Effects of temperature, salinity and feeding frequency on growth and mortality of twaite shad (Alosa fallax) larvae

Available knowledge on the ecological requirements of the twaite shad Alosa fallax larvae is limited, restricting the development of effective management and conservation measures for this anadromous clupeid in European rivers. In this study, the effects of water temperature, salinity and feeding frequency on A. fallax larval growth and mortality were evaluated. For a period of ten days after the onset of exogenous feeding, A. fallax larvae exhibited higher survival rates when subjected to salinities of 2.5 g.L-1 and 5 g.L-1, from trials conducted at 0 g.L-1, 2.5 g.L-1, 5 g.L-1, 10 g.L-1, 15 g.L-1, 20 g.L-1. Higher food availability resulted in higher larval growth and survival rates during this period. Water temperature effects on larvae growth and survival was evaluated for a period of three months after hatching. Alosa fallax larvae exhibited higher growth and survival rates when subjected to temperatures of 24 degrees C and 28 degrees C, in contrast to trials conducted at 20 degrees C. These results are compared to other Alosa spp. and considerations on conservation measures are discussed in light of the results.