Skeletal development and abnormalities of the vertebral column and fins in larval stage of hatchery‐reared American shad,Alosa sapidissima

The present study describes the skeletal development and the occurrence of deformities in American shad, Alosa sapidissima, larvae from hatching to 45 days after hatching (DAH). The ontogeny of the vertebral column started at 16 DAH (days after hatching), with the formation of the posterior neural and haemal arches, and was complete at 28 DAH. In comparison, the vertebral centra started to form at 16 DAH, with ossification being visible in all centra at 38 DAH. The pectorals were the only fins that formed before the onset of feeding (at 2 DAH), with ossification being complete at 45 DAH. The caudal fin formed at 5 DAH, with ossification being complete at 40 DAH. Dorsal and pelvic fin development began at 6 DAH and 20 DAH respectively. The ossification of both the dorsal and pelvic fins was visible at 45 DAH. The anal fin began forming at 14 DAH, and was complete at 30 DAH. The ossification of the anal fin was complete at 45 DAH. Overall, 22 types of skeletal deformities were detected in about 41% of individuals. Most anomalies were detected in the haemal region, while the fewest anomalies were detected in the anal fin. In addition, the frequency of deformities gradually increased with fish age at the different developmental stages. Our results are expected to contribute baseline information on how rearing conditions impact skeletal development, in addition to identifying potential causative factors of skeletal deformities.     

美洲鲥仔稚鱼脊柱及附肢骨骼系统的早期发育

使用软骨-硬骨双染色技术,描述了美洲鲥(Alosa sapidissima)仔稚鱼(1~51日龄)脊柱、胸鳍、尾鳍、背鳍等附肢骨骼的形态发育特征。结果显示,脊柱的发育开始于10日龄仔鱼尾部的髓弓、脉弓和尾下骨的出现,16日龄髓弓和脉弓延伸形成髓棘和脉棘,19日龄脊柱出现分节的硬骨环,23日龄所有椎体形成。各附鳍支鳍骨发育顺序先后依次为胸鳍、尾鳍、背鳍、臀鳍和腹鳍。胸鳍在2日龄时出现乌喙骨,13日龄形成软骨质的胸鳍支鳍骨,19日龄仔鱼肩带和上匙骨开始骨化;尾鳍的尾下骨最早出现在5日龄,12日龄尾鳍形成2枚尾上骨、1枚尾杆骨和6枚尾下骨,19日龄仔鱼尾椎和尾鳍率先开始骨化,直至23日龄尾鳍骨骼系统钙化完全。最终背鳍和臀鳍分别形成18和22根鳍条。美洲鲥骨骼发育研究对其早期发育功能趋向、环境优化及分类鉴定有重要作用。     

Early life history of yellow puffer,Chonerhinos naritus (Richardson, 1848) from Sarawak,Northwestern Borneo

The growth and morphological development including fins, spine distribution and pigmentation of larval and juvenile of hatchery‐reared yellow puffer, Chonerhinos naritus were described to provide essential information on the early life history of this species. The total length (TL) of newly hatched larvae was 3.42 ± 0.23 (mean ± SD) mm, reaching 5.66 ± 0.38 mm on 5 days after hatched (DAH), 7.80 ± 0.28 mm on 11 DAH, 9.88 ± 0.40 mm on 27 DAH and 10.92 ± 0.58 mm on 30 DAH. The yolk was completely absorbed in preflexion larvae at 4 DAH. The mouth opening started at 3 DAH of yolk sac larvae, while the teeth appeared starting from preflexion larvae at 7 DAH. Overall aggregate fin ray numbers including caudal fin attained full complement in postflexion larvae at 27 DAH. Several melanophores with appearance of small stellate were first appeared dorsally on the head of flexion larvae at 13 DAH, expanded at the dorsal region of the head, above the eye in juveniles at 30 DAH. The spines first appeared in preflexion larvae of C. naritus at 7 DAH, covering the ventral skin region below pectoral fin base and expanded to the ventral part of the body and nearly covered the whole abdomen region before the anus and below the eyes in juveniles. C. naritus remain as larvae for approximately 29 days, during which they metamorphose to the juvenile stage prior to sexual maturation. Observations in larvae development of C. naritus revealed similar characteristics with other Tetraodontidae species.     

