Ibañez Ana L, Romo-Coronel Marco A
Universidad Autónoma Metropolitana-Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México, DF México.
Rev Biol Trop. 2007 Sep-Dec;55(3-4):1005-13. doi: 10.15517/rbt.v55i3-4.5973.
Lake Metztitlán was dried up completely in the spring of 1998 and refilled in August of that year. In the period September-November, two cohorts of 1.6 million juveniles of a tilapia hybrid were stocked (Oreochromis aureus/O. niloticus), and monitored every month for one year. Since the date of birth of these juveniles was known, the analyses focused on whether the ring marks of the scales, sagittae and opercula or the circuli of the scales could be used to age them. The ring marks of the scales and opercula showed great variability, and the sagittae had a significant relationship with length, but it is unclear if at least the first ring mark could be formed at the hatchery and reflect changes in diet and/or tank movements in the fish farm. The circuli had a continuous regular behavior, with a formation rate of 10.38 +/- 0.93 and 11.38 +/- 0.95 circuli/month for the first and second cohorts, respectively. This proportion was maintained during the study period, and could be of help to calculate an approximate age of juveniles, especially in stocked fish that show multiple ring marks because of manipulation in fish farms and stocking events.
梅茨蒂特兰湖在1998年春季完全干涸，并于同年8月重新蓄水。在9月至11月期间，投放了两批共160万尾罗非鱼杂交幼鱼（奥利亚罗非鱼/尼罗罗非鱼），并对其进行了为期一年的每月监测。由于这些幼鱼的出生日期已知，分析重点在于鳞片、矢耳石和鳃盖骨的环纹或鳞片的轮纹是否可用于确定它们的年龄。鳞片和鳃盖骨的环纹显示出很大的变异性，矢耳石与体长有显著关系，但尚不清楚至少第一个环纹是否能在孵化场形成，并反映鱼苗场中饮食和/或养殖池活动的变化。轮纹具有连续规律的特征，第一批和第二批幼鱼的形成速率分别为每月10.38±0.93条和11.38±0.95条。这一比例在研究期间保持稳定，有助于计算幼鱼的大致年龄，特别是对于那些因鱼苗场操作和放养事件而出现多个环纹的放养鱼类。
