长江口鮻矢耳石形态特征及质量与年龄的关系

为研究长江口鮻矢耳石形态特征及其质量与年龄的关系,2017年2—6月从长江口水域采集鮻358尾,解剖并提取耳石324对,并对其形态学参数进行测量分析.结果表明:鮻矢耳石具有基叶和翼叶,中央听沟明显,矢耳石的大小和形状随个体生长变化明显,矢耳石由边缘规则的圆润瓜子状渐变为褊窄的叶片状,边缘波浪状突起逐渐变多.矢耳石平均密度为1.52 mg·mm^-2,平均矩形趋近率为0.68,耳石长占其体长的0.021%~0.047%,耳石宽占其体长的0.009%~0.021%,耳石质量占其体质量的0.045‰~0.731‰.鮻矢耳石长(OL)、宽(OW)、质量(OM)均与体长呈显著相关,耳石宽与耳石质量函数关系式的决定系数(R^2)最高(0.928).耳石质量与体长(BL)最佳拟合方程为幂函数:OM=0.0009BL1.8737(R2=0.967);耳石质量与年龄(A)以及体长与年龄的最佳拟合方程为多项式:OM=2.9262A^2+4.8437A+2.1894(R^2=0.847);BL=-3.2248A^2+102.54A+38.373(R^2=0.858),矢耳石质量与年龄呈显著线性相关,用耳石质量与年龄关系估算的年龄与从耳石上直接读取的年龄无显著差异,矢耳石质量可以作为鉴定鮻年龄的有效辅助手段.     

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。     

长江口近岸水域棘头梅童鱼资源现状的评估

为了评估长江口近岸水域棘头梅童鱼的资源状况,利用2012—2013年底拖网调查数据,基于体长频率分布的方法研究了长江口近岸棘头梅童鱼的生长和种群参数.采用FiSATⅡ软件中的ELEFAN模块计算了长江口棘头梅童鱼的Von Bertalanffy生长参数,结合Pauly经验公式估算其自然死亡系数,并建立Beverton-Holt动态综合模型预测其资源变化趋势.结果表明: 2012—2013年共采集到棘头梅童鱼样本4201尾,体长范围18~155 mm,其生长系数(K)和极限体长(L_∞)分别为1.1和162.75 mm,种群总死亡系数(Z)、自然死亡系数(M)和捕捞死亡系数(F)分别为4.040、1.683和2.357.当前长江口近岸水域棘头梅童鱼的资源开发率(E)为0.583,大于F_opt (0.5),年平均资源数量为1.33亿尾,对应的资源量为576.02 t.目前长江口水域棘头梅童鱼资源已处于过度捕捞状态.
     

采用耳石日轮研究珠江口黄唇鱼幼鱼的产卵期及生长

通过矢耳石日轮对采自珠江口的黄唇鱼Bahaba flavolabiata幼鱼进行日龄鉴定,并据此研究其产卵期和生长特性。黄唇鱼的产卵时间最早为2月8日,最晚是5月17日,产卵期主要集中在3—5月。体长为16.40—26.30 cm的黄唇鱼幼鱼的体长与体重之间的关系为幂函数关系,体重生长为匀速生长;体长和体重随日龄的生长关系均以幂函数模型符合程度较好;体长和体重平均生长率分别为0.55 mm·d-1和1.60 g·d-1,特定生长率分别为0.27%·d-1和0.82%·d-1。研究结果表明,利用耳石日龄来推算黄唇鱼的产卵期是可行的,并可据此推算其特定阶段的生长模型。     

