软刺裸裂尻鱼耳石日轮及年轮沉积规律研究

研究利用软刺裸裂尻鱼(Schizopygopsis malacanthus)确证了耳石生长轮沉积规律,并在此基础上,探究了其生长轮与年轮关系,推算了第一年轮形成时间。研究结果表明:仔鱼微耳石第一轮纹在出膜后第二天形成,在实验条件下,轮纹沉积具有日周期性,生长轮为日轮;成鱼轮纹沉积具有年周期性,生长轮每年增加1轮。基于耳石日轮技术推算养殖和野生软刺裸裂尻鱼第一年轮形成时间分别为2021年1月28日至3月13日(n=40)和2017年3月8日至5月10日(n=75)。养殖和野生样本耳石轮纹数年际间的分析结果发现,软刺裸裂尻鱼耳石轮纹数和耳石年生长宽度随着年龄增加逐渐降低,耳石年生长面积随着年龄增加逐渐增加。这些结果揭示了软刺裸裂尻鱼耳石轮纹沉积规律,有助于增加年龄鉴定的准确性,进而为种群动态研究和渔业管理政策制定等提供参考。     

大麻哈鱼胚胎耳石微结构及其群体环境标记

采用人工调控环境方法对黑龙江、绥芬河大麻哈鱼发眼期胚胎群体耳石日轮进行周期性持续标记。实验分４组: 1组为对照组, 2－3组为变温标记组, 4组为“暴气”-变温标记组, 实验用发眼卵1.2万粒。待胚胎发育至耳石日轮结构形成后实施标记。实验胚胎耳石随着标记期间环境周期性变化及其持续的时间, 形成相应变化节律的日轮标记区。获得各实验组设定环境的日轮标记图谱。人工环境标记的耳石日轮图谱, 暗带色度加深, 明带亮度增大, 并可形成生长轮距不同的标记轮, 与对照组耳石微结构有明显区别, 标记率达到100%。初步建立鱼类耳石标记及其识别技术, 适用于大麻哈鱼等鲑鳟鱼类群体标记。作为安全有效、成本低廉的群体标记技术方法, 鱼类耳石日轮标记在鱼类资源评估和增殖放流效果评价中将会得到广泛应用。       

南极冰鱼年龄与生长的研究进展

南极冰鱼在南极海洋生态系统物质与能量循环中起着至关重要的作用。作为"白血鱼",其科学研究意义和商业价值也为全球所关注,但其年龄与生长研究仍存在较多的不确定性。为此,本文综述了国内外近50年来南极冰鱼年龄与生长的研究进展,概述了南极冰鱼基本分类及其在南极海域的地理分布。在总结南极冰鱼年龄与生长研究的基本方法(包括渔获物体长频度法及钙化组织分析法等)的基础上,着重对南极冰鱼耳石处理及研究进行了归纳,通过耳石前处理(直接观察、燃烧和切割打磨)和轮纹鉴定等,对耳石研究中的耳石鉴龄方法、耳石形态学及耳石日轮等做了总结。通过总结南极冰鱼年龄与生长研究方面的困难和不足,如幼鱼耳石的处理方式及首轮形成的时间等,对今后中国开展南极冰鱼年龄与生长研究提出了展望。     

鱼类耳石微结构的计算机自动识别

本文介绍了鱼类耳石微结构图像识别系统的工作原理和应用实例 ,该系统实现了对鱼类的耳石日轮的自动识别计数和测量日轮宽度 ,并将分析结果自动保存为Excel可识别格式的数据文件。用草鱼微耳石对该系统进行测试的结果表明 ,在随机抽取的 30个样本中 ,有 2 8个样本日轮自动识别的正确率为 1 0 0 % ,其余 2个样本经过手工修改后也能达到对日轮的完全识别。此外 ,采用 768× 5 82像素的BMP格式数字图像测量日轮宽度 ,计算机的分辨率比显微镜提高了约 1 3倍。该系统还可应用于鱼类的鳞片、胸鳍棘和脊椎骨等年龄鉴定材料的微结构分析     

