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Successful breeding of an endemic species, the sea carp (Cyprinus acutiodorsalis Wang), in a brackishwater pond
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Genetic improvement of farmed tilapia: a complete diallele cross between four African and Asian strains of Nile tilapia ( Oreochromis niloticus > A.E. Eknath”, M.M. Tayamenb, M. Palada”, J. Casayuran-Dantingb, R.A. Reyesb, E. Dioisiob, H. Bolivaf, H.B. Bentsend, B. Gjerded, T. Gjedremd and R.S.V. Pullin” YCLARM, Makati, Metro Manila, Philippines bBFAR/NFFTRC, Munoz, Nueva Ecija, Philippines “FAUCLSU, Munoz, Nueva Ecoa, Philippines dAKVAFORSK, As-NLH, Norway
The objective of this study was to determine the magnitude of non-additive (heterotic) genetic effects when four African and four Asian strains of Nile tilapia were crossed and reared under different Philippine tilapia farming systems. The purpose was to decide if a breeding program for farmed tilapia may be based on a simple purebreeding strategy from a mixed base population, or if a crossbreeding program should be established. A total of 26000 individually tagged fingerlings representing the 64 possible different pure strain and reciprocal crosses were reared in eight different test environments for 90 days. Additive, reciprocal and heterotic effects were estimated. The heterotic effect for growth and survival ranged from - 5Ohto 10%. The overall heterosis for growth and survival was negligible (2.3%). Thus, the results do not justify a crossbreeding program. Protocols for establishing a base population by selecting the purebred and crossbred test fish on their additive performance across test environments can be developed.
Successful breeding of an endemic species, the sea carp ( Cyprinus acutiodorsalis Wang), in a brackishwater pond
Chen Xianglin, Fu Guyian and Wang Chun Department ofBiology, South China Normal University,Guangzhou 510631, China
As a novel species discovered in the 1970s the sea carp, known as the sea crucian carp by native people, is endemic to the estuaries of the South China Sea. It has some important economic characters such as large body size, high flesh percentage and excellent palatability. On the other hand, it has a few peculiarities of the skull and chromosomes that differentiate it from common carp and crucian carp. On-the-spot investigations and experiments on rearing sea carp showed that this species is characterized by adaptation to both saline and freshwater, low food
298 chain trophic level, and rapid growth. The sea carp appears mainly in brackish estuaries and occasionally in shallow sea. In nature, it is euryphagous, feeding mainly on small mollusca (clams and mussels), brackish water worms (especially polychaetes), aquatic plants, organic debris and benthic algae. When raised in ponds, it is omnivorous. One-year-old individuals in nature are 25-28 cm in body length and 0.6-0.8 kg in body weight; 2-year-old individuals can reach a body length of 34-38 cm and a body weight of 1.35-1.8 kg. Thirty larvae and juveniles were first introduced into Guangzhou in the summer of 1990. After one year of brackishwater pond culture (with a salinity of less 0.5W), the sea carp reached a body length and weight close to that of fish in the wild. Two-year-old individuals can reach sexual maturity. We have succeeded in inducing spawning, fertilization, hatching and nursing of fry. A total of 12000 juveniles have been produced this year. Sea carp also survive the winter in the Guangzhou region. It is also noted that myomere number and pigment distribution of the fry are different from those of common carp.
Breeding and seedling production of Porphyra protoplasts Dai Jixun, Zhang Quanqi and Bao Zhenmin Department ofBiology, Ocean Universityof Quingdao, Qingdao. China
Breeding and seedling production experiments were carried out with enzymatically isolated protoplasts from vegetative cells of Porphyra. The genetic differentiation and development patterns of cells from different growth stages and different parts of the blade were studied. Several morphological mutants and pure lines were obtained after UV irradiation and cholchicine treatment. PEG-induced interspecific protoplast fusion between P. yezoensis and P. haitenesis was also conducted. The hybrid cells divided and formed callus-like cell masses, but no blade differentiation has been observed to date. For seedling production in cultivation, these protoplasts and individual cells were attached to nylon rope nets, as if they were “seeds” or “spores”, and the rope nets were placed in the sea. Commercial products have been harvested from these cultures. This technique omitted the whole process of filament culture, used manpower sparingly, and reduced production costs. It is expected that this technique might be adopted to replace the conventional cultivation method in the near future, especially for seedling production.
Effect of sire and dam on survival of rainbow trout from fertilization to first feeding Hans M. Gjsen and Bjame Gjerde AKVAFORSK, P.O. Box IO, N-1432As-NLH, Norway
Data were obtained from 190 full-sib families of 95 dams and 95 sires, with three replicates. Each dam and each sire was crossed with two different mates to make the data completely linked.
