Development of a foraging model framework to reliably estimate daily food consumption by young fishes

Abstract

We developed a foraging model for young fishes that incorporates handling and digestion rate to estimate daily food consumption. Feeding trials were used to quantify functional feeding response, satiation, and gut evacuation rate. Once parameterized, the foraging model was then applied to evaluate effects of prey type, prey density, water temperature, and fish size on daily feeding rate by age-0 (19–70 mm) pallid sturgeon (Scaphirhynchus albus). Prey consumption was positively related to prey density (for fish >30 mm) and water temperature, but negatively related to prey size and the presence of sand substrate. Model evaluation results revealed good agreement between observed estimates of daily consumption and those predicted by the model (r2 = 0.95). Model simulations showed that fish feeding on Chironomidae or Ephemeroptera larvae were able to gain mass, whereas fish feeding solely on zooplankton lost mass under most conditions. By accounting for satiation and digestive processes in addition to handling time and prey density, the model provides realistic estimates of daily food consumption that can prove useful for evaluating rearing conditions for age-0 fishes.

Diet and Condition of Age‐0 Scaphirhynchus Sturgeon: Implications for Shallow‐Water Habitat Restoration

“…Box plot distribution of the modeled 24‐h change in body weight (g) using the Fish Bioenergetics 4.0 application (Deslauriers et al. 2017a) and the Pallid Sturgeon model (Heironimus ) for each of the six length categories of age‐0 sturgeon. For more detail on box plot components and statistical interpretation see caption for Figure .…”

“…Using age‐0 Pallid Sturgeon (41–108 mm), Deslauriers et al. (2017b) found that gut residence time decreased exponentially over time at water temperatures of 14°C, 18°C, and 24°C, which usually resulted in low gut fullness values after 24 h. As such, the prey weight present in the gut at the time of capture likely underestimated 24‐h consumption for most individuals. Despite this, nearly 5% of the fish examined during this study exhibited modeled weight gains; this included individuals from all six length categories.…”

“…Other bioenergetic model inputs included initial body weight at the time of capture, water temperature, energy density of the fish (2,736 J/g: Deslauriers et al. 2017b), and energy density of chironomid prey (2,922 J/g: Deslauriers et al. 2017b).…”

“…2017b), and energy density of chironomid prey (2,922 J/g: Deslauriers et al. 2017b). We used the chironomid energy density because weight was not recorded for each individual prey taxon and chironomids represented over 91% of the prey items consumed.…”

The influence of depth and velocity on age‐0 Scaphirhynchus sturgeon prey consumption: Implications for aquatic habitat restoration

“…To account for fish size, we regressed prey weight with body weight in order to calculate the studentized residuals for prey weight, which were used as the dependent variable in subsequent linear regression analyses at the reach, bend, and trawl spatial scales. Laboratory diet experiments demonstrated that age‐0 pallid sturgeon (41–108 mm) usually had low‐gut fullness values after 24 hr at water temperatures of 14, 18, and 24°C (Deslauriers, Rosburg, & Chipps, ); thus, foraging habitat was calculated by averaging estimates from the day of capture and the previous day, which was then used as the independent variable. We used a Bonferroni correction (0.05/3 = 0.017) to decrease the potential for a Type 1 error from multiple foraging habitat regressions.…”