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。     

长江口棘头梅童鱼幼鱼栖息地的初步评估

为了评估鱼类对长江口栖息地的选择偏好,选取长江口春季的优势种棘头梅童鱼幼鱼为模式物种,从19个水文、水质因子及生物因素指标中,筛选出狭额绒螯蟹丰度、盐度、底质类型和水深4个因子作为棘头梅童鱼栖息地指示因子,建立栖息地适合曲线,并计算了栖息地适宜度指数(HSI).结果表明:长江口北支水域棘头梅童鱼幼鱼HSI普遍较高,基本在0.5以上,而南支水域普遍较低,基本上在0.2以下,表明长江口北支为棘头梅童鱼幼鱼的主要索饵场,同时发现,其幼鱼的最适生长水域为盐度大于14、底质平均粒径在29μm以下、水深2~5 m的水域,与HSI的空间分布一致.生物因子可较好地表征棘头梅童鱼幼鱼对水文、水质等因素的响应;化学需氧量、铵氮、总磷和挥发性酚与棘头梅童鱼幼鱼丰度不具有显著相关性,亚硝酸盐氮、硝酸盐氮和总氮与其丰度具有显著正相关性,说明调查水域内水质的富营养化尚未对棘头梅童鱼栖息地造成破坏;而铜离子和镉离子浓度与其丰度具有极显著的负相关性,表明重金属污染已经对棘头梅童鱼幼鱼的生长和分布造成了一定的危害,推测重金属污染对长江口水域的鱼类栖息地分布具有限制性影响.     

鸭绿江香鱼耳石日轮与生产的研究

１９９２年对鸭绿江香鱼耳石日轮与生长进行了研究。人工受精孵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。在当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。耳石矩径与鱼体长呈线性关系,７５尾幼、成鱼的关系式为ｙ＝３＼２８ｘ＋２４８．３０     

短吻舌鳎生长特性的研究

用多元统计分析方法对短吻舌鳎的生长规律、生长特性及雌雄之间的生长差异进行了研究。结果表明：1-4龄的短吻舌鳎处于生长期。在生长速度上,1-2龄生长速度最快。以后生长速度逐渐减慢;在生长方式上,1-2龄体长、体高、体厚的生长基本同步,3龄,体高、体厚生长更快,到4龄。以体厚生长最快;生长方式不同,使不同年龄鱼的体型不同。3-4龄鱼比1-2龄更宽厚;在同一年龄组中,雄鱼不仅显著地小于雌鱼,而且比雌鱼更细长、侧扁,用多项式来描写短吻舌鳎的生长过程,并求出生长拐点年龄为2．35龄。     

2017—2020年珠江口棘头梅童鱼的种群特征

为了掌握珠江口重要经济鱼类棘头梅童鱼的种群特征,根据2017—2020年春(3—4月)、秋(9—10月)两季在珠江口海域开展的底拖网调查及采集到的棘头梅童鱼样本,对其生物学特征和资源密度分布特征进行了初步分析。结果表明: 珠江口棘头梅童鱼体长、体重变化范围分别为22～168 mm、0.23～103.11 g,其中雌性个体的体长、体重均大于雄性个体,未见明显的小型化现象;性成熟体长集中在90～140 mm,未见性成熟提早现象。总体长体重关系式中的异速生长因子b值为2.9057,且年际变化小,而条件因子a值(3.029×10^-5)小于1988年该海域的调查结果,说明珠江口棘头梅童鱼整体生长发育良好,但栖息地环境质量(饵料供应、生长环境)下降。研究海域梅童鱼的开发率E为0.67,处于过度捕捞状态;梅童鱼资源密度平均值为77.73 kg·km^-2, 中西侧资源密度大于东侧,在纬度方向上总体分布均匀;根据4个资源密度高值区初步推测其产卵场在南沙港附近。2017—2020年的年平均资源密度比1980—1982年下降了93.5%,为持续利用该资源,建议条件成熟时可于春季在产卵场设立保护区,以保护补充群体与产卵群体。     

东海南部竹筴鱼形态特征参数及其相关性比较分析

2012年4月采集东海南部水域100尾竹筴鱼样本,测量其体长、全长、头长、头高、体高、体厚、吻长、眼径、眼后头长、尾柄长、尾柄高、体重等共12个形态特征指标.采用方差分析、偏相关分析、通径分析及回归分析,研究竹筴鱼东海南部种群各形态特征参数间的相关关系,确定与竹筴鱼体重显著相关的主要形态特征参数.结果表明:东海南部竹筴鱼的头长、头高、体厚、吻长、眼径、眼后头长、尾柄高、体重与体长呈指数相关(P＜0.01);而全长、体高、尾柄长则与体长呈线性相关(P＜0.01).竹筴鱼体长和体重的拟合方程为:y=0.0185x28736 (R2=0.9714);竹筴鱼的b值为2.8736,小于3,为负异速增长,即体长的增长速度要高于体重.头长、头高、体高、眼后头长、尾柄高对竹筴鱼体质量的影响存在显著关系;对竹筴鱼体质量的直接作用影响大小依次为:头长(0.242**)＞尾柄高(0.223**)＞头高(0.197**)＞眼后头长(0.161**)＞体高(0.155**),建立了竹筴鱼体质量的最优回归数学模型:y=-46.845 +3.892x1+9.623 x2+ 12.354x3+7.128x4+ 8.361x5.     

