Influência dos fatores ambientais no crescimento da tilápia do Nilo (Oreochromis niloticus) em viveiros escavados no brejo paraibano.

Abstract

Of different production systems used in fish farming, fish culture in ponds and earth dams, is the most widespread in the world. Studies of growth curves by adjusting the weight prediction equations based on age of the animal has been important because they can summarize information from a data series in a small number of important biologically interpretable parameters, for example, weather . The objective of this work to analyze the nonlinear models to describe the growth of Nile tilapia in ponds associated with environmental factors and limnology in Areia - PB. The experiment was performed at the Fish Culture Centre of Agrarian Sciences, Federal University of Paraiba in the municipality of Areia - PB during the period from May 20 to November 4, 2009.10 ponds were used in natural terrain, with an area of250m2 and with dimensions of 10m (width) X 25m (length) x lm (depth) with water supply and drainage independent. The ponds were stocked with fingerlings of Nile tilapia (Oreochromis niloticus) strain Chitralada, sexually reverted to male, with average initial weight of 12.38 ± 1.21 g and average total length of 11.51 ± 0.97 cm. Initially the water monitoring was conducted biweekly, with the last four monitoring done at intervals of 28 days between them. Background information on the behavior of the main meteorological variables during the creation of fish by monitoring the following parameters: temperature, rainfall and sunshine. Estimates of the parameters was done using non-linear regressions, the NLIN procedure of SAS (Statistical Analysis System), using the modified method of Grauss-Newton. To choose the best models, we used the coefficient of determination (R2) and the graphic distribution of residuals. The correlation between meteorological data and the weight, and physical and chemical parameters of water were analyzed using parametric Pearson (r) using the statistical program SAS (2003). The variations in air temperature observed over the 180 days of the growing period for the whole period, the values of average temperature, monthly maximum and minimum are located in the range of 18.5 ° C (minimum) in August to 29.1 0 C (maximum ). The total rainfall during the 180 days of the experiment in the region where the nurseries were installed was 1044.2 mm. According to the values found the month of November was the period with the highest average hours of sunshine, totaling 227.5 hours per month. The analysis of Pearson Correlation (r) indicated a positive correlation of temperature and body weight (0.43), the water temperature. Among the models studied, which showed a better fit for the growth of tilapia under the terms of the Brejo the quadratic model was logarithmic.