Larval and juvenile Australian smelt Retropinna semoni somatic and otolith growth parameters – implications for growth interpretation of wild fish

Abstract –  Relationships between fish length, otolith size, age and weight were assessed for a population of wild Australian smelt ( Retropinna semoni ) larvae and juveniles captured over a 4-year period to aid further interpretation of growth and condition during the early life history of the species. Nonlinear smoothed generalized additive models best described the fish–otolith size relationship during the larval and juvenile period, indicating that the proportionality between fish length and otolith size varies in relation to size. It is proposed that back-calculated predictions of fish size at a previous age or otolith size, accounting for individual variation is possible by assuming a body proportional hypothesis. Growth rate of larval and juvenile Australian smelt was best described using the Gompertz model that indicated a steady decline in growth rate after around 30 days of age. The allometric growth of larval and juvenile Australian smelt established from the length/weight relationship can subsequently be used to assess the condition of fish within this population using a relative condition or relative weight condition index. The results of the study have provided significant information to enable more precise growth reconstruction and condition assessment for the species in Australian lowland rivers.     

The amount of calcium in bony structures used for age determination in Cyprinion macrostomus (Heckel, 1843)

In this study, the ages of 76 individuals belonging to the Cyprinion macrostomus (Heckel, 1843) population caught from Murat River near Bingöl city were determined from six different bony structures and the level of calcium mineral of each bony structure was measured using an atomic absorption spectrophotometer. The determined element was statistically examined according to the age, length, weight and sex of the fish. The age, length and weight ranges of the fish were found to be 2–6, 12.0–21.2 mm and 16.3–135.3 g respectively. The relationships between the accumulation of calcium in all bony structures and the fish size (both length and weight) were found to be insignificant (P>0.05). However, a strong relationship was found between fish weight and accumulation of the mineral in vertebra and otolith. A strong correlation was also found between fish length and accumulation of calcium in the dorsal fin ray, followed by the otolith, vertebra and cleithrum bones respectively. Whereas the accumulation of calcium according to the age groups was found to be insignificant for scale and operculum (P>0.05), it was found to be significant for all the other bony structures examined (P<0.05). In conclusion, the accumulation of calcium on some bony structures of C. macrostomus was observed to increase with an increase in age, length and weight of fish, although the increases were not statistically significant at least for some bony structures (P>0.05).     

Using otolith weight–age relationships to predict age based metrics of coral reef fish populations across different temporal scales

We assess the use of otolith weight to predict population age structure of an important harvested coral reef fish at different temporal scales up to 4 years, and explore the implications of age prediction for estimates of key fishery parameters. Fish age and otolith weight relationships were estimated for common coral trout, Plectropomus leopardus (Serranidae: Epinephelinae), at 24 coral reefs located in four different regions spanning 7° of latitude along the Great Barrier Reef of Australia from 1995 to 1999. We explored the robustness of predictions of population age structures from otolith weights where age structure in 1 year was derived from otolith weights using the age–otolith weight relationships derived in another year up to 4 years earlier. The accuracy of predictions of age structure varied depending upon the temporal scale over which the prediction was made. Predictive accuracy was highest for predictions in the same year as the age–otolith weight relationship was derived and worst at the longest scale, when predictions spanned 4 years. Predictions of age based on the age–otolith weight relationships generally overestimated the minimum age of a population and underestimated the maximum age. Mean predicted age was generally within ±1% difference of the mean observed age while mean predicted length at modal age (growth index) was largely within ±5% difference of mean observed length at modal age. Predicted age structures gave less accurate estimates of total mortality rate than those estimated from directly determined age structures. Fish age–otolith weight relationships generally predicted modal age within ±1 year at all temporal scales. These results have significance for making rapid, initial estimates of key parameters for long-term monitoring of tropical reef fish stocks, especially in circumstances where available resources are insufficient for a comprehensive program of direct age estimation.     