Development of deformities at the vertebral column in Diplodus sargus (L., 1758) early larval stages

One of the bottleneck problems of Diplodus sargus farming is a high incidence of skeletal deformities at the vertebral column. In this study, the pattern of vertebral deformities were determined in three different larval batches from 2 to 30 days after hatching (DAH). During this period, 60 larvae per spawn were observed at 2, 8, 13, 15, 18, 21, 23, 25, 27 and 30 DAH and the different types and frequency of vertebral column malformations were registered. Deformities started from 8 to 13 DAH, when the percentage of deformed larvae rose from approximately 5% to 40%. At 15 DAH, skeletal malformations had frequencies up to 80% of the observed larvae. Serious malformations such as kyphosis, scoliosis and lordosis were observed at 18 DAH but seldom in percentages higher than 15%. Vertebral fusions and compressions especially affected the preurostyle region. Abnormal shape vertebrae were more frequent between vertebrae 15 and 21. Other malformations observed were hypertrophic vertebrae, more common in the trunk and caudal regions, reaching percentages higher than 50% in the former. This study has useful information concerning skeletal malformations at the vertebral column of D. sargus larvae, as it identifies the main deformities observed and the ages of highest incidence.     

Comparing skeletal development of wild and hatchery-reared Senegalese sole (Solea senegalensis, Kaup 1858): evaluation in larval and postlarval stages

The Senegalese sole is a marine pleuronectiform that naturally occurs in Southern Europe and Mediterranean region where it is being produced in aquaculture, in particular in Portugal and Spain. The aim of this study was to assess the quality of hatchery-reared larvae in comparison with those reared in the wild, and determine to which extension wild growing larvae are also affected by skeletal deformities. The main structures affected included those forming the axial skeleton, the caudal fin complex and both anal and dorsal fins, with the most prevalent anomalies affecting caudal vertebrae and arches. Hatchery-reared fish presented a higher incidence of deformities (79%) compared with the 19% observed in wild specimens. In wild postlarvae collected in Autumn no deformities were observed. This work clearly shows that wild Senegalese sole present less skeletal deformities than those hatchery-reared during larval stages, indicating a selective mortality of wild deformed fish and/or an effect of aquaculture-related rearing conditions in the development of skeletal deformities in sole.     

鳜仔稚鱼骨骼系统骨化发育

采用软骨―硬骨双染色技术,描述了鳜(Siniperca chuatsi)仔稚鱼(1～35日龄)头骨、脊柱、附肢骨骼的骨化发育特征。结果显示:(1)头骨前鳃盖骨于14日龄最先骨化, 15日龄上下颌骨骨化,且上下颌骨相对长度呈现连续变化过程。17日龄后,颌齿、关节骨、舌颌骨骨化;19日龄,隅骨、间鳃盖骨、鳃盖骨、鳃条骨、额骨骨化。20日龄后,方骨、下鳃盖骨、辅上颌骨等骨化; 35日龄,头骨骨化基本完成。(2)脊柱于15日龄由前向后骨化, 20日龄背肋与腹肋由基部向末端骨化, 29日龄骨化完成。脉弓与脉棘、髓弓与髓棘均由前向后、由基部向末端骨化,脉棘与髓棘骨化时间晚于相应的椎体。(3)附肢骨骼骨化顺序依次为胸鳍、背鳍、臀鳍、腹鳍、尾鳍。胸鳍匙骨于16日龄骨化,乌喙骨与肩胛骨于25日龄骨化;背鳍、臀鳍分别于18日龄、20日龄骨化,骨化方式相似;腹鳍于23日龄骨化,骨化方式与胸鳍相反;尾杆骨、尾下骨于25日龄骨化,附肢骨骼于35日龄基本骨化完成。结果表明,鳜骨骼骨化发育与其早期运动、摄食与御敌等行为密切相关。     

