Constraints on seedstock production in eighth generation domesticated Penaeus monodon broodstock Stuart J. Arnold a, ⁎, Greg J. Coman a , Mauricio Emerenciano b a CSIRO Food Futures National Research Flagship, CSIRO Marine and Atmospheric Research, Bribie Island, Brisbane, QLD 4507, Australia b Universidade Estadual de Santa Catarina (UDESC), Laguna, Santa Catarina, Brazil abstract article info Article history: Received 11 April 2013 Received in revised form 7 June 2013 Accepted 23 June 2013 Available online 3 July 2013 Keywords: Ovary development Maturation Spawning Fertility Hatch Embryo development Improving the seedstock production of domesticated broodstock remains a high priority for the black tiger shrimp, Penaeus monodon, farming industry in Australia and other shrimp farming regions. In this study, wild-caught (W) broodstock were reciprocally crossed with eighth generation (domesticated-selected) broodstock (G8) and the reproductive performance was evaluated to identify the key parameters and gender influences currently constraining seedstock production from domesticated broodstock. Nauplii production was significantly lower in G8 than W broodstock and differences in nauplii production were found to be more influenced by the female than the male origin of the broodstock. The main constraints on nauplii pro- duction in G8 females were inferior egg hatch rates and egg production. The percentage of eggs that hatched was 44% lower in G8 females (24.3%) than W females (43.7%). The total number of eggs per spawning was 25% lower in G8 females (413,000) than W females (552,000) and the relative number of eggs spawned per gram female body weight was 37% lower in G8 females (2476) than W females (3909). In addition, a significantly higher percentage of the W females (70.8 ± 5.7%) matured to ovary stage 4 than G8 females (2.1 ± 2.1%). But there was no difference in the percentage of females that developed stage 3 ovaries or the percentage of females that spawned. There was no difference in the total number of sperm per spermatophore or sperm quality (based on acrosome reaction) between W and G8 males, which may explain the lack of any male effect on fertilization. Our results suggest that female broodstock quality may often explain the low nauplii output of domesticated broodstock. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. 1. Introduction The production benefits of domesticated-selected Penaeus monodon stocks (over wild-progeny stocks) have been demonstrated in terms of superior growth and feed utilization (Glencross et al., 2013), improved harvest yields from commercial ponds (Preston et al., 2009, 2010) and lower viral loads (Preston et al., 2010). And while reproductive performance of domesticated broodstock has also improved over early generations (Coman et al., 2013; Preston et al., 2009), Australian experiences have still often found that the seedstock production from such domesticated broodstock is less efficient than from wild broodstock and below levels desirable for commercial production. Considering the high costs associated with maintaining broodstock and producing nauplii, improvements in the reproductive output of domesticated broodstock will greatly improve the cost-effectiveness of domesticated seedstock production. There are numerous variables that influence nauplii production in penaeid broodstock. The main female influences are ovary development (Peixoto et al., 2005) and egg quantity and quality (Cahu et al., 1995; Coman et al., 2007; Palacios et al., 1998; Xu et al., 1994), while the main male influences include spermatophore quality and sperm quantity and quality (Arnold et al., 2012; Pongtippatee et al., 2007; Pratoomchat et al., 1993). In addition, problems with mating are influenced by either gender (Marsden, 2008). One reproductive problem with many domesticated P. monodon stocks is the lower hatch rates of eggs (Coman et al., 2005, 2007; Hall et al., 2003; Makinouchi and Hirata, 1995; Preston et al., 2009; Primavera and Posadas, 1981) than commonly reported for wild stocks (Hall et al., 2003; Liao and Huang, 1972; Marsden, 2008; Primavera and Caballero, 1992). Poor hatch rates have been associated with both the male (Hall et al., 2003; Makinouchi and Hirata, 1995) and female P. monodon domesticated broodstock (Primavera and Posadas, 1981), and Marsden (2008) suggested that lower hatch rates could be partially explained by the lower mating rates contributed by both genders from domesticated P. monodon. In other studies, repro- ductive output has been constrained by inferior ovary maturation, spawning and egg production in domesticated females compared with wild females (Coman et al., 2006; Hall et al., 2003; Menasveta et al., 1993; Peixoto et al., 2005). These previous reports demonstrate that reproductive issues in domesticated P. monodon can be multifaceted. Therefore, to better understand the poorer reproductive performance of Aquaculture 410–411 (2013) 95–100 ⁎ Corresponding author. Tel.: +61 7 3410 3102. E-mail address: Stuart.Arnold@csiro.au (S.J. Arnold). 0044-8486/$ – see front matter. Crown Copyright © 2013 Published by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.aquaculture.2013.06.023 Contents lists available at ScienceDirect Aquaculture journal homepage: www.elsevier.com/locate/aqua-online