野生尖吻棘鳞鱼人工驯养及营养强化技术

<正>尖吻棘鳞鱼(Sargocentron spiniferum)又称尖吻金鳞鱼、金鳞鱼，隶属于辐鳍鱼纲、金眼鲷目、金鳞鱼科、棘鳞鱼属，分布在澳大利亚大堡礁，我国台湾岛南部、西沙群岛、中沙群岛及南沙群岛等。头部与身体呈红色，鳞片边缘呈银白色，背鳍的硬棘部鳍膜呈深红色，余鳍呈橘黄色，眼后方的前鳃盖骨上有一个垂直的长方形深红色斑块，属于国内外名贵观赏鱼。     

乌苏里江二种细鳞鱼生物学比较研究

尖吻细鳞Brachymystax lenok和钝吻细鳞B．tumensis在吻的形状上和鳃耙数上有很大差异。尖吻细鳞有长而肉厚的吻,上颌突出明显,口半下位,上颌骨较短,延伸到眼径垂直中线前；钝吻细鳞上颌不突出,口端位,上颌骨较长,延伸到眼径垂直中线或中线后。尖吻细鳞的鳃耙数在26—30；钝吻细鳞的鳃耙数在19—23。尖吻细鳞在头后部、体侧、背鳍、脂鳍有相对密而大的黑色斑点,但颜色较暗；钝吻细鳞在同样位置上的黑色斑点稀而小,非常清晰；但在幼鱼阶段二种鱼的斑点很难区分。体长/体高、体长/头长、头长/眼径、头长/眼间距的平均值,二种鱼的差异显著,但个体值间相互有交叉。生长速度：尖吻＞钝吻；绝对生殖力：尖吻＞钝吻；相对生殖力：钝吻＞尖吻。     

优良新品种—金鲈和银鲈

原产澳大利亚的金鲈和银鲈,象一对孪生姐妹,是我国淡水名贵鱼——鳜鱼的近亲,同属鲈形目。它们的外形很象鳜鱼,背鳍前部为鳍棘,后部为鳍条,背鳍和臀鳍都有尖锐的硬棘。都具有细栉鳞。一、形态特征金鲈体侧扁,头小,吻尖,口裂大,尾鳍圆。背部深棕色或青铜色,腹部变淡呈黄白色,鳍黄色或淡红色。体长可达76厘米,体重达23公斤,但一般小于5公斤;银鲈头小,眼     

条石鲷早期鳞被的形成和初生鳞的发育

采用茜素红染色法对条石鲷(Oplegnathus fasciatus)早期发育阶段鳞片的形成和发育过程进行了观察和测量。结果显示条石鲷鳞片的起始中心有3个,分别是鳃盖后缘、侧线上方和尾柄处。在水温为24~27℃的人工培育条件下,20日龄在这3个起始中心最早出现鳞片,鳃盖后缘至胸鳍基部的鳞被向上下前后扩展,胸鳍后缘的侧线上方鳞被向下和向前后扩展,尾柄处的鳞被前后扩展,头顶部的鳞被向四周扩展,到40日龄时鱼体全身被鳞进入幼鱼期。通过观察还发现,鳞片向下方发育的速度快于上方,上下方向的发育速度快于前后方向。向前扩展到鳃盖后暂停,向后发育到达尾柄末端,最后出现鳞片的部位是鳃盖。条石鲷鳞片为栉鳞,较细小。在鱼体的同一时期同一部位,鳞片的大小存在较大的差异。初生鳞鳞嵴(环片)数目与发育阶段的关系可用二次方程表示。     

中华乌塘鳢生物学特性及苗种生产技术

<正> 1 中华乌塘鳢生物学特性1.1 形态特征 乌塘鳢成体体长一般为17～25cm,鱼体前部略呈圆筒状,向后部呈延长形而侧扁。头部稍膨大,吻部宽而圆,口裂斜,眼小。体被细小栉鳞,纵列鳞100以上。体表粘滑。腹鳍分离,胸鳍大,两背鳍分离距离较远,尾鳍圆或稍尖、其基部上端有一带白色的大型黑色眼状斑。前鳃盖骨边缘无小刺,犁骨具齿。体呈褐色或带暗褐色斑纹,腹面淡褐色。     

