Alizarin Complexone Marking of Otoliths of Juvenile Cynoglossus semilaevis
As a result of the scaled stock enhancement of tongue sole,Cynoglossus semilaevis,since 2006 in China,millions of juveniles were released into the Bohai Sea and the Yellow Sea annually.However,it is difficult to evaluate the effectiveness of this operation because of a lack in efficient marking techniques.Here we tested the potential of alizarin complexone (ALC) as a marking material on tongue sole otolith.ALC solutions with 5 concentrations ranging from 0 to 200 mg/L in undiluted seawater were prepared.One hundred tongue sole juveniles of two sizes (70 d and 170 d post hatching) were randomly assigned into the 5 groups of ALC solutions and in each group the subjects were immersed into the solution for 12 hours,24 hours,and 36 hours.Duplication was performed for each group.The results showed strong markings with ALC on otoliths of tongue soles.The optimal concentrations of ALC were 100 mg/L for 36-h marking and 150 mg/L for 24-h marking,which ensured both sound survival rate and strong marking signals.The marking quality (MQ) was assessed with scores from 0 to 3,and a score ＞ 2 was regarded acceptable for adequate mark identification.The marking signals on the otolith were enhanced as the solution concentration increased,which however also increased the mortality rate.The marked juveniles (170 d) were cultured in indoor tanks for 4 months to determine how long the ALC marking could last.The marking signals were still clear at the end of the culture,and there was no difference in the growth between marked and unmarked subjects with the same size.These results indicated that ALC could form lasting signals on otoliths of tongue soles,and thus may be a useful tool in the evaluation of stock enhancement and the identification of tongue sole populations.
国家科技期刊平台
NSTL
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