Use of calcein and alizarin red S for immersion marking of black rockfish Sebastes schlegelii juveniles

Black rockfish Sebastes schlegelii juveniles (30–40 mm total length) were immersed in a range of calcein (CAL) solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S (ARS) solutions at concentrations ranging from 100 to 500 mg/L in filtered seawater (salinity 30) for 24 h. Fluorescent marks were detected in otoliths (sagittae, asteriscus), scales, fin rays (dorsal, pectoral, ventral, anal, and caudal fin rays), and fin spines (dorsal, ventral, and anal fin spines) after a 60-d growth experiment. With the exception of 50–100 mg/L CAL, acceptable marks were produced in the otoliths and fin spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fin spines of fish immersed in 200–500 mg/L, 300–500 mg/L, and 200–500 mg/L ARS, respectively. Scales and fin rays had acceptable marks at much higher concentrations (≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL, ≥200 mg/L ARS for fin rays). The mark quality was highest (i.e., acceptable marks were observed in all sampled structures after immersion marking) in fish immersed in 150–250 mg/L CAL or 300–500 mg/L ARS. In addition, there was no significant difference in survival and growth of marked fish compared with controls 60 d post-marking ( P >0.05).