色林错裸鲤的年龄鉴定

本文对色体错裸鲤（Gymnocypris selincuoensis) 的年龄、年龄形成时间以及臀鳞、背鳍条磨片和耳石磨对年龄解释的一致性问题进行了探讨。结果表明在取样的258尾标本中,臀鳞鉴定的年龄在1－21龄之间,背鳍条磨片为1－20龄,耳石磨片为1－29龄。背鳍条和耳石磨片对年龄的判别能力分别为98.41%和94.44%,而臀鳞只有62.30%。在这三种年龄鉴定的材料中,以耳石磨片上的年轮计数最高;尤其是15龄以上的个体,耳石磨片年龄计数与臀鳞及背鳍条磨片计数相差可达5－8龄。年轮的形成时间在每年的4－6月。     

色林错裸鲤的年轮特征

本文描述了色林错裸鲤 (Gymnocyprisselincuoensis)的臀鳞、背鳍条磨片和耳石磨片上的生长标志及特征 ,指出色林错裸鲤臀鳞上的繁殖痕迹 ,以及耳石磨片早期生长中出现类似月周期的生长阻断、光镜下透明带中日生长增长的减少甚至消失等现象与色林错裸鲤的繁殖习性及多变的高原环境相关。在 5种年龄鉴定的材料中 ,以耳石磨片上的轮纹特征最为明显、清晰且规律性强 ,是最好的年龄解释材料 ,而鳃盖骨和脊椎骨上都只能观察到少数几个轮纹 ,并不适合用作年龄鉴定的材料。     

色林错裸鲤的年轮行征

本文描述了色林错裸鲤（Gymnocypris selincuoensis）的臀鳞、背鳍条磨片和耳石磨片上的生长标志及特征,指出色林错裸鲤臀鳞上的繁殖痕迹,以及耳石磨片早期生长中出现类似月周期的生长阻断、光镜下透明带中日生长减少甚至消失等现象与色林错裸鲤的繁殖习性及多变的高原环境相关,在5种年龄鉴定的材料中,以耳石磨片上的轮纹特征最为明显、清晰且规律性强,是最好的年龄解释材料,而鳃盖骨和脊椎骨上都只能观察到到少几个轮纹,并不适用用作年龄鉴定的材料。     

花斑裸鲤年龄鉴定材料的比较与年龄判别

鱼类年龄的准确鉴定是研究鱼类生态学和保护生物学的基础。本文对黄河上游花斑裸鲤(Gymnocypris eckloni)耳石、背鳍条和臀鳞等3种年龄材料的年龄解释一致性以及最佳年龄材料的选择进行了比较和分析,并首次建立了花斑裸鲤低龄个体年龄判别方程。结果表明:花斑裸鲤3种年龄材料上年轮可读性依次是耳石背鳍条臀鳞,最大鉴定年龄分别为25龄、17龄和16龄;对于6龄及以下个体,背鳍条作为年龄鉴定材料更有优势;对7龄及以上个体,耳石效果最佳;同时对6龄及以下个体以全长、体长、体重和空壳重为自变量,采用逐步选择法进行判别分析,最终提取全长和体重建立年龄的分类函数;全部样本正判率和交叉验证正判率显示,该年龄判别模型的正确区分度较高,可用于6龄及以下个体(全长93~259 mm;体重6.25~177.10 g)的年龄判别。     