Genetic improvement of farmed tilapia: a complete diallele cross between four African and Asian strains of Nile tilapia ( Oreochromis niloticus > A.E. Eknath”, M.M. Tayamenb, M. Palada”, J. Casayuran-Dantingb, R.A. Reyesb, E. Dioisiob, H. Bolivaf, H.B. Bentsend, B. Gjerded, T. Gjedremd and R.S.V. Pullin” YCLARM, Makati, Metro Manila, Philippines bBFAR/NFFTRC, Munoz, Nueva Ecija, Philippines “FAUCLSU, Munoz, Nueva Ecoa, Philippines dAKVAFORSK, As-NLH, Norway
The objective of this study was to determine the magnitude of non-additive (heterotic) genetic effects when four African and four Asian strains of Nile tilapia were crossed and reared under different Philippine tilapia farming systems. The purpose was to decide if a breeding program for farmed tilapia may be based on a simple purebreeding strategy from a mixed base population, or if a crossbreeding program should be established. A total of 26000 individually tagged fingerlings representing the 64 possible different pure strain and reciprocal crosses were reared in eight different test environments for 90 days. Additive, reciprocal and heterotic effects were estimated. The heterotic effect for growth and survival ranged from - 5Ohto 10%. The overall heterosis for growth and survival was negligible (2.3%). Thus, the results do not justify a crossbreeding program. Protocols for establishing a base population by selecting the purebred and crossbred test fish on their additive performance across test environments can be developed.
Successful breeding of an endemic species, the sea carp ( Cyprinus acutiodorsalis Wang), in a brackishwater pond
Chen Xianglin, Fu Guyian and Wang Chun Department ofBiology, South China Normal University,Guangzhou 510631, China
As a novel species discovered in the 1970s the sea carp, known as the sea crucian carp by native people, is endemic to the estuaries of the South China Sea. It has some important economic characters such as large body size, high flesh percentage and excellent palatability. On the other hand, it has a few peculiarities of the skull and chromosomes that differentiate it from common carp and crucian carp. On-the-spot investigations and experiments on rearing sea carp showed that this species is characterized by adaptation to both saline and freshwater, low food
298 chain trophic level, and rapid growth. The sea carp appears mainly in brackish estuaries and occasionally in shallow sea. In nature, it is euryphagous, feeding mainly on small mollusca (clams and mussels), brackish water worms (especially polychaetes), aquatic plants, organic debris and benthic algae. When raised in ponds, it is omnivorous. One-year-old individuals in nature are 25-28 cm in body length and 0.6-0.8 kg in body weight; 2-year-old individuals can reach a body length of 34-38 cm and a body weight of 1.35-1.8 kg. Thirty larvae and juveniles were first introduced into Guangzhou in the summer of 1990. After one year of brackishwater pond culture (with a salinity of less 0.5W), the sea carp reached a body length and weight close to that of fish in the wild. Two-year-old individuals can reach sexual maturity. We have succeeded in inducing spawning, fertilization, hatching and nursing of fry. A total of 12000 juveniles have been produced this year. Sea carp also survive the winter in the Guangzhou region. It is also noted that myomere number and pigment distribution of the fry are different from those of common carp.
Breeding and seedling production of Porphyra protoplasts Dai Jixun, Zhang Quanqi and Bao Zhenmin Department ofBiology, Ocean Universityof Quingdao, Qingdao. China
Breeding and seedling production experiments were carried out with enzymatically isolated protoplasts from vegetative cells of Porphyra. The genetic differentiation and development patterns of cells from different growth stages and different parts of the blade were studied. Several morphological mutants and pure lines were obtained after UV irradiation and cholchicine treatment. PEG-induced interspecific protoplast fusion between P. yezoensis and P. haitenesis was also conducted. The hybrid cells divided and formed callus-like cell masses, but no blade differentiation has been observed to date. For seedling production in cultivation, these protoplasts and individual cells were attached to nylon rope nets, as if they were “seeds” or “spores”, and the rope nets were placed in the sea. Commercial products have been harvested from these cultures. This technique omitted the whole process of filament culture, used manpower sparingly, and reduced production costs. It is expected that this technique might be adopted to replace the conventional cultivation method in the near future, especially for seedling production.
Effect of sire and dam on survival of rainbow trout from fertilization to first feeding Hans M. Gjsen and Bjame Gjerde AKVAFORSK, P.O. Box IO, N-1432As-NLH, Norway
Data were obtained from 190 full-sib families of 95 dams and 95 sires, with three replicates. Each dam and each sire was crossed with two different mates to make the data completely linked.