2019 IN-POND RACEWAY SYSTEM PRODUCTION TRIALS GROWING STOCKER AND FOODSIZE HYBRID CATFISH PLUS TILAPIA
Continuous pond water circulation and destratification, increased control of the raceway production environment and efficient feed conversion ratio (FCR) allows In-Pond Raceway Systems (IPRS) to produce higher fish yields (greater than 15,000 kg/ha) than in conventionally managed catfish ponds (8,000 kg/ha). The goal of this study was to evaluate the fish production and growth performance of hybrid catfish (channel catfish, Ictalurus punctatus, ♀ x blue catfish, I. furcatus, ♂) raised in IPRS and Tilapia (Oreochromis nilotica) grown in cages. Large floating IPRS units, called "growout" units, were placed into two 0.4 ha ponds (B1, B2) and were 64 m3 (4.9 m x 10.7 m x 1.2 m deep) and smaller growout units were placed into two 0.4 ha ponds (B3, B4) and were 45 m3 (3.1 m x 12.2 m x 1.22 m). These units grew fingerlings and stockers to foodsize fish. In addition, "stocker generator" IPRS units (14 m3 - 1.8 m x 5.8 m x 1.30 m) were place into each pond next to the growout units and were used to grow fingerlings to stocker size. Once growout units were harvested, the produced stockers would be harvested and placed into the vacated, adjacent growout unit for growth to foodsize fish. Additionally, a tilapia cage was placed into 2 of the 4 ponds (B2 and B4), were 36 m3 (4.26 m x 7.16 m x 1.20 m) and were used to reduce blue-green algae populations. Each pond had a total of 5 HP of aeration: a 1.5 HP blower for the growout unit, a 1.0 HP blower for the stocker generator unit, a 1.5 HP and 1.0 HP blower for the two in-pond water mover-destratification units.
Hybrid catfish fingerlings for the growout and stocker generator units were stocked in June 2019 and tilapia were stocked in July 2019. Catfish were fed a 35% CP commercial diet twice daily; tilapia were not fed and allowed to graze the phytoplankton flow generated by the growout and stocker IPRS units. Initial tilapia biomass stocked was 506.1 kg in B2 (mean wt 126.5 g) and 460.3 kg in B4 (mean wt 115.07 g). Current biomass estimates for B2 and B4 are 884.4 kg and 620.6 kg respectively. Each l tilapia has gained an average of 94.6 g (B2) and 41.4 g (B4). Catfish sampling at day 61 (Table 1), showed an estimated biomass (growout wt + stocker wt + tilapia wt) of 13,887 kg/ha for B1; 7,022 kg/ha for B2; 5,092 kg/ha for B3 and 14,563 kg/ha for B4. Ponds B1 and B4 have produced more than the average yield of traditional pond production systems already with 90 days to go in the study. Full trial results and enterprise budgets will be presented at the WAS conference.