两种无鳞高原鳅年龄鉴定方法探讨

分析了采自新疆克孜河174尾长身高原鳅(Triplophysa teunis)和258尾叶尔羌高原鳅(T.yarkandensis)的矢耳石及部分个体的背鳍条(n=11和12)、主鳃盖骨(n=20和25)和脊椎骨(n=38和45)的轮纹标志,探讨了用其鉴定年龄的可行性。结果显示,背鳍条磨片和主鳃盖骨均无明显可辨的年轮标志。小个体长身高原鳅的脊椎骨磨片年轮比较模糊,总的判别能力及鉴定吻合率分别为52.63%和70.00%。叶尔羌高原鳅脊椎骨磨片的年龄判别能力为93.33%,但5龄以下个体存在轮纹的断裂、分支和聚合现象,鉴定吻合率为78.57%。所有矢耳石磨片均有日生长增长、生长阻断和年轮等生长标记,年轮由宽而不透明的暗带和窄而透明的亮带组成。174尾长身高原鳅中有171尾矢耳石磨片能观察到年轮特征,判别能力及鉴定吻合率高达98.28%和94.74%。258尾叶尔羌高原鳅有244尾矢耳石磨片能观察到年轮特征,判别能力及鉴定吻合率也高达94.57%和93.44%。两位鉴定者对同一尾鱼的脊椎骨磨片和矢耳石磨片进行年龄计数,长身高原鳅的总吻合率分别为75.00%和80.00%,叶尔羌高原鳅的总吻合率分别为73.81%和83.33%,两鉴定者间无显著性差异(P0.05)。研究表明,矢耳石是两种无鳞高原鳅类最好的年龄鉴定材料,脊椎骨可作为高龄个体的辅助鉴定材料。     

西藏双须叶须鱼八种年龄鉴定材料的比较研究

用微耳石、星耳石、脊椎骨、鳃盖骨、臀鳞、胸鳞、侧线鳞和背鳞等8种年龄鉴定材料识别和鉴定西藏双须叶须鱼的年龄特征并进行比较分析, 以确定适宜的年龄鉴定材料。结果显示: 臀鳞形态特化严重, 胸鳞、侧线鳞、背鳞的年轮特征不明显, 与微耳石比较的平均百分比误差(IAPE)分别为41.63%、51.26%、50.50%和51.26%, 其他4种年龄材料与微耳石比较的IAPE相差不大, 依次为: 星耳石(12.28%)、脊椎骨(15.67%)、鳃盖骨(17.81%); 低于23龄时, 微耳石鉴定的平均年龄与耳石和脊椎骨鉴定的平均年龄较为接近(P>0.05), 分别为14.39龄、13.13龄和13.20龄, 显著高于鳃盖骨和4种鳞片(P<0.05); 高于23龄时, 7种年龄鉴定材料都显著低于微耳石所鉴定的平均年龄(P<0.05)。用微耳石鉴定所得的最大年龄为49龄, 星耳石鉴定所得的最大年龄为35龄, 脊椎骨鉴定所得最大年龄为34龄, 鳃盖骨为34龄, 臀鳞为22龄, 胸鳞为19龄, 侧线鳞为16龄, 背鳞为17龄。微耳石年龄鉴定的年龄读数与体长呈极显著的对数函数关系(P<0.01)。综合分析认为, 微耳石最适宜作为双须叶须鱼的年龄鉴定材料。     

错鄂裸鲤年轮与生长特征的探讨

在描述鳞片、背鳍条和矢耳石三种材料轮纹特征的基础上,比较了这些年龄鉴定材料在判读错鄂裸鲤年龄和反映生长特征上的异同。在个体早期生长阶段,耳石轮纹阻断、8龄以上个体鳞片上年轮环纹的缺失和背鳍条出现轮纹的重叠是影响错鄂裸鲤年龄准确判读的主要因素。采用耳石和鳞片的体长退算数据,Von Bertalanffy方程较好地描述了错鄂裸鲤的生长。由于背鳍条的生长在个体的生长过程中始终呈现为负的异速生长,因此耳石、鳞片在解释个体生长时优于鳍条。     

