Otolith increment widths and lipid contents during starvation and recovery feeding in adult Ambassis vachelli (Richardson)

Abstract

Adult Ambassis vachelli (Richardson) were used to test the effects of starvation and recovery feeding on otolith increment widths, Fulton's K and levels of carcass and viscera lipid. Three laboratory treatments (fed throughout the experiment; fed for 41 days then starved for 37 days, starved for 41 days then fed for 37 days), were compared. Fish were also collected from the field throughout the experiment to assess the natural fluctuations of variables examined in this study. Starvation and recovery induced significant changes in Fulton's K and lipid contents and were permanently recorded in the widths of otolith increments. Although changes in increment widths did occur in a predictable way, changes in increment widths due to starvation and recovery feeding were not of the same magnitude as changes in lipid levels. Thus, the widths of otolith increments may be determined by feeding regime, but increment widths vary in a more conservative fashion than do lipid levels. Increment widths in field fish showed similar variations compared to fish in the laboratory. Condition and lipid levels, as well as results from a canonical discriminant analysis, indicated that field fish were exposed to intermediate feeding environments, compared to the fed and starved regimes in the laboratory.