Using otolith weight to predict the age of Pennahia macrocephalus in the mouth of the Beibu Gulf

The relation between otolith weight (OW) and the age of marine fish is studied. A total of 222 individuals of bighead white croaker, Pennahia macrocephalus were sampled seasonally in the mouth of the Beibu Gulf, the South China Sea, in 2007. Since there are no significant differences in sagittal OW between otolith in pairs (Pa parts per thousand yen0.05), the undamaged left sagittal otolith is used for age determination. The highest correlations among standard length, OW and fish ages are confirmed by linear, exponential and multinomial regression. Results show that sagittal OW overlaps only occasionally among age groups, and to individuals with similar standard length, the older and slower-growing fish has a heavier otolith because of the continued otolith material deposition. There are differences in sagittal OW among different age groups and significant positive linear relationship with age (P < 0.05). The age readings can be verified by plotting the sagittal OW versus the standard length for age groups, and the individuals with similar standard length but in different ages can be separated by sagittal OW frequency analysis. Mostly, the predicted ages using the regression between sagittal OW and ages are closed to the observed ages by counting annulus on scale. It indicates that the sagittal OW analysis is a useful technique for validating the accuracy of age determination by annuli counts, especially for individuals of similar size. Furthermore, the technique is applied for Pennahia macrocephalus with discussion in this paper.

Dietary phosphorus requirement of juvenile black seabream, Sparus macrocephalus

A growth trial was conducted to estimate the optimum requirement of dietary available phosphorus (P) for black seabream (Sparus macrocephalus) in indoor net cages (1.5x1.0x1.0 m). Triplicate groups of black seabream (11.45 +/- 0.02 g) were fed diets containing graded levels (0.18, 0.36, 0.54, 0.72, 0.89 and 1.07%) of available P to satiation for 8 weeks. The basal diet (diet 1), containing 0.18% available P, was supplemented with graded levels of monosodium phosphate (NaH2PO4 2H(2)O) to formulate five experimental diets. The fish were fed twice daily (08:00 h and 16:00 h) and reared in seawater (salinity, 26-29 g l(-1)) at a temperature of 28 +/- 1 degrees C. Dissolved oxygen during the experiment was above 5 mg l(-1). The specific growth rate (SGR), weight gain (WG), feed efficiency (FE) and protein efficiency ratio (PER) were all significantly improved by dietary phosphorus up to 0.54% (P<0.05) and then leveled off beyond this level. Hepatosomatic index (HSI) was inversely correlated with dietary phosphorus levels (P< 0.05). Efficiency of P utilization stabled in fish fed diets containing 0.18%-0.54% available P and then decreased dramatically with further supplementation of dietary phosphorus. Body composition analysis showed that the whole-body lipid, ash, calcium and phosphorus contents were all significantly affected by dietary available P concentration (P<0.05), however, no significance were found in whole-body calcium/phosphorus (Ca/P) ratios among all the treatments (P>0.05). Dietary phosphorus levels also affected the mineralization of vertebrae, skin and scale (P<0.05). Ca/P ratios in vertebrae and scale were not influenced by dietary P supplementation, while skin Ca/P ratio increased statistically with dietary available P levels (quadratic effect, P<0.001). The blood chemistry analysis showed that dietary available P had distinct effects on enzyme activities of alkaline phosphatase (ALP) and plasma lysozyme (LSZ), as well as contents of triacyglycerol (TG) and total cholesterol (T-CHO) (P<0.05). Broken-line analysis showed maximum weight gain (WG) was obtained at dietary available P concentrations of 0.55%. Quadratic analysis based on P contents in whole fish, vertebrae or scale indicated that the requirements were 0.81, 0.87 and 0.88%, respectively. Signs of phosphorus deficiency were characterized by poor growth, slightly reduced mineralization and an increase in body lipid content. (C) 2008 Published by Elsevier B.V.

Spawning areas and early development of long spiky-head carp (Luciobrama macrocephalus) in the Yangtze River and Pearl River, China

The spawning areas and early development of long spiky-head carp, Luciobrama macrocephalus (Lacepede), an endemic fish species in China, were investigated in the Yangtze River and Pearl River of central and southeastern China between 1961 and 1993. The potamodromous fish migrated upstream to spawn between May and July as the floodwater began to rise. The water-hardened eggs drifted down the river, and the embryos and larvae developed in the course of drifting. The spawning areas of the fish were widely found in the upper and middle main channels and large tributaries. Two large dams (Gezhouba dam and Danjiangkou dam) did not significantly impact on the reproduction of the fish. Fifty stages of the early development from one cell to the juvenile with fully formed fins were observed and characterized pictorially. The larvae of long spiky-head carp could be distinguished from the larvae of other co-occurring species by counting the number of somites and comparing the proportion of sizes of eye to otic capsule.

