EFFECT OF TEMPERATURE ON HATCHING AND GROWTH OF CUBAN GAR (Atractosteus tristoechus) LARVAE

Abstract

Hatching success, growth, development and survival of Cuban gar (Atractosteus tristoechus) larvae were examined at different temperatures (26, 28 and 30 ^ºC) up to 18 days after hatching (DAH). The time to hatching was inversely related to the incubation temperature (87, 100 and 111 h). Larval survival at the time of hatching was significantly lower at 30 ^oC (50.3 %), coinciding with the highest larval mortality (30.2 %). Growth rates were 1.75 mmd^-1 -10.4 % d^-1 at 26 ^ºC,1.30 mm d^-1 -10.2 % d^-1-1 at 28 ^ºC and 1.40 mm d^-1 -10 % d ^-1 at 30 ^ºC. Three similar critical periods were identified: 0-6, 7-11 and 12-18 DAH. During the first period, a similar increase in weight and a significant increase in total length occurred, mainly at 30 ^ºC, indicating a more efficient reconversion of the yolk reserves. Later, growth was equally slow, corresponding with the transitional period from endogenous to exogenous feeding, indicating a similar physiologic pattern regardless of incubation temperature. Weight and length increased during the last period, with the greatest increase at 26 ^ºC in contrast with the lowest gain at 30 ^ºC. The inflexion points of many morphometric characters and the developmental stages accelerated with the increasing temperature. Although it was impossible to determine the optimal temperature, it was evident that 26 ^ºC favored hatching success and larval growth.