Preliminary examination on lapillus utility for otolith increment analysis in Malawian cyprinid <Emphasis Type="Italic">Engraulicypris sardella</Emphasis>

Features and increments of otoliths in Engraulicypris sardella were observed. The sagitta was arrowhead shaped with an obvious core and rostra, the latter being fragile and easily destroyed by extracting and grinding processes. Increments around the core were readable but not in rostra. The lapillus was round fan-shaped with an obvious core. Increments in the lapillus were clearly deposited from the core to the margin. The asteriscus had an ambiguous core that led to difficulty in discerning the first increment and had fewer increments than the lapilli. Thus, the lapillus is the most appropriate for reading otolith increments.     

Otolith development and daily increment formation in larvae of the Kabyabya,a Malawian cyprinid, <Emphasis Type="Italic">Opsaridium tweddleorum</Emphasis>

Features of the sagitta, asteriscus, and lapillus of laboratory-hatched larvae of the Kabyabya, Opsaridium tweddleorum, were investigated until day 33 after hatching. The sagitta was round until day 17, subsequently becoming arrowhead-shaped with the development of anterior and posterior rostra. Increments in the sagitta increased at the rate of one per day before rostrum formation. However, they were occasionally overestimated in rostrum sections as a result of subdaily increment occurrence. Furthermore, both anterior and posterior rostra were fragile, being thin and platelike, and were often damaged during the extraction and grinding processes. The lapillus was also round until day 17, thereafter becoming fan-shaped. Increments in the lapillus were distinctive from the core to the margin, usually increasing at the rate of one per day after hatching. The asteriscus appeared in fish larger than 9.15 mm in standard length (from day 17), being oval with a somewhat ambiguous core, causing difficulty in discerning the first increment. These features indicated that the lapillus was the most appropriate otolith part for daily increment analysis in this species, although the sagitta was useful before rostrum formation.     

Otolith features and utility of lapillus for daily increment analysis in <Emphasis Type="Italic">Opsaridium microcephalum</Emphasis> (Cyprinidae) juveniles collected from Lake Malawi

 Features of otoliths in Opsaridium microcephalum juveniles were observed, and the increment formation pattern was validated using Alizarin Complexone (ALC). The sagitta was arrowhead shaped with an obvious core and rostra, the latter being fragile and easily destroyed by extracting and grinding processes. Increments around the core were readable but not in the rostra. The asteriscus was oval shaped with an ambiguous core leading to difficulty in discerning the first increment. The lapillus was round and fan shaped with an obvious core. Increments in the lapillus were clearly deposited from the core to the margin. These features made the lapillus the most appropriate for reading otolith increments. Increments counts in the lapillus formed after ALC treatment agreed with days elapsed, showing the daily formation of increments. Consequently, the lapillus is only appropriate for daily increment analysis in Opsaridium microcephalum. Received: December 4, 2001 / Revised: August 14, 2002 / Accepted: September 11, 2002 Acknowledgments The authors express great thanks to J.S. Likongwe and E. Kaunda, Department of Aquaculture and Fisheries Science, Bunda College of Agriculture, University of Malawi, for their advisory comments. The authors are also grateful to the Japan International Cooperation Agency (JICA) for giving us an opportunity to work on this subject. Correspondence to:Shinsuke Morioka     

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.     