BFJ-21诱变小轮虫品系在不同饵料培养下的增殖、营养及其对黑鲷（Sparus macrocephalus）仔鱼的饵料效果

BFJ-21是从褶皱臂尾轮虫(Brachionus plicatilis)中人工诱变产生的一个小型品系。本文从“饵料—轮虫—仔鱼”的食生链角度研究了该轮虫品系在三种海洋微藻及面包酵母培养下的增殖、营养及其对黑鲷 (Sparus macrocephalus)仔鱼的饵料效果。结果表明：在单一饵料培养下，轮虫摄食球等鞭金藻(Isochrysis galbana)增殖最快(r = 0.6297)，摄食三角褐指藻(Phaeodactylum tricornutum)次之(r = 0.5976)，摄食小球藻(chlorella sp.)再次(r = 0.5096)，摄食面包酵母增殖最慢(r = 0.2041)。各饵料所培养的轮虫，其营养质量及饵料效果由优至劣依次为，小球藻轮虫，褐指藻轮虫，金藻轮虫和酵母轮虫。但酵母轮虫经小球藻营养强化12小时后，营养质量及饵料效果则明显改善。另外，轮虫在小球藻及金藻的混合饵培养下比单用小球藻或金藻培养有更高的种群增长率(r = 0.6492)。对各饵料及轮虫的营养成分含量及其相互关系进行了考查，结果表明酵母中不含w3HUFA，而小球藻中含量很丰富(24.7%)。w3HUFA含量在饵料与轮虫之间有明显的正相关关系。蛋白质及糖含量在饵料及轮虫之间则不相关。脂肪含量在藻类饵料及其培养的轮虫之间亦有正相关性。对不同饵料下轮虫个体培养的生长繁殖亦作了研究。同时，通过与非诱变轮虫作对照，进一步证实了该诱变轮虫系的某些优良特性。最后，对如何在大量培养中使BFJ-21轮虫品系既可快速增殖又具高营养质量的培养方法进行了探讨。

青岛近海六种海产鱼染色体组型的比较研究

采用活体注射秋水仙碱制备鱼类肾细胞染色体、PHA肌肉注射制备肾细胞染色体和鱼类早期胚胎制备染色体等多种方法。以空气干燥法制片Giemsa染色，对鲻鱼Mugil cephalus Linnaeus、真鲷Pagrosomus major（Temminck et Schlegel）、黑鲷Sparus macrocephalus（Basilewsky）、黑鮶Sebastes schlegeli （Hilgendorf）、石鲽Kareius bicoloratus （Basilewsky）、牙鲆Paralichthys olivaceus （Temminck et Schlegel）等分属四目、五科的六种海产鱼的染色体组型进行了考察和分析。研究结果表明：1、一般活体注射秋水仙碱制备海产鱼肾细胞染色体方法的有丝分裂指数虽然略低于PHA制备肾细胞染色体方法的有丝分裂指数。但它是最快最简便且很有效的方法，利用鱼类早期胚胎制备海产鱼染色体标本的方法也很有效，但要受到生物季节的限制。2、通过对六种海产鱼染色体组型分析得到，鲻鱼为48条端部着丝点染色体；真鲷的二倍体2n=48，有1对亚端部着丝点染色体。其余全部为端部着丝点染色体；黑鲷的二倍体2n=48。有3对中部着丝点染色体。2对亚中部着丝点染色体，其余全部为端部着丝点染色体。黑鮶的二倍体2n=48，有1对中部着丝点染色体，其余全部为端部着丝点染色体，石鲽的二倍体2n=48。全部为端部着丝点染色体；牙鲆的二倍体2n=48，全部为端部着丝点染色体。本文还对鱼类染色体的多态现象以及染色与进化的关系进行了讨论。