软刺裸裂尻鱼的年龄鉴定

检测并比较了软刺裸裂尻鱼（Schizopygopsis malacanthus）鳞片、耳石、脊椎骨和背鳍条的年轮特征。结果表明,这4种材料上均具有年轮特征,以耳石最明显,且易于识别,为最好的年龄鉴定材料;鳞片上的年轮也较明显,但高龄鱼外围的年轮常挤在一起,使鉴定结果偏低;背鳍条上的环纹清晰,但边缘出现轮纹的重叠,影响年龄准确判读;脊椎骨上通常只能观察到比较有限的环纹,不适合用作年龄鉴定。     

黄山九龙峰尖头鱥的年龄鉴定

鱼类的年龄鉴定及其最佳骨质材料的选择,是鱼类年龄研究的必要前提,也是鱼类基础生物学和生态学研究的基础。利用2012年4月于黄山九龙峰采集的132尾尖头鱥标本,研究了其鳞片、鳃盖骨、脊椎骨和耳石等骨质材料的年轮特征,并以根据全长分布频率确定的"真实年龄"为参照,比较了鳃盖骨、脊椎骨和微耳石在年龄判读中的精确度和准确度。尖头鱥体侧部和尾柄部的鳞片均无任何年轮标志,星耳石磨片上暗带和明带排列无明显规律,但鳃盖骨、脊椎骨和微耳石上存在明显年轮。鳃盖骨、脊椎骨和微耳石3种骨质材料的年龄判读精确度或准确度差异视不同年龄组有所不同。总体上,脊椎骨年龄判读的精确度最高,鳃盖骨次之,微耳石最低;但年龄判读的准确度正好相反,即微耳石最高、脊椎骨最低。因此,微耳石是尖头鱥年龄鉴定的最佳骨质材料,而其较低的年龄鉴定精确度及其对准确度的潜在影响可通过提高磨片质量和优化判读方法来改善。     

大渡河上游麻尔柯河高原鳅的年龄与生长

研究了采自大渡河上游麻尔柯河及其支流则曲的129尾麻尔柯河高原鳅(Triplophysa markehenensis)的年龄结构和生长特性。结果表明,耳石和脊椎骨都可作为年龄鉴定的材料,其中耳石是进行年龄鉴定的最适材料,脊椎骨则可作为辅助材料;背鳍条不适合用于年龄鉴定。这批麻尔柯河高原鳅的年龄范围为2～8龄,以3～6龄居多,占总数的83.5%;体长体重呈幂函数关系:W=0.000015L2.951931;Von Bertalanffy生长方程为:Lt=173.1241[1-e-0.1597(t+0.5328)],Wt=60.7531[1-e-0.1597(t+0.5328)]2.9519;体重生长曲线的拐点为t=6.25,拐点时体长为114.5mm,体重为17.9g。关键词:耳石;脊椎骨;年龄;生长     

Precision of Age Estimates Obtained from Five Calcified Structure for Wels Catfish,Silurus glanis

Journal of Ichthyology - In this study, vertebrae, otoliths (asteriscus and lapillus), sectioned lapillus and pectoral fin rays were evaluated for age determination of Silurus glanis L., 1758...     

Age determination in common carp <Emphasis Type="Italic">Cyprinus carpio</Emphasis>: history,relative utility of ageing structures,precision and accuracy

The common carp Cyprinus carpio is one of the most widely-distributed freshwater fishes in the world. Due to its value for conservation and fisheries in several native/translocated areas of distribution and its detrimental effects on the aquatic ecosystem in most invasive areas, robust age-based population dynamics models are required for successful management of this species. The present study provides a global review of age determination in carp, including a historical account of ageing methods, an assessment of the relative utility of ageing structures, and an evaluation of precision and accuracy (i.e. validation) of age estimates. Historically, scales were by far the most widely-employed structure, followed by the operculum, otolith, dorsal spine, vertebra and fin ray. However, in countries where carp is categorised as ‘high risk’ of impact, use of alternative structures to the scale was predominant. Causal criteria analysis showed scales and opercula to provide inconsistent evidence for successful annulus identification/counting, whereas consistent evidence was found for otoliths, dorsal spines, vertebrae and (pectoral) fin rays. Precision was always above reference thresholds for scales, whereas for otoliths, dorsal spines and fin rays was in several cases below. Accuracy was addressed sporadically and mostly in high-risk countries. It is suggested that dorsal spines or pectoral fin rays should be used in lieu of scales as non-lethal ageing structures, and otoliths (or vertebrae, pending more research) otherwise, and that validation should always be attempted as part of the set-up of more appropriate ageing protocols and use of correct terminology.     