Sexual dimorphism in the otolith shape of shi drum,Umbrina cirrosa (L.), in the eastern Mediterranean Sea: Fish size–otolith size relationships

Little is known about possible differences in sagitta otolith size and shape between sexes of the shi drum, Umbrina cirrosa, and relationships between their body and otolith size. Thus, this study aimed to fill this knowledge gap via examination of 414 sagittal otoliths from 108 male (total length 13.8–26.8 cm) and 99 female (13.5–26.7 cm) U. cirrosa caught between May 2017 and April 2018 in gillnets set at a depth of ~15 m in Mersin Bay, Eastern Mediterranean Sea. No statistical differences were observed between the shape indices of the left-sided and right-sided sagitta. However, there were significant differences in the size and shape of otoliths between males and females. The slopes of allometric power functions from otolith width × fish sizes gave significant differences between males and females (ANCOVA, P < 0.05). The relationship for length × weight of otoliths from both males and females showed isometric growth, whereas the relationship of otolith width × otolith weight showed positive allometry. Negative allometric growth was observed for the relationship otolith length × otolith width. In summary, this study revealed the presence of sexual dimorphism in the otolith shape of U. cirrosa, and the data on regression relationships of fish-otolith sizes can be used to estimate fish size from U. cirrosa otolith sizes.     

Age and growth of manybar goatfish Parupeneus multifasciatus (Mullidae) from the Nha Trang Bay of the South China Sea

The growth of individuals is analyzed in the mass tropical species manybar goatfish Parupeneus multifasciatus from the Nha Trang Bay of the South China Sea. The relationship between the body weight and body length is determined for the females and males. Among the fishes larger 180 mm fork length (FL), the males prevail. Linear growth of the sagitta is characterized by negative allometry in relation to body length, and sagitta growth in length is faster than in width. Age of fish assessed based on the analysis of daily increments on the sagitta does not exceed three years, and the majority of individuals reach the first sexual maturity by the age of one year. The growth rate of the fish is characterized by a large individual variation.     

Otolith and somatic growth rates in Atlantic salmon parr, Salmo salar L: evidence against coupling

It is often assumed that otolith growth is in some way dependent on somatic growth (i.e. that the two processes are coupled). We examined the relationships between sagitta radius and fork length in 0+ Atlantic salmon parr that would subsequently smolt aged 1 + (UMG fish) or 2+ (LMG fish). Repeated measurements of fork lengths of individually marked parr, taken over a 211-day period from first feeding, were compared to sagitta radii on the same measuring dates (obtained by analysis of daily increments). The results showed that there was a linear relationship between fork length and otolith radius in UMG parr. However, this was not true for LMG parr. These fish enter a state of natural anorexia in their first autumn (despite excess food), but their otoliths continued to grow at the same rate despite the virtual cessation of somatic growth; they had therefore developed disproportionately large otoliths by the end of the study period. The relative growth rates of soma and otoliths first changed in LMG fish in late July/early August; this is the most precise estimate yet obtained of the timing of divergence in the developmental pathways of UMG and LMG parr. The rate of sagitta accretion was consistently lower in LMG parr, possibly indicating a lower metabolic rate in these fish. The results are discussed in relation to previous theories of the relationship between otolith and somatic growth.     

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.     

