Laboratory propagation and culture of juveniles of the endangered freshwater mussel Margaritifera auricularia (Spengler, 1793)

We infested three fish species, blenny (Salaria fluviatilis), Adriatic sturgeon (Acipenser naccarii) and gambusia (Gambusia holbrooki), with glochidia of the endangered freshwater mussel Margaritifera auricularia at different holding temperatures, and developed a system to grow and maintain cultured juvenile mussels. The sturgeon and blenny were successfully infested, although these fish sloughed the glochidia in the 24°C experiment. Release of juveniles began 30 days post-infestation for sturgeon and 31 days post-infestation for blennies, and excystment occurred over 8 and 10 days, respectively. The total number of juveniles cultured was 2,562. Although the mortality rate was high, juveniles were maintained alive for at least 4 weeks in the four test tanks. In the most successful tank, 13 juveniles were found after 6 weeks (39 days) of culture. Maximum dimensions for juveniles after culture were: length= 325 pm, width= 250 pm, height = 500 pm, indicating a mean increase of 51% in length, 60% in height and 23% in width.