Meristic character counts and incidence of skeletal anomalies in the wild Diplodus puntazzo (Cetti, 1777) of an area of the south-eastern Mediterranean Sea

The sharpsnout seabream (Diplodus puntazzo, Cetti 1777) is a species rarely found in coastal areas of Sicily, but is important in Mediterranean aquaculture. In order to detect the number of meristic characters and the main types of body deformation, 588 specimens of sharpsnout seabream were collected from a coastal zone of south-east Sicily (Licata, AG—Italy). Different sized classes were examined and the relationship between size and the number of meristic characters (number of fin rays) was found. The number of vertebrae, anal fin hard rays and dorsal fin hard rays was constant and did not vary with size. Seventeen types of skeletal and fin anomalies were observed, but no grave anomalies were found, such as the absence of a swimbladder, lordosis, kyphosis and calculi in the terminal tract of the urinary duct. The most prevalent anomalies were associated with the fins, especially E7 (pectoral fin rays), F7 (anal fin rays) and I7 (dorsal fin soft rays). There was no correlation between frequency of anomaly and size class. The malformation index was 4.54.     

Fin development in stream- and hatchery-reared Atlantic salmon

To determine the effect of development and environment on fin growth, we measured fin lengths of juvenile Atlantic salmon (Salmo salar) from two hatcheries (August, October and April–May), stream-reared fish (July and October) stocked as fry into two tributaries, and smolts from the main stem of the Connecticut River (May). For stream-reared parr, there was a linear relationship between the dorsal, caudal and anal fins with fork length, while the pectoral, pelvic and adipose fins exhibited a curvilinear relationship with fork length. Parr from a high gradient stream had larger caudal fins than fish from a low gradient stream, but other fins did not differ. Regression lines for the fins of stream-reared smolts were all linear when fin length was regressed against fork length. Stream-reared parr had larger pectoral, pelvic and anal fins than smolts of similar size while dorsal and caudal fin lengths did not differ. Regression equations formulated using the fins of stream-reared parr were used to calculate the percent difference (100×observed fin length/expected) in fin lengths between stream- and hatchery-reared parr. The pelvic, adipose, caudal and anal fins of hatchery-reared parr showed no signs of degeneration by the first sampling period 7 months after hatching, whereas degeneration in the pectoral (13–20%) and dorsal (15–18%) fins was evident at this time. By the end of the study, degeneration was present in every fin except the adipose, with the pectoral (35–65%) and dorsal (32–58%) fins exhibiting the greatest amount of fin loss. All fins of hatchery-reared parr became shorter with time. There were minor differences in fin degeneration among parr from the two hatcheries, but the overall pattern of decreasing fin size was similar, indicating a common cause of fin degeneration. Comparison of stream- and hatchery-reared fish is a valuable means of determining the impact of captive environments on fin growth.     

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 effect of rearing conditions on development of saddleback syndrome and caudal fin deformities in Dentex dentex (L.)

The development of saddleback syndrome and of caudal fin deformities in Dentex dentex (Linnaeus, 1758) was compared under two rearing methods, extensive (E) and semi-extensive (S). The osteological appearance and the meristic characters of the reared fish were compared to that of D. dentex juveniles, collected from the natural environment. All the wild juveniles were normal in respect to their osteological appearance, while the reared specimens presented skeletal deformities resulting from different rearing methods applied. Saddleback syndrome (4.0–4.4%) and severe external deformities of the caudal fin (14.3–15.0%) characterised exclusively the semi-extensive populations, while the extensive populations presented severe abnormalities of the pre-ural centra (25.0–25.6%) with significantly higher frequency than the S reared fish (5.8%). Saddleback syndrome was expressed as a lack of one to all the hard spines of the dorsal fin, accompanied by shape, number and position abnormalities of the related pterygiophores. Caudal fin deformities were mainly characterised by the lack of the upper lepidotrichia or/and dermatotrichia, accompanied by severe deformities of the supporting elements of the upper lobe. The saddleback syndrome and severe caudal fin deformities were anatomically and ontogenetically related to each other, originating at the early larval stage as a result of abnormalities of the primordial marginal finfold and of the posterior tip of the notochord. In respect to the dominant phenotypes, the meristic characters of the normal reared fish were not differentiated from those of the wild, but they presented higher variability.

