Food sources of common dolphinfish (Coryphaena hippurus) based on stomach content and stable isotopes analyses

Abstract

Dolphinfish (Mahimahi) are a high-demand resource for sport and coastal fisheries, mainly in the Pacific Ocean. Due to their economic and ecological importance, studies of their biology are very important to understand their function in ecosystems. We used stable isotope and stomach content analyses to determine the most important prey of the common dolphinfish, as well as the trophic level of this species in two areas of the southern Gulf of California. Stomach contents of 445 specimens were analysed. Using both techniques, we found that the most important prey for dolphinfish in the southern Gulf of California were three invertebrate species followed by fish. This contrasts with results from other authors who found that this species was mainly piscivorous in other locations. Stomach content analysis indicated differences in prey biomass by area, season and size class. The isotopic analysis did not show significant differences between seasons or sexes. Both stomach contents and stable isotope analyses showed that although this predator consumed a wide prey spectrum, only a few prey items made up the bulk of the diet, which resulted in a low SD in δ15N values and low Levin's index values. We conclude that this fish is an opportunistic predator that may consume a wide prey spectrum, but that it mainly consumes prey that are abundant in the area, such as crustaceans and cephalopods in the Gulf of California.

Feeding Ecology of Dolphinfish in the Western Gulf of Mexico

“…This dietary shift may be the result of changing foraging strategies with age (Nunes et al 2015) or simply gape limitation. Ontogenetic shifts in Dolphinfish diets have been observed in other regions; however, specific trends in feeding have varied by location (Manooch 1984;Tripp-Valdez 2015). Our study suggests that Dolphinfish feeding ecology and habitat use are highly dynamic and vary ontogenetically throughout the species' range.…”

“…For example, female Dolphinfish in the Gulf of Mexico may be dedicating more energy towards reproduction than males. In the Pacific Ocean, females can reach maturity at smaller sizes (Alejo-Plata et al 2011), and in that region similar feeding ecology between sexes has also been observed through stomach content (Tripp-Valdez et al 2010;Torres-Rojas et al 2014) and stable isotope analysis (Tripp-Valdez et al 2015). As such, despite varying growth rates and potential differences in energetic requirements, males and females still appear to occupy similar ecological feeding niches across a large portion of the species' range.…”

“…Perhaps due to their fast-growing nature, Dolphinfish are known to be voracious eaters with a high metabolic rate (Benetti et al 1995). The diet of Dolphinfish has been examined in various ocean basins, including the Mediterranean Sea (Bannister 1976;Massuti et al 1998), Arabian Sea (Varghese et al 2013), Caribbean Sea (Oxenford and Hunte 1999), western Atlantic Ocean (Manooch et al 1984;Rudershausen et al 2010), and eastern Pacific Ocean (Olson and Galván-Magaña 2002;Torres-Rojas et al 2014;Tripp-Valdez et al 2015). However, only one study has examined Dolphinfish diets in the Gulf of Mexico (Manooch et al 1984), and this was conducted several decades ago.…”

Feeding habits of the Mexican barracuda, Sphyraena ensis Jordan and Gilbert, 1882, in the southeastern end of the Gulf of California

“…The trophic level calculated for the Mexican barracuda was 4.1. This is similar to what has been reported for other ichthyophagous predators with specialist tendencies, such as Xiphias gladius (Linnaeus, 1758) (4.5), Coryphaena hippurus (Linnaeus, 1758) (4.3), Fistularia commersonii (Rüppell, 1838) (4.3), Scomberomorus sierra (Jordan and Starks, 1895) (4.2), Thunnus albacares (Bonnaterre, 1788) (4.1), and Alectis ciliaris (Bloch, 1787) (4.0) (López-Peralta and Arcila 2002, Stergiou and Karpouzi 2002, Moreno-Sánchez et al 2011, Tripp-Valdez et al 2015, Froese and Pauly 2016, Alatorre-Ramirez et al 2017, which also feed on schoolforming pelagic fishes and on cephalopods and crustaceans. It should be noted that the Mexican barracuda is part of the same trophic guild and interacts with these species in the ecosystems of the southern Gulf of California, which suggests possible interspecific competition.…”

“…It should be noted that the Mexican barracuda is part of the same trophic guild and interacts with these species in the ecosystems of the southern Gulf of California, which suggests possible interspecific competition. However, it seems that the availability and abundance of small pelagic fishes that form large schools (families Engraulidae and Clupeidae) (Tripp-Valdez et al 2015, Varela et al 2017, Zambrano-Zambrano et al 2019, in addition to the morphological differences of predators, allow these species to coexist without affecting their population densities (Cruz-Escalona et al 2000, Moreno-Sánchez et al 2015.…”