Optimization of Stocking Ratios of the GIFT Optimization of Stocking Ratios of the GIFT Strain of Nile Tilapia ( Oreochromis niloticus Oreochromis niloticus ) ) Strain of Nile Tilapia ( and Freshwater Prawn ( Macrobrachium Macrobrachium and Freshwater Prawn ( rosenbergii ) in a Periphyton ) in a Periphyton- -Based System Based System rosenbergii 1 , M. A. Wahab and M. S. Haq M. S. Uddin, M. E. Azim 1 M. S. Uddin, M. E. Azim , M. A. Wahab and M. S. Haq Faculty of Fisheries Faculty of Fisheries Bangladesh Agricultural University (BAU) Bangladesh Agricultural University (BAU) 1 Laboratory of Applied Ecological Engineering 1 Laboratory of Applied Ecological Engineering Saitama University, Japan Saitama University, Japan
significance of research significance of research ! Fisheries and aquaculture are vital to the national economy in ! Fisheries and aquaculture are vital to the national economy in terms of nutrition, income, employment generation and foreign terms of nutrition, income, employment generation and foreign exchange earning exchange earning ! Periphyton ! Periphyton- -based aquaculture system is a modern concept and based aquaculture system is a modern concept and eco- -friendly approach in closed water aquaculture friendly approach in closed water aquaculture eco ! Periphyton is a preferable natural food for Indian major carps, ! Periphyton is a preferable natural food for Indian major carps, tilapia and freshwater prawn ( Macrobrachium rosenbergii Macrobrachium rosenbergii ) ) tilapia and freshwater prawn ( ! Periphyton ! Periphyton- -based aquaculture systems offer the possibilities of based aquaculture systems offer the possibilities of increasing both primary production and food availability for fish, h, increasing both primary production and food availability for fis which is an important consideration of its use in resource- - which is an important consideration of its use in resource constrained countries constrained countries ! Pond trials demonstrated that fish production from ponds with ! Pond trials demonstrated that fish production from ponds with substrates (for periphyton) was higher than that of substrate free substrates (for periphyton) was higher than that of substrate fr ee ponds ponds
(cont’d) ! Tilapia is known to be a periphyton grazer in recent years and ! Tilapia is known to be a periphyton grazer in recent years and grew well in substrate- -based systems based systems grew well in substrate ! Monoculture ponds with freshwater prawn might have been ! Monoculture ponds with freshwater prawn might have been experienced with excessive algal blooms leading to water quality experienced with excessive algal blooms leading to water quality deterioration deterioration ! Tilapia may be able to potentially utilize the remaining food ! Tilapia may be able to potentially utilize the remaining food resources in freshwater prawn culture ponds resources in freshwater prawn culture ponds ! Therefore, it may be advantageous to culture tilapia and ! Therefore, it may be advantageous to culture tilapia and freshwater prawn together in periphyton- -based systems based systems freshwater prawn together in periphyton ! However, the optimum stocking combination of these two ! However, the optimum stocking combination of these two species is unknown, especially in this new system species is unknown, especially in this new system
objectives objectives ! To test the technical viability of a periphyton ! To test the technical viability of a periphyton based polyculture with GIFT and freshwater based polyculture with GIFT and freshwater prawn prawn ! To compare yields from different stocking ratios ! To compare yields from different stocking ratios of GIFT and freshwater prawn in polyculture as of GIFT and freshwater prawn in polyculture as well as monoculture of either species in substrate- - well as monoculture of either species in substrate based system based system
GI FT GI FT PRAWN PRAWN
research design research design " Site: Farmers’ ponds in rural area of Mymensingh, Bangladesh " Pond facility: 15 earthen ponds of size ranging from 200 to 300 m 2 with depths 1.5 m " Culture period: Jul- Dec 2003, 125 days " Design Treatments T 1 T 2 T 3 T 4 T 5 100 75 50 25 0 % 0 25 50 75 100 20,000 15,000 10,000 5,000 0 density (ha -1 ) 0 5,000 10,000 15,000 20,000
household pond with substrates
