Marisia - Maros Megyei Múzeum Évkönyve 29-30/2. (2010)
Zoology
Gabriela GRIGORAS dhe Allometric Condition Factor of fish sampled during the autumn shows a positive (b>3.0) and negative (b<3.0) allometric growing both (Table 5) and a variability of weight/length relationship as default, in relation with the species, sampling station, experiment. The weight/ length relationship assesed at the beginning of the wintering depends on the availability of the trophic resources during the vegetative season that allow a length grow of juvenile during summer and the accumulaton of the energetic reserve during the autumn required for an optimal strength during the winter. In all four fish species sampled in Vladesti ponds at the beginning of the two winter seasons it notes a length increasing that is not proportional with the weight growing. Although the samples within each experiment (at the beginning and the end of cold season) are obtained by random drawing from the same population, the weight/length relationship which undergoes changes during the winter, will be distorted by the influence of some typical factors to fish farms such as high fish stocking into the ponds, interspecific fish relationships and specific hibernal behaviour, low temperature, water chemical parameters etc. Having in view these aspects, it can be notes the results obtained by Fulton Factor calculation using the variable b coefficient have a higher relevance allowing a correctly assesment of weight/length relationship, condition state of fish and the modification degree of its, the environment and anthropic factors impact. The similar results obtained by other authors [1, 4]. There are some researches [2, 3, 9, 14] considering the constant b coefficient (calculated from an unique assemblage that links all the individuals, with a constant value for all subsamples collected in distinct seasons) as the most convenient procedure for studying fish Condition Factor. Conclusions The environment factors that influence the fish stocked into the winter ponds were differed during the experiments. Their combined action produces a concurrence of stress responses in fish (Winter Stress Syndrome) with different amplitudes and significations. The Fulton Factor (as expression of general condition state) reached in autumn varied from one species to another and also from one cold season to another during the experiments. An alteration of the condition state during the wintering has been observed in all four cyprinids species and all three experimental variants. The differences between the Fulton Factor values arrays calculated for individuals sampled at the beginning and the end of cold season are statistically significant (P<0.05). The amplitude of modifications depends on fattening state of fish reached in autumn and also wintering conditions. Under some circumstances: a certain depot of debris into the pond, a satisfactory fattening state reached in autumn, the silver carp with an average level of Condition Factor of К = 1.5 uses this available trophic source even under severe winter conditions and this fact could induce statistically not significant changes during the winter (P = 0.26, P > 0.05). No special numerical losses were recorded but only physiological alterations and weight loss. The general tendency of condition state alteration is the more so as increases the time of fish stocking into the pond during on spring. By applying the two methods of Allometric Condition Factor, the results obtained by index calculation using the variable b coefficient have a higher relevance allowing a correctly assesment of weight/length relationship, condition state of fish and the modification degree of its, the environment and anthropic factors impact. 92
