Seasonal and Ontogenetic Variation in the Diet and Daily Ration of Estuarine Red Drum as Derived from Field‐Based Estimates of Gastric Evacuation and Consumption

Abstract

The application of ecosystem‐based approaches in fisheries management has been limited by a lack of empirical data for quantifying the ecological interactions among many common and valuable fishery species. The red drum Sciaenops ocellatus, a large, carnivorous member of estuarine communities, is experiencing population recovery throughout its range in the U.S. South Atlantic and Gulf of Mexico. Using a field‐based approach, we determined seasonal and ontogenetic variation in the contribution of valuable fishery resource species to red drum diets, estimated red drum daily ration, and quantified per capita and population‐level predation by juvenile and subadult red drum in a North Carolina estuarine system. Despite seasonal, interannual, and ontogenetic variation in diet composition, red drum fed mainly on macrocrustaceans and juvenile fishes, including several economically important resource species (e.g., blue crab Callinectes sapidus, penaeid shrimp, and Atlantic menhaden Brevoortia tyrannus). Both juvenile and subadult red drum demonstrated strong diel feeding patterns, with peak feeding occurring during the hours just after dark. Gastric evacuation rates during periods of declining gut fullness were estimated on seven sampling dates and produced mean daily ration estimates between 1.2% and 3.4% of predator mass depending on age‐group. Combining field‐observed red drum growth rates with published laboratory estimates of gross growth efficiency suggested that our estimates of daily ration were likely biased low. During the seasonal period of rapid growth, the aggregate consumption of blue crabs, penaeid shrimp, and Atlantic menhaden by juvenile and subadult red drum in North Carolina waters was estimated at 3.4 × 106 to 5.1 × 106 kg/year. Received October 12, 2011; accepted May 24, 2012

PCR‐based prevalence of a fatal reovirus of the blue crab, Callinectes sapidus (Rathbun) along the northern Atlantic coast of the USA

“…; MD DNR ). Much of this variation may reflect fluctuation in recruitment and predation (Orth, van Montfrans & Fishman ; Hines ; Facendola & Scharf ). However, now receiving recognition among resource managers, and proposed more than a decade ago, is the possibility that diseases play a significant role in blue crab natural mortality (Messick & Shields ; Shields ; CBSAC ).…”

Density-dependent habitat use and growth of an estuarine fish

“…There is increasing evidence that estuaries may be food-limited (e.g., Kneib 1997;Kimmerer et al 2000), especially for species with high predatory demands. Juvenile red drum are a likely candidate to experience food limitation in estuaries because they exhibit high predatory demand (Facendola and Scharf 2012), high individual growth rates (Scharf 2000;Lanier and Scharf 2007), and tend to aggregate at small and medium spatial scales (Bacheler et al 2008b;Arnott et al 2010). Juvenile red drum may also exhibit interference competition, as has been found in other sciaenid species (Gibbard et al 1979).…”

“…Apparent growth rates of age-1 and age-2 red drum were estimated based on the slope of a linear regression fit to lengths of individuals by date of collection using IGNS and tagging data. Only fish collected between 1 June and 31 September were included in this analysis, which corresponds to the peak growth period of juvenile red drum (Facendola and Scharf 2012). The major benefit of using the IGNS survey is that the experimental gill nets (with many different mesh sizes) collect the entire range of sizes of age-1 and age-2 red drum, but the primary drawbacks are that the time series is relatively short (8 years), and in some years sample sizes were small for part of the year.…”

Using Survival Models to Estimate Invertebrate Prey Identification Times in a Generalist Stream Fish

“…Alternatively, feeding rates can be estimated from predator diet data in the field. One method for estimating fish feeding rates combines mass-based representations of stomach content data obtained from field surveys with gastric evacuation rates of prey mass (e.g., Benkwitt et al 2009;Facendola and Scharf 2012;Hughes et al 2014;Haskell et al 2017). The latter are obtained by regression using laboratory experiments in which the mass of prey in the stomachs of a sample of individuals fed at known times is measured after varying lengths of elapsed time (Jobling 1986).…”

“…This situation is common in studies of fishes that feed on a large diversity of small prey with potentially variable evacuation and identification times, such as benthic macroinvertebrates or plankton (e.g., Allan 1981). Applications of gastric evacuation models have frequently ignored this prey-specific variation, instead focusing on a predator's total feeding rate summed over all prey types (e.g., Benkwitt et al 2009;Facendola and Scharf 2012;Haskell et al 2017). In contrast, the presence of unidentifiable prey in a predator's stomach is irrelevant to the approach based on prey identification times (Woodward et al 2005;Baker et al 2014;Novak et al 2017).…”