Table 1 Main behavioral criteria of Russian sturgeon Acipenser gueldenstaedtii prelarvae assessed in this study
Behavioral criteria | Behavioral characteristics in tank |
|---|---|
Negative geotaxis and drifting behavior | Upward movement toward water surface by active propelling of the posterior body trunk and tail, and then passive settlement to the bottom; prelarvae rest on their side or yolk sac before active swimming-up starts again |
Pelagic swimming | Swimming at water surface or upper water column for a long time in a certain direction |
Benthic swimming | Free swimming for a short or long distance along the bottom of the tank, without displaying other behavioral types |
Early corner-gathering | Approaching the corner(s) of the tank; hatchlings and early prelarvae gather and aggregate loosely into a “school-like” appearance at the corner(s) |
Rheotactic schooling | Aggregation of large number of positively rheotactic prelarvae into a school-shaped group on the bottom of the tank; prelarvae swim against water current with active propelling movement |
Non-rheotactic schooling | Dense aggregation of large number of prelarvae into schools, usually at the corner(s) of the tank where no significant water current exists; prelarvae approach the center of the corner with active propelling of posterior body trunk and tail |
Post-schooling behavior | Non-locomotory, inactive, being dispersed or scattered over the bottom of the tank; prelarvae represent a sign of the initiation of the post-schooling behavior as a slow-wagging motion without locomotory activity |