PRESENT STATUS OF THE MAIN SHADS’ POPULATIONS IN PORTUGAL.

Abstract

The allis shad (Alosa alosa) and the twaite shad (Alosa fallax) are anadromous migratory species, which are threatened not only in Portugal but also in most of their geographic area of distribution. Overfishing and illegal fishing, pollution, physical barriers and river-bed changes seem to be the main reasons for the populations gradual decline. The progressive reduction in the numbers of anadromous fish registered in the last decades in some Portuguese river basins requires urgent action, namely the implementation of measures to promote the recovery of those populations. The current status of shads populations in Portugal is discussed, and the distribution along the main Portuguese watersheds and major threats to these species are presented, as well.

Keywords

• shads
• Alosa alosa
• Alosa fallax
• conservation
• Portugal