EFFECT OF TEMPERATURE ON GROWTH OF THE FRESHWATER CRAYFISH Cherax quadricarinatus

CAROLINA TROPEA; LAURA S. LÓPEZ GRECO*

VERACRUZ, MEXICO

Congreso; WAS AQUACULTURE 2009; 2009

World AQUACULTURE SOCIETY

Effect of temperature on growth of the freshwater crayfish Cherax quadricarinatus Carolina Tropea; Laura S. López Greco* Dept. of Biodiversity and Experimental Biology, FCEyN, University of Buenos Aires Ciudad Univ. C1428EHA, Buenos Aires, Argentina. laura@bg.fcen.uba.ar Cherax quadricarinatus is a freshwater crayfish native of Australia, which is cultured with commercial purposes. The culture strategies are aimed at the production of monosex all male populations and the increase of females somatic growth, in order to obtain greater meat yields. Temperature is an important abiotic factor that modulates many aspects of this species biology and according to this, the objective of the present study is to analyze the effect of a temperature higher than the one commonly used in culture on both males and females growth. Juveniles from both sexes were exposed to one of the following treatments: high temperature (30±1ºC) and normal culture temperature (27±1ºC). The animals were weighted and sexed twice a month, during 360 days. At the end of the experiment all animals were dissected and the gonads were processed for histological analysis. Temperature did not affect the growth of the females but it could have some effect over gonad maturation since 3 females exposed to high temperature (from a total of 25) spawned normal oocytes. With respect to males, growth increment (GI) was statistically different (p<0.05) between treatments from day 270, being higher for those exposed to normal temperature (Fig. 1).When comparing between sexes, the approximate weight from which males growth became larger than females growth could be determined (15 grams; Fig. 2). From this size, secondary sexual characters of males, such as the “red patch” and the claws “broadening”, become far evident. This is the first study that evaluates the effect of temperature on growth of C. quadricarinatus from the juvenile stage to the sexually mature stage. It was demonstrated that high temperature tends to affect negatively the growth of males, and that it could accelerate ovarian maturation in females. Both results are important to optimize commercial exploitation of this species and they will be far studied with the histological analysis of the gonads. FIGURE 1. Effect of temperature on growth increment of C. quadricarinatus males along a 360 days period. FIGURE 2. Comparative curves of C. quadricarinatus males and females weight exposed to normal culture temperature along a 360 days period. Financial support: UBACYT X458; PIP 112-200801-00129 and PICT 2007 area: PESCA 01187. We thank Lic. Carlos Anselmi, Las Golondrinas Farm, Argentina, for supplying the crayfishes.