Environmental conditions of 2 river drainages into the Northern Gulf of Mexico during successful hatching of Alabama shad (Alosa alabamae)
In recent years, the Alabama shad (Alosa alabamae) has experienced dramatic declines and extirpations from portions of its native range. Habitat degradation and barriers to migration are considered contributing factors to contraction in the distributional range this species. To identify conditions during successful spawning, river temperatures and discharges in 2 drainages of the northern Gulf of Mexico (the Apalachicola and Pascagoula rivers) were characterized during successful hatching “windows.” Sampling during 2005–2009 yielded 400 juvenile Alabama shad of which 261 were aged from counts of rings on sagittal otoliths. Results from logistic regression revealed that successful spawning coincided with increases in temperature within a specific range (9.4–21.5°C) and with an average drainage-dependent discharge volume (625.6 m³/s in the Apalachicola River and >400.7 m³/s in the Pascagoula River). Timing of successful hatching windows differed between drainages but not between years within each drainage. Documenting and identifying the river conditions during successful reproduction provide important information on how to manage rivers to aid in the recovery of this species of conservation concern.