骨唇黄河鱼耳石早期形态发育和轮纹特征研究

研究了骨唇黄河鱼仔稚鱼耳石在实验室养殖条件下的发育过程和生长特点,确证了轮纹沉积规律。结果表明,在14.0-17.8℃孵化条件下,微耳石和矢耳石在受精后96h 30min出现,星耳石在出膜后第16天出现。仔稚鱼生长过程中矢耳石形状变化较大,由出膜时的圆形发育到稳定时的箭矢状。微耳石由近圆形发育成贻贝形,其中心核位置随发育明显偏移。星耳石形状不规则,从出现时的心形发育成为星芒状。微耳石和矢耳石在前后轴方向上后区的生长快于前区（P0.05）;在背腹轴方向上,微耳石腹区的生长快于背区（P0.05）,矢耳石背区的生长快于腹区（P0.05）,两对耳石的前后区半径之和与全长均呈线性相关。微耳石和矢耳石的第1个轮纹均在出膜后第2天形成,新增的轮纹数（微耳石IL,矢耳石IS）与出膜后的天数（D）表现出显著的线性相关,方程分别为: IL=0.9911D-1.0008（R2=0.9971,n=220,P0.001）和IS=0.9925D-0.10873（R2=0.9919,n=161,P0.001）,方程的斜率与1均无显著差异（P0.05）,表明两对耳石轮纹沉积均呈日周期性,生长轮为日轮。研究结果丰富了骨唇黄河鱼的发育生物学资料,可为研究其自然种群早期生活史提供参考。       

Validation of daily otolith increments in larval and juvenile Chinese sucker, <Emphasis Type="Italic">Myxocyprinus asiaticus</Emphasis>

Otolith development was observed and the formation of daily growth increments in otoliths of Chinese sucker, Myxocyprinus asiaticus, was validated by monitoring known-age larvae and juveniles in the laboratory from 2003 to 2005. Otolith shape changed with larval and juvenile development, and there was an exponential relationship until a body length of 16 mm or so, and a linear relationship after a body length of 16 mm between otolith size and fish size. The first increment was identified in larvae 1 day after hatching. The regressed equations between daily age (D) and increment number in otoliths (N) were N = −0.64 + 0.96D in lapillus, and N = −0.31 + 0.98D in sagitta. The slopes were not significantly different than 1.0. This demonstrated that otolith increments in this species were formed daily and can be used for daily age determination.     

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.     

Age and growth information available from the otoliths of the Hawaiian snapper,Pristipomoides filamentosus

The otoliths of tropical fish may provide important life history information incorporated within their structural and chemical constituents. All three otoliths (sagitta, lapillus, asteriscus) of the tropical fish Pristipomoides filamentosus were examined internally by Scanning Electron Microscope methods to observe micro-increments and externally to determine three dimensional structure. It was discovered that the sagitta contained four cores and that the plane chosen to be sectioned for micro-increment enumeration could result in errors if more than one core were transversed. The medial cross sectional plane was consequently resolved to effer the most accurate micro-increment counts. Obserations of lapilli also revealed micro-increments and subsequent counts were closely correlated to those detected in the sagittae. The visualization of increments made it feasible to assess age and evolve a growth model. In addition, sagitta weight was found to be related to growth rate and may provide a quick estimate of relative growth. Chemical analyses of otoliths for stable isotopes and Sr/Ca ratios all suggested that an individual fish inhabited warmer waters as it became older. A combination of otolith structural and chemical information can provide age and growth data which is essential to the calculation of accurate population parameters.     

齐口裂腹鱼耳石早期生长发育与日轮特征研究

文章研究了在实验室条件下齐口裂腹鱼仔稚鱼耳石早期形态发育与生长特点、第一轮纹出现时间和轮纹沉积规律。结果表明: 在13.5-17.2℃孵化条件下,微耳石和矢耳石在出膜前形成,而星耳石于出膜后第12天出现。在仔稚鱼生长过程中,微耳石由近圆形发育成贻贝形,矢耳石经历近圆形、锲形后发育为箭矢状,星耳石形状由近圆形发育为星芒状。微耳石的前区、背区和腹区及矢耳石的背区和腹区生长呈幂函数关系,而微耳石的后区、矢耳石前区和后区生长以及两对耳石的前后区半径之和与全长均呈线性相关。在(18.50.5)℃和(15.61.1)℃条件下,50%矢耳石样本第一轮纹均在出膜后第 2 天形成(分别为出膜后18h和19h),以后每天形成一轮。微耳石和矢耳石轮纹数均与日龄呈线性相关,方程斜率均与1差异不显著(P0.05),表明两对耳石的轮纹沉积均为日周期性。这些结果为研究齐口裂腹鱼野生种群繁殖期和早期生活史特征等生态学问题提供了重要依据。     

