青海湖裸鲤仔稚鱼耳石结构特征与早期生长相关性分析

Correlation between otolith structure and early growth of Gymnocypris przewalskii larvae and juveniles

为了解青海湖裸鲤(Gymnocypris przewalskii)仔稚鱼耳石结构特征与其早期生长的相关性,通过采集典型洄游产卵河道的青海湖裸鲤野生仔稚鱼和同期人工培育的仔稚鱼,观察仔稚鱼耳石微结构特征,确认第一轮纹出现时间和耳石轮纹沉积规律,并拟合耳石轮纹数、轮纹间距与日龄间的关系。结果表明:青海湖裸鲤仔稚鱼耳石生长呈日周期性,日龄以轮纹数(N)+1进行推算;根据日龄和采样日期推算,2020年从青海湖支流沙柳河采集的野生仔稚鱼孵化期为6月5日—8月14日,主要集中于7月中旬和8月初,从泉吉河采集的野生仔稚鱼孵化期为6月27日—8月3日,孵化高峰期在7月中旬,与早期野外资源现场调查发现鱼卵的孵化期时间基本吻合;野生与人工培育仔稚鱼全长(LT)与日龄(t)均呈极显著线性相关(P<0.001),耳石长度与仔稚鱼全长呈显著线性相关(P<0.05),其中,15℃条件下人工培育的仔稚鱼相关系数最高,此条件下的人工培育仔稚鱼全长拟合方程为L_(T)=0.1672t+10.377(R^(2)=0.6890,P<0.001)。研究表明,青海湖裸鲤仔稚鱼耳石生长受环境因子影响较大,且耳石的沉积变化与仔稚鱼生长发育关系密切。

In order to clarify relationship between structure of otolith and early growth characteristics in larval and juvenile Gymnocypris przewalskii,the microstructural characteristics was observed and the appearance time of the first rings and deposition pattern of the otolith rings were comparatively identified in larval otolith of cultured and wild G.przewalskii from artificial breeding and collected from Shaliu River(37°18′50.93″N,100°08′6.86″E)and Quanji River(37°14′7.10″N,99°53′3.78″E),the migratory spawning tributaries of Qinghai Lake.The otolith deposition was observed in the larvae and juveniles exposed to 10,15,and 20℃in temperature marking test and the correlations between the otolith daily age,width of otolith marking rings and daily age were fitted.It was found that the deposition of otolith diurnal cycle is daily.The larval fish daily age was calculated by the otolith rings number plus 1(N+1).The daily age and sampling date revealed that the larvae and juveniles collected in Shaliu River in 2020 were incubated from June 5th to August 14th,peak in mid-July and early August.The larvae and juveniles in Quanji River were incubated from June 27th to August 3rd,the peak period in the mid-July.The results above were basically consistent with the fish larvae appearance time found in field investigation.The total length of larval and juvenile had significant linear,correlated with daily age,the otoliths length had significant line-ar correlated with fish total length with the maximal correlation coefficient in the artificially cultivated larvae and ju-veniles at water temperature of 15℃.The fitted equation was shown to be L_(T)=0.1672t+10.377(R^(2)=0.6890,P<0.001).The otolith growth of the larvae and juvenile was greatly affected by the environmental factors,and the variation of otolith deposition was closely related to the growth and development of larvae and juveniles.