基于线性混合模型的蓝点马鲛叉长和体重关系的月间及性别差异

为了研究蓝点马鲛（）生活史特征的异质性，根据2018年10月至2019年3月在东海外海渔场的拖网调查采样数据，对其叉长和体重关系的月间及性别差异进行了研究。依据收集的367尾蓝点马鲛样本，求得其叉长和体重关系（b的估计均值为2.794。本研究构建了广义线性模型和9个线性混合模型，用于研究蓝点马鲛的叉长和体重关系（）在时间及性别上的差异。贝叶斯信息准则（BIC）值和均方根误差值均表明，最复杂的线性混合模型（即月份和性别对两个参数P<0.01）。在最优模型中，a值则与此相反。本研究表明，月份和性别对蓝点马鲛叉长和体重关系具有显著的影响，线性混合模型能把月份和性别的异质性通过随机效应在单个模型中更准确、快速地体现，从而进一步证实了此模型在数据来源异质性研究中的优势。     

长湖短颌鲚耳石重量与年龄关系

利用2014年采自湖北长湖的378尾短颌鲚(Coilia brachygnathus)样本,去除包膜和黏液的矢耳石于55℃烘箱中烘烤24 h,电子天平称重(精确至0.001 g),成对t检验结果表明,短颌鲚左右矢耳石重量之间无显著差异(P0.05),数据分析以左右矢耳石重量的平均值计为矢耳石重量;采用直线、幂函数和多项式3种回归方程研究了其耳石重量与年龄的关系。结果显示,长湖短颌鲚的耳石和鳞片均可用于鉴定其年龄,且两者鉴定年龄的吻合度达到75.8%;根据222尾耳石与鳞片年龄一致的短颌鲚样本数据,发现耳石重量与个体的年龄呈显著相关(P0.05);按年龄组以耳石重量与相应的体长作图,可以初步判断所观测年龄的可靠性;利用建立的耳石重量-年龄关系函数估算得到的个体年龄,与直接读取耳石磨片获得的年龄结果无显著差异(P0.05),表明利用矢耳石重量直接推算其个体年龄,可以作为辅助短颌鲚年龄鉴定尤其快速鉴定的一种有效方法。     

Otolith biochronologies as multidecadal indicators of body size anomalies in yellowfin sole (Limanda aspera)

Dendrochronology (tree‐ring analysis) techniques have been increasingly applied to generate biochronologies from the otolith growth‐increment widths of marine and freshwater fish species. These time series strongly relate to instrumental climate records and are presumed to reflect interannual variability in mean fish condition or size. However, the relationship of these otolith chronologies to fish somatic growth has not been well described. Here, this issue was addressed using yellowfin sole (Limanda aspera) in the eastern Bering Sea, for which a 43‐yr otolith chronology was developed from 47 otoliths and compared with body size for 6943 individuals collected in 1987, 1994, and 1999 through 2006. Among several metrics of size normalized for age and sex, average body mass index (defined as weight/length) had the strongest relationship to the otolith chronology, especially when the chronology was averaged over the 5 yr preceding fish capture date (R² = 0.88; P < 0.001). Overall, sample‐wide anomalies in otolith growth reflected sample‐wide anomalies in body size. These findings suggest that otolith chronologies could be used as proxies of body size in data‐poor regions or to hind‐cast somatic growth patterns prior to the start of fisheries sampling programs.     

西藏哲古错高原裸鲤年龄结构与生长特性

对西藏哲古错高原裸鲤（）的年龄结构与生长特性进行研究。2017—2019年，在西藏哲古错共采集高原裸鲤样本432尾，采用微耳石鉴定年龄，测量耳石半径，进行体长退算，研究其年龄结构与生长特性。结果显示，所采集高原裸鲤样本体长范围为3.1~35.6 cm，体重范围为0.4~645.9 g；年龄范围为1~11龄，6~8龄鱼比例超过35%。体长（2=0.9911，>0.05），拟合建立von Bertalanffy生长方程，=1114.233[1-e^{-0.149（=27.826 cm、为4.399。综上，哲古错高原裸鲤年龄结构简单化，处于增长期，可能是受哲古错特殊的地理位置和生态生境等因素影响。本研究旨在为西藏脆弱的生态系统中该物种的保护提供基础数据，并建议通过入湖河流水量管理、限制捕捞等人类活动等措施，改善哲古错生态环境，对哲古错高原裸鲤种群进行保护。}     