鱼类耳石日轮

介绍了国内外鱼类耳石日轮研究概况,包括其发现和研究进展、形态特征、生长规律、观察研究方法、形成机理、研究意义和发展前景。     

松潘裸鲤仔稚鱼耳石生长轮日周期确证及其孵化期推算

以2015年和2016年在孟屯河上游捕获的仔稚鱼为研究对象, 对其种属进行了鉴定, 观察了耳石形态特征、确证了耳石轮纹沉积规律, 并基于耳石日轮技术对其孵化期进行了推算。结果表明: 基于线粒体细胞色素氧化酶亚单位Ⅰ(Cytochrome oxidase subunit Ⅰ, COⅠ)序列构建的系统进化树显示, 采集仔稚鱼为松潘裸鲤(Gymnocypris potanini)。在松潘裸鲤仔稚鱼生长过程中, 微耳石由近圆形发育成贻贝形, 矢耳石由锲形发育为箭矢状。采用温度标记处理松潘裸鲤仔稚鱼, 确定耳石轮纹沉积具有日周期性, 生长轮为日轮。依据耳石日轮数, 结合采样时间及耳石轮纹沉积规律, 并采用大多数裂腹鱼类日龄为日轮数N+1的关系, 推算出2015年松潘裸鲤样本的孵化时间为6月29日至7月15日, 2016年样本孵化时间为7月13日至8月18日, 这些结果为研究松潘裸鲤野生种群繁殖期及其资源保护等提供了基础数据。     

唐鱼仔鱼耳石的形态发育及日轮

观察了实验室人工繁殖饲养的唐鱼(Tanichthys albonubes)仔鱼耳石形态发育,研究了其生长轮的沉积规律。唐鱼仔鱼耳石长径与鱼体全长(TL)均呈线性相关,其关系式为:微耳石Dl=0.019 6TL-0.031 0(r=0.961 6,P<0.001,n=218),矢耳石Ds=0.027 6TL-0.043 7(r=0.924 0,P<0.001,n=219),星耳石Da=0.016 6TL-0.004 1(r=0.369 6,P<0.001,n=44)。仔鱼耳石上第一个轮纹在孵出后第2 d形成,生长轮数目与仔鱼日龄(D)呈线性相关,其斜率与1无显著差异,因此生长轮为日轮,其关系式为:微耳石LI=1.006D-1.700 1(r=0.994 2,P<0.001,n=205),矢耳石SI=0.953 8D-0.911 6(r=0.993 5,P<0.001,n=161)。生长过程中矢耳石形状变化较大,星耳石出现时间较晚,而微耳石形状稳定,日轮可读性较好,故更适合作为日轮研究的材料。     

鸭绿江香鱼耳石日轮与生长的研究

１９９２年对鸭绿江香鱼耳石日轮与生长进行了研究。人工受精卵胚胎发育后期和前仔鱼期连续剖察表明，受精后约９６小时胚体听囊内出现一对矢耳石，孵出后第２天耳石上出现第一个日轮，之后每天形成一轮。在光镜和扫描电镜下测定了幼、成鱼矢耳石的形态、直径、日轮数及其间距变化。耳石短径（ｖ， μｍ）与鱼体长（ｘ， ｍｍ）呈线性关系， ７５尾幼、成鱼的关系式为ｙ＝３．２８ｘ＋２４８．３０。以耳石日轮数推算其产卵孵化期与实地调查结果一致。耳石日轮数（Ｄ）可用孵化后日数（Ｎ）减１表示。日轮间距有规律性变化，与鱼体生长发育和生态条件密切有关。依据日龄和相关体长体重资料进行了香鱼生长特性研究，用生长方程描绘的生长速度曲线和生长拐点（位于２８３日龄）等均较客观地反映了其生长特点。     

黑龙江秋大麻哈鱼耳石形态发育研究

对进入中国黑龙江的秋大麻哈鱼生殖群体进行人工繁育, 观察不同发育阶段和回归成体的耳石形态及其结构变化。结果表明:秋大麻哈鱼胚胎、胚后仔稚鱼、幼鱼和二龄鱼的矢耳石随个体生长发育,其大小在不断增长, 轮廓和表面形态结构也在发生演变, 逐渐趋似于回归成体的耳石形态。秋大麻哈鱼回归生殖群体的不同年龄和雌雄个体间矢耳石、微耳石形态基本一致。矢耳石形似梨形, 大小约为3 mm×5 mm×1 mm, 重量约为9 mg, 光镜下可见耳石日轮和年轮结构。日轮形成在胚胎发眼后约5日, 采用人工标记方法证实了生长轮的日周期特性。二龄鱼耳石已出现边缘生长区, 形成年轮。矢耳石增长与鱼体叉长生长显著相关(SL=21.574 OL-7.005,R2=0.9926)。       