不同光照强度对豹纹鳃棘鲈生长和体色变化的影响

人工养殖条件下维持豹纹鳃棘鲈(Plectropomus leopardus)的体色是决定经济价值的关键,所以本文设计不同梯度光照强度区间的养殖环境,观察豹纹鳃棘鲈生长情况和体色变化情况。从试验结果可以看出当豹纹鳃棘鲈处于50～300 lx光照强度区间内,会一直维持较快的生长速率,体长、体重增加速率高于其他光照强度区间;而光照强度处于300～700 lx区间时,在养殖周期内积累的红色素含量最多,观察到明显的体色变化,即光照强度确实会影响豹纹鳃棘鲈色素累积,改变体色。     

光环境因子对豹纹鳃棘鲈幼鱼栖息特性的影响

以豹纹鳃棘鲈[全长(17.5±0.6)cm、体质量(205.2±1.7)g]为研究对象,分别采用光梯度法和正交试验法,在小型循环水养殖系统中一个特制的养殖水槽和一组常规的养殖水槽内探究了豹纹鳃棘鲈幼鱼对白、蓝、绿、黄和红5种光环境的喜好性和三原色(红色A1、绿色A2、蓝色A3)及光周期(16L︰8D,B1;12L︰12D,B2;8L︰16D,B3)和光照度(1000lx,C1;1500lx,C2;2000lx,C3)对豹纹鳃棘鲈幼鱼栖息的影响。结果表明,光色和光照度对幼鱼幼鱼的栖息习性均有显著影响,在试验设定的光色和光照度范围内,同光色照射下,随着光照度的升高,幼鱼对光照度的敏感性越来越低,在不同光照度下的分布率差异不显著(P0.05);同强度光照射下,光波长越大,幼鱼分布率越高,随着光照度的升高,幼鱼对光波长的敏感度逐渐降低,但在不同光色下的分布率显著差异(P0.05)。正交试验结果,光色对豹纹鳃棘鲈幼鱼的栖息有显著影响(P0.05),光周期和光照度对豹纹鳃棘鲈栖息影响不显著(P0.05);极差分析结果,豹纹鳃棘鲈幼鱼最适宜栖息的光照环境是绿色光;光周期16L∶8D;光照度1500lx;影响豹纹鳃棘鲈幼鱼栖息的主要光照因子是光色,其次是光照度和光照周期。     

圓吻鲴的放养和繁殖

圆吻鲴(Distoechodon tumirostrisPeters) 俗称翼鱼、鲜鱼、力燥、鮟鱼。属鲤科密鲴亚科圆吻鲴属。头小而尖,体侧扁,腹部稍圆,无腹棱,口下位呈一横裂,眼小无须。侧线鳞72～74,鳞小而密,侧线鳞以上呈灰黑色,侧线鳞以下为银白色,各鳍均呈灰白色。下咽齿两行,第一行6～7个,第二行2个,是瓯江最主要的经济鱼类,年产量最高可达30-40万斤,最大个体     

肉红鲫鱼

<正> 鱼体呈纺锤型,全身鳞片呈透明状,侧线鳞下面二至三行以上的鳞片均呈肉桔红色(直至背鳍中部),侧线鳞下面三行至腹部为肉红色(类似咸瘦肉色),鳃盖骨透明可见紫红色鳃耙,眼睛上有眼脸可转动,乌黑。背鳍上半部较透明,下半部呈桔红色,     