An assessment of otoliths,dorsal spines and scales to age the long‐finned gurnard,Lepidotrigla argus,Ogilby, 1910 (Family: Triglidae)

Sagittal otoliths, dorsal spines and scales were critically assessed as structures to potentially determine the age of the long‐finned gurnard, Lepidotrigla argus. Counts were made of opaque growth increments and a readability score was assigned to each structure. Comparisons of growth increment counts were made between structures and between readings. All three structures showed some degree of readability and quantifiable growth increments, but this varied within fishes and between structures. Initial results showed that whole otoliths were more suitable to determine age estimates than dorsal spines and scales. Scales were considered unsuitable due to between reading ageing bias, variation in age estimates between structures, low precision and poor readability for this species. Dorsal spines showed evidence of loss of growth increments due to hollowing of the vascular core, which resulted in underestimation of older individuals in comparison to whole otoliths. Further analysis showed that growth increment counts from whole otoliths were lower for older individuals in comparison to sectioned otoliths. It is suggested that this is because of decreased clarity of growth increments towards the outer margin of whole otoliths in older individuals; this problem was not present with sectioned otoliths. It was concluded that sectioned otoliths were a more suitable structure from which to estimate age of L. argus than were whole otoliths, dorsal spines and/or scales.     

Evaluating the effectiveness of teeth and dorsal fin spines for non‐lethal age estimation of a tropical reef fish,coral trout Plectropomus leopardus

This study investigated whether teeth and dorsal fin spines could be used as non‐lethal methods of age estimation for a vulnerable and highly valued tropical fisheries species, coral trout Plectropomus leopardus. Age estimation of individuals from 2 to 9 years old revealed that dorsal spines represent an accurate ageing method (90% agreement with otoliths) that was more precise [average per cent error (APE) = 4·1, coefficient of variation (c.v .) = 5·8%] than otoliths (APE = 6·2, c.v . = 8·7%). Of the three methods for age estimation (otoliths, dorsal spines and teeth), spines were the most time and cost efficient. An aquarium‐based study also found that removing a dorsal spine or tooth did not affect survivorship or growth of P. leopardus. No annuli were visible in teeth despite taking transverse and longitudinal sections throughout the tooth and trialling several different laboratory methods. Although teeth may not be suitable for estimating age of P. leopardus, dorsal spines appear to be an acceptably accurate, precise and efficient method for non‐lethal ageing of individuals from 2 to 9 years old in this tropical species.     

Otolith annulus validation and variables influencing false annuli formation in dorsal spines of saugeye

Marginal increment analysis is a common technique for validating formation of a single annual growth ring on an ageing structure. False annuli can form on ageing structures when environmental variables affect growth of a fish, potentially resulting in age estimation bias. Therefore, validating ageing structures is essential to ensure that accurate and precise age estimates are collected when assessing fish population dynamics. Saugeye (Sander vitreus, [Mitchill, 1818]) and S. Canadensis, [Griffith and Smith, 1834]) are highly valued sport fish that are stocked across the Midwest United States. Using marginal increment analysis, we confirmed that a single annulus was formed yearly in otoliths of juvenile saugeye, however two annuli formed in dorsal spines in a single year. Timing of the first annulus formation in both otoliths and dorsal spines was completed after a slow growth period during winter (otoliths forming in April; dorsal spines forming in March). The second annulus (false annulus) that formed during August in dorsal spines did not form in otoliths. To understand what environmental factors may influence the false annulus to form, we collected monthly water temperatures and percent empty stomachs of juvenile saugeye. The highest water temperatures of the year occur during July and August, which resulted in saugeye seeking thermal refuge and affecting feeding habits. Mean monthly temperature and percent empty stomachs were positively correlated, so during times of high temperatures foraging rates declined, suggesting the formation of false annulus on dorsal spines of juvenile saugeye. This study demonstrates how thermal stress affected accuracy of non‐lethal aging structures and further emphasizes the need for age validation studies prior to using non‐lethal ageing structures to estimate age for a particular species from different aquatic systems.     