Otolith Morphology of Amur Sleeper Perccottus glenii (Odontobutidae)

Journal of Ichthyology - Morphology of the sagitta, lapillus, and asteriscus is described in Amur sleeper Perccottus glenii, 19–245 mm TL. The sagitta is characterized by an almost quadratic...     

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.     

Otolith microstructure of Japanese sea bass larvae and juveniles: interpretation and utility for ageing

This paper interprets and discusses the usefulness of otolith microstructure for ageing Japanese sea bass ( Lateolabrax japonicus ) larvae and juveniles. Samples were collected from the Tango Sea along the Japan Sea coast, January–March 2007. Known-age (0-day and 10-day-old) larvae were obtained from the Ibaragi Prefectural Hatchery, Japan. Sagittal and lapillar otolith were processed and read using an otolith reading system. Clearly discernible hatch- and first-feeding marks were evident on sagitta, and development of accessory premordia (AP) appeared to be associated with larva-juvenile transition; however, no other marks indicating metamorphosis or settlement were evident. In lapillus, no discernible check mark was found. Known-age larvae showed that deposition of the first daily increment (DI) corresponded to first-feeding, which occurred at day-4 post-hatch. However, mean increment counts were significantly lower in lapillus than in sagitta, caused by poorly expressed increments around the centrum as well as relatively unclear centrum of the lapillus. The authors suggest that the use of lapillus can cause significant underestimation of age. Therefore, the sagitta is recommended for age and growth estimations of larvae and juveniles, although the presence of numerous subdaily increments warrants careful preparation and interpretation of the microstructure. A test for asymmetry showed the right and left otoliths to be quite symmetrical and their DI counts not significantly different, suggesting that either otolith can be used for studying age and growth of Japanese sea bass larvae and juveniles.     

Daily growth increments in the larval otolith of the Japanese eel,Anguilla japonica

Early formation of otolith was studied on artificially hatched larvae of the Japanese eel,Anguilla japonica. Newly hatched larvae had a pair of sagittae which were flat and subelliptical with 8.3 μm in mean diameter. The diameter of the sagitta increased linearly with age. No growth increments were observed in the sagitta at hatching, while larvae which were 2, 4 and 6 days old had on average 2.1, 3.6 and 6.0 increments, respectively. The number of the increments (Y) and the age in days after hatching (X) showed a close linear relationship (Y=0.96X+ 0.06, r = 0.913, n = 40), suggesting daily deposition of sagittal increments. In 95 % of the field-caught elvers of this species, a distinct dark ring (check) with the diameter of 6–12 μm was found around the nucleus of the sagitta. This seems to be a “hatch check” deposited at hatching, since its diameter roughly agreed with that of the sagitta in the newly-hatched larvae. Possibly, the number of the increments outside the hatch check represents the age of the fish in days.     

Otolith characteristics and age determination of an endemic Ptychobarbus dipogon (Regan, 1905) (Cyprinidae: Schizothoracinae) in the Yarlung Tsangpo River, Tibet

We describe the microincrements, checks and annuli in the lapilli of the schizothoracine Ptychobarbus dipogon, an endemic species of the Tibetan plateau. We collected samples in the Yarlung Tsangpo River and its tributaries on a monthly basis (from April 2004 to August 2006). We describe the shape features of the three pairs of otoliths and document the full trajectory of lapillus development. We found that five to seven checks were clearly visible in the opaque zone of the first annulus. The pattern of 21–23 daily growth increments within each check might be explained as a lunar-induced deposition. We counted between 137 and 154 increments within the first annulus. Annuli appeared as a sequence of gradually declining increment widths, whereas false rings were characterized by abrupt checks. Our oldest estimates were 23⁺years for males and 44⁺ for females. The time of annulus completion was clearly between March and April each year using monthly marginal increments analysis. We consider the factors responsible for daily increment formation as an endogenous circadian rhythm. Environmental information, such as strong sunlight and cold water temperatures in the Tibetan Plateau, could reinforce the endogenous daily cycle. Our results provided important data addressing the ecology and population dynamics of P. dipogon.     