瓯江彩鲤的生物学特性与资源保护

瓯江彩鲤俗称田鱼(1999年上海水产大学首席教授李思发教授命名为瓯江彩鲤),是浙南区域的优良养殖品种。其生长快、食性杂、肉质洁白细嫩、味道鲜美、营养丰富、无泥腥味,且鳞片柔软可食,可谓淡水鱼中一绝。田鱼色彩丰富,有红、黑、花、白、青、粉等颜色,可与日本锦鲤相媲美,是一个既能养殖又能观赏的优良品种。一、生物学特性1.形态特性瓯江彩鲤,体长而侧扁,中部稍高,腹部圆,吻圆钝,口前位,口裂呈马蹄形,眼中等大,上侧位,眼间宽。有二对短须,鳃孔中等大,鳃盖膜在颊部相连;体披大而柔软的圆鳞,胸部鳞片较小。侧线完全,中前部弯曲度较大,背鳍…     

Fin damage and growth parameters relative to stocking density and feeding method in intensively cultured European perch (Perca fluviatilis L.)

We evaluated the relationship of stocking density to survival, growth performance and fin condition of European perch Perca fluviatilis with hand feeding and self-feeders. Hand-fed perch (body weight 19.1 ± 5.1 g and total length 107 ± 9 mm) were reared at 0.5, 1.0, 1.5 and 2.0 fish/L. Self-feeding perch (body weight 25.4 ± 3.9 g and total length 128 ± 7 mm) were reared at stocking densities of 0.6, 1.0 and 1.4 fish/L. Pond-reared perch served as a comparison group for fin damage assessment. We found no differences in survival rate among stocking densities with either feeding method. Hand-fed fish displayed the highest weight gain and SGR at stocking density of 0.5 fish/L. The self-feeding fish showed a non-linear association of weight gain with stocking density with the highest growth at 1.0 fish/L. Fin length was noticeably greater in pond-reared fish compared with RAS-reared fish regardless of feeding method. In both experiments, fin length relative to standard length showed a negative relationship with stocking density, with pectoral fins showing the greatest effect. Fin condition deteriorated with increasing stocking density, and growth was highest at 0.5 and 1.0 fish/L in hand-fed and self-feeding fish, respectively.     

黄金鲈♀×伊犁鲈♂杂交代的形态特征与人工养殖技术

对黄金鲈♀×伊犁鲈♂杂交后代的形态特征与黄金鲈和伊犁鲈进行了比较,并就其人工养殖技术进行了探讨。结果表明:2龄杂交鲈体长26.5～31.5cm,(L=28.53±1.69cm),体重339.0～650.5g,(=447.31±94.23g)。体长为体高的3.58～3.93倍,两背鳍分离,第一背鳍棘14～16根,体侧扁,长椭圆形,形态特征与黄金鲈相似,体背为灰绿色,颜色介于黄金鲈与伊犁鲈之间,身体两侧有5～9条黑色横斑,属于温、冷水性鱼类,生长的最适温度为22～25℃,室内养殖条件下,投喂颗粒饵料,并辅以动物性饵料,生长迅速,日均增重率可达0.62g/d。     

The shift to smaller zooplankton in Lake Victoria cannot be attributed to the ‘sardine’ Rastrineobola argentea (Cyprinidae)

After the population increase of introduced Nile perch (Lates niloticus) in Lake Victoria, a decrease in the relative abundance of herbivorous cladocerans and calanoids was reported for the pelagic zone. The shift from large herbivores to small-bodied predatory cyclopoids has been attributed to the increase of the zooplanktivorous cyprinid dagaa (Rastrineobola argentea), which rose concomitantly with the Nile perch. However, we observed that in the Mwanza Gulf of the lake cyclopoids dominated the zooplankton community already before the rise of dagaa. Furthermore, there are indications that dagaa takes fewer calanoids than expected from their representation in the environment, although a slight preference for cladocerans may exist. Calanoids dominated the diet of small Nile perch of about 4 cm length, but juvenile Nile perch did not occur in the study area until after the size shift in zooplankton. The lumped biomass of dagaa and small Nile perch is lower than the biomass of the original haplochromine-dominated community of zooplanktivorous fish. Thus, the decline of large zooplankters in the lake cannot be explained by intensified predation after the replacement of zooplanktivorous haplochromines by dagaa and Nile perch. Increased eutrophication, resulting in a shift in predominance from diatoms to cyanophytes, is suggested as an alternative explanation for the shift in zooplankton composition.     

