Reproductive and nursery performance of Kuruma shrimp Penaeus (Marsupenaeus) japonicus Form II: effect of sandy bottom and light intensity in the rearing system

To popularize Kuruma shrimp, Penaeus (Marsupenaeus) japonicus Form II, as a part of the diversification of shrimp farming across India, seed production and growth performance studies were conducted. In experiment I, the reproductive performance of Kuruma shrimp was studied in captive system. In experiment II, a 75-day growth performance study was carried out in 2 × 2 factorial design with and without sandy bottom (S) as the first factor and outdoor units having natural light (O) and indoor units with restricted light (I) as the second factor resulting in four treatments: O+S, O-S, I+S and I-S. The seed production trial recorded an average survival of nauplius to post larvae (PL) 36 ± 12%. In experiment II, the PL (0.02 ± 0.01 g) was stocked at 300 PL m⁻³ to study the effect of sandy bottom and light intensity on growth performance. Results indicated that the highest final body weight (0.63 ± 0.05 g) and survival (80 ± 2.0 %) were registered in outdoor units without (O-S) and with sandy bottom (O+S), respectively. Although no difference (p > 0.05) in body weights were recorded among the treatments, the Kuruma shrimps reared under indoor units with restricted light intensity had lower (p < 0.05) survival (43–45%). The light intensity varied from 459 to 6583 lux in the outdoor system whereas indoor units had only 8–35 lux. A significant interaction effect (p < 0.01) between the sandy bottom and light intensity on food conversion ratio (FCR), coefficient of variation at final weight, CV_abw (%), nitrite-N, TSS and chl–a level were noticed. The Kuruma shrimp reared under outdoor units (O+S and O+S) had well-developed chromatophores; meanwhile, the transparent colouration was recorded in the shrimps reared under restricted light intensity. The present study concludes the potential to rear P. japonicus Form II in tank or lined rearing system without the sandy bottom and scope to develop location-specific culture and seed production techniques.