Research Article

In vivo staining with alizarin for ageing studies on chondrichthyan fishes

¹ Muséum national d'Histoire naturelle, Station Marine de Concarneau, Place de la Croix, 29900 Concarneau, France
² Bureau d'études FISH PASS, Z.A. des 3 Prés, 18 rue de la Plaine, 35890 Laillé, France
³ Institut de Systématique, Évolution, Biodiversité (ISYEB), Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE, Université des Antilles, Station Marine de Concarneau, Place de la Croix, 29900 Concarneau, France

^* Corresponding author: jean-marie.caraguel@mnhn.fr

Handling Editor: François Le Loc’h

Received: 23 January 2019
Accepted: 21 January 2020

Abstract

Age determination for stock assessments and conservation of cartilaginous fishes is mainly obtained by counting the annual growth bands in vertebrae. Recent studies show numerous inconsistencies and the need for systematic validation. We assessed the effectiveness of the fluorochrome alizarin red S, a common skeleton vital marker used as a time stamp for teleost fishes, on chondrichthyan. Twenty-five captive small-spotted catsharks (Scyliorhinus canicula) were marked by alizarin red S intraperitoneal injections. The fluorochrome produced a wide fluorescent mark on sectioned vertebral centra of all injected fish. Alizarin red S did not have a deleterious effect on growth during three months monitoring. The marks obtained remained stable in vivo for more than four years after injections and were resistant to fading during the observation under the microscope excitation light. Our results suggest that alizarin red S is an effective tool for long time vital marking of chondrichthyans.