pond management pond management pre- -stocking stocking pre • Ponds renovation • Ponds renovation -1 1 ft -1 1 water ( 2 ) dec - ft - = 40 m 2 • Rotenone application: 30g dec water (dec dec = 40 m ) • Rotenone application: 30g , 250 kg ha - -1 1 • Liming: CaCO 3 • Liming: CaCO 3 , 250 kg ha 2 with mean diameter 6.2 cm -2 Bamboo installation: 5.5 poles m - • with mean diameter 6.2 cm • Bamboo installation: 5.5 poles m (covers 60% of pond surface area) (covers 60% of pond surface area) • Fertilization: cow manure, urea and TSP at 3,000, 100 and Fertilization: cow manure, urea and TSP at 3,000, 100 and • 100 kg ha - -1 1 100 kg ha post stocking post stocking • GIFT and prawn were sampled at monthly intervals using lift GIFT and prawn were sampled at monthly intervals using lift • net net • 3- -5% commercial feed of total fish (GIFT+prawn) body 5% commercial feed of total fish (GIFT+prawn) body • 3 weight per day weight per day 1 fortnightly -1 1 , TSP -1 50 kg ha - 50 kg ha - • Urea- Urea - 50 kg ha , TSP- - 50 kg ha fortnightly •
GI FT grazing on substrate
means (and ranges) of water quality parameters means (and ranges) of water quality parameters Parameters Treatments T 1 T 2 T 3 T 4 T 5 28.40 28.17 28.05 27.90 28.40 Temperature ( 0 C) (27-31) (26-30) (27-30) (26-30) (25-32) 42.60 a 38.43 ab 42.57 a 35.80 b 38.10 ab Secchi depth (cm) (27-67) (23-59) (25-68) (22-50) (26-57) 4.89 c 5.07 bc 4.65 c 5.60 ab 6.06 a DO (mg l -1 ) (1.9-9.8) (2.0-7.1) (3.7-6.2) (2.9-6.9) (2.8-9.2) 7.10 ab 6.81 b 9.78 b 7.27 a 6.94 ab pH (6.1-8.5) (6.1-9.3) (5.8-7.7) (6.1-9.8) (5.8-9.4) 0.095 0.053 0.057 0.057 0.065 Nitrate nitrogen (mg l -1 ) (0.02-0.36) (0.01-0.23) (0.01-0.21) (0.01-0.17) (0.01-0.18) 0.415 0.243 0.282 0.314 0.346 Ammonia nitrogen (mg l -1 ) (0.03-0.81) (0.03-0.83) (0.04-0.74) (0.01-0.78) (0.01-0.69) 0.268 0.235 0.229 0.258 0.272 Phosphate phosphorus (mg l -1 ) (0.10-0.63) (0.12-0.38) (0.12-0.45) (0.09-0.63) (0.13-0.43) 165.69 172.29 161.94 173.71 152.96 Chlorophyll a ( µ g l -1 ) (70-258) (8-320) (69-304) (54-339) (54-297)
N (mg l - -1 1 ) in the ponds means (± ±SD) of nitrate SD) of nitrate- -N (mg l ) in the ponds means ( 0.5 Treat-1 Treat-2 0.4 Treat-3 Treat-4 -1 ) Treat-5 Nitrate-N (mg l 0.3 0.2 0.1 0 Jul Jul Aug Aug Sep Sep Oct Oct Nov Nov 05 20 05 20 05 20 05 20 05 20
N (mg l - -1 1 ) mean (± ±SD) of SD) of ammonia ammonia- -N (mg l ) in the ponds in the ponds mean ( 1.2 Treat-1 1 Treat-2 Ammonia-N (mg l -1 ) Treat-3 Treat-4 0.8 Treat-5 0.6 0.4 0.2 0 Jul Jul Aug Aug Sep Sep Oct Oct Nov Nov 05 20 05 20 05 20 05 20 05 20
P (mg l - -1 1 ) mean (± ±SD) of SD) of phosphate phosphate- -P (mg l ) in the ponds in the ponds mean ( 0.7 Treat-1 Treat-2 0.6 Phosphate-P (mg l -1 ) Treat-3 Treat-4 Treat-5 0.5 0.4 0.3 0.2 0.1 0 Jul Jul Aug Aug Sep Sep Oct Oct Nov Nov 05 20 05 20 05 20 05 20 05 20
means (± ±SD) of periphyton biomass and pigment SD) of periphyton biomass and pigment means ( parameters (materials scraped from bamboo substrates) parameters (materials scraped from bamboo substrates) Parameters Treatments T 1 T 2 T 3 T 4 T 5 2060 b 2191 b 2650 b 2480 b 3550 a Dry matter ( µ g cm -2 ) (779) (910) (1029) (687) (1283) 1430 b 1530 b 1680 b 1560 b 2140 a AFDM ( µ g cm -2 ) (539) (501) (580) (437) (656) 29.94 29.62 34.52 35.94 37.17 Ash (%) (5.93) (7.55) (9.28) (9.52) (10.79) 8.898 b 9.434 b 10.506 b 11.471 ab 15.37 a Chlorophyll a ( µ g cm -2 ) (2.919) (3.630) (3.032) (2.997) (5.014) 3.075 b 3.066 b 3.200 b 3.180 b 4.029 a Pheophytin a ( µ g cm -2 ) (0.694) (0.550) (0.732) (0.770) (1.485)
means (± ±SD) SD) of periphyton dry matter per unit surface of periphyton dry matter per unit surface means ( area of substrate area of substrate 6000 Treat-1 Treat-2 Treat-3 Treat-4 Treat-5 5000 Periphyton DM ( µ g cm -2 ) 4000 3000 2000 1000 0 Aug 04 Sep 05 Oct 04 Nov 04 Dec 04
means (±SD) of Chlorophyll a concentration in periphyton per unit surface area of substrate 30 Treat-1 Treat-2 Chlorophyll a ( µ g cm -2 ) 25 Treat-3 Treat-4 Treat-5 20 15 10 5 0 Aug 04 Sep 05 Oct 04 Nov 04 Dec 04
means (± ±SD) SD) of pheophytin of pheophytin a a concentration in concentration in means ( periphyton per unit surface area of substrate periphyton per unit surface area of substrate 7 Treat-1 Treat-2 Pheophytin a ( g cm -2 ) 6 Treat-3 Treat-4 Treat-5 5 4 3 2 1 0 Aug 04 Sep 05 Oct 04 Nov 04 Dec 04
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