In recent decades, aquaculture has been one of the highest growing food production sectors from an animal source. The barred sand bass Paralabrax nebulifer, is one of the most important sources of small-scale commercial fisheries which represents the largest economic stream for cooperatives in Baja California Sur. Being a species of great fishery importance, it can be said that this species can also be of aquacultural importance. Being temperature a primary factor in the survival and growth of many aquatic organisms, the intention is to evaluate and determine an adequate temperature at which a better survival of embryos during incubation of the barred sand bass can be observed.
Eggs were obtained by voluntary spawning, the incubation of embryos were carried out at controlled water temperatures (23, 25, 27, and 29 ºC). To determine the optimal incubation temperature a system was constructed consisting of 4 incubators each at different temperatures. Four steel inserts were used to attain the water temperature of 23 °C, this was regulated through the control of ambient temperature with the help of an air-conditioning mini-Split in automatic mode. We used resistance immersion heaters to increase the temperature to 25, 27, and 29 °C. The incubators were maintained in constant aeration for a better dispersion of temperature throughout the water. The embryos were randomly selected and transferred in 24-well microtiter plates (one embryo per well). Each well was filled with 3.0 ml UV-sterilized sea water and were taken to the incubation area, each temperature treatment was replicated three times. During the incubation, the photoperiod (13:11 L:O) was kept up with neon lights. To ensure accurate measurements of the time intervals, the microtiter plates were examined every 6 hours to determine the hatching status and health of the embryos and larvae, for which a dissecting microscope was used. To obtain the LD50 (average lethal dose), after which 50% of the organisms died, a binary logistic regression “probit” was applied using the Minitab program.
According to survival probality program the LD50 was 22.4 °C (Figure). This indicates that 50% of the embryos survived to this temperature. The incubation period is particularly sensitive to extreme temperatures within the tested temperature range.
From a probabilistic perspective, the binary logistic model revels that at 22.4 degrees, an organism has a 50% probability of survival.