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.     

Ring formation on otoliths and scales of Pagrus pagrus: a comparative study

One annulus formed on the scales of farmed red porgy Pagrus pagrus each year during March and one opaque zone on the otoliths during June. Scales proved to be more sensitive than otoliths in recording the life history of the red porgy. A false annulus (ring of capture) was observed on the scales of the 0+ age group, but not on the otoliths. A gradual lengthening of the period of annulus formation was observed, from the younger to the older fish. The annulus formation in fish older than 2+ was less synchronized, due to the aquaculture conditions. Scales were more accurate than otoliths in annuli formation. A high percentage of missing or additional opaque zones were observed on otoliths of older fish. These irregularities were related to fish maturation and/or farming conditions. Farmed fish grew three times as fast as the wild fish.     

Growth and annual check formation in scales of dace, Leuciscus leuciscm (L.)

The first annual check appears on the scales of Thames dace as the fish begin their third year of life. Counting of annuli does not give the true age of the fish. Data from 4 other habitats are re-examined and on one occasion it is evident that ageing has been incorrect.     

Life-history strategies of Acrossocheilus fasciatus (Barbinae, Cyprinidae) in the Huishui Stream of the Qingyi watershed, China

Life-history traits of Acrossocheilus fasciatus were examined using 384 specimens collected monthly during May 2009 and April 2010 in the Huishui Stream of the Qingyi watershed, China. Using scales for age determination, female and male fish comprised five and four age groups, respectively. The monthly changes in marginal increment ratio suggested that annuli on scales were formed during March through May. Total lengths back-calculated significantly increased with age for both sexes and varied significantly between the two sexes at each age. The fact that females had larger body size and grew faster than males indicated the sexual size dimorphism for this species. Both sexes got their 50% maturity at age 3, when females and males were 105.3 and 112.1?mm total length, respectively. Based on the monthly changes in the gonado-somatic index and egg-development process, fish spawned from April through August. Absolute fecundity ranged from 295 to 3,573 eggs per fish and increased significantly with age. But relative fecundity, ranging from 11.77 to 69.96?eggs/g, was not significantly different among age groups. Compared with the life-history traits of an upstream population in the Puxi Stream (a headwater stream within this study watershed), the downstream population of A. fasciatus in the Huishui Stream (a 4th-order stream) exhibits larger body size, faster somatic growth, later sexual maturity, and lower reproductive investment. These variations in life-history strategies between the two populations could perhaps be explained by the spatial heterogeneity in habitat environment along the upstream–downstream gradient in this watershed.     

Thermal enrichment of a reservoir and the effects on annulus formation and growth of largemouth bass, Micropterus salmoides

Analysis of largemouth bass scales, including those from 48 tagged and recaptured fish, revealed that many scales had more 'annuli' than possible for the age of Flint Creek Cooling Reservoir. The mark-recapture data indicated the formation of one supernumerary annulus per year for most bass. Time of formation of true and supernumerary annuli and the causative factors are discussed.
Growth of bass from this reservoir greatly exceeded that reported for thermally unaltered reservoirs of Northwest Arkansas, due to the existence of a nearly year-round growing season, a result of thermal enrichment. The relationship between the ratio of electric power output to reservoir surface area and growth offish was evaluated with reference to published data on cooling reservoirs.     

新疆乌伦古湖拟鲤生长退算材料和方法的比较研究

研究以鳞片和微耳石为生长退算材料, 用4 种常用的鱼类生长退算方法(Dahl-Lea、Regression、Fraser-Lee 和BPH 方法)对新疆乌伦古湖拟鲤(Rutilus rutilus Linnaeus, 1758)的生长进行了退算, 比较分析了退算材料和方法对退算全长的影响, 以此确定适宜的生长退算材料和方法。结果显示, 无论采用哪种退算方法, 用微耳石退算拟鲤生长的结果均好于鳞片, 表现为退算全长更接近实测全长, 与实测体长之间的差异百分比更小。用鳞片退算时, Dahl-Lea 方法退算全长远小于实测全长, 整体差异百分比高达?26.0%, 与其他方法之间的差异也较大, 效果最差; Regression、Fraser-Lee 和BPH 三种方法退算全长与实测全长之间的差异相近, 差异百分比分别为?6.7%、7.0%和7.0%。用微耳石退算时, Dahl-Lea 方法退算全长最接近实测全长, 退算全长与实测全长之间的差异百分比最小, 总体仅为?1.9%, 效果最好; Fraser-Lee 和BPH方法各龄退算全长与实测全长之间的差异百分比相等, 在?1.4%— ?3.2%之间, 总体均为?2.6%, 效果次之; Regression 方法与Fraser-Lee 和BPH 方法之间虽然无显著差异, 但退算全长与实测全长之间的差异百分比最大, 总体为?4.5%,效果最差。       

