Osmotic induction marking with Alizarin Red S on juveniles of pejerrey, Odontesthes bonariensis (Atherinopsidae)

• Main Authors: Daniela Campanella, Angela Garriz, Dario C. Colautti, Gustavo M. Somoza, Leandro A. Miranda
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Ictiologia
• Series: Neotropical Ichthyology
• Subjects: Fin rays; Fish tag; Otolith; Scales
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-62252013000100095&lng=en&tlng=en

Juveniles of pejerrey, Odontesthes bonariensis, were exposed to 0.1% Alizarin Red S (ARS) alone or with a previous immersion in 2.2% saline solution (Osmotic Induction, OI) to enhance the ARS marking method. Fish were marked in the field and immediately released in 1 m3 cages in "La Salada de Monasterio" lagoon, Chascomús, Buenos Aires , Argentina. After 73 days, clear marks were observed in the otoliths, caudal fin rays and scales with both treatments, being the intensity of the signal in the scales of OI+ARS treated fish higher. On the other hand, no marks were observed in the control group on the same structures. Approximately one year post-treatment (385 days), only marks in caudal fin rays were found clearly in OI+ARS treated fish. After this period, no significant differences in total length or weight between marked or control fish were observed and the mortality ranged between 30-40 % in all cages. These results provide strong evidence for the potential applicability of this cost-effective marking technique in differentiation of wild and hatchery-produced pejerrey. The success in the caudal fin rays marking is also important because it is easy to do and does not require the sacrifice of fish.