西藏浪错兰格湖裸鲤种群繁殖生物学特征

2017年7月至2018年6月,于西藏自治区昂仁县浪错采集兰格湖裸鲤(Gymnocypris chui)307尾,开展种群繁殖生物学研究。结果显示,浪错兰格湖裸鲤在3～5月性成熟系数较高。雌性最小性成熟个体年龄为7龄,体长217mm,体重122.68g,成熟系数为3.92%;雄性最小性成熟个体年龄为6龄,体长198 mm,体重91.93 g,成熟系数为3.34%。其平均成熟卵径为2.18 mm,卵径分布为单峰型。绝对繁殖力为862～8 933粒/尾,平均绝对繁殖力为(2 885±2 765)粒,相对繁殖力为7～43粒/g,平均相对繁殖力为(15±11)粒/g。绝对繁殖力与体长和体重呈显著正相关,相对繁殖力与体长、体重的相关性不显著。繁殖群体性比(♀︰♂)为1︰0.967,符合1︰1比例。     

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。     

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。     

西藏朗错秋季裸鲤属营养生态位及种间食物关系

西藏朗错海拔4300 m,是典型的高原湖泊之一。湖内具有兰格湖裸鲤和拉孜裸鲤共存的现象。本研究采用碳、氮稳定同位素技术分析了2018年秋季兰格湖裸鲤和拉孜裸鲤的食物组成和营养生态位,探讨了两种裸鲤的种间食物关系,包括饵料相似性和重叠系数。结果表明: 兰格湖裸鲤主要摄食蜉蝣类幼虫、摇蚊类幼虫、着生藻类、钩虾类和浮游生物;拉孜裸鲤主要摄食蜉蝣类幼虫、着生藻类、摇蚊类幼虫、钩虾类和水生维管束植物。两种裸鲤的营养生态位存在重叠,兰格湖裸鲤的δ¹³C值变幅(CR=1.60)、δ¹⁵N值变幅(NR=1.89)和凸多边形,总面积(TA=1.80)均小于拉孜裸鲤,差值分别为0.09、0.57和1.29。两种裸鲤的饵料相似性系数(94.2％)和重叠系数(91.5%)均较高,表明秋季西藏朗错两种裸鲤可能存在激烈的种间食物竞争关系。     

青海湖裸鲤生长特征的研究

对2002年5月—2003年7月采自青海湖的1174尾青海湖裸鲤样本年龄进行了耳石鉴定,并依据年龄推算了生长率。青海湖裸鲤体长与体重的关系为:W=0.000174×L2.4990(♀)、W=0.0000402×L2.7538(♂),雌、雄个体生长差异显著。其体长Von Bertalanffy生长方程为:Lt=551.9301(1-e-0.0711(t 0.3044))(♀),Lt=682.8688(1-e-0.0530(t 0.4240))(♂);体重Von Bertalanffy生长方程为:Wt=1237.3431(1-e-0.0711(t 0.3044))2.4990(♀),Wt=2567.3242×(1-e-0.0530(t 0.4240))2.7538(♂)。其雌、雄生长拐点分别为12.57龄和18.67龄。     

色林错裸鲤的生长

对藏北高原色林错湖泊中色林错裸鲤（Gymnocypris selincuoensis)的生长方程、生长拐点以及生长指标等生长特征进行了分析。结果表明von Bertalanffy生长方程、Gompertz方程和三次多项式方程都可以反映色林错裸鲤的生长过程,但Gompertz方程能够很好地描述12龄之前的生长特征,而von Bertalanffy生长方程更适合描述18龄以后的生长特征。这种情况反映了色林错裸鲤具有洄游性鱼类更换生活环境的生活史特征。雄性体长的von Bertalanffy生长方程为：Lt=484.1906[1-e^-0.06839(t-0.06028)],雄性为Lt=485.3285[1-e^-0.0710(t-0.5679)]。体长和体重关系为W＝0.00023L^-5.5303(♂）和W＝0.00046L^2.4072(♀）。生长拐点为12.9龄（♀）和14．2龄（♂）。与其它裂腹鱼类相比,色林错裸鲤的生长过程尤为缓慢,这与其生存的环境条件更为恶劣直接相关。     

青海湖裸鲤不同年龄鉴定材料的年轮特征

通过各种年龄鉴定材料比较研究了青海湖裸鲤的年轮特征。微耳石和星耳石可用于鉴定年龄,而矢耳石易碎,不适合鉴定年龄。4种年龄鉴定材料对青海湖裸鲤年龄的判别能力为:背鳍条>微耳石>臀鳞>脊椎骨。对8龄以下个体,用背鳍条磨片鉴定年龄效果较佳;对8龄以上个体,臀鳞、背鳍条磨片和脊椎骨上的年轮计数明显低于微耳石磨片,微耳石磨片是高龄青海湖裸鲤较为可靠的年龄鉴定材料。       