Observations on the age, growth, reproduction and food of the roach Rutilus rutilus (L.) in two rivers in southern England

Scales and opercular bones from 632 roach from the River Stour were used for age and back-calculated growth determinations. The scales had clearer inner annuli but operculars clearer outer annuli in fish more than nine years old. The annuli were laid in late May or early June at the beginning of the growth period. Growth was minimal between November and April. Roach from both rivers grow faster than those in most other European waters. Female roach grow faster than males; River Frome roach faster than those from the Stour. Spawning occurred in May and elaboration of gonads between September and May. Immature roach have an annual cycle in condition with a maximum in June and a minimum in early Spring. The condition of mature females is affected by the gonad cycle. The fecundity of Stour roach is represented by the formula: log egg number=4.43 log length (mm)—1.69. Approximately half of the Stour males attained sexual maturity at age III and most of the rest by age IV. Half of the females were mature at age IV and the remainder by age V. Both brood success and growth rate varied from year to year but independently of one another. Most Stour roach ate aquatic insect larvae and molluscs but algae were more frequent in the diet of larger fish.     

Age determination and growth of luderick, Girella tricuspidata (Quoy and Gaimard), taken from Moreton Bay, Australia

Age and growth patterns of luderick, Girella tricuspidata (Quoy and Gaimard), taken in the Moreton Bay net fishery are described. Scales have prominent annuli which are formed during the period May-July. The mean body length is similar for males and females, except for age class III where female fish are significantly larger. This probably results from the early movement of faster growing females onto the fishing ground. The scale method and length-frequency analysis both indicate that the variation in body lengths in each age class is large. The length-weight relationship was obtained and relative condition factor was found to be highest in July which corresponded with the peak in gonosomatic index.     

Age, growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.     

长江干流圆筒吻鮈的年龄与生长

根据 5 5 1尾标本研究了生活在长江干流中圆筒吻的年龄与生长 ,并提出了资源合理利用建议。圆筒吻的鳞片可作为年龄鉴定的依据 ,年轮形成期主要在 2～ 5月。圆筒吻的体长与鳞长呈直线关系 ,与体重呈幂指数关系 ,生长适合VonBertalanffy生长方程。在 1～ 2龄生长最快 ,为保护圆筒吻资源 ,应限捕体长 2 0 0mm以下的个体     

长江干流圆筒吻(鱼句)的年龄与生长

根据551尾标本研究了生活在长江干流中圆筒吻(鱼句)的年龄与生长,并提出了资源合理利用建议.圆筒吻(鱼句)的鳞片可作为年龄鉴定的依据,年轮形成期主要在2～5月.圆筒吻(鱼句)的体长与鳞长呈直线关系,与体重呈幂指数关系,生长适合Von Bertalanffy生长方程.在1～2龄生长最快,为保护圆筒吻(鱼句)资源,应限捕体长200 mm以下的个体.     

用鳞片和耳石鉴定鲫年龄的比较研究

两观测者独立观测了分别采自洪湖的175尾和洞庭湖的168尾鲫样本的鲜片和耳石,结果显示鳞片适于鉴定年龄组成简单、生长较快的洞庭湖鲫种群的年龄,两观测者年轮读数的总吻合率可达90.5%,与耳石上年轮读数的吻合率也可高达91.7%;但用鳞片鉴定年龄结构复杂、生长缓慢的洪湖鲫种群年龄,两观测者总吻合率只有50.9%,各龄组吻合率随年龄上升而迅速下降。与耳石上年轮读数总吻合率也仅为56.6A%,存在比耳石低估高龄个体年龄的问题,用耳石鉴定鲫年龄具有易于识别、精确度高的优点,用之鉴定洪湖和洞庭湖鲫种群年龄,两观测者年轮读数的总吻合率都很高,分别为92.7%和97.0%,且随年龄上升,依然可保持较高的精确度,对洪湖鲫种群应用耳石为宜。     

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。       

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.     

Validation of scale‐age determination in European grayling Thymallus thymallus using tag‐recapture analysis

To validate age determination from scales in European grayling Thymallus thymallus, the scale‐read age of fish was compared with the true age obtained by tag‐recapture analysis. A total of 3997 individuals were tagged with visible implant tags and passive integrated transponder (PIT) tags in the River Wylye, south‐west England during 1999–2007. Annual repeat surveys were undertaken and collected scales read without prior knowledge of tag‐recapture age. Accuracy of fish ageing by scales was highest in 1 and 2 year‐old fish but decreased in older fish. In later life stages (>4 years old), underestimation of age occurred and the error in reading scales rose to 51·9% in 5 year‐old fish. Age assigned from scales underestimated the tag‐recapture assigned age by as much as 3 years. This study suggests that use of scales is an appropriate method to age a short‐lived population of T. thymallus inhabiting productive lotic systems. The underestimation of age in older fish, however, needs to be considered in the management of fish stocks because it may lead to undesirable exploitation of population.     