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。     

The record of daily growth in otoliths of Atlantic silversides, Menidia menidia, from field and laboratory

Otoliths were removed from field-collected silversides of age less than 3 months. Otolith diameter was highly correlated with total length of the fish. Daily growth ring counts for this species are known to be a function of age rather than size, so widths for the daily growth rings provide a record of daily increases in length of the fish. Measurement of ring widths showed that weekly specific growth rate was greater than 70% at age 1 week, but declined to about 30% at age 1 month and about 15% at age 2 months. A laboratory experiment in which temperature was changed on a weekly basis demonstrated that environmental variables can affect the width of rings. Nevertheless, the growth rate of field-collected fish, as calculated from otolith ring widths, was more highly correlated with size of fish, as measured by otolith radius, than with the environmental variables of temperature, salinity and plankton abundance. Back-calculation of growth rates from otolith ring widths of five fish collected at the end of the growing season yielded the same age-growth curves as were obtained from 203 fish collected biweekly during the season.     

Validation of daily increment formation in otoliths for Gymnocypris selincuoensis in the Tibetan Plateau,China

Daily increment validation in fish otolith is fundamental to studies on fish otolith microstructure, age determination and life history traits, and thus is critical for species conservation and fishery management. However, it has never been done for Schizothoracine fish, which is the dominant component of fish fauna in the Tibetan Plateau. This study validated the daily increment formation of Gymnocypris selincuoensis, as a representative of Schizothoracine fish, by monitoring the growth of hatchery‐reared larvae group and wild‐caught post‐yolk‐sac larvae group under controlled experiments. The results from monitoring the hatchery‐reared larvae group showed that sagittae and lapilli were found in yolk‐sac larvae, and formed 5–7 days before hatching, but asterisci were not found until 11 days post‐hatching. The first increment in sagittae and lapilli was formed in the first day after hatching. The daily periodicity of increment formation was examined and confirmed in sagittae and lapilli of both larvae groups. However, sagittae were better for age determination than lapilli for larvae at earlier days. For larval G. selincuoensis older than 50 days, lapilli were the only otolith pair suitable for larvae daily age determination. This study validated the daily increment formation in Schizothoracine fish for the first time has primary implications to other fishes from this subfamily.     

Comparison of otolith growth and morphology with somatic growth and age in young-of-the-year bluefin tuna

Otolith morphological characteristics were studied using image analysis techniques and the relationships between otolith growth and somatic growth and age, as estimated from counting daily otolith increments, were examined in young-of-the-year (YOY) bluefin tuna Thunnus thynnus ranging in fork length ( L _F) from 8·5 to 55·5 cm. Whole otolith length, width, area and perimeter, and three shape indexes, circularity, E value and rectangularity, were extracted for each pair of sagittae. Since no statistical significant differences between left and right otolith morphometrics were found, only one otolith from each fish was used for correlations. Statistically significant relationships were observed between otoliths measurements and fish somatic growth when a linear regression was applied after logarithmic transformation of all variables tested. Among the variables, otolith length was the one that showed the highest correlation with L _F, followed by otolith area and perimeter, whereas otolith rectangularity exhibited the lowest correlation. Statistically significant relationships were also observed between the otolith variables tested and the age of the fish, which ranged from 20 to 129 days. The ages estimated using otolith mass were very close to those assessed using daily increment counts (bias ranged from 1 to 24 days). Therefore, otolith mass could represent a valuable criterion for age estimation in YOY bluefin tuna that is objective, economic and easy to perform compared to daily increment counting method.     