The results are discussed in view of the aetiology, applications and research targets for the erasure of skeletal malformations.     

Ontogeny of the shi drum Umbrina cirrosa (Linnaeus 1758), a candidate new species for aquaculture

The ontogeny of shi drum Umbrina cirrosa (Linnaeus 1758), a candidate new species for aquaculture, was studied throughout the entire larval phase. Geometric morphometric analysis revealed two clear inflection points (7.0 and 12.7 mm total length, TL) in the shape ontogeny of this species, separating the studied period into three phases of different allometric priorities. Spline graphs demonstrated that the major non‐uniform shape ontogeny correlated with the development of the fins, the anterior dorsal area of the body, the caudal peduncle, the eye and the mouth. Concerning the morphological features, shi drum larvae are characterized by an upward anterior bending of the notochord. The ontogeny of the fins began with the formation of the pectoral buds (2.9 mm TL), continued with the notochord flexion (4.3 mm TL, associated with the caudal fin development), the appearance of the pelvic buds, the first anal rays (4.5 mm TL) and the first dorsal rays (4.8 mm TL). Shi drum juveniles presented 25 vertebrae and the following dominant fin types: D XI,23, AII,6, VI,5, P17 and C17.     

Osteological development and deformities in hatchery‐reared longtooth grouper (Epinephelus bruneus): Vertebral column,dorsal‐fin supports and caudal‐fin skeleton

Skeletal deformities are one of the serious problems in hatchery‐reared longtooth grouper (Epinephelus bruneus). In this study, seed production of longtooth grouper was carried out in four large hatchery‐grade tanks. Osteological development of the vertebral column, caudal‐fin skeleton and dorsal‐fin supports in larvae and juveniles was described. The vertebral ontogeny started at 4.8 mm total length (TL) with the formation of neural spines 2 and 3, and the vertebral centra began forming at 5.3 mm TL. By 16 mm TL, all vertebral bony elements were formed except for the dorsal ribs. The onsets of the ontogeny of the caudal‐fin skeleton and dorsal‐fin supports occurred at approximately 5.1 mm and 3.9 mm TL, respectively, and the completion of these bony elements occurred at approximately 20 mm TL. The incidence of deformity was examined; some type of deformity was observed in 57%–68% of the specimens. These deformities mainly occurred as three types: lordosis, around vertebrae 1–5; saddleback‐like syndrome, around vertebrae 7–11; and vertebrae fusion, around vertebrae 22–24. The incidence of prehaemal lordosis was significantly higher among individuals with an uninflated swim bladder than among those with an inflated swim bladder.     

The prevalence of vertebral deformities is increased with higher egg incubation temperatures and triploidy in Atlantic salmon Salmo salar L.

Suboptimal egg incubation temperature is a risk factor for the development of skeletal deformities in teleosts. Triplicate diploid and triploid Atlantic salmon, Salmo salar L., egg batches were incubated at 6, 8 and 10 °C up until first feeding, whereupon fish were reared on a natural temperature before examination for externally visible skeletal deformities (jaw and spine) and radiographed for vertebral deformities and morphology at the parr stage. Increasing incubation temperatures and triploidy increased the number of fish showing one or more deformed vertebrae. Triploids had significantly higher mean vertebrae cranio‐caudal length (L) and dorsal‐ventral height (H) ratio at 6 and 10 °C than diploids, but triploidy had no effect on mean vertebrae centra area. Triploids demonstrated an increase in lower jaw deformities with increased incubation temperature, whereas jaw deformities were rare in diploids. Fish incubated at 10 °C had a significantly lower mean vertebral number than fish incubated at 6 °C, and triploids had lower mean vertebral numbers than diploids. Diploid fish with 58 vertebrae had a significantly higher mean vertebral centra area than fish with 59 vertebrae, but vertebral number did not affect the mean vertebral L/H ratio. The results are discussed with respect to the welfare and production of farmed salmonids.     

