Energy Density Predictors for Argentine Anchovy Engraulis anchoita, a Key Species of the Southwestern Atlantic Ocean

Forage fishes have a cosmopolitan distribution and constitute key species in marine trophic webs throughout the world. We estimated the energy density of the Argentine Anchovy Engraulis anchoita , a key component of the base of the food web in a large fraction of the southwestern Atlantic Ocean. We also examined the relationships between energy density and different proxies (condition factor, fork length, and percent dry weight) and compared the relationship of energy density to percent dry weight for Argentine Anchovy to this relationship in other forage fishes. A regression model that includes percent dry weight and fork length was the best predictor for the energy density in this species. The Argentine Anchovy had similar energy density to percent dry weight to all species in the Engraulidae family (anchovies) and to most of the species in the Clupeidae family (sardines). Engraulidae species showed smaller mean energy density and smaller energy density to percent dry weight compared with the Clupeidae species. The difference in energy density between these two families could have direct implications on population dynamics of predators in oscillating sardine–anchovy systems or in regions where these two families are spatially segregated.