Age determination of corvina reina (Cynoscion albus) in the Gulf of Nicoya, Costa Rica, based on examination and analysis of hyaline zones, morphology and microstructure of otoliths

This is the first age determination study for Cynoscion albus , a large tropical sciaenid, using otolith morphology and daily increment analysis. The practicality of both methods for age determination is illustrated by their consistent estimates of age and von Bertalanffy growth parameters. The daily increment analysis was used to validate the surface readings. An alternative, otolith morphometrics, is shown to hold promise for rapid prediction of fish age. Two multivariate linear regression models using gross otolith dimensions can estimate the age of C. albus to within 1 year. Growth parameter estimates are: from surface readings: L =127.5cm with K =0.12; from daily increment readings: L = 122.1 cm with K =0.17. Implications for the stock assessment of tropical fish using size instead of age are discussed.     

Otolith shape analysis and daily increment validation during ontogeny of larval and juvenile European chub Squalius cephalus

This assesses features of otoliths from laboratory-reared embryos, larvae and juvenile European chub Squalius cephalus from hatching to 180 days post-hatching (dph). We observed the development of the three pairs of otoliths (lapilli, sagittae and asterisci) and more precisely shape changes, as well as timing and deposition rate of increments of the lapilli. The lapilli and the sagittae were present at hatching, whereas the asterisci formed between 20 and 30 dph. The lapillus and sagitta shapes were round until 20 dph. From 60 dph the anterior and the posterior rostra of the sagittae were well developed, but very thin, making this otolith too fragile to manipulate for further studies of shape and validation of otolith increment deposition rate. The lapilli provided reliable age estimates for free embryos, larvae and juveniles up to 120 dph. However, caution should be taken when ageing fish older than 150 dph as an underestimation was noticeable. The regression of the number of otolith increments on age showed a slope and an intercept not significantly different from 1 and 0, respectively, which indicated that otolith growth increments were deposited on a daily basis, with the first microincrement occurring at hatching. Increment counts were consistent between three interpreters, indicating a consistent and reliable age estimate. This study validates that the otolith increment deposition rate can be used to assess hatching dates and daily growth of wild S. cephalus under 150 dph and in environments similar to the conditions used in this study.     

All in the ears: unlocking the early life history biology and spatial ecology of fishes

Obtaining biological and spatial information of the early life history (ELH) phases of fishes has been problematic, such that larval and juvenile phases are often referred to as the ‘black box’ of fish population biology and ecology. However, a potent source of life‐history data has been mined from the earstones (otoliths) of bony fishes. We systematically reviewed 476 empirical papers published between 2005 and 2012 (inclusive) that used otoliths to examine fish ELH phases, which has been an area of increasing attention over this period. We found that otolith‐based research during this period could be split into two broad themes according to whether studies examined: (i) biological objectives related to intrinsic processes such as larval and juvenile age, growth and mortality, and/or (ii) spatial objectives, such as habitat use, dispersal and migration. Surprisingly, just 24 studies (5%) explored a combined biological–spatial objective by simultaneously exploiting biological and spatial information from otoliths, suggesting much more scope for such integrated research objectives to be answered via the use of multiple otolith‐based techniques in a single study. Mapping otolith analytical techniques across these two approaches revealed that otolith structural analysis was mainly used to investigate biological processes, while otolith chemical analyses were most often applied to spatial questions. Heavy skew in research effort was apparent across biomes, with most (62%) publications specific to marine species, despite comparable levels of species richness and the importance of freshwater taxa (just 15% of papers). Indeed, around 1% (380 species) of a possible 31400+ extant species were examined in our surveyed papers, with a strong emphasis on temperate marine species of commercial value. Potential model species for otolith‐based ELH ecology research are arising, with the eel genus Anguilla (24 studies) and the European anchovy Engraulis encrasicolis (14 studies) attracting more research effort than most other taxa. While there is a preponderance of common techniques (e.g. daily otolith increment counts, increment widths), novel techniques such as transgenerational marking and computed X‐ray tomography, are increasingly being applied in published studies. The application of an integrative approach based on a combination of emerging techniques and traditional methods holds promise for major advances in our understanding of ELH fish ecology and to shine light into the ‘black box’ of fish ecology.     

