Feeding Dynamics of the Artificially Raised Juvenile Fish of Olive Flounder Paralichthys olivaceus and Ocellate Puffer Takifugu rubripes

Abstract

Feeding activity was investigated for the artificially raised juvenile fish of olive flounder Paralichthys olivaceus and ocellate puffer Takifugu rubripes which incurred hunger trials for various time spans. They were fed brine shrimp Artemia salina nauplii programatically every 6 hours, and the time interval between two sequential gulps (GI) was monitored for about half an hour. Their statistics demonstrated that the flounder's gulping pitch was susceptible to hunger: it varied the fickle attack in the early trials to the periodic one in the late trials with the acceleration of the pitch. On the contrary, the puffer demonstrated a shift in mean GI that didn't correlate to the hunger persistence and stable pitch of any trials, which may mean that the puffer was under the control of some other factor than the stimulus of hunger. The stochastic estimates on the gulping number per mean GI for each trial typified those of either binomial, Poisson's or negative binomial distribution type. The flounder indicated the succession from negative binomial type (via Poisson's) to binomial. The puffer, on the other hand, nearly conveys Poisson's with one exception. These lend support to the explanation between hunger persistence and the gulping mode, which is the focus of our research.