Thermal optimum for pikeperch ( Sander lucioperca) and the use of ventilation frequency as a predictor of metabolic rate

Abstract

Pikeperch is of increasing interest to the aquaculture industry, as a novel high value species. To our knowledge there is currently no information available on the metabolic rates of adult pikeperch. The present study determined the standard and maximum metabolic rates and ventilation frequency at six temperatures, ranging from 13 to 28 °C, in order to identify the temperature where pikeperch has the largest metabolic scope (MS). Between 13 and 25 °C, standard metabolic rates (SMR) increased as expected with a Q 10 = 1.8 in response to increasing temperatures, while maximum metabolic rate (MMR) did not change significantly within this temperature range. As a result, MS was not significantly affected by acclimation temperature between 13 and 25 °C. Above 25 °C, SMR increased significantly with a Q 10 = 2.5 while MMR declined, resulting in a decreased MS. In the present study, the maximum MS (MS MAX) was found at 18.8 °C. Defining the optimal temperature as the thermal range where fish can maintain 80% of MS MAX, shows that adult pikeperch have a broad thermal optimum between 10.4 and 26.9 °C. Since earlier studies on juvenile pikeperch have reported an optimal temperature range of 25–30 °C, we show that pikeperch have an ontogenetic shift in their thermal optimum, emphasizing the importance of considering fish size when deciding the temperature in aquaculture facilities. As a secondary objective we investigated whether gill ventilation frequency ( f V) could be used as an accurate predictor of oxygen consumption rate ( M ˙ O 2), during normoxia and progressive hypoxia. A strong correlation was found between f V and M ˙ O 2 across all temperatures, and f V could predict M ˙ O 2 with a high degree of accuracy in normoxia.