Statistical learning applied to computer-assisted fish age and growth estimation from otolith images

Computer-assisted tools need to be developed to help in the accurate and efficient acquisition of fish age and growth data for ecological and assessment issues. Stating fish age and growth analysis as pattern classification issues, the proposed approach relies on a statistical learning strategy. Given otolith images interpreted by an expert, probabilistic kernel-based methods (namely Kernel Logistic Regression) are used to infer interpretation rules. More precisely, two different probabilistic models are introduced: one to infer fish age from otolith images and a second one aiming at evaluating whether or not a given otolith growth pattern is realistic w.r.t. training examples. These probabilistic models provide us with the basis for coping with three different issues: the automated estimation of fish age from otolith images, the estimation of individual otolith growth patterns, and the definition of a confidence measure of otolith interpretations. These computer-assisted ageing tools are validated for a dataset of plaice otoliths.     

大宁河红尾副鳅年龄与生长的研究

利用耳石、脊椎骨对2006年10月至2007年11月采自大宁河的129尾红尾副鳅(Paracobitis variegates)的年轮特征进行研究,并对生长情况进行分析。结果显示:低龄脊椎骨钙质沉积不明显,轮纹观察不清楚,耳石轮纹较清楚。红尾副鳅群体由2~6龄共5个龄组组成,体重体长关系为W=1.95×10-4L2.309,耳石直径与体长的关系为L=263.24R+9.03,生长方程为Lt=222.708[1-e-0.092(t+2.162)];Wt=51.399[1-e-0.092(t+2.162)]2.309。结果表明:红尾副鳅体重生长拐点年龄为6.97龄,7龄前后为合理的捕捞时期。     

达里湖瓦氏雅罗鱼耳石质量与年龄关系

2017年5月—2018年1月,在内蒙古达里湖采集瓦氏雅罗鱼404尾,取出微耳石清洗、烘干、称量质量后,先用热熔胶定于载玻片上打磨后,再热熔胶高温熔化取下耳石,用透光率更高的透明指甲油固定、打磨,至出现清晰轮纹,读取鱼类年龄。分别采用4种方程(直线、幂函数、指数函数和多项式)回归拟合耳石质量与体长、年龄之间的关系,得出瓦氏雅罗鱼耳石质量( m _O)与年龄( A )之间的函数关系式: m O =-0.0445 A ² +1.9601 A -1.3978( r^( 2) =0.8772)。基于拟合方程和各龄组耳石质量和体长统计图表结果,证明瓦氏雅罗鱼耳石质量可用于鉴定其年龄。利用耳石质量推算鱼类年龄,将推算年龄与耳石年轮读取年龄进行对比,结果表明,瓦氏雅罗鱼耳石质量可以直接推断鱼的年龄,是一种快速简单且稳定的年龄鉴定方法。     

Analysis of growth, weight and relevant indices of diploid and triploid population of tench Tinca tinca (Linnaeus 1758)

This study determined biometric and weight parameters and relevant indices of diploid and triploid tench. Altogether, 137 siblings of tench were studied. The effect of ploidy level appeared in significantly better growth of triploids (P<0.001) as to biometric [total length (TL), standard length (SL), body height (BH), body width (BW)] and weight [fish weight (FW), carcass weight (CW)] parameters of T₃ of both sexes and of T₃₊ females. The effect of ploidy level also appeared as significantly higher dressing percentage (DP; P<0.001) of triploid T₃ females compared with other groups, significantly higher gonad weight (GW) and gonadosomatic index (GSI; P<0.001) of diploid T₃ females, as well as GSI and hepatosomatic index of diploid T₃₊ females. The effect of sex appeared in significantly higher (P<0.001) biometric (TL, SL, BH, BW) and weight (FW, CW) parameters of T₃ females of both ploidy levels, as well as of triploid T₃₊ females. The effect of sex also appeared as significantly higher DP (P<0.001) of males in diploid T₃ fish, as well as of males of both ploidy levels in T₃₊ fish and significantly higher GW and GSI (P<0.001) of females in diploid T₃ fish, as well as of females of both ploidy levels in T₃₊ fish. This study shows evidence for faster somatic growth and bigger final weight of triploid populations of tench compared with diploids in both age categories T₃ and T₃₊.     