Effect of Light Intensity on Color Performance of False Clownfish,Amphiprion ocellaris Cuvier

Color performance of false clownfish, Amphiprion ocellaris Cuvier, was examined under three levels of light intensity (20–50 , 600–850 , and 2700–3500 lx) for 5 wk. The experiment was conducted in nine rectangular glass aquaria (25 × 25 × 20 cm) with three replicates. Each aquarium was stocked with 36 fish, and 3 fish were randomly sampled from each aquarium every other week. Digital images were taken weekly on each individual fish after it was anesthetized in MS‐222. The color performance in hue, saturation, and brightness was quantified using image analysis. In addition to the whole‐body analysis, each fish image was divided into ventral and dorsal parts to assess the body position‐dependent effect. Furthermore, color differences between dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. The whole body was brighter at low light than at medium or at high light intensity. Irrespective of light intensity, the dorsal side was more orange but less bright than the ventral side. Brighter light strengthened overall orange color on fish fins. The dorsal fin and ventral fins appeared more orange than the anal and caudal fins regardless of light intensity and exposure duration. Similar to body color, low light also led to brighter fins, especially for caudal and dorsal fins. Our results indicate that ambient light could regulate fish color performance but could not change the pigment dominance by β‐carotene. Light intensity is unlikely to change the contrast between dorsal and ventral sides, but dim light tends to make fish body brighter, and bright light strengthens orange color on fins.     

New insight on vertebral anomalies in cultured Senegalese sole (Solea senegalensis,Kaup) at early stages of development

Senegalese sole (Solea senegalensis, Kaup) is a promising flatfish species in aquaculture. However, skeletal anomalies are still a great concern in sole farming. Investigation of this issue is crucial to improving larval quality and optimizing production. The aim of this study was to thoroughly assess anomalies in the rachis of reared sole at early developmental stages. Sole (n = 507) were sampled at 31 or 32 days after hatching (dah). The specimens were stained with alcian blue and alizarin red and evaluated for the detection of vertebral deformities. Most fish presented 9:34:3 vertebrae in abdominal, caudal and caudal complex regions, respectively. Remarkably, all specimens showed at least one spinal anomaly. Alterations of neural/haemal elements, as well as deformities of hypurals, parhypural and epural, were recurrent. Vertebral body anomalies and/or vertebral column deviations were identified in 52% of the individuals. Vertebral deformations and fusions were common, especially in caudal complex. ‘Minor’ anomalies were predominant, and some of the detected disorders might be a result of non‐/low‐pathological processes. These results contribute a new insight into the main skeletal anomalies affecting cultured sole larvae. Further research is required to determine their impact on fish welfare and external appearances at commercial stages.     

Impact of Background on Color Performance of False Clownfish,Amphiprion ocellaris,Cuvier

Color performance of false clownfish, Amphiprion ocellaris, Cuvier was first examined at four color backgrounds (blue, green red, and white) for 4 wk, then all fish were transferred to a white background for another 4 wk to test whether the impact of background colors on fish skin could have a lasting effect when the environment colors are changed. The experiment was conducted in 10‐L rectangular plastic buckets with three replicates. Thirty fish were stocked in each bucket and three fish were randomly sampled from each tank in Weeks 1, 4, and 8. The color hue, saturation, and brightness were quantified using image analysis. In addition to the whole body analysis, each fish image was divided into ventral and dorsal parts to examine the body position‐dependent response. Furthermore, color differences among the dorsal fin, anal fin, ventral fin, and caudal fin were also quantified. Blue or green background enhanced red orange color on fish skin, whereas white background made fish color brighter. Irrespective of background color, the dorsal side of fish exhibited more red orange, but the color was less bright and less saturated than that of ventral side. Upper fins (dorsal and caudal fins) were more red orange in a blue background than in a white background. Transferring fish from colored backgrounds to a white background made the fish skin and fins brighter, the color of ventral body and ventral fins less saturated, and the bottom fins more yellow orange. The results indicate that blue or green background could strengthen the orange color, whereas white background made fish color less saturated but brighter. The impact of background on the performance of fish color is temporary and likely to disappear when environmental color changes.     