金沙江上游软刺裸裂尻鱼年龄和生长的研究

以2011年4～5月和2011年9～10月期间采集于金沙江上游的328尾软刺裸裂尻鱼Schizopygopsis malacanthus Herzenstein为材料,用微耳石鉴定年轮,对其年龄和生长进行研究,以期为进一步的鱼类生态学研究和资源保护提供依据.结果表明,微耳石上宽而暗的增长带与窄而透明的增长带交替出现,窄带与宽带交界处为年轮;体长与体重呈幂函数关系:W=0.00002L2.970;von Bertalanffy方程为:Lt=382.1067×(1-e-0.1058(t+0.1045)),Wt=949.0577×(1-e-0.1058(t +0.1045))2.970;体重生长拐点年龄为10.2龄,对应的体长和体重分别为253.4 mm、280.4 g.软刺裸裂尻鱼是裂腹鱼类中生长较慢、体型较小的种类,是对金沙江上游生态与环境适应的结果.     

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。     

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。     

Otolith Microstructure of Larval Gymnocypris potanini Herzenstein from the Minjiang River in China

Synopsis Otolith microstructure of about 120 Gymnocypris potanini larvae from the Minjiang River in China was examined and analyzed. Larvae had multiple primordia in most lapilli and sagittae, while had only one primordium in a few specimens. There had only one nucleus in otoliths of the larvae, except for some few specimens with 2 nuclei. The transparence of many otoliths differed from center to edge, and part of them could be divided into inner low optically dense zone (LODZ) and outer optically dense zone (ODZ). Based on increment clarity, otoliths of this species could be classified into three types, which were otolith with subtile increments, otolith with almost identified increments, and otolith with fairly clear increments characterized by high contrast. The last two types of otolith accounted for 87.07% in lapilli and 94.46% in sagittae, respectively. Increment clarity of sagitta was higher than that of lapillus. Natural checks were identified in 32.50% lapilli and 48.33% sagittae. These checks primarily located in the first to sixth increment. According to the number of increments in otoliths, the age of this batch larvae was 14 – 22 days, birth date was on June 17 – 25, and average growth rate of body length was 0.8936 ± 0.08769 mm/d.     

Growth of the clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon, in the Zambian waters of Lake Tanganyika

The age and growth of two endemic Lake Tanganyikan clupeid fishes, Stolothrissa tanganicae and Limnothrissa miodon , were estimated from analysis of otolith microstructure in specimens collected in Zambian waters from October to December 1990. Both species had relatively clear, concentric otolith increments which were believed to represent daily increments based on their similarity to daily increments found in some marine clupeid species. The growth rates estimated from length-at-age data were: for S. tanganicae, L_t = 104·0 (1 – exp (– 0.00512 ( t – 5·8))); for L. miodon, L_t = 155.4 (1 – exp (– 0.00236 ( t +8.1))). In most cases, the growth parameters obtained from otolith analyses generally agreed with those previously estimated from analyses of length-frequency distributions.     

Age validation and growth of three commercially important hemiramphids in south-eastern Australia

The method of using sectioned otoliths to estimate age in three species of garfishes (family Hemiramphidae) was validated by: (1) staining fishes with the vital stain alizarin complexone (ALC) and periodically examining their otolith growth, and (2) marginal increment analyses. Staining fishes with ALC indicated that opaque zones were formed during winter and spring, but did not become visible on the otolith edge until late spring and summer. Hyporhamphus australis were found to be similar to the hemiramphids of the Atlantic in having fast growth rates and a maximum observed age of 4+ years old. Hyporhamphus regularis ardelio and Arrhamphus sclerolepis krefftii were found to be more similar to the southern sea garfish, Hyporhamphus melanochir , in being moderately long-lived, with maximum observed ages of 7+ years old for both species. Females grew faster and attained greater fork lengths than males for each species. Sectioned otoliths showed large variation in the appearance of opaque zones between the three species studied, with those from the wide-ranging, oceanic H. australis appearing inconsistent and diffuse when compared to the estuarine H. r. ardelio and A. s . krefftii . This variation was also apparent from fishes kept in aquaria, suggesting that the appearance of opaque zones in otoliths of these species is largely influenced by physiology, rather than by environmental conditions.     

Age and growth of albacore Thunnus alalunga in the North Pacific Ocean

The age and growth of North Pacific albacore Thunnus alalunga were investigated using obliquely sectioned sagittal otoliths from samples of 126 females and 148 males. Otolith edge analysis indicated that the identified annulus in a sagittal otolith is primarily formed during the period from September to February. The assessments of the fish age at first annulus formation indicated that the first annulus represents an age of <1 year. This study presents an age estimate (0·75 years) for the formation of the first annulus. The oldest fish ages observed in this study were 10 years for females and 14 years for males. The von Bertalanffy growth parameters of females estimated were L(∞) = 103·5 cm in fork length (L(F) ), K = 0·340 year(-1) and t(0) = -0·53 years, and the parameters of males were L(∞) = 114·0 cm, K = 0·253 year(-1) and t(0) = -1·01 years. Sexual size dimorphism between males and females seemed to occur after reaching sexual maturity. The coefficients of the power function for expressing the L(F) -mass relationship obtained from sex-pooled data were a = 2·964 × 10(-5) and b = 2·928.     

