新疆乌伦古湖湖拟鲤4种钙化组织鉴定年龄的比较

Comparative studies on four calcified structures for age determination of roach Rutilus rutilus in Ulungur Lake,Xinjiang Uigur Autonomous Region,China

对新疆乌伦古湖湖拟鲤4种钙化组织(鳞片、鳃盖骨、匙骨和耳石)的形态和年轮标志进行了描述,并对这4种钙化组织鉴定湖拟鲤年龄的一致性进行了探讨。在各钙化组织中,鳞片、鳃盖骨和微耳石磨片上检出的最大年龄均为6+龄,而星耳石、完整微耳石和匙骨上检出的最大年龄为5+龄。微耳石磨片上的年轮特征最为清晰,判别能力最高(94.0%),同一鉴定者两次年龄读数之间的吻合率也最高(95.1%),是湖拟鲤年龄鉴定的最佳材料。鳞片和鳃盖骨的判别能力和同一鉴定者两次年龄读数间的吻合率次之,分别为92.0%、90.8%和87.5%、86.1%;4+龄及以下个体鳞片上的年龄读数与微耳石磨片吻合较好,而4+龄以上个体鳃盖骨上的年龄读数与微耳石磨片吻合较好,两者配合使用可取得较好的鉴定效果。匙骨除个别年龄标志非常清楚外,其他大多因干扰轮纹过多或没有明显的年龄标志,判别能力最差,只有78.2%,同一鉴定者两次年龄读数之间,以及与微耳石磨片年龄读数之间的吻合率也较差,仅为55.7%和43.5%,不适于湖拟鲤的年龄鉴定。3+龄及以下个体完整微耳石和星耳石的年龄读数与微耳石磨片吻合较好,但4+龄及以上个体用完整微耳石难以准确确定其年龄,星耳石则效果更差。

This paper deals with the interpretability and agreement of age readings from a suite of calcified structures （ scales, lapilli, opercula and cleithra）, and the consistency of age interpretations for roach Rutilus rutilus （Linnaeus, 1758） from Ulungur Lake, in North Xinjiang Uigur Autonomous Region, China. Among these calcified structures, the largest ages observed on scales, opercula and the sectioned lapilli were 6 ^＋ years old, while 5 ^＋ years on the asteriscus, whole lapilli and cleithra. The sectioned lapillus was demonstrated as the best structure for ageing roach with the clearest annuli, the highest interpretability （94.0 %, n = 306 ） and the highest agreement （ 95. 1% , n = 288 ） between two times age readings by the same reader. The interpretability of scales and opercula reaches 92.0 % （ n = 287 ） and 90.8 % （ n = 87 ）, respectively, and the agreement between two times age readings using the scales and opercula by the same reader reaches 87.5 % （ n = 264） and 86.1% （ n = 79）, respectively. There wound be achieve a better result if the scales and the opercula were used together in age determination for that the scales are fit for aging those individuals less than 4 years old and the opercula are suitable for aging those individuals 4 years old and above. The cleithrum had the lowest interpretability （78.2 % , n = 87） and agreement between two times age readings （55.7 % , n = 68 ） because in most cases, it was uninterpretable as there were no annuli or did not display a clear pattern of annuli on it. The interpretability of the whole lapilli and the ateriscus are 90.0 % （ n = 330） and 80.1% （n = 330）, respectively. However, they are only suitable for age estimation of those individuals less than 4 years old because the annuli on those of the older individuals will become less distinct with age increase.