Asteriscus v. lapillus: comparing the chemistry of two otolith types and their ability to delineate riverine populations of common carp Cyprinus carpio

The chemical composition of common carp Cyprinus carpio asteriscus (vaterite) and lapillus (aragonite) otoliths from the same individual and reflecting the same growth period was measured to (1) determine whether there are differences in the uptake of trace metals (Mg:Ca, Mn:Ca, Sr:Ca and Ba:Ca ) and Sr isotope ratios (⁸⁷Sr:⁸⁶Sr) in co‐precipitating lapilli and asterisci and (2) compare the ability of multi‐element and isotopic signatures from lapilli, asterisci and both otolith types combined to discriminate C. carpio populations over a large spatial scale within a river basin. Depth profile analyses at the otolith edge using laser‐ablation inductively coupled plasma mass spectrometry showed that asterisci were enriched in Mg and Mn and depleted in Sr and Ba relative to lapilli, whilst ⁸⁷Sr:⁸⁶Sr values were nearly identical in both otolith types. Significant spatial differences among capture locations were found when all trace element and Sr isotope ratio data were aggregated into a multi‐element and isotopic signature, regardless of which otolith type was used or if they were used in combination. Discriminatory power was enhanced, however, when data for both otolith types were combined, suggesting that analysis of multiple otolith types may be useful for studies attempting to delineate C. carpio populations at finer spatial or temporal scales.     

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。     

鲈鲤早期鱼苗的耳石标记研究

为研究鲈鲤早期鱼苗耳石标记的可行性,先采用高温水(20.8±0.3)℃和低温水(10.8±1.2)℃交替饲养对20日龄鲈鲤进行热标记,然后将经热标记的35和45日龄鲈鲤浸泡在50—200 mg/L的茜素络合物(AC)或茜素红S(ARS)溶液中进行荧光标记。热标记的耳石生长轮清晰可见,明显区别于其他轮纹,微耳石热标记轮轮纹宽度(IW)和高温期持续时间(T)的线性回归方程为IW=0.16462+0.24762T。经荧光物质浸泡后鲈鲤耳石在绿光下均能检测到橘红色标记; AC标记质量受溶液浓度影响显著(P<0.05),受全长的影响不显著(P>0.05),微耳石、矢耳石和星耳石间的标记质量差异显著(P<0.05); ARS标记质量受全长和溶液浓度影响不显著(P>0.05),微耳石、矢耳石和星耳石间的标记质量差异显著(P<0.05)。研究结果表明,耳石热标记、荧光标记及两者结合使用均可用于大规模标记鲈鲤早期鱼苗。     

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。     

Use of otolith microincrements for estimating the age and growth of young armoured catfish Hoplosternum littorale

At 27·0–28·0°, the lapilli of Hoplosternum littorale developed rapidly in the embryo between 35 and 21 h before hatching. At hatching, lapilli averaged 78 μ;m on their longest axis and 69 μ;m on their shortest axis, and had up to three faint narrow microstructures. Primordia were fused and the large core was surrounded by a conspicuous discontinuous zone, formed at hatching, and visible in both sagittal and transverse preparations. The deposition rate of microincrements, counted in transverse thin sections of lapilli, was daily at least for the first 50 days and the innermost microincrements were deposited from hatching on. The growth rates of H. littorale differed significantly between two different rice field habitats in Suriname.