Effect of stocking density and biofilm on the performance of the pink shrimp Farfantepenaeus paulensis grown in cages in the nursery and live bait production phases
Three experiments were carried out with the objective of analyzing the influence of biofilm and stocking density on the survival and growth of the pink shrimp Farfantepenaeus paulensis in the nursery and growth phases aiming at the production of live baits in cages. The first experiment, lasting 35 days, analyzed the influence of different stocking densities (100, 200, 300, 400 and 500 ind./m2) on the survival and growth of cultured F. paulensis (PL25) post-larvae in cages, inside which artificial substrates were placed for the growth of the biofilm, during the nursery phase. The main microorganisms present in the biofilm that formed on artificial substrates were identified and quantified, as well as the chlorophyll a concentration of this biofilm. The second experiment,in which the influence of the addition of artificial substrates on the survival and growth of F. paulensis post-larvae cultivated in cages in the nursery phase for a period of 35 days was analyzed, was carried out simultaneously to the first, using post-larvae with the same characteristics as the previous experiment. In this experiment, the main microorganisms present in the biofilm were also identified and quantified, in addition to measuring the chlorophyll a concentration. The third experiment, lasting 42 days, analyzed the influence of different stocking densities (50, 100 and 200 ind./m2) on survival, growth and apparent feed conversion of F. paulensis juveniles (initial average weight of 1.04 g) grown in cages to obtain live baits.In experiment 1, a negative relationship was observed between the increase in the stocking density of shrimps and their survival/growth, with 400 ind./m2 being the stocking density recommended for cultivation in cages in the nursery phase. There was also a preference for prawns for the consumption of centric diatoms. In experiment 2, no significant differences were found in shrimp survival and growth when adding artificial substrates to the crop. In experiment 3, a negative relationship was also observed between the increase in the stocking density and the survival/growth of the shrimps, in addition to noticing a tendency to increase the feed conversion of the shrimps with the increase in density. However,it is considered that the results obtained in all the densities tested in this experiment were satisfactory, being possible to use a cultivation strategy where different densities are used to obtain live baits at different times, supplying the demand for a longer period of time. Thus, the technical feasibility of cultivating live F. paulensis baits in cages was demonstrated.