Dr. Md. Samsul Alam
Professor
Department of Fisheries Biology and Genetics, BAU, Mymensingh-2202
The development instability, growth and genetic variability of hatchery and natural population of rohu (Labeo rohita) have been compared. The results of the two growth trials conducted between Brahmaputra hatchery, Mymensingh and the Jamuna river fish and between Bhai Bhai hatchery, Dhola, Mymensingh and the Halda river spawn revealed that both the Jamuna and the Halda fish grew faster than the respective hatchery fish. The study of developmental instability showed that some of the hatchery fish were found to be deformed while none of the river fish showed such deformity and the percentage of asymmetry in pectoral fin rays was higher in hatchery fish compared to the river fish. The level of genetic variation provides the raw material for selective improvement of a stock and indicates the impact of hatchery management. To compare the genetic variability between the river and the hatchery fish, genomic DNA was extracted from fin tissues of rohu collected from two rivers viz. the Jamuna and the Halda as well as two hatcheries such as Bhai Bhai hatchery, Mymensingh and Halda fish Centre, Jessore by proteinase-K digestion, phenol: chloroform: isoamly alcohol extraction and ethanol precipitation method. Before performing PCR amplification, fifteen decamer random primers were tested to select the best primers having good resolution and potentiality to differ the populations of rohu effectively. Finally, DNA samples were amplified by four selected primers such as OPB08, OPB09, OPB12 and OPB13 (Operon Technologies, USA). The proportion of polymorphic loci and Nei’s (1973) gene diversity estimates for the Jamuna, Halda, Bhai Bhai hatchery and Haque Fish Centre were 65.52% and 0.186, 65.52% and 0.183, 55.17% and 0.175 and 62.07% and 0.201 respectively. The proportion of polymorphic loci and gene diversity estimates were found to be higher in the river populations whereas the estimates were relatively low in the hatchery populations. The results indicate that the river populations are genetically more hatchery populations. The results indicate that the river populations are genetically more diversified than the hatchery populations. The relatively low level of genetic variability in the hatchery populations may be attributed to inbreeding and genetic drift that might have taken place over years captive management in the hatcheries. The UPGMA dendrogram based on Nei’s (1972) genetic distance depicted the relationship among the different rohu populations. The proportions were segregated into two clusters: the Jamuna and the Bhai Bhai hatchery were in one cluster whereas the Halda and Haque Fish Centre made another cluster. The main objective of the study was to compare the genetic variation between the hatchery and natural population. The study reveals that the genetic variations in the hatchery populations are lower than either of the river populations. To get more precise information about the genetic variability of rohu populations, additional samples and primers should be used in future.
Instability, growth, hatchery population, natural population, genetic variations, fishes.
Brahmaputra hatchery, Mymensingh.
1. To present morphological evidence that the loss of genetic variation in the hatchery stocks has adversely affected the embryological development of the Indian major carp species.
2. To quantify the loss in fish production incurring due stockings of poor quality fish seed produced in the hatcheries under the current management practices.
3. To quantify the loss of genetic variability in the hatchery stocks with respect to a wild population.
4. To find any correlation between the level of heterozygosity and growth performance.
5. To aware the farmers/hatchery operators about the importance of good broodstock management.
a. Material, b. Study of developmental instability, c. Growth comparison- i. Design of Experiments ii. Collection and analysis of growth data, d. Study of genetic variation by randomly amplified polymorphic DNA (RAPD) technique- Screening primers and testing reproducibility.
Bangladesh Agricultural University Research Progress, Volume 15,
Proceedings of the Workshop 15-16 January 2005,
Bangladesh Agricultural University Research System (BAURES), Mymensingh
Bangladesh.
225000
Finally, DNA samples were amplified by four selected primers such as OPB08, OPB09, OPB12 and OPB13 (Operon Technologies, USA). The proportion of polymorphic loci and Nei’s (1973) gene diversity estimates for the Jamuna, Halda, Bhai Bhai hatchery and Haque Fish Centre were 65.52% and 0.186, 65.52% and 0.183, 55.17% and 0.175 and 62.07% and 0.201 respectively. The results indicate that the river populations are genetically more diversified than the hatchery populations. The study reveals that the genetic variations in the hatchery populations are lower than either of the river populations. To get more precise information about the genetic variability of rohu populations, additional samples and primers should be used in future.
Report/Proceedings