Seasonal change in the relationship between otolith radius and body length in age-zero Pacific saury <Emphasis Type="Italic">Cololabis saira</Emphasis>

We examined seasonal changes in the relationship between otolith radius and body length in age-zero Pacific saury Cololabis saira collected from June to December 2002–2004, based on 12,164 specimens. Results of the analysis using a generalized linear model indicated that there were differences in the intercepts among months, but no difference was seen in the slopes. In addition, post hoc analysis showed that the intercepts got larger as the month progressed from June to December. These results suggested that although the body length growth rate decreased, the growth of the otolith does not decrease to the same degree as the body after September, so the ratio of otolith radius to body length becomes larger as the months pass. Consequently, we consider that the seasonal change in relation between otolith radius and body length affects the back-calculation of body length based on otolith radius.     

An individual-based model for the direct conversion of otolith into somatic growth rates

Otolith increment width and larval fish data (length and weight) were used to develop an individual‐based model (IBM) to describe daily resolved growth rates of North Sea herring (Clupea harengus) larvae (Autumn Spawners) caught during International Herring Larvae Surveys in the ICES area IVa from 1990 to 1998. The model combines sagittal otolith readings (core and individual increment measurements), larval standard length and weight data, and solves an over‐determined set of linear system equations for all parameters using the method of least square residuals. The model consists of a matrix, which describes the increment width formation of 119 larvae, a vector containing their length/weight measurements, and a vector describing residuals. The solution vector yields age‐dependent maximum somatic growth rates of herring larvae up to an age of 41 days with sizes ranging from 10 to 25 mm. The observed environmental temperature in which larvae dwelled was relatively uniform. Therefore, measured increment width was individually used to determine daily growth from any single larva in relation to their potential maximum growth under optimal feeding conditions. The results are discussed with respect to the spatial and temporal variability of larval occurrence. Finally, an analysis of error estimation of the larval growth characteristics is presented.     

Impact of river regulation and hydropeaking on the growth,condition and field metabolism of Brook Trout (Salvelinus fontinalis)

Brook Trout (Salvelinus fontinalis) is an important fish species in Ontario, Canada, supporting recreational fisheries that contribute significantly to local economies. Hydroelectric dams disrupt the river continuum, altering downstream conditions and impacting riverine fish populations. Specifically, Brook Trout activity has been found to increase during hydropeaking periods, when dam operators rapidly increase river discharge to meet electricity demands. Higher energetic outputs driven by hydropeaking may decrease the energy available to allocate towards fish growth and condition, negatively impacting Brook Trout. We investigated the impact of two different hydropeaking regimes on resident Brook Trout populations downstream from a 15‐MW dam used for hydropeaking, compared to a population in a nearby naturally flowing river. Length‐at‐age as determined by otolith back‐calculations was higher in the regulated river relative to the naturally flowing river. Muscle tissue caloric content and weight–length relationships did not differ between rivers. Field metabolism, as inferred from fish otolith δ¹³C values, was higher in the regulated river relative to the naturally flowing river and was significantly positively related to time spent hydropeaking. Higher metabolic outputs in the regulated river were likely offset by an increased food supply, allowing for higher Brook Trout length‐at‐age. The opposing and complicated impacts of river regulation on Brook Trout highlight the need for studies to consider multiple indicators of fish health when characterising the response of fish populations to river regulation.     

