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Caracterização da assistência técnica prestada em unidades produtoras de alevinos na mesorregião Sudeste do ParáCharacterization of technical assistance provided in alevine producing units in the southeast Mesoregion of Pará

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The objective of this pilot work was to perform a study about the main elements of the productive chain of rheophilic fingerlings in the Mesorregião of Southeast of Pará, in Amazon region, raising their main characteristics of productive, installations and management. From the information obtained, questionnaires were applied to fish producers. Were identified 6 fish farms in region. Among the interviewed fish farmers, the average time (years) that work in the production of fingerlings is 10.8 years. Tambaqui, is the native fish most produced besides other round species. The total number of ponds of the region is 239, and 44% used for raising and 56% used in the stocking of breeders (male and female). All producers interviewed monitor water quality, the majority (33%) comes from dams. And regarding sanitary issues, 67% say they do not have problems with diseases in animals. The total number of fish that make up the reproductive is 3,740 animals. We conclude with this pilot study that the fingerlings production units are lacking in technical information, fundamental factor for a change in the system by means of management and planning, ensuring sustainability for the development of fish farming in the region.

The aim of this study was to characterize the limnological parameters and analyse the biological effects of different ponds in a commercial fish farm in the Pará State, Brazil. One pond is designated for fingerling production (N) while the other is for fattening and termination (F). The other three ponds are named supply tanks, from which the water from the Parauapebas River is collected to fill N and F tanks. For the physical–chemical analysis, samples from N and F ponds were collected at a depth of 50 cm close to the water's outlets of the ponds, with the aid of a commercial kit for water analysis. Caenorhabditis elegans nematodes were used for water quality biomonitoring and exposed for 24 h to samples from all five tanks collected during three different days, being assessed through physiological endpoints. During the study, values of transparency and pH were higher in N, both with significant differences between the ponds. The other parameters did not show any differences among them in the different days and times analysed. The results showed that the water quality of N and F ponds is in accordance with the current legislation in the country. Despite being in accordance with legislation and with acceptable metal levels, samples caused toxicity to worms, which indicate that for fish production, a continuous supervision is essential for the success of the activity. Therefore, the limnological variables in relation to biomonitoring should be constantly assessed in fish farm enterprises in order to maintain a more efficient and sustainable productive system.