Effects of variable ration levels on direct and indirect measures of growth in juvenile red drum (Sciaenops ocellatus)

Relationships between somatic growth (length and weight) and two indirect measures of growth (otolith growth, RNA/DNA ratio) were assessed for red drum (Sciaenops ocellatus) under different feeding rations [0%, 2.5%, 5%, 10%, 15%, and 20% body weight (BW)/day] for 30 days. Representative samples from each ration level were taken in 10-day intervals between Day 0 and Day 30 for evaluation of direct and indirect growth measures. Positive correlations were observed between ration levels, somatic growth, and otolith growth. Statistical differences in weight and length of red drum were observed among ration levels by Days 10 and 20, respectively. Statistical differences for measures of otolith growth among ration levels were evident by Days 20 and 30. In addition, RNA/DNA ratios showed clear separation between fish that were starved and fish that were fed but demonstrated minimal separation among ration levels. Overall, the combination of a measure of somatic growth (weight) and a measure of otolith growth (otolith weight) resulted in the most statistical separation among ration levels. Findings from this study suggest that somatic growth, otolith growth and RNA/DNA ratios are suitable measures of relative growth of red drum; however, due to differences in sensitivity, caution must be exercised when using indirect growth (otolith growth, RNA/DNA ratios) measures to estimate recent growth.     

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.     

Growth during the early life history of the Pacific tarpon,Megalops cyprinoides

The early growth of the Pacific tarpon,Megalops cyprinoides, was studied by larval otolith analysis and rearing of larvae and juveniles in the laboratory. Morphology of the sagitta, validation of sagittal daily increments, age at the start of metamorphosis, decrement of standard length in early metamorphosis, and growth under rearing conditions are described. The sagitta of fully-grown Pacific tarpon leptocephali were transparent and circular, with regular intervals between the neighboring rings becoming wider at the onset of metamorphosis. Alizarin complexone treatment of larvae confirmed the daily formation of the sagittal rings. Metamorphosis was estimated to start about one month after hatching. After drastic shrinkage during the first several days of metamorphosis, the body length more or less stabilized for one month and then resumed rapid growth. The early growth of Pacific tarpon was divided into four phases as follows: A) leptocephalus positive growth phase; B) leptocephalus negative growth phase; C) sluggish growth phase; and D) juvenile growth phase.     

Eco-morphological patterns of the sagitta of Antarctic fish

Morphology and morphometry of the sagittae otolith were studied in pelagic and mesopelagic fish. The shape, margins and rostrum of four groups of otoliths from several species were analyzed: group 1 (pelagic fish associated with the under ice cover N = 42), group 2 (pelagic fish associated with water offshore N = 9), group 3 (mesopelagic fish associated with extensive vertical migration N = 57) and group 4 (mesopelagic fish associated with short vertical migration N = 54). E (maximum width of the sagitta /maximum length of the sagitta %), R (rostrum length (RL)/maximum length of the sagitta %) and S (sulcus area (SS)/otolith area (OS) %) indexes were calculated for each species. Sagittae of pelagic groups (1 and 2) showed the smallest sagitta dimensions in relation to the total length of the fish, in this group the sagitta shape is variable. Sagittae of mesopelagic fish (groups 3 and 4) showed variable shape and edges. The shape in group 4 was polygonal and these species have more width than length. Statistical analysis showed significant differences in the E, R and S indexes. These results were compared with other 19 species, belonging to six families, taken from a publisher-edited literature. E, R and S-values could be used to characterize the sagittae of the Antarctic fish and could be considered as a useful tool for fish ecology studies.     

Biometric relationships between body and otolith measurements in nine demersal fishes from north‐eastern Tasmanian waters,Australia

Relationships between fish and otolith measurements were analyzed in nine demersal fishes from the north‐eastern Tasmanian waters: Foetorepus calauropomus, Trachurus declivis, Parequula melbournensis, Neosebastes scorpaenoides, Platycephalus aurimaculatus, Platycephalus bassensis, Platycephalus conatus, Lepidotrigla mulhalli and Lepidotrigla vanessa. The values of exponent b from the relationships between fish weight and fish total length, total length and otolith length, total length and otolith width, and fish weight and otolith length were estimated. All above relationships were statistically significant. The analysis of covariance (ANCOVA) was used to test the effect of the categorical factor of species in the fish length and otolith length relationship. Significant differences in fish length and otolith length relationship between species were highlighted in both gurnards and flatheads. Results from this study will provide novel information on quantitative biometric relationships between body and otolith measurements of fish species in Australian waters.     

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.