaviour, being able to adapt its trophic niche to the most readily available food items from the mesopelagic community.

Summer diet and feeding strategy of Pacific cod (Gadus macrocephalus) inhabiting the southern coast of Hokkaido, Japan

“…Knowledge of the ontogenetic variation in fish diet helps clarify intraspecific food resource utilization tactics in the ecosystem. It is common for the diet composition of fish to change with increasing body size, mainly due to superior swimming performance and hunting ability (e.g., Yamamura et al 2002;Temperoni et al 2021). In this study, the diet of Pacific cod tended to gradually shift from decapods to fish after reaching ~400 mm SL.…”

“…The food spectrum of smaller fish is usually limited by the mouth gape size and swimming ability (Ingram and De Silva 2007;Temperoni et al 2021).…”

“…This method has been widely used to determine the feeding ecology of many fish species, such as hairtail (Trichiurus japonicus (Mammel et al 2022)), arrowtooth flounder (Atheresthes stomias (Draper 2022)), and rough scad (Trachurus lathami (Temperoni et al 2021)). One shortcoming of this method is that it can only reflect a snapshot of the diet composition.…”

Spatiotemporal variability in diet composition of Greenland halibut (Reinhardtius hippoglossoides) from the eastern Canadian Arctic

“…Generally, small R. hippoglossoides (<20 cm) fed on small crustaceans (i.e., amphipods) and then quickly transitioned (<20 to 20-29.9 cm) to a diet based on fish and shrimp (i.e., B. saida, Sebastes sp., and Pandalus shrimp), whereas larger specimens (≥60 cm) preyed mainly on fish. Size-related dietary shifts have been commonly observed and documented in fish (e.g., Brown-Vuillemin et al, 2022;Sánchez-Hernández et al, 2019;Temperoni et al, 2021), including R. hippoglossoides (Dwyer et al, 2010;Orr & Bowering, 1997;Vollen et al, 2004). These changes are attributed to a combination of factors, which include prey availability (Kimirei et al, 2013;Sánchez-Hernández & Cobo, 2018), predation risks (Kimirei et al, 2013;Reñones et al, 2005), habitat use (Hammar et al, 2018), morphological constraints (Sánchez-Hernández Thus, they typically inhabit shallower depths where they feed on smaller prey while avoiding large groundfish predators, including conspecifics (Dwyer et al, 2010;Wheeland & Morgan, 2020).…”