Effect of water temperature on egg incubation time and quality of newly hatched larvae of northern pike (Esox lucius L., 1758)

Abstract

This study examined the effect of temperature on egg incubation, survival of eggs during embryonic development and quality of newly hatched larvae of northern pike (Esox lucius L.) under laboratory conditions. Eggs of similar size (diameter 2.7 ± 0.16 mm and weight 6.11 ± 0.35 mg) from five females were incubated at 3, 6, 10, 14, and 18°C (groups A, B, C, D, and E, respectively). The lowest fertilization (FR) and hatching rates (HR) were observed in larvae incubated in group A, 44.6 ± 3.2% and 18.26 ± 2.25%, respectively. The highest FR and HR were found in group B (FR, 71.3 ± 4.3%; HR, 56.2 ± 3.21%) and C (FR, 65.6 ± 3.1%; HR, 65.5 ± 5.41%). Time of incubation period varied from 38 ± 0.33 days (120 ± 1.03°d) when 5% larvae were hatched to 46 ± 0.42 days (144 ± 1.31°d) when 95% larvae were hatched in group A and 2.5 ± 0.08 days (44.67 ± 1.42°d) when 5% larvae were hatched to 3.42 ± 0.06 days (61.11 ± 1.07°d) when 95% larvae were hatched in group E. Larvae from groups A, D, and E were characterized by the lowest values of variables such as resistance to osmotic stress after 90 min of exposure of saline solution (OS = 54 ± 3–76 ± 3%), frequency of normally developed larvae (FNL = 23.8 ± 4.14–87. 1 ± 2.42%), and yolk sac volume (YsV = 3.41 ± 0.44–3.89 ± 0.45 μl3). The highest quality larvae were recorded in groups B and C: OS = 92 ± 3% and 80 ± 4%, FNL = 89.7 ± 3.62% and 93.8 ± 3.17, YsV = 3.3 ± 0.66 μl3 and 3.04 ± 0.42 μl3). Fertilization and hatching rates and quality of larvae showed optimal temperature for successful egg incubation and production of high quality larvae to be 6 to 10°C. Relationship of ontogenic rate to temperature showed development of the pike embryo to be hypothetically stopped at 3.3°C.