Marisia - Maros Megyei Múzeum Évkönyve 29-30/2. (2010)
Zoology
Application ofallometric condition factor in studying of wintering period influence _______________________ on the condition status of juvenile reared Cyprinids species _______________________ silver carp, Hypophthalmichthys molitrix (Valenciennes, 1844) and big head carp Aristichthys nobilis (Richardson, 1845). A total of 1370 specimens of all four cyprinids were sampled during two years in the three experiments, on the pre-winter period (autumn) and after winter pond harvesting (spring) respectively. Before biometric measurements by ichthyometer, the fish were kept into aquaria for a 24 hours period to empty the digestive tract content. The minimum and maximum values of the biometric parameters from each species and also the statistical differences (P < 0.05, Т-Student test) between the values arrays measured before and after wintering were recorded in the tables. The graphics indicate the average values and also the quartile range (25-75%) for each biometric parameter. The allometric condition factor is described by the expression: K= W/Lh in which W represents the weight. L represents the standard length. b represents a coefficient that is estimated by the weight/length regression curve equation (W = a*Lb) being adjusted from data of the sampled individuals. a represents the slope of the regression curve. Results and discussions The normal value for Fulton Factor as indicator of a good condition status mentioned by scientific papers is differed. So, some of fish culture books mention the next minimum value of К reached by juvenile common carp: • 1.8 for the fish with a weight lower than 10 g; • 1.7 for the fish with 10-30 g range weight; • 1.6 for the fish with a weight bigger than 30 g. Some authors [10, 16] estimated that next values of К could allow the survival of juvenile common carp and reduced weight losses during the winter. • minimum К 1.6 for the fish with a weight more than 20 g. • minimum К 1.7 for the 15 - 20 g range weight. • minimum 2.0 for the fish with a weight lower than 15 g. The survival time of common carp with different condition state levels under starvation circumstances mentioned by Nikolski, G., V. (1962) [13] is shown in table 2. Tab. 2: The survival time of common carp (Cyprinus carpio carpio Linnaeus, 1758) under starvation circumstances in relation with condition state levels [13] _______Fulton Factor_____________Lipids content (%)__________Survival period (days) ___________T56_______________________2Л5________________________141____________ 2.81 4.25 191 The Fulton Factor in genuine grass carp, Ctenopharyngodon idella (Valenciennes, 1844) as indicator of a good condition status recommended by Kirpicinikov & Berg quoted by Nikolski, G., V., (1962) [13] is К = 2.4 while the culture grass carp has 2.9 and the hybrids К = 2.7. The same author mentions these values in relation with the weight ranges as it is shown in table 3. 85
