ASSESSMENT OF INBREEDING RATES IN CARP HATCHERY IN THANJAVUR DISTRICT OF TAMIL NADU, SOUTH INDIA

Hatcheries from Thanjavur District of Tamil Nadu is the major supplier of fish seed to the carp farming in Tamil Nadu. These hatcheries mainly breed catla, rohu and mrigal. Generally, these hatcheries maintain the broodstock without adequate attention of genetic consideration. They use the same brooders for seed production continuously without exchange or replacement. Due to this, inbreeding may occur at faster rate due to the small effective population size. Therefore, the present study was conducted to estimate effective population size and inbreeding rate in Indian Major Carps in Tamil Nadu hatcheries.

The data for this study were collected from four hatcheries from 2014 to 2018 for four breeding seasons. Pedigree records are not maintained in these hatcheries. The data were collected on the species, month and year of breeding, number of males, number of females used for breeding and number of females spawned. The inbreeding rate was estimated based on the effective population size. The effective population size (Ne) was estimated by the method described by Falconer and Mackay (1998). In the present study, the effective population size for catla ranged from 3 to 49. It was 8 to 39 in rohu and 3 to 49 in Mrigal. The inbreeding rate ranged from 1.50 to 24.63, 3.75 to 19.53 and 1.50 to 24.63 per cent for catla, rohu and mrigal respectively. It was observed maximum inbreeding rate in catla due to smaller effective population size.