Morphological development of larval and juvenile blacktip grouper, <Emphasis Type="Italic">Epinephelus fasciatus</Emphasis>

The morphological development of larval and juvenile blacktip grouper, Epinephelus fasciatus, was examined using a hatchery-reared series. By about 5 mm body length (BL), the larvae developed characteristic pigmentation patterns of groupers, such as melanophores on the dorsal part of the gut, on the tips of the second-dorsal and pelvic fin spines, and on the midpoint of the tail to form a cluster. In addition, characteristic spines of groupers, such as spinelets on the second-dorsal and pelvic fin spines, and the preopercular angle spine developed by about 6 mm BL. The notochord end was in the process of flexion in larvae of 6–7 mm BL, by when major melanophores, spines, and jaw teeth started to appear. After the fin ray counts attained the adult complement at about 14 mm BL, somewhat densely pigmented bands started to appear on the body. The fish had the five distinct transverse bands and attained adult-like attire at about 40 mm BL when the major head spines disappeared and body parts in relation to BL became stable.     

Hypoxic wetland tributaries as faunal refugia from an introduced predator

Abstract– The introduction of Nile perch ( Lates niloticus ) into the Lake Victoria basin of East Africa has coincided with the decline or disappearance of hundreds of indigenous species. To mitigate additional biodiversity loss, we must learn what limits the spread of Nile perch and what habitats serve as refugia for prey species. Heavily vegetated wetlands may protect fishes from Nile perch predation by providing both structural and low-oxygen refugia for prey species tolerant of hypoxia. To examine the potential of wetlands as refugia we quantified the composition, persistence, and stability of fish assemblages in a wetland tributary of Lake Nabugabo, a satellite lake of Lake Victoria in which Nile perch have been introduced. Nile perch were extremely rare in the wetland, and nine of the 18 species that have disappeared from the open waters of the satellite lake were captured in the tributary in this study. Dissolved oxygen was chronically low in the river and may be important in shaping fish community characteristics. Faunal attenuation occurred as the dry season progressed and oxygen levels dropped; however, the most common species remained through seasonal changes. The chronically low oxygen conditions in the werland tributary may permit persistence of only hypoxia-tolerant species. However, wetland conditions seem to limit exploitation by Nile perch providing critical refugia for a subset of the basin fauna.     

中国南海银鲈科鱼类——新记录

2008年11月在广西北海市侨港镇码头采获银鲈科Gerreidae、银鲈属Gerres鱼类标本两尾,经鉴定为大棘银鲈Gerres macracanthus Bleeker,1854,系我国南海鱼类一新记录。其主要特征为：体长卵圆形,侧扁,体长为体高的2.2～2.3倍;体背腹缘均呈弧状隆起,体高以背鳍起点处最高。口小,能活动,伸出时略向下倾斜。体被薄圆鳞,易脱落;侧线鳞41～43枚。背鳍鳍棘部与鳍条部相连;背鳍IX-10,第2鳍棘延长呈丝状,压倒时末端伸达尾柄;臀鳍Ⅲ-7,以第3鳍棘最长;胸鳍长,末端可达臀鳍起点上方;尾鳍叉形。新鲜标本体背部银灰色,腹部银白色,体侧有7～10条青灰色横带;背鳍灰白色,第2鳍棘黑色;臀鳍、胸鳍和腹鳍淡黄色;尾鳍灰黄色,上、下叶内缘暗色,下叶外缘白色。     

The sexually dimorphic adipose fin is an androgen target tissue in the brown trout (Salmo trutta fario)