The Morphology and Periodic Structures of the Otolith of the Chinook Salmon (Oncorhynchus tshawytscha), and Temperature-dependent Variation in Otolith Microscopic Growth Increment Width

The otolith (sagitta) of the chinook salmon (Oncorhynchus tshawytscha) has a variable external crystalline morphology which is related to differences in the growth rate of crystals in different parts of the otolith. The internal crystal structure of the otolith is complex with different mineral phases in different growth fields of the otolith and a well-defined series of microscopic growth increments in both the dorsal and the ventral parts (orientation in situ) of the otolith. The period of the microscopic growth increments was shown, by both a rearing experiment and interpolation from fish of known age, to be daily. By rearing sibling chinook salmon at different temperatures (while still maintaining them on the same diet) it was shown that the width of the daily growth increment varies with temperature, but neither multi- nor sub-daily increments appear in the area of regular, daily growth incrementation. Inclusions of the vaterite morph of calcium carbonate crystallizing in the botryoidal habit occur in the otherwise aragonitic otolith. Regularly spaced check rings in the sulcul part of the otolith are homologous with those occurring in the dorsal and ventral growth axis and are. on average, separated by about 28 microincrements.     

Using otolith weight to age fish

The problem of determining and verifying ages of fish, from populations having a considerable variation in size at age, has been investigated using the relationship between otolith size and fish size, which has been shown by several authors to be influenced by growth rate. In such a population of Sardinella aurita Val. an index of age can be obtained for individual fish by calculating the equivalent otolith weight at a particular fish length, using the otolith weight–fish length relationship determined for each age group. This statistic not only permits a much greater proportion of fish to be assigned ages than is possible with otolith reading alone, but also enables the age groups to be verified as year classes. However, it is concluded that, although appropriate models based on otolith-fish size relationships can predict age for groups of fish in which growth rates are known or can be assumed to be consistent, such techniques have a limited application in ageing fish from wild populations with highly variable growth rates.     

cost-effective method of preparing larval fish otoliths for reading using enzyme digestion and staining

A fast and cost-effective method for examining otoliths in fish larvae was developed whereby the otolith remains in situ . Whole fish of the clownfish Amphiprion melanopus were enzymecleared using a laundry pre-soak and then stained using the Von Kossa silver staining method for calcium. The otolith nucleus, daily rings and the otolith edge were all clearly visible and were suitable for a variety of age and growth analyses. The total 'hands on' time required to process these otoliths was c . 3 min, and multiple samples could be processed simultaneously. The reduction in labour of this method to produce clear daily rings in the otolith lends itself to broad use in fish biology where large quantities of otoliths need to be examined in a cost- and time-efficient manner.     

Accounting for Age Uncertainty in Growth Modeling,the Case Study of Yellowfin Tuna (Thunnus albacares) of the Indian Ocean

Age estimates, typically determined by counting periodic growth increments in calcified structures of vertebrates, are the basis of population dynamics models used for managing exploited or threatened species. In fisheries research, the use of otolith growth rings as an indicator of fish age has increased considerably in recent decades. However, otolith readings include various sources of uncertainty. Current ageing methods, which converts an average count of rings into age, only provide periodic age estimates in which the range of uncertainty is fully ignored. In this study, we describe a hierarchical model for estimating individual ages from repeated otolith readings. The model was developed within a Bayesian framework to explicitly represent the sources of uncertainty associated with age estimation, to allow for individual variations and to include knowledge on parameters from expertise. The performance of the proposed model was examined through simulations, and then it was coupled to a two-stanza somatic growth model to evaluate the impact of the age estimation method on the age composition of commercial fisheries catches. We illustrate our approach using the saggital otoliths of yellowfin tuna of the Indian Ocean collected through large-scale mark-recapture experiments. The simulation performance suggested that the ageing error model was able to estimate the ageing biases and provide accurate age estimates, regardless of the age of the fish. Coupled with the growth model, this approach appeared suitable for modeling the growth of Indian Ocean yellowfin and is consistent with findings of previous studies. The simulations showed that the choice of the ageing method can strongly affect growth estimates with subsequent implications for age-structured data used as inputs for population models. Finally, our modeling approach revealed particularly useful to reflect uncertainty around age estimates into the process of growth estimation and it can be applied to any study relying on age estimation.