Comparison of ageing methods and growth rates for largemouth bass,Micropterus salmoides Lacépède,from northern latitudes

Synopsis Ages determined by counts of apparent annuli on scales, sagittae, vertebrae, pectoral fin ray and dorsal fin spine cross sections of largemouth bass from northern populations, which are older and slower growing fish than in the southern parts of its native range, were compared to establish the accuracy of each method. Linear regression techniques indicated strong agreement (r> 0.9) among ages assigned from the examination of scales, sagittae, and vertebrae. The pattern of growth zones on pectoral fin ray and dorsal fm spine cross sections proved too variable for accurate age determination. Limited data suggest that ages greater than 7+ assigned from scales were more likely to underestimate true ages than the other body parts used, although none of these methods gave satisfactory results. Examination of scales from recovered tagged fish, and the similarity between back-calculated lengths of fish through age 7+ to annulus I and observed lengths of juvenile largemouth bass near the end of their first growing season, support the validity of ages determined from scales. Despite a very limited amount of habitat suitable for largemouth bass and severe climatic conditions, growth of this species in Tadenac Lake was similar to growth in other waters north of the Great Lakes. Differences in physical characteristics among these waters does not appear to influence growth rates of largemouth bass, but probably affects production and biomass.     

Incorporation time of oxytetracycline into calcified structures of the elasmobranch Heterodontus portusjacksoni

The time taken for oxytetracycline to be incorporated as an intense, discrete band was determined by examining vertebrae and dorsal fin spines of Heterodontus portusjacksoni that were injected with oxytetracycline 2–180 days post-treatment. Oxytetracycline was visible in dorsal fin spines 2 days after treatment and 3 days after treatment in sectioned vertebrae. A distinct mark could not be identified in unsectioned vertebrae.     

Age estimation and validation for South Pacific albacore Thunnus alalunga

Validated estimates of age are presented for albacore Thunnus alalunga, sampled from a large part of the south‐western Pacific Ocean, based on counts of annual opaque growth zones from transverse sections of otoliths. Counts of daily increments were used to estimate the location of the first opaque growth zone, which was completed before the first assumed birthday. The periodicity of opaque zones was estimated by marginal increment analysis and an oxytetracycline mark–recapture experiment. Both validation methods indicated that opaque zones formed over the austral summer and were completed by autumn to winter (April to August). The direct comparison of age estimates obtained from otoliths and dorsal‐fin spines of the same fish indicated bias, which was assumed to be due to poor increment clarity and resorption of early growth zones in spines, resulting in imprecise age estimates. As such, age estimates from otoliths are considered to be more accurate than those from spines for T. alalunga. This is consistent with results for a growing number of tropical and temperate tuna Thunnini species. It is recommend that validated counts of annual growth zones from sectioned otoliths is used as the preferred method for estimating age‐based parameters for assessment and management advice for these important stocks.     

Non‐destructive ageing in Notolabrus tetricus using dorsal spines with an emphasis on the benefits for protected, endangered and fished species

Age estimates from clipped dorsal spines were compared to otoliths and scales in the blue throat wrasse Notolabrus tetricus . Dorsal spines provided accurate, non‐destructive ageing and are recommended in favour of destructive methods for conservation purposes.