Characteristic and Deposition Regularity of Otolith Annuli in Schizothorax o'connori
Influenced by changes in external environment and human factors,the population size of Schizothorax o'con-nori has experienced a significant decline.Otolith microstructure is well recognized as a prevalent phenomenon in teleost fishes and is widely accepted as a powerful tool for studying population dynamics throughout various life stages.In order to improve the accuracy of age identification and explore the annuli characteristics of S.o'connori for resource conservation purposes,the annual increment periodicity of farmed S.o'connori with known age was determined in this study.The tim-ing of the first annulus formation and analysis of otolith annuli characteristics between farmed and wild samples were con-ducted through otolith microstructure analysis.The results showed that lapilli is a material suitable for studying of annuli characteristics.The cultured fish exhibited an annual deposition pattern in the lapilli,with one opaque zone and translu-cent zone added per year.Utilizing otolith increment technique,it was calculated that the first annulus formation time for both wild(n=56)and farmed(n=45)specimens occurred from late March to early May.Additionally,the microstructural analysis of otoliths revealed a significant disparity between farmed and wild populations,notably in the width of opaque zone and translucent zone of the 1st annulus(P<0.01).This disparity suggested that these bands could serve as distinct markers for distinguishing the farmed and wild populations.The association between otolith radius and fish standard length was examined,revealing a power function relationship.Furthermore,a linear correlation was observed between otolith ra-dius and fish body length.Considering the current situation of hydropower development,multiplication efforts,and fish re-lease in Yarlung Zangbo River's main stream,this study contributes to improving the age identification accuracy,provid-ing references for studying fish population dynamics and formulating fisheries management policies.
Schizothorax o'connoriotolithmicrostructureannuli characteristicstiming of 1st annulus formationYarlung Zangbo River
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