Age validation of juvenile Notothenia rossii at Potter Cove, South Shetland Islands, using mark-recapture data

Among all validation methods of age determination in fish, release of known age and marked specimens gives the most reliable information. We carried out a tag-recapture experiment on Notothenia rossii at Potter Cove, to validate, for first time for this species using this method, the principle of annual deposition of an annulus in scales and otoliths. Of 132 juvenile specimens (TL = 22.1–38.1 cm) tagged and released in successive years from 2004 to 2010, 7 were recaptured at the same site after periods of 1–13 months. In scales of five specimens recovered after 10–13 months, one extra annulus was laid down, exhibiting an additional winter zone of closely spaced sclerites. Consistently, the same analysis in two individuals marked and recaptured during the same summer, after 1–3 months at liberty, did not show the deposition of an additional annulus. All the fish tagged or recaptured during the experiment period (December to March) showed in their scales an edge zone of widely spaced sclerites, in agreement with the known pattern of growth in summer. Likewise, an analysis in selected specimens showed good consistency between the numbers of sclerites deposited in scales and the time of fish release. The comparative analysis between scales taken at recapture and otoliths of the same individual allowed a simultaneous counting of the annuli with complete correspondence. The growth in length of fish ranged from 0.5 to 6.1 cm, depending on the time of release.     

Using otolith weight to estimate the age of haddock (Melanogrammus aeglefinus): a tree model application

In this study, we investigated whether otolith weight can be used to estimate fish age with the same level of accuracy as that of the traditional annuli counting technique in a commercially important species such as haddock (Melanogrammus aeglefinus). Results indicate that this method is highly effective for young fish (around 97% correct classification), whereas its powers of prediction decrease with the increasing age of the fish. For older fish, the otolith weight cannot be an accurate estimator of fish age if the weight overlap between the different age classes is too large. Nevertheless, the otolith weight technique is strictly dependent on correct age determination through the counting of annuli of those individuals used in the calibration. Hence, an increase in the accuracy of ageing obviously determines an increase of the power of otolith weight to estimate fish age. Therefore, we suggest that otolith weight could represent a routine technique for determination of the age structure of haddock populations. This technique has the merit to be objective, fast, 100% repeatable and has the same level of accuracy as that of annuli counting.     

刀鲚的年龄和生长

鉴定刀鲚年龄的方法很多。本文以鳞片为主,对照耳石、胸鳍鳍条等方面的材料,做了比较全面的研究。发现它们都有明显的年龄标志,但各有优缺点。其中以鳞片取材最容易,观察最方便,缺点是年轮标志比较复杂,有时还有副轮和幼轮等。再生鳞也比较多。刀鲚鱼苗和幼鱼在生长过程中,体长增加较快,至11月份,幼鱼最大个体可达200毫米左右。成鱼体长增加速度逐渐减慢,最大个体只410毫米。但随着年龄的变化,其体重却有显著增加。刀鲚鳞片的生长和体长的增加基本上成正比关系。刀鲚寿命不长,一般只有4-5冬龄,最大个体不超过6冬龄。       

'Ferox' trout, Salmo trutta L. of Loughs Mask and Corrib

Sets of scales with the relevant information were collected by the Irish Specimen Fish Committee from large or specimen brown trout taken by angling from Loughs Mask, and Corrib. The relationship between lengths and age were determined for those fish for which the necessary information was available. It was concluded that those fish destined to become specimens (10 lb or over in weight) had adopted a fish-eating habit to enable them to maintain a high rate of growth.     

The growth of the freshwater murrel,Ophicephalus punctatus Bloch

Summary The growth of O. punctatus has been studied from the zones on the opercular bones and scales. Size estimates obtained from the opercular bones and scales were further substantiated by length frequency distribution and back-calculations. A close agreement in length-age relationship was obtained by various methods. These observations provide adequate evidence towards the validity of age determination in O. punctatus.Growth rate differs markedly in the two sexes. Males grow faster than the females. To study the changes in length with age, von Bertalanffy growth equation and Gompertz curve were used. The theoretical lengths obtained from the von Bertalanffy equation agreed very closely with the observed lengths.There is sexual difference in the weight-length relationship of O. punctatus. Modal weight of each year class obtained according to age reading showed that growth in weight is faster in males. The theoretical growth equation gives a good fit for weight-age data. O. punctatus is generally a fish of the impounded waters. The interrelationship between pond environment and growth characteristics has been discussed.