| This paper studied on the growth, development and microstructure of Schizothorax prenanti larva and juveniles otolith, which were reared in laboratory conditons during 2013 and 2014.And on this basis,characteristic of otolith microstructure,growth of larva and juveniles and breeding season were researched,which collected from the Dadu river from 2012 to 2014. The main results as follows:1.When water tempreture was 13.5-17.2℃, lapilli and sagittae were appeared before hatching and asteriscus appeared 12 days post hatching (dph). Precursors of lapilli and sagittae were dispersed tiny particles at 136 hours post fertilization (hpf), gathered into 2 to 5 crystallization, and then fused development to suborbicular until hatching. The morphological of lapillus changed from near round to mussel shape accompanied their development. And the sagittae changed from nearly elliptic to rhombus and their stable morphological were the arrow sagittal. However, the morphological of asteriscus was irregular and changed from heart-shaped to nearly flabellate. The radius (OR) of lapilli, anterior and poeterior area, and the days post hatching (D) were linear correlation, but dorsal and venter area were power fuction. The radius (OR) of sagitta, anterior and poeterior area, and the days post hatching (D) were linear correlation, but dorsal and venter area were power fuction.2.When water tempreture was 18.5±0.5℃ and 15.6±1.1℃, the first increment of sagittae was formed at 2dph, respectively,18 hours and 19 hours post hatching, later forming round every day. The increase number of sagittae and lapilli (Is) and the days post hatching (D) was a linear correlation. Upon examination, the relation between slope and 1 had no significant difference (.P>0.05), showed that 2 pair of otolith deposied daily, and could be regarded as daily growth increment. So, the days post hatching (D) could be showed with increase number (I):D=I+1.3.In the conditions of laboratory,central nuclear (N) and primordium (P) of lapillus, S. prenanti (2013, n=280; 2014, n=517), were main formed of 1N1P,1N2P,1N3P and 2N2P, whose proportion were 54.08%,33.75%,8.28% and 3.01%, respectively, the others were 0.88%. Lapilli likely, proportion of the sagittae (2013, n=293; 2014, n=485) were 23.01%,44.99%,19.67% and 7.32%, the others were higher than which were lapillus. The result shown that, the lapilli (n=35) and sagittae (n=51) of 40 dph, the width of the Mst increment in sagittae (21.25±3.98μm) were bigger than that of lapilli (18.90±2.04μm), and then, the same change trendency had appeared in the two pair of otolith before the fifth increment.Then,the width of increments were continue to narrow in lapilli, but fluctuating in sgaittae, but both of them became steady at later stage.4.The total length (TL) and body weight (BW) of larva and juveniles, S. prenanti, were power fuction. The radius (OR) of lapillus and sagitta, anterior, poeterior, sum of them, dorsal, venter area, and the total length (TL) were linear correlation. Statistical results of central nuclear and primordium of otolith, which collected 3 years, showed that 1N1P (23.25-59.72%) and 1N2P were most,lN3P and 2N2P were more, the others were less in which of lapilli. Most of sagittae were 1N1P (21.43-38.40%) and 1N3P (17.02-40.63%), but 1N1P,2N2P and the others were less. Increment width of lapilli and sagittae of wild larva and juveniles, S. prenanti, had difference between different years, the trendency were gradually narrow in lapilli, but remarkable broadening in sagittae.5.Using the relationship of incream numbers (Ⅰ) of otolith and daily age (D) which was studied in laboratory,and combining the round grain number of wild samples,to calculater the range of daily age were 30-112d in May 2012; 48-166d in May 2013, 50-183d in June 2013; 49-129d in April 2014,64-164d in May 2014,77-194d in June 2014. On this basis, combination of sampling time to calculate the breeding, S. Prenanti, were from December 3 to the April 13 of next year, the mainly hatching peak were early January to mid-march in Dadu river. |
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