Growth and survival of six stocks of rohu (Labeo rohita, Hamilton) in mono and polyculture production systems

Sammendrag

One farmed stock (Local) and five riverine stocks of Rohu (Labeo rohita, Hamilton) from 2-year classes (1993 and 1994) were evaluated for growth and survival under monoculture and polyculture systems at the Central Institute of Freshwater Aquaculture (CIFA), India. In the 1993 year-class, 29 full-sib groups of Local and 28 full-sib groups of river Ganga were tested while in the 1994 year-class the stocks tested were of Local and of rivers Brahmaputra, Ganga, Gomati, Sutlej and Yamuna with 6, 8, 7, 7, 18 and 11 full-sib groups, respectively. For each year-class, individually tagged fingerlings were stocked into three 0.1 ha monoculture ponds (9 fish/full-sib group/pond) and two 0.4 ha polyculture ponds (13 fish/full-sib group/pond). In polyculture, Rohu were stocked together with Catla (Catla catla, Hamilton) and Mrigal (Cirrhinus mrigala, Hamilton) in the ratio of 1.2:1:1, respectively. The stock effect on body weight at harvest was not significant in the 1993 year-class but highly significant in the 1994 year-class. The stock effect on survival from tagging to harvest was not significant in any of the year-classes. The interaction between production system and stock on growth and survival was significant but low, particularly compared to the significant and important full-sib effect. Thus, the growth performance of the stocks was relatively consistent in monoculture and polyculture. The significant full-sib effects for growth and survival suggest that these traits can be improved through selective breeding. The implications of the results for the development of a selective breeding program for Rohu in India are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.