Hábitos alimenticios de la trucha arcoiris, Oncorhynchus mykiss (Salmoniformes: Salmonidae), en una quebrada altiandina venezolana / Food habits of the rainbow trout Oncorhynchus mykiss (Salmoniformes: Salmonidae) in an Andean creek of Venezuela

Monthly stomach context samples of rainbow trout from Mucunután stream (Mérida, Venezuela), were collected from, March 1987 to February 1988 (n = 306). The major dietary components were Ephemeroptera, Trichoptera and Diptera. Baetodes sp. was the most important food item based on numerical composition (43 per cent) and frequency of occurrence (88 per cent). When the gravimetric method was used Leptonema sp. was the major dietary component. The diet was not a function of sex. The consumed fauna was more similar to the drift invertebrate fauna than to that of benthos (p < 0.01). The fluctuations on the stomach content paralleled changes of food availability in the environment

Reproducción y talla media de madurez de la trucha Oncorphynchus mykiss (Salmoniformes: Salmonidae) en los Andes venezolanos / Reproduction and average size at maturity of the trout Oncorphynchus mykiss (Salmoniformes: Salmonidae) in the Venezuelan Andes

From January 1987 to February 1988, a total of 393 rainbow trout were captured in a high mountain stream of the Venezuelan Andes (8 degrees 40'N; 71 degrees 5'W). Gonadal development was measured using the Nikolsky method. The mean size for sexual maturation was analyzed with the method of relative frequency of adults and young for each size class. Males reproduced throughout the year, while ripe females were observed only in January (11 per cent). A half of the males was sexually mature at the minimum size of 13.40 cm SL (16.25 for females). All individuals were sexually mature at 26.40 cm (males) and 26.80 cm (females)