鲔脊椎骨与附肢骨骼描述

为揭示鲔(Euthynnus affinis)的骨骼形态特征,采用X射线拍照法对鲔进行拍照及相关研究.研究发现,鲔脊柱由20枚躯椎和18枚尾椎构成,第4—第30枚脊椎骨连接27枚髓棘,第16—第28枚脊椎骨前后两端的椎体横突向下延伸后相互连接形成特殊骨骼结构,第35—第37脊椎骨上下两侧向斜后方延伸构成3块尾上骨和3块...     

Vertebral deformities in cultured red sea bream, Pagrus major, Temminck and Schlegel

Vertebral deformities were investigated in cultured red sea bream, Pagrus major. In the field, deformities in seedlings were categorized and their incidence was calculated. In the laboratory, the symptoms of major vertebral deformities were examined morphologically using radiographs and by making transparent skeletal specimens. The internal structure of deformed vertebrae was examined histologically. The shortened body condition had the highest incidence (0.9–8.3%) of all deformities in the seedlings. In individuals with the shortened body condition, the ratio of trunk and caudal part length to body height was smaller. These fish had skeletal anomalies in the vertebrae, mainly centrum defects (64.3%) or undersized centrums (25.2%). The specimens with centrum defects had a characteristic anomaly in the vertebrae, with plural pairs of neural and haemal spines on a single centrum. This anomaly was frequently observed in the posterior abdominal vertebrae. The internal skeletal structure of such abnormal centrums was basically the same as that of normal centrums. In all the specimens with undersized centrums, both the centrum length and diameter were shorter than normal except for the first and second centrum, and urostyle.     

瓯江产唇(鱼骨)的早期形态发育研究

试验结果表明,受精卵授精后120 h,仔鱼开始出膜,初孵仔鱼(体长5.6~6.8 mm,平均体长6.35 mm)鱼体透明,体表和卵黄囊均无黑色素分布,尾鳍透明光滑,具口凹和眼色素并形成胸鳍原基,至卵黄被完全吸收时胸鳍鳍条开始形成,至28日龄时仔鱼各鳍发育完全,肌节数38~42。根据卵黄囊存在的情况和脊索的弯曲程度将仔鱼划分为卵黄囊仔鱼、前弯曲期仔鱼、弯曲期仔鱼、后弯曲期仔鱼。仔鱼眼径与头长比呈递减趋势,进入后弯曲期,体长迅速增加(≥11.8 mm)。唇鱼骨仔鱼体背与体侧黑色素由背鳍下方向尾部扩散,继而由中部至头部扩散。胸鳍附近最早出现鳞片,然后向后侧覆盖,最后在腹部出现鳞片。     

Development of short-snouted seahorse (<Emphasis Type="Italic">Hippocampus hippocampus</Emphasis>, L. 1758): osteological and morphological aspects

Information about early development after male release lags behind studies of juveniles and adult seahorses, and newborn seahorses, similar in shape to adults, are considered juveniles or fry. During early life, Hippocampus hippocampus present behavioural (shift in habitat, from planktonic to benthic) and morphological changes; for this reasons, the aims of this study are to define the stage of development of H. hippocampus after they are expelled from the male brood pouch and to establish direct or indirect development through an osteological analysis. The ossification process was studied in 120 individuals, from their release to 30 days after birth. To analyse the osteological development, Alcian Blue-Alizarin Red double staining technique for bone and cartilage was adapted to this species. At birth, H. hippocampus presents a mainly cartilaginous structure that ossifies in approximately 1 month. The bony armour composed of bony rings and plates develops in 10 days. The caudal fin, a structure absent in juveniles and adult seahorses, is present at birth and progressively disappears with age. The absence of adult osteological structure in newborns, like coronet, bony rings and plates, head spines and components allowing tail prehensile abilities, suggests a metamorphosis before the juvenile stage. During the indirect development, the metamorphic stage started inside brood pouch and followed outside and leads up to reconsider the status of H. hippocampus newborns.