How Often Do Fishes “Run on Empty”?

Abstract

We used a large data set of African, Neotropical, and North American fishes to examine the frequency with which fishes have empty stomachs (n species ϭ 254; n individuals ϭ 36 875). Mean percentage of empty stomachs was low across all fishes (16.2 Ϯ 1.2%) but varied from 0% to 79.4% among individual species. Nocturnal fishes had empty stomachs more frequently than diurnal fishes. Trophic classification was strongly associated with the percentage of empty stomachs, a pattern also revealed from an intraspecific analysis. Fishes appear to adjust their feeding intervals relative to the energy density, conversion efficiency, and particle size of their food. Piscivorous fishes seem to be the only trophic group that regularly experience long periods of empty stomachs, with species that consume prey whole and those that provide extended parental care having the highest proportions of empty stomachs. Activity patterns and life histories of some piscivorous species probably have evolved in partial response to energetic benefits of large, energy-rich food resources.

When carnivores are “full and lazy”

“…The results are in line with Huey et al (2001) and Arrington et al (2002) who showed that the average percentage of lizards and fish with empty stomachs is rather low (13 and 16%, respectively). According to Jeschke and Tollrian (2005a), herbivores also frequently reach satiation in the field.…”

What do the empty stomachs of northern pike (Esox lucius) reveal? Insights from carbon (δ13C) and nitrogen (δ15N) stable isotopes

“…Hence, any northern pike population should have some individuals representing each of the foraging sequences (i.e., searching, digesting, satiated). The feeding intervals of fishes are known to be related to the energy content, conversion efficiency, and particle size of their food (Arrington et al 2002). The consumption of high-quality food items allows individuals to rely on stored energy and forgo foraging for longer periods (Bowen 1996).…”

“…The consumption of high-quality food items allows individuals to rely on stored energy and forgo foraging for longer periods (Bowen 1996). Empty stomachs are not necessarily related to a negative energy balance but may rather reflect the high energy content of a previously assimilated prey (Arrington et al 2002). Chapman et al (1989) suggested that the proportion of empty stomachs in northern pike is directly related to the proportion of piscivorous individuals in the population.…”

“…Here we defined the stomach as that section of the alimentary canal between the pyloric and the intestinal narrowings (Bucke 1971). Stomachs were considered empty when there was an absence of any measurable organic material (Arrington et al 2002). We classified individuals in the piscivorous group based on the presence of fish in their stomachs.…”

“…These authors argued that individuals occupying high trophic levels are more likely to have empty stomachs than those at lower levels because prey density is relatively low for most top predators. In a study of 254 fish species with different foraging behaviours, Arrington et al (2002) found that the average FES was 16.2%, with piscivorous fishes being the only trophic group with a high proportion of empty stomachs. Species feeding on whole fish prey, a behaviour often associated with reduced foraging, had the highest proportions of empty stomachs (Arrington et al 2002).…”