Age and growth of Saurenchelys (Nettastomatidae) and Dysomma (Synaphobranchidae) leptocephali in the East China Sea

The otolith microstructures of the leptocephali of Saurenchelys stylura and Dysomma sp., collected in November and December 2000 in the East China Sea, were examined to determine their larval ages and growth rates, and the spawning times of these two species of outer shelf and slope marine eels. Leptocephali ranging in size from 8 to 48 mm total length were examined, and the nettastomatid, S. stylura , and the synaphobranchid, Dysomma sp., had estimated ages that ranged from 16 to 75 days and 17 to 66 days, respectively. The overall growth rate of S. stylura was 0·68 mm day⁻¹( n  = 21), and of Dysomma sp. was 0·44 mm day⁻¹( n  = 22). These growth rates were similar or slightly faster than those observed for anguillid leptocephali in offshore areas of the western Pacific. The backcalculated hatching dates for these two species were from September to November. The otolith increment widths of S. stylura showed an increase before 20 to 30 days that were similar to those in anguillid species, but in Dysomma sp. there were no remarkable increases.     

Age and growth of the dusky grouper Epinephelus marginatus (Lowe 1834) in an exploited population of the western Mediterranean Sea

The age and growth of the dusky grouper, Epinephelus marginatus , in the Balearic Islands (western Mediterranean) were studied by otolith analysis from a sample of 358 specimens ranging in total length ( L _T) from 6·6 to 105·6 cm. The specimens came from commercial artisanal and recreational spear fisheries between 1999 and 2003. Otoliths grew asymmetrically throughout the range of L _T studied, showing a clear pattern of alternating translucent and opaque bands. Marginal increment analysis of specimens up to 8 years-old indicated that a single opaque band was formed each year during spring and summer. Whole otoliths allowed ageing specimens up to 10 years old, but above that age whole otoliths yielded lower age estimates than sectioned otoliths. The maximum estimated age was 61 years, which significantly extends the estimated life span of the species from a maximum of 36 years in a previous study. The von Bertalanffy growth parameters were estimated as L _∞= 95·5 cm L _T, K = 0·087 and T _O=−1·12. The study revealed differences in mean L _T at age and age structure between the shallow- and deep-water samples which may be attributed to different fishing pressure and environmental conditions.     

Gymnocypris chui Tchang,Yueh & Hwang, 1964 and Gymnocypris scleracanthus Tsao,Wu, Chen & Zhu, 1992 from Lake Langcuo,Qinghai‐Tibet Plateau

This study presents length‐weight relationships (LWRs) for two sympatric species of the subfamily Schizothoracinae (Cyprinidae), Gymnocypris chui and G. scleracanthus, captured in Lake Langcuo in Tibet, China. A total of 193 specimens were collected in June and July of 2014 and 2015 using gill nets of different mesh sizes (mesh size: 2 × 2 cm, 3 × 3 cm). Specimens included 76 G. chui and 117 G. scleracanthus. The values of parameter b in the LWRs equations were estimated as 2.875 for G. chui, and 2.773 for G. scleracanthus, respectively. These are the first LWRs records for the two sympatric species.     

Relationships between climate and growth of Gymnocypris selincuoensis in the Tibetan Plateau

The consequences of climate change are becoming increasingly evident in the Tibetan Plateau, represented by glaciers retreating and lakes expanding, but the biological response to climate change by plateau–lake ecosystems is poorly known. In this study, we applied dendrochronology methods to develop a growth index chronology with otolith increment widths of Selincuo naked carp (Gymnocypris selincuoensis), which is an endemic species in Lake Selincuo (4530 m), and investigated the relationships between fish growth and climate variables (regional and global) in the last three decades. A correlation analysis and principle component regression analysis between regional climate factors and the growth index chronology indicated that the growth of G. selincuoensis was significantly and positively correlated with length of the growing season and temperature‐related variables, particularly during the growing season. Most of global climate variables, which are relevant to the Asian monsoon and the midlatitude westerlies, such as El Nino Southern Oscillation Index, the Arctic Oscillation, North Atlantic Oscillation, and North America Pattern, showed negative but not significant correlations with the annual growth of Selincuo naked carp. This may have resulted from the high elevation of the Tibetan Plateau and the high mountains surrounding this area. In comparison, the Pacific Decade Oscillation (PDO) negatively affected the growth of G. selincuoensis. The reason maybe that enhancement of the PDO can lead to cold conditions in this area. Taken together, the results indicate that the Tibetan Plateau fish has been affected by global climate change, particularly during the growing season, and global climate change likely has important effects on productivity of aquatic ecosystems in this area.