海洋经济动物精子超低温保存的研究

从1949年以来经过近五十年的发展，超低温保存种质细胞技术已经趋于成熟，特别是在家畜推广良种化的过程中发挥重要作用。对海洋动物种质细胞保存研究的范围主要集中在鲑鳟鱼类和牡蛎等少数几种海洋生物上。本研究结合“国家自然科学基金”研究项目，进行了三种贝类和两种鱼类精子的超低温保存实验，得到了它们在液氮（－196 ℃）条件下的适宜保存条件。栉孔扇贝（Chlamys farreri）冻精解冻后复苏比例、受精率和孵化率最高可达到49.39％、42.06％和12.15睦栉孔扇贝精子超低温保存时发生冷冻伤害的温度范围在－30 ℃～－60 ℃；其低温保存的最适降温速率为20 ℃／min；使用抗冻剂二甲基亚砜（DMSO）的最适浓度为5 ℃，其保存效果优于甘油；样品保存的最佳体积为0.6ml～1ml；解冻精子的最适水温为35 ℃，50 ℃次之，20 ℃最差；用自然海水激活解冻后精子的效果好于低盐度溶液；在0 ℃进行预处理平衡时间不宜太长；在抗冻液中加入蛋黄对保存效果没有改善，并且会对冻精的孵化率有抑制作用；用20 ℃／min和5％DMSO冷冻精子，液氮中保存栉孔扇贝精子55天后其复苏比例达到42.17％。超低温保存紫贻贝（Mytilus galloprovincialis Lamarck）精子，解冻后其复苏比例、受精率和孵化率最高可达到41.63％、69.52％和54.74％。保存紫贻贝精子最适降温速率为5 ℃／min，发生冻伤的温度范围是－20 ℃～－60 ℃；使用抗冻剂DMSO的保存效果好于甘油，且使用抗冻剂DMSO的最适浓度为15％；利用自然海水激活冻精效果好于低盐度或高pH值的溶液；样品体积（在0.2～1ml之间）对保存效果没有影响；采用15％DMSO和5 ℃／min的降温速率处理精子，液氮中保存90天后复苏比例仍达到41.8％。保存菲律宾蛤仔（Ruditapes philippinarum （Adams and Reeve））精子的最适降温速率为5 ℃／min，发生冻伤的温度范围是－30 ℃～－60 ℃；抗冻剂DMSO的保存效果好于甘油，也用DMSO与甘油混合使用，使用抗冻剂DMSO的最适浓度为10％；利用自然海水激活冻精效果好于低盐度或高pH的溶液；样品体积（在0.2％～1.6ml之间）对保存效果有显著影响。冷冻保存后精子复苏比例、受精率和孵化率最高达到40.84％、68.87％和47.17％；以最适降温速率和抗冻剂浓度处理精子，并在液氮中保存36天后冻精复苏比例仍可以达到38.54％。黑鲷（Sparus macrocephalus）精子经过超低温保存后复苏率、存活率最高可以达到61.37％和61.4。保存黑鲷精子时发生冷冻伤害的温度范围是－20 ℃～－60 ℃，适宜的降温速率为20 ℃／min；使用抗冻剂DMSO的适宜浓度为20％；样品体积对保存效果有相关性；利用自然海水激活冻精效果好于低盐度或高pH值的溶液；使用20％DMSO和20 ℃／min降温速率处理，在液氮中保存黑鲷精子66天后解冻，其复苏率和存活率分别为59.81％和58.45％。在液氮中保存真鲷（Pagrosomus major）精子时发生冷冻伤害的温域为－30 ℃～－60 ℃，适宜的降温速率为20 ℃／min；使用抗冻剂DMSO的适宜浓度为20％；采用低盐度或高pH值的溶液激活冻精的效果不如自然海水。真鲷冻精的复苏率和存活率最高可达到50.73％和62.5；以20 ℃／min和20％DMSO处理真鲷精子，保存在液氮中46天后冻精复苏率和存活率为50.63％和61.02％。通过对多种贝类和鱼类精子的超低温保存实验，不仅获得超低温保存基本条件，并且通过显微镜观察结合前人的研究，对产生冻伤的原因和保护的机理提出了一个模式。

Mitochondrial DNA phylogeny of two morphologically enigmatic fishes in the subfamily Schizothoracinae (Teleostei : Cyprinidae) in the Qinghai-Tibetan Plateau

The complete mitochondrial DNA (mtDNA) cytochrome b gene (1140 bp) was sequenced in Herzenstein macrocephalus and Gymnocypris namensis and in 13 other species and sub-species (n = 22), representing four closely related genera in the subfamily Schizothoracinae. Conflicting taxonomies of H. macrocephalus and G. namensis have been proposed because of the character instability among individuals. Parsimony, maximum likelihood and Bayesian methods produced phylogenetic trees with the same topology and resolved several distinctive clades. Previous taxonomic treatments, which variously placed these two species of separate genera or as sub-species, are inconsistent with the mtDNA phylogeny. Both H. macrocephalus and G. namensis appear in a well-supported clade, which also includes nine species of Schizopygopsis, and hence should be transferred to the genus Schizopygopsis. Morphological changes are further illustrated, and their adaptive evolution in response to the local habitat shifts during the speciation process appears to be responsible for conflicting views on the systematics of these two species and hence the contrasting taxonomic treatments. These species are endemic to the Qinghai-Tibetan Plateau, a region with a history of geological activity and a rich diversity of habitats that may have result in the parallel and reversal evolution of some morphological characters used in their taxonomies. Our results further suggest that speciation and morphological evolution of fishes in this region may be more complex than those previously expected. (c) 2007 The Authors Journal compilation (c) 2007 The Fisheries Society of the British Isles.