Efeitos da natação sustentada no crescimento, na densidade de estocagem e na composição corporal em juvenis de matrinxã, Brycon amazonicus. Aspectos adaptativos e respostas metabólicas.
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Data
2007-02-28Autor
Rojas, Gustavo Alberto Arbeláez
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Fast growth, followed by high stocking density set up
productivity and profitability in aquaculture intensive systems.
These are actually challenges for fish producers and researchers.
Matrinxa, Brycon amazonicus is a Neotropical Characiform that
presents high growth rates, good quality filet, easy adaptation to
artificial diets, and good commercial values. It is a reofilic
species, demands good waters, lives in rapids, shows a biological
plasticity, which make it proper to intensive fish culture. It
presents a good potential to studies on sustained exercise and
under high stocking densities. Therefore, the present study was
focused in the investigation of the swimming effects on growth,
stocking density and body composition as well as in the evaluation
of the metabolic responses and adaptive aspects in juvenile
matrinxa submitted to increasing swimming speeds associated to long
term sustained exercise.
To investigate the effects of swimming speeds, 100 juveniles
of matrinxa with initial average weight and size of 33.33±0.95 g
and 13.44±0.10 cm respectively were transferred to five fiber glass
tanks under water speed of: 0.0; 1.0; 1.5; 2.0 and 2.5 BL/sec (body
length) for 90 days. In a second trial 210 juveniles of matrinxa
with average length and size of 18.44±0.1 g and 12.33±0.5cm
respectively, were divided into two groups. One group was endured
at 1BL/sec and stocked at three densities (88, 176 and 353 fish per
m3) in circular tanks of 250L; a second group of fish were endured
the same density conditions but without exercise for 70 days.
The water speed affected the growth in both trials. In the
first trial the highest growth rates were observed in fish that
swam 1 and 1.5 BL/sec. The average weight was 20% higher than
control and than the highest water speed (2.5 BL/sec). In the
second trial the highest growth and survival were observed in the
exercised group and stocked in the average density. The adaptive
responses biochemical, physiological observed through the
intermediary metabolites in plasma and tissues (liver, white muscle
and red muscle), hematological parameters, ions, hormonal, in the
juveniles of matrinxa under several water speed and several stock
densities indicate that matrinxa is a fish species well responsive
to exercise stimulus, and adapts easily to confinement at high
stock densities.