Impact of selected abiotic and biotic factors on the results of rearing juvenile stages of northern pike Esox lucius L. in recirculating systems

Abstract

The aim of this study was to determine the impact of selected parameters (water temperature, light intensity, feed ration and granulation size, daily feeding period, stocking density, tank shape, sorting, covering the rearing tanks) on the rearing indices of northern pike, Esox lucius L. The impact of these factors on the intensity of cannibalism was determined, as was their role at various stages of early northern pike development. The study results presented indicate that the factors that most influence the results of rearing include water temperature, the type of tank used, fish sorting, and the size of the daily feed ration. The optimal water temperature for growing juvenile specimens of northern pike is 28°C, but effective rearing can be achieved within a temperature range of 20 to 28oC. At the lower temperature, the length of the feeding period and the application of tank covers had less of an impact on the final rearing results. Lighting and feed grain had the least influence on the rearing results, which indicates that northern pike are highly flexible with regard to these parameters. The greatest problem in rearing northern pike juveniles was cannibalism, which accounted for as much as 93% of overall fish losses. During early ontogenic growth, substantial changes in behavior were noted which meant that the northern pike were increasingly sensitive to external stimuli. Behavioral changes noted during the growth of juvenile northern pike could have impacted reactions to various parameters. For example, the optimal feeding period is continuous over 24 hours in the initial rearing stage and then 12-hour feeding periods for older fish (with body weights exceeding 5 g).

CORRESPONDING AUTHOR:

Mirosław Szczepkowski
Department of Sturgeon Fish Breeding
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn
Pieczarki 50, 11-610 Pozezdrze, Poland
Tel. +48 (87) 428 36 66; e-mail: mszczepkowski@wp.pl