Effects of consecutive spawning on offspring quality in the freshwater crayfish Cherax quadricarinatus (Decapoda, Parastacidae).

CAROLINA TROPEA; MAGDALENA ARIAS; NATALIA S. CALVO; LAURA S. LÓPEZ GRECO

Atenas

Congreso; The Crustacean Society Summer Meeting; 2012

Introduction Consecutive spawning was demonstrated to negatively affect certain parameters of offspring quality in decapod crustaceans, such as fecundity, spawning rate and larval survival [1; 2; 4]. Cherax quadricarinatus is a freshwater crayfish that is cultured with commercial purposes in many tropical and subtropical countries. Females can spawn 3 to 5 times during the reproductive cycle [3]. The objective of the present study was to evaluate the possible influence of consecutive spawning on the offspring quality of the species.   Materials and Methods Females (50-70 g) were mated with males (70-90 g) and the following variables were measured for the first and second spawns: - production variables per female: actual fecundity (number of juveniles III/female), relative actual fecundity (number of juveniles III/female weight), spawning rate, successful spawning rate and reproductive output (weight of the brood/female weight); - morphological variables of the juveniles III: body weight, postorbital cephalothorax length, relative weight of the pleon, relative weight of the hepatopancreas; - juveniles? survival at the end of a 30 day-period following their independence from the mother.  Results The 80% of the initial number of females spawned once (n=12), while 40% spawned twice (n=6). All the first spawns but only half of the second spawns successfully hatched. Hence, the spawning rate and successful spawning rate tended to be lower for the second spawns with respect to the first ones, although no statistical differences were found. The rest of the variables measured were similar between the first and second spawns. Discussion This is the first report of a certain deterioration of some production variables with consecutive spawning in the freshwater crayfish C. quadricarinatus. The results suggest the need to carefully control in hatcheries and improve during the reproductive season of the species those factors that also influence offspring quality, such as broodstock nutrition, as a way to compensate the possible ?energetic exhaustion? of the females. References 1. Kobayashi, S., 2001. Benthos Res. 56, 1-7. 2. Marsden, G.E., McGuren, J., Hansford, S.W., Burke, M.J., 1997. Aquaculture 149, 145-156. 3. Masser, M.P., Rouse, D.B., 1997. Australian red claw crayfish. 8 pp. 4. Wu, X., Cheng, Y., Zeng, C., Wang, C., Cui, Z., 2010. Aquaculture 303, 94-100. Financial support: PICT 2007- 01187, CONICET (PIP 129) and UBACYT (projects X458 and 2011-2014.