Preliminary Assessment of Growth of FlatfishParalichthys adspersus Juveniles in Different Culture Systems Lili Carrera, Noemí Cota, Angélica Castro, Melissa Montes and Jorge Tam FIGURE 1. Juvenile culture of flatfishParalichthys adspersus in a static system. In Peru, aquaculture sector Peruvian cuisine. Additionally, policy is driven by the National in recent years there has been a Aquaculture Development decrease in the volume of flatfish Plan 2010-2021 (DS N ° fisheries catches. Some years 001-2010-PRODUCE) that ago flatfish reproduction and guides research to strengthen culture were developed under the value chain of consolidated captive conditions in public and emerging species, and and private institutions, which promote and execute aquaculture conducted experimental research diversification with native and production at a commercial species that have market pilot level to achieve sustained potential and can become production of the species. the basis for major industries. However, there continues to be The National Program problems of quality, quantity and for Aquaculture Science, growth of juveniles to support Technological Development grow-out operations. and Innovation 2013-2021 (RP FIGURE 2. Juvenile culture of flatfish Paralichthys adspersus in a recirculating The Peruvian Marine No. 064-2013-CONCYTEC-P) system at the IMARPE laboratory. Research Institute (IMARPE) established priorities for has been conducting research on aquaculture research and development. One research line is oriented reproduction, larval development and juvenile rearing of P. adspersus to developing a culture technique for the flatfish Paralichthys in the laboratory. In addition, and with great effort, Pacific Deep adspersus and transferring the technology to the commercial sector. Frozen SA (PDFSA), a commercial producer and marketer of quality The focus is on improving the techniques for reproduction, larval hydrobiological products has also initiated the culture of marine development and production of quality fingerlings. fish in its aquaculture facility in Huarmey (Ancash, Peru), including Paralichthys adspersus is distributed from Paita, Peru, to commercial production of flatfish. Lota and Juan Fernández Islands in Chile (Acuña and Cid 1995, In this context, the objective of the study reported here was to Chirichigno 1998, Sielfeld et al. 2003). It is a species of commercial compare the effect of different culture systems on growth of juvenile importance for the national market because it is a valuable fish in P. adspersus. 44 SEPTEMBER 2017 • WORLD AQUACULTURE • WWW.WAS.ORG FIGURE 3. Biometric sampling of juvenile Paralichthys adspersus in a recirculating system at the IMARPE laboratory. FIGURE 4. Juvenile culture of Paralichthys adspersus in recirculating system FIGURE 5. Biometric sampling of Paralichthys adspersus in a recirculating at commercial pilot level at Pacific Deep Frozen S.A. aquaculture system at commercial pilot level at Pacific Deep Frozen S.A. Broodstock Management The management and protocol of larval and post-larval feeding are The Fish Culture Laboratory of the Alexander von Humboldt summarized in Table 1. Aquaculture Research Center of IMARPE has a stock of P. adspersus At PDFSA, larvae were also grown in static systems in 1000-L breeders in two recirculating aquaculture systems (RAS) (Carrera fiberglass tanks, with seawater (35 UPS) filtered and sterilized by UV et al. 2013). Gonadal maturation was induced through application radiation. Photoperiod was controlled with an automatic timer and set of a regular photoperiod (12 light hours and 12 dark hours) and a to 12 h light and 12 h dark. The management and protocol of larval and temperature of 16.7 ± 0.8 C. For spawning, a mature female was post-larval feeding are summarized in Table 2. selected with an average oocyte diameter > 500 μm and two males with sperm motility greater than 50 percent. A synthetic analogue of Juvenile Culture gonadotropin-releasing hormone (buserelin acetate, Conceptase®) Juveniles were reared in three types of systems: 1) a static system was given to the female by intraperitoneal injection at 0.1 mL/kg (SS) from 110 to 194 DPH (~ 1 kg/m2), 2) a RAS in the Fish Culture and, in the case of the two males, 0.1 mL/kg fish by intramuscular Laboratory of IMARPE (RAS-L) from 103 to 194 DPH (~ 2 kg/ injection. Broodstock management and spawning technique carried m2) and 3) a RAS at a commercial pilot level in the Culture Center out at PDFSA was similar to that at IMARPE, also in RAS. of PDFSA (RAS-C) from 105 to 196 DPH, where juveniles were maintained at a higher density (~ 4 kg/m2). In