Growth performance of mixed sex, hormonally sex reversed and progeny of YY male tilapia of the GIFT strain, Oreochromis niloticus

The growth performance of three experimental groups consisting of mixed sex fish (control), hormone-treated fish and progeny of YY male tilapia, all originated from the genetically improved farmed tilapia (GIFT) strain was evaluated. Masculinization of sexually undifferentiated fry was achieved by providing a supplement of 5 mg of 17-α-methyltestosterone per kg of feed over a period of 21 days (after sac absorption). Both mixed sex and progeny of YY male groups were fed a standard commercial ration. Mixed sex fish did not deviate significantly ( P >0.05) from the 1:1 male to female ratio. Percentages of male averaged 75% in hormone-treated fish and 95% in YY male group over the sampling periods and at final harvest. The effect of sex on weight and length was statistically significant ( P <0.001). The model used to analyse weight and length included experimental group and sex in each culture period as the fixed effects, and replicate cages as the random effect. Over the culture period of 141 days, there were no statistical differences ( P >0.05) in body weight and length between mixed sex, hormonally treated and progeny of YY males. There were also no significant differences in level of variability in harvest weight between three groups of fish when the data were classified into five categories (=<100, 100 to <150, 150 to <200, 200 to <250 and ≥250 g). It is concluded that monosex culture of all male tilapia would be of no advantage over mixed sex culture for the GIFT strain under conditions of cages suspended in earthen ponds.     

长江口凤鲚仔稚鱼不同发育阶段矢耳石生长

2014年4—8月于凤鲚(Coilia mystus)的主要繁殖期在长江口采集仔稚鱼103尾。分析凤鲚仔稚鱼样本得出日龄范围为5~48 d,体长为4.20~26.21 mm。为研究长江口凤鲚早期发育不同阶段生长,测定了凤鲚仔稚鱼(5~48日龄)体长随日龄的生长变化,其变化分为3个阶段(5~11日龄、12~30日龄、31~48日龄)。不同日龄阶段,体长的生长速率差异性显著(P0.05)。耳石早期发育研究发现耳石长、耳石宽随鱼体的生长而增长,在17~19日龄之后其生长速率增大约2倍。采用分段回归方法分析耳石长、耳石宽与日龄的关系,发现二者异速生长的拐点均出现在19~20日龄,拐点前为慢速生长,之后为快速生长。研究发现凤鲚早期生长发育阶段的耳石形态有较为显著的改变:卵黄囊期、前弯曲期为圆形;弯曲期耳石长的生长大于耳石宽的生长,耳石逐渐变成椭圆形;耳石变成稳定形态后,长宽比基本保持稳定。     

Seasonal changes in otolith and somatic growth in age-0 Pacific saury <Emphasis Type="Italic">Cololabis saira</Emphasis>

We evaluated the seasonal changes in otolith and somatic growth of age-0 Pacific saury Cololabis saira in 223 fish collected between June and November 2002. We calculated the age in days of each individual by measuring otolith growth increments under a scanning electron microscope. The age was correlated with body length and otolith radius. We also observed seasonal changes in the rate of increase in body length and otolith radius and in the pattern of otolith growth. Until August, both body length and otolith radius increased with age. Thereafter, the otolith radius continued to increase, whereas the rate of somatic growth decreased. As a result, the ratio of otolith radius to body length increased. After August, the percentage of otoliths with unreadable increments on their edge increased due to the formation of hyaline zones. Otoliths grew both radially and in thickness until July, but gradually stopped growing in thickness after August. Beginning in October, more than 80% of otoliths only grew radially. After August, the otolith not only continued growing but the morphological growth pattern also changed.     

