Critical swimming speed of sterlet (Acipenser ruthenus): Does intraspecific hybridization affect swimming performance?

Abstract

Summary We studied the effect of intraspecific hybridization on swimming performance in sterlet, hypothesizing that such hybridization increases the performance by inducing the hybrid vigor. A total of 12 purebred and hybrid crosses were reproduced from Danube (D) and Volga (V) populations of Acipenser ruthenus. Within each cross, one group of fish was exposed to temperature challenges mimicking the temperature variation in the natural environment during summer. Temperature challenges comprised a constant increase from 19°C to 24°C and then return to 19°C within 12 hr (dT<1°C/hr), and were carried out every third day over the experimental period of 20 days. As a control, fish from each cross were kept at a constant temperature of 19°C. Critical swimming speed (Ucrit) was assessed on day 0 (29 days post hatch, dph), 10 (39 dph) and 20 (49 dph). The critical swimming speeds ranged from 5.12 cm/s (1.63 TL/s) to 16.44 cm/s (2.4 TL/s) during the experimental period (29–49 dph). There were no significant differences observed in Ucrit between repeatedly temperature challenged and control groups, indicating that the temperature challenge did not alter the swimming performance. The critical swimming speed showed positive relationship with total body length. Comparing intraspecific hybrid crosses with purebred crosses, no significant difference in swimming performance was observed. It is thus concluded that swimming performance is a family specific trait. There is no indication that intraspecific hybridization affects swimming performance nor that close‐to‐natural temperature regimes increase swimming performance.

3D upstream passability of novel river training structures by migratory fish in the river Waal

“…The results for this species however are similar to those obtained in another study. U crit studies on other Acipenser species have yielded results consistent with ours, such as 3.26 ± 0.11 BL/s (Acipenser baeri; 0.06-0.22 m/s absolute difference; Cai et al, 2015) but also 1.63-2.4 TL/s (Acipenser ruthenus; 0.99-1.96 m/s absolute difference; Shivaramu et al, 2019); however the last study was performed on early life stages, which may explain the differing swimming performance.…”

Sturgeon re‐introduction in the Upper and Middle Danube River Basin

“…However, in the case of very rare species such as the Russian sturgeon, it may be necessary to treat the whole Danube population as a single ESU as it may not be feasible anymore to split them due to the low overall number of spawners still present or the lack of distinct population dynamics still observable. However, to which extent such an amalgamation or intra‐specific hybridization further reduces the fitness due to a lack of adaptation remains open (Sharavamu et al, ).…”