Abstract

The rocky fish Graus nigra (Kyphosidae) commonly named mulata, is an important resource for artisanal and recreational fishery off northern Chile, but unfortunately shows show signs of depletion in terms of abundance and size, so have been developing initiatives to its aquaculture with repopulation potential actions. In this paper we report a study of the thermal tolerances in the early stages of development. Fertilized eggs of Graus nigra (Kyphosidae) were obtained from captive adults and incubated at different temperatures between 12 and 22 degrees C to study the effect on the development rate, hatching success and survival of early-stages until the total absorption of the yolk. The highest percentage of hatched eggs occurred between 14 and 18 degrees C. The highest survival was observed between 16 and 18 degrees C. Yolk exhaustion was observed after 128.3 h at 12 degrees C, 48.6 h at 18 degrees C and 51.2 h at 20 degrees C. A significant reduction in the larvae sizes was observed after 28 to 30 hours post-hatching at 18 degrees C (4.32 to 2.75 mm) and 20 degrees C (4.18 to 2.99 mm). The incubation experiments suggest that the optimal temperature for maximizing the eggs hatching success, growth and survival of early larvae is 16 degrees C, which is coincident with the temperature of maximum spawning intensity in the adult broodstock.