all systems, water filtered Larval Development through 1 μm mesh and sterilized by UV radiation was used. At IMARPE, larvae were cultured in static systems from 1 day At IMARPE, in the SS, juveniles were held in eight fiberglass post hatch (DPH) in 150-L fiberglass tanks with seawater (35 UPS) tanks of 500-L capacity (Fig. 1). A daily water exchange of 80 to 100 filtered and sterilized by ultraviolet (UV) radiation, with constant percent was applied and biometric samples were collected every fifteen aeration and illumination between 905 and 1245 lux. Continuous light days. In the RAS-L, individuals were kept in two 700-L fiberglass was applied for the first ten days of culture and then a photoperiod of tanks and the components of the system included a biofilter, UV light 12 h light and 12 h dark was applied until the end of the experiment. (CONTINUED ON PAGE 46) WWW.WAS.ORG • WORLD AQUACULTURE • SEPTEMBER 2017 45 TABLE 1. Larval and post-larval culture protocol of the flatfishParalichthys adspersus under laboratory conditions at IMARPE. DPH Water FEEDING Bottom Cleaning exchange(%) Microalgae Rotifers Artemia sp. Microdiet siphoning of the tank Larval Phase 1 - 5 0 x x 6 50 x x 7 - 10 0 x x 11 10 x x 12 - 14 15 x x 15 - 20 20 x x x x 21 - 23 50 x x x x x 24 - 27 100 x x x x x 28 - 40 100 x x x Post-larval Phase 40 - 50 100 x x x x 50 - 60 100 x x x TABLE 2. Larval and post-larval culture in Paralichthys adspersus at PDFSA. DPH Water FEEDING Bottom Cleaning exchange(%) Microalgae Rotifers Artemia sp. Microdiet siphoning of the tank Larval Phase 1-3 0 x x 4-10 10 x x 11-14 25 x x 15 25 x x 16-19 30 x x 20-23 40 x x x x 24-26 50 x x x x x 27 70 x x x x 28-35 100 x x x x Post-larval Phase 35-50 100 x x x x 50-60 100 x x x water sterilizer, heat pump and water pump (Fig. 2). Sampling was C and was relatively stable in all systems, with the greatest variation performed monthly (Fig. 3) and the daily water exchange rate was in the static system (Fig. 6). Average temperatures were 20.5 ± 1.0 C, 10-20 percent. 21.1 ± 1.1 C and 19.8 ± 0.7 C in SS, RAS-L and RAS-C, respectively. Feed was supplied to apparent satiety or ad libitum with extruded Thiese temperatures are greater than those (14.9-17.3 C) used by pellets1 from 0.84 to 2.1 mm particle size. Feed was provided four Silva (2001), whose flatfishes reached the commercial size of 1 kg times per day, between 2 and 4 percent of total biomass. In addition, in 3.5 years. Wasielesky et al. (1998) observed that juveniles of P. physicochemical parameters were monitored daily. orbignyanus accepted feed at a temperature range of 10-27 C, with an At PDFSA, commercial juvenile culture was carried out in optimum temperature range in the pre-fattening period of 18-21 C. It is six fiberglass tanks of 1500 L coupled to two RAS (Fig. 4). These important to determine species-specific optimal temperature ranges at systems consisted of a sedimentation tank, sand filter, biological filter, each stage of the life cycle. degasser and UV sterilizer. For maintenance of the system, water Mean values of dissolved oxygen concentration were 7.7 ± 0.6 was replaced at 15 to 20 percent/d, with biweekly sampling during mg/L, 6.2 ± 0.6 mg/L and 5.7 ± 1.1 mg/L in SS, RASL and RAS-C, the culture period (Fig. 5). Extruded pellets of 1-2 mm particle size respectively. Average values of pH were 7.7 ± 0.3 and 7.3 ± 0.7, in the (Otohime1, Aquaxcel®2 and Nicovita3) was supplied ad libitum three SS and RAS-L, respectively; this parameter was not measured in the to six times, depending on consumption. RAS-C. Water temperature in all systems was maintained between 19-22 In all culture systems, total length (cm) and weight (g) were 46 SEPTEMBER 2017 • WORLD AQUACULTURE • WWW.WAS.ORG measured to obtain the specific growth al. 2001) and open flow in Senegalese sole rate, condition factor (Innis 1990), (Sánchez et al. 2010). The present research coefficient of variation, calculated evaluated the growth of P. adspersus juve- according to Merino et al. (2007). niles in different culture systems, obtaining a greater growth in recirculating systems Results and Discussion than in a static system. Silva and Oliva The final total length and weight of (2010) obtained an average size of 8.9 cm juveniles in the two recirculating systems and a weight and 9.5 g in juvenile culture was similar to each other and greater than of P. adspersus. Growth of P. adspersus that in the static system (Table 3). The juveniles was less than that of turbot, which specific growth rate of juvenile flatfish reached 9-10 g in 90-100 DPH (Stoss et al. cultured in the RAS-L was greater than 2004).