EFFECT OF SORTING ON SELECTED REARING FACTORS OF PIKEPERCH SANDER LUCIOPERCA (L.)
Zdzisław Zakęś, Agata Kowalska, Stanisław Czerniak
The Stanisław Sakowicz Inland Fisheries Institute in Olsztyn, Poland
ABSTRACT. The aim of the experiment was to determine the effect sorting had on the effectiveness of rearing juvenile pikeperch in recirculation systems. The fish were reared in three groups – small specimens (group S – average body weight (BW) 28.5 g), large specimens (group L – BW 49.6 g), and unsorted specimens (group U – BW 38.8 g). After eight weeks of rearing, the average specific growth rate (SGR) for fish from group S was significantly higher than for those from the groups U and L (P < 0.05). A similar pattern was found for the feed conversion ratio (FCR), percentage of stock biomass gain and survival rate. However, there were no statistically significant intergroup differences between values of the rearing factors obtained in group U and in the combined sorted groups (S + L) (P > 0.05). Thus, it appears that the sorting of juvenile pikeperch does not improve the rearing effectiveness for this species.
Key words: PIKEPERCH (SANDER LUCIOPERCA), SORTING, GROWTH, SURVIVAL, INTERINDIVIDUAL VARIATIONS
Zdzisław Zakęś, Instytut Rybactwa Śródlądowego, Zakład Akwakultury, ul. Oczapowskiego 10, 10-719 Olsztyn, tel./fax: +48 89 5241022,+48 89 5240505; e-mail: firstname.lastname@example.org