Growth of the leopard grouper, Myeteroperca rosacea (Streets, 1877), was analyzed in its natural habitat. Age determination was based on the reading of otoliths, and the method was validated under three main criteria: (1) proportionality, (2) seasonality, and (3) concordance with another method. Otolith growth is proportional to organism growth, with a slight degree of allometry, and the otolith registers the growth of the individual, even at advanced ages. The opaque growth zone in the otolith is deposited once a year, between July and October. Thus, taken together, one opaque and one hyaline mark represent an annual cycle. Back-calculated lengths-at-age agreed reasonably well with observed lengths-at-age at the time of capture, considering that back-calculated lengths represent an exact age (birthday), and observed lengths are taken at an intermediate age between birthdays. Fish length and otolith age data were fitted to the von Bertalanffy growth function by two methods: (1) linear regression (Ford-Walford and Beverton), using transformed data, and (2) nonlinear regression, by iteration. Although the nonlinear regression gave a fit with unbiased error, parameters resulting from linear regressions had a better biological meaning for the species. The resulting parameters were compared with those reported for other species of the family Serranidae.

A total of 198 digestive tracts of ocean whitefish (Caulolatilus princeps, Jenyns, 1842) were examined from monthly catches, from February 1986 to January 1987. Using four indices (numeric, volumetric, frequency of occurrence and relative importance), the food components of the trophic spectrum were determined and categorized. This was made up of five major taxa: annelids, molluscs, crustaceans, echinoderms and fishes. The spectrum is dominated, most of the year, by the ostracod Conchoecia pacifìca, along with other secondary food items like hyperiid amphipods (Vibilia sp.), euphausiids (Nycthiphanes simplex), galatheids (Pleuroncodes planipes), pteropod molluscs (Hyaloselix striata, Clio piramidata), cephalopods (Loligo opalescens) and fishes, and with a range of incidental food items, like gammarids (Ampheliscidae), crab larvae (Callinectes sp.), isopods, penaeids, thalassinoideans, small gastropods, polychaetes and echinoderms. There are no significant differences in the spectra from males and females (Wilcoxon’s test, P = 0.05). The number of food components in the diet seems to increase with length. The most intensive feeding takes place between the end of the reproductive period and its start. In conclusion, the ocean whitefish is a passive predatory teleost, that feeds mainly during daylight hours upon organisms associated with the sea floor.