An investigation has been described on the relationship of body length, age and sex with adipose fin length and the number of androgen receptor (AR)-containing cells in the adipose fin as a secondary sexual characteristic for brown trout (Salmo trutta fario). Firstly, body and adipose fin lengths of 2- to 5-year-old brown trout were measured. Thereafter, these fish were killed by decapitation, then their sexes were determined, and adipose fins were excised. The cellular bases of AR binding activities in the adipose fins were analyzed with an antibody against human/rat AR peptide. Immunocytochemistry and western blotting techniques were performed with this antibody. Analysis of morphological measurements indicated that body length and age had a linear relationship with adipose fin length. The coefficients of determination for the body length and age were 0.92 and 0.85 in the male fish and 0.76 and 0.73 in the female fish against the adipose fin length, respectively. At 2 years of age, cells in the adipose fin did not exhibit AR immunoreactivity. However, AR-immunopositive cells were abundant in the adipose fin of 3- to 5-year-old fish. Moreover, the number of AR-immunopositive cells was significantly (P < 0.05) high in males and increased with age. These observations indicate that the adipose fin in the brown trout is a probable target for androgen action and that tissue function or development may to some extent be androgen dependent. In addition, it is likely that such an effect will be mediated by specific androgen receptors.     

Checking the pulse of the major commercial fisheries of lake Victoria Kenya,for sustainable management

The present study demonstrates the declining state of the major commercial fisheries of Lake Victoria, Kenya, a situation threatening sustainability of the lake's fishery. Data in the present study were derived from resource monitoring programmes that included hydro‐acoustics (2009–2018), trawl net fishing (2011–2018), frame surveys (2000–2016) and catch assessment surveys (2000–2015). The activities provided information on fish stocks and supported advice for fisheries management. The average fish stock densities for Tanzania, Uganda and Kenya of 8.92, 8.25 and 8.19 t/km², respectively, were relatively similar. Diplomatic and sustainable efforts for harmony in fish harvesting among the fishers of the riparian countries are encouraged given the interdependence of the lake. The Kenyan and River Kagera regions had a higher proportion (≈ 4% each) of big‐sized Nile perch (≥50 cm total length) in 2018, signifying the critical breeding areas for Nile perch. To sustain the fishery, there is need to enforce a 36%–44% effort reduction for all the major fisheries, and enforcement of gear limits to avoid harvesting of immature fish and destruction of the lake ecosystem.     

Effects of thyroxine and thiourea on the metamorphosis of coral trout grouper Plectropomus leopardus

The contribution of the thyroid hormone to the metamorphosis of the coral trout Plectropomus leopardus was examined. Juveniles, aged 35 days, were exposed to thyroxine (T4, 0.1 p.p.m) and thiourea (TU; inhibitor of thyroid hormone synthesis, 30 p.p.m) for 13 days. All the fish in the T4-treated group had completed metamorphosis (second metamorphosis, pigmentation and resorption of fin spines) within three days after the beginning of the experiment (day 3), whereas it took 13 days for this to occur in the control fish. Moreover, the fish in the TU group had not completed metamorphosis even by day 13. Settling behavior was significantly stimulated by T4 treatment, as was the resorption of the dorsal and pelvic fin spines, the reduction of serration on the spines, and the transition of body color into an opaque reddish hue. Fish in the TU group had longer dorsal and pelvic spines, retarded pigmentation and an abnormal black coloration. These results suggest that thyroid hormone accelerates most changes during the second metamorphosis in the coral trout.     

Effects of environmental factors on size-related growth efficiency of perch, Perca fluviatilis

Abstract – Two aspects of size-dependent growth were addressed using perch, Perca fluviatilis L, from 22 Swedish lakes. Firstly, maximum annual growth decreased linearly with length after the previous year. Secondly, median or realized growth showed a non-linear pattern, with minimum growth efficiency at intermediate length, probably related to the shift from invertebrate to fish diet. Between-lake variation in size-related growth efficiency was better explained by fish community characteristics than by abiotic factors. The growth of most size classes was negatively related to fish biomass, especially to biomass of 100 to 199-mm perch. Growth efficiency of perch >200 mm was positively related to the proportion of large perch in the community. These size- and density-dependent growth responses suggest that effects of competitive and predatory interactions will often mask the controlling or limiting effects of abiotic factors, such that realized growth of individuals and populations are poorly described by deterministic asymptotic growth models.