The utility of otolith weight as a predictor of age in the emperor Lethrinus mahsena and other tropical fish species

This study examines the potential use of otolith weight as a proxy for age in the lethrinid Lethrinus mahsena from different sites in the tropical Indian Ocean: the banks of Seychelles, Mauritius and British Indian Ocean Territory (BIOT, Chagos Archipelago). The reliability of age–frequency distributions and individual ages estimated using otolith weight–age relationships was examined through comparison with those estimated through the standard method of ageing using otolith increments. Two other methods for estimating age–frequencies using age-slicing via an estimated growth curve were also examined; these used growth curves estimated by a length-based method (ELEFAN), or by fitting directly to length-at-age data (an ‘age-based’ method). Age-slicing using length-based growth parameters failed to produce reliable age–frequencies, due to inaccuracies in the growth parameter estimates. The use of age-based growth parameter estimates improved the results of age-slicing, however, age–frequencies remained significantly different from those obtained from ageing using otolith increments in two locations. The use of otolith weight–age relationships resulted in estimated age–frequency distributions that in all locations were not significantly different from those assessed through otolith increment counts. In contrast, L. mahsena otolith weight–age relationships could not be used to estimate individual ages accurately, due to the level of overlap in otolith weight between age classes. Where otolith increments are routinely used to age commercial fish species, the fact that otolith weight–age relationships could not be used to age individuals accurately may limit its application. However, where routine ageing of individuals through otolith increments is considered impractical, for instance because of its cost, the use of otolith weight–age relationships to derive catch age–frequencies represents a viable alternative approach. With this in mind, this study has also demonstrated that there is the potential to use otolith weight–age relationships for five other species caught around the Seychelles, following the validation of their otolith increments.     

嘉陵江瓦氏黄颡鱼星耳石重量与年龄的关系

在重庆市北碚区嘉陵江白庙子江段采集瓦氏黄颡鱼(Pelteobagrus vachelli(Richardson))标本586尾,对其星耳石重量与年龄之间的关系进行了研究。结果显示:瓦氏黄颡鱼星耳石重量在不同年龄组间的重叠相对较少,大小相近的个体,年龄大的(即生长慢的)星耳石重量比年龄小的(即生长快的)大,不同年龄组之间星耳石重量差异显著(P<0.05)。按年龄组以星耳石重量与相应的体长作图,可初步判断所观测年龄的可靠性。分析星耳石重量的频率分布,能分离出体长相近但年龄不同的个体,其结果与依据星耳石年轮观测的基本一致,星耳石重量与年龄呈显著线性相关(P<0.05);用该相关性估算年龄,与从星耳石上直接读取的年龄并无显著差异(P>0.05),它们之间的吻合度高达96.2%。因此,星耳石重量具有直接确定嘉陵江瓦氏黄颡鱼年龄的潜能或作为验证依据钙化组织判断年龄准确性的辅助手段。     

水体钙离子质量浓度对褐牙鲆幼鱼鱼体和耳石元素成分的影响

在盐度30和水温20 ℃条件下,分别配制钙离子ρ（Ca2＋）质量浓度为200 mg·L-1（A组）、400 mg·L-1（B组,对照）、800 mg·L-1（C组）、1 600 mg·L-1（D组）和3 000 mg·L-1（E组）的人工海水,研究了水体ρ（Ca2＋）对褐牙鲆（Paralichthys olivaceus）幼鱼鱼体和耳石元素成分的影响。经60 d养殖发现褐牙鲆鱼体中仅钙（Ca）、锌（Zn）和铜（Cu）质量分数差异不显著（P〉0.05）;鱼体中磷（P）、钠（Na）、镁（Mg）、锶（Sr）、铁（Fe）、锰（Mn）和镍（Ni）质量分数随水体ρ（Ca2＋）的增加而下降。不同ρ（Ca2＋）对褐牙鲆幼鱼耳石长、宽、长宽比和耳石质量影响显著（P〈0.05）。低浓度A组耳石长和耳石宽显著低于B组和C组,A组耳石长宽比（L/W）显著低于D组,A组的耳石质量显著低于B组和D组（P〈0.05）。其中w（Sr）随ρ（Ca2＋）的增加显著下降,锶/钙（Sr/Ca）比、镁/钙（Mg/Ca）比随ρ（Ca2＋）增加而下降。结果表明,水体ρ（Ca2＋）对褐牙鲆鱼体成分、耳石形成及组分产生明显影响,ρ（Ca2＋）能够影响鱼体和耳石元素的累积。