Comparative
growth performance of diploid and triploid European sea bass over the first
four spawning seasons
A.
Felip, F. Piferrer, S. Zanuy, M. Carrillo-2001
Journal of Fish Biology, 58(1): 76-88
Abstract:
During
their 3-4 first years of life, triploid sea bass Dicentrarchus
labrax grew in a similar fashion to diploids
in fork length but more slowly than diploids (P<
0·05) in body weight, even when the diploids reached
full sexual maturity. However, from 48-53 months of
age triploids exhibited non-significantly higher instantaneous
growth rates, and thus when fish were 4 years or
older, differences in weight with diploids were no
longer apparent, suggesting that triploidy could be of
benefit in the culture of large (>1kg) sea bass.
The condition factor was reduced in both ploidies
during the spawning season which took place in winter
when the temperature was low. These observations
suggest that any growth advantage in triploids, which
were functionally sterile, may be offset by unfavourable
environmental conditions. Thus, the potential gain of
triploid fish, because they do not direct energy to
gonadal growth, could not overcome the effects of low
temperature on somatic growth, which coincided with
the spawning season. This suggests that the low growth
of this species during winter is more a consequence of
low temperature than of the energetic cost associated
with reproduction. On the other hand, the lower
hepatosomatic index in triploid females in contrast to
diploid females might be indicative of the lack of
gonadal oestradiol-mediated hepatic synthesis of vitellogenin.
Also, erythrocyte and haematocrit measurements showed
an increased nuclear and cellular volume in triploids,
but with similar cell numbers to those of diploids,
respectively.
(Consejo Superior de Investigaciones Científicas
(CSIC), Instituto de Acuicultura de Torre la Sal, 12595, Ribera de Cabanes,
Castellón, Spain, tel.: +34 964 319500; fax: +34 964 319509; e-mail:zanuy@iats.csic.es