Physiologically based limits to food consumption, and individual-based modeling of foraging and growth of larval fishes

Abstract

Larval fish individual-based models (IBMs) that include foraging subroutines to depict prey encounter, capture and ingestion often include static parameters (e.g. a maximum feeding rate, C MAX ) to prevent 'overfeeding' and unrealistically high growth rates. We formulated 2 physiologically based approaches to limit food consumption rate (C ) based on gut capacity and evacuation rate (GER) and feeding rate-dependent changes in assimilation efficiency (AE ). Parameterizations were based on data reported for a variety of marine and freshwater teleost larvae. The effects of the 3 approaches (C MAX , GER and AE ) on feeding and growth were compared in IBM simulations of 12 mm larval sprat Sprattus sprattus L. foraging within homogenous and patchy prey fields. Prey concentrations for maximum growth were between 5 and 10 copepodites l -1 , similar to thresholds determined for successful foraging by larvae of other marine fish species in laboratory studies. The AE limit allowed larvae to exploit prey patches (to consume prey at higher rates but at lower AEs). In simulations using prey concentrations observed in productive areas of the southern North Sea (e.g. 21.0 copepodites l -1 ), larvae benefited little (benefited much) from adopting this patch feeding strategy when patch prey concentrations were ≤ 2-fold (≥ 5-fold) those outside of the patches. At ≤10 copepodites l -1 , foraging model predictions of C were close to limits imposed by C MAX , GER and AE methods. In patches (20 to 40 copepodites l -1 ), foraging model estimates of C were 2-to 4-fold greater than the highest (AEbased) limit. Physiological-based limits to C are recommended for larval fish IBMs and will be necessary to adequately assess the impacts of prey patchiness on survival and growth of marine fish larvae.

Predation of threespine stickleback (Gasterosteus aculeatus) on the eggs of Atlantic herring (Clupea harengus) in a Baltic Sea lagoon

“…As in our study, most investigations are thereby based on a single-meal approach ignoring the rather continuous feeding behavior of most predatory fish species (Bromley 1994), including threespine stickleback (Allen and Wootton 1984). However, Peck and Daewel (2007) concluded that a continuous feeding of larval and early juvenile fish might cause a 2-5-fold increase in the gastric evacuation compared to a single-meal-based feeding experiment. Since the M PS values are directly proportional to the gastric evacuation rates, our single-meal approach might underestimate the predation effect.…”

“…4). An even higher predation rate could be expected for an exposure time of 7 d, which is the mean egg development time at 15uC applied during the experiment (Klinkhardt 1986;Peck et al 2012). However, we assume the mortality to be lower during the peak spawning period, which is characterized by lower temperatures, higher egg concentrations, and lower stickleback abundances (Table 1).…”

“…where M PS describes the mortality of herring spawn due to predation by sticklebacks (%), N is the abundance of sticklebacks on the spawning ground (n m 22 ), DP is the development time of herring eggs at a certain temperature according to Peck et al (2012) approximated to the number of days, C HS describes the mean in situ egg concentration (g wet weight m 22 ), and DC HS is defined as the mean daily herring egg consumption of a single stickleback (g wet weight per day). DC HS was estimated through combining the amount of herring eggs found in the in situ stickleback stomachs with a gastric evacuation rate from the feeding experiments.…”

Temporal variability of larval growth, size, stage duration and recruitment of a wrasse, <i>Coris julis</i> (Pisces: Labridae), from the Azores

“…However, this was not the case in our study, as temperature explained no or little variation in age-corrected growth. Nevertheless, growth must be sustained with adequate food, or higher metabolic rates associated with warmer water may increase susceptibility to starvation (Houde, 1989;Peck and Daewel, 2007). Stronger competition for food (Agnew et al, 2000), cannibalistic behaviour (Woods and Barkmann, 1995) and faster yolk absorption with lower conversion efficiency of yolk to tissues (Heming, 1982) may also be expected at high temperatures, when metabolism and energy requirements are higher.…”

A coupled plankton–anchovy population dynamics model assessing nonlinear controls of anchovy and gelatinous biomass in the Black Sea

“…The utilization efficiency parameter, ε A , was set to 0.5 (Table 5). It does not vary with body size and feeding conditions and therefore does not constrain the weight growth under high food conditions (Rose et al 1999, Peck & Daewel 2007.…”