JUVENILE BLUEBACK HERRING (ALOSA-AESTIVALIS) SURVIVAL VIA TURBINE ANDSPILLWAY

The 48 h survival of emigrating juvenile blueback herring (Alosa aesti valis) was estimated at 96 +/- 6.7 percent in passage through a Kaplan -type turbine and at 88.3 +/- 10.7 percent (90 percent confidence inte rval) over a spillway (3.7 m high and spillage of 1.2 m(3)/s) of a low -head hydro dam (8.3 m). These results suggest that diversion of juven ile alosids over spillways may not be assumed to he a totally benign s trategy without obtaining site-specific data. A remarkable similarity in survival rates of fish observed through turbine routes in this stud y and others suggests that these trends may be common. However, due to a lack of sufficient data, such a conclusion cannot be made for survi val over spillways.