Influence of light intensity on feeding, growth, and early survival of leopard coral grouper (Plectropomus leopardus) larvae under mass-scale rearing conditions

This study investigated the effect of different light intensities on feeding, growth and survival of early stage leopard coral grouper Plectropomus leopardus larvae. Four different light intensities (0, 500, 1000 and 3000 lx) were used and larvae were kept under constant light conditions from 0 day after hatching (DAH) to 5 DAH. The larvae were fed a small S-type of Thai strain rotifers at a density of 20 individuals/mL from 2 DAH. The number of rotifers in larval digestive organ and total length of larvae were examined at 3 h intervals between 04:00 and 22:00 h on 3 DAH, and thereafter at 6 h intervals until the end of the experiment (5 DAH). Four experimental trials of the larval rearing were repeated using by 60 kL mass-scale rearing tanks. The results indicate that coral grouper larvae are visual feeders and their food intake increases with increasing light intensity. Food intake of larvae reared at 3000 lx was significantly higher than those reared at 0–1000 lx on 3 DAH despite being the first-feeding day (P < 0.01). On 4 DAH, total length of larvae reared at 3000 lx was significantly larger than those reared at the lower light intensities (0, 500 and 1000 lx), and thereafter light intensity significantly influenced larval feeding and growth until the end of the experiment. Survival on 5 DAH did not show a significant difference between light intensities, but survival rate at 3000 lx and 1000 lx had a tendency to be higher than those reared at the lower light intensities (0 and 500 lx). In contrast, larvae reared at 0 lx exhibited stagnant and/or negative growth. These results indicate that light intensity is significantly the factor affecting larval feeding, growth, and survival in coral grouper larvae under the rearing conditions.     

豹纹鳃棘鲈工厂化养殖试验

利用闲置的鲍鱼养殖池进行豹纹鳃棘鲈工厂化养殖模式的研究。养殖池长宽高为9 m×3 m×2 m,有效水深约1.7 m,设3个进水口,采用下排上溢的排水方式,在距池底高20 cm处建3排6个进气管,管上打孔增氧。在池中放置一长宽高为6.0 m×3.0 m×1.5 m的网箱,将豹纹鳃棘鲈放在网箱中养殖,有效水体深1.2 m。养殖用水处理:海边沙滤井→沉淀池→三级过滤池→紫外线消毒池→活化珊瑚石过滤→养殖池(下排上溢)→上溢养殖废水用于东风螺或双壳贝类养殖,下排养殖废水进入污水沉淀处理池。在2011年7月放养9 000尾全长10 cm的优质豹纹鳃棘鲈苗种,经过约15个月的养殖,共养成每尾平均体重约742 g的商品鱼5 710 kg,养殖成活率达85.5%,单位产量达12.4 kg·m-3。     

环境光色对工业化养殖豹纹鳃棘鲈幼鱼生长、肤色及生理指标的影响

为探究环境光色对工业化养殖豹纹鳃棘鲈(Plectropomus leopardus)幼鱼生长、肤色和生理指标的影响,本试验设计了红色光、蓝色光、黑暗和昼夜4种养殖光照环境处理,进行豹纹鳃棘鲈幼鱼(64.2g±1.1g)94 d动物实验及其相关指标检测。结果表明:1)试验鱼增重率,昼夜组较黑暗组和红光组分别显著和极显著提高28.6%和39.2%(P0.05,P0.01),与蓝光组差异不显著;而蓝光组比红光组显著提高31.2%(P0.05)。2)试验鱼皮肤胡萝卜素含量,昼夜组分别显著高于蓝光组和黑暗组45.7%和68.5%(P0.05),与红光组的差异不显著。同时新发现,各处理组试验鱼皮肤胡萝卜素和黑色素含量出现增减同时进行,但增减量前者较大后者较小的"同步异幅"现象。3)昼夜组试验鱼胃蛋白酶活性较其他组显著提高48.0%~88.5%(P0.05),血清SOD和LZM活力极显著提高20.4%~39.7%和140.4%~161.2%(P0.01);蓝光组试验鱼胰蛋白酶活力显著高于红光组和昼夜组(P0.05);红光组试验鱼Na~+,K~+-ATP酶活力极显著高于蓝光组和黑暗组(P0.01)。总之,豹纹鳃棘鲈幼鱼在昼夜组光照下,生长、肤色及生理等指标都表现出显著优势;蓝色光提高蛋白质消化能力、促进生长;红色光提高皮肤胡萝卜素含量和吸收能力;"同步异幅"新发现,对调控和优化鱼类肤色具有重要价值。     

豹纹鳃棘鲈(Plectropomus leopardus)早期形态与色素变化及添加剂对其体色的影响

为研究豹纹鳃棘鲈色素变化过程以及添加剂对其产生的影响,本研究在室内工厂化养殖条件下,对豹纹鳃棘鲈的早期色素积累、转变过程进行描述,并采用螺旋藻粉和虾青素两种添加剂对其仔、稚、幼鱼的生长及体色变化的影响进行观察。结果显示,从2 d仔鱼开始,眼点色素增多,并由透明转为黑色,摄食明显;3 d仔鱼其背部鳍褶上的树枝状黑色素扩大,脊椎下方出现1列黑色素细胞丛;22 d的鱼体脊椎上方出现1排黑色素斑点,下方黑色素斑点数量减少,此时口、各鳍基部及沿脊椎两侧黄色素增加;28 d的稚鱼体表黄色素与红色素进一步增多,各鳍沿鳍条均有红色素斑点分布,鱼体呈橘红色,颜色鲜艳;30–33 d的幼鱼体表两侧布满黑色与橘红色斑点,脊椎下方斑点消失,仅在尾椎下方存有1块黑色素斑点。增色剂实验结果显示,实验15 d时,螺旋藻粉组与虾青素组全长、体重差异不显著,但均显著高于对照组(P0.05),各实验组内梯度之间差异不显著(P0.05)。30 d时,3%和6%螺旋藻粉组较对照组的体重值高,但差异不显著(P0.05),9%螺旋藻粉组显著低于对照组(P0.05);虾青素组均高于对照组,除与0.6%组差异不显著(P0.05)外,其他组均差异显著(P0.05)。0.1%实验组体重高于对照组和螺旋藻粉组,并高于组内其他梯度组。经过15 d添加虾青素的幼鱼体色红色素有明显增加,与对照组差异显著;30 d时,螺旋藻组没有达到增色效果。结果表明,螺旋藻粉对幼鱼生长初期有促进作用,随着添加浓度与养殖时间的增加其效果不明显,出现负效应;添加浓度为0.1%的虾青素可使全长、体重增长率最高并具有明显增色效果。     

豹纹鳃棘鲈室外大型水泥池的人工育苗技术

为了探索利用室外大型水泥池进行豹纹鳃棘鲈(Plectropomus leopardus)人工育苗的技术模式,通过在室外大型水泥池顶部加盖遮光太阳板半封闭顶棚,对育苗水体进行控光、控温和防雨,进行该鱼人工育苗过程中水处理技术、饵料培育技术和育苗方法的研究。2010年3～7月,累计放卵5批次,共培育出全长2.5～3.0 cm的鱼苗21.9×104ind,受精卵平均孵化率达81.4%,育苗平均成活率达5.59%;初孵仔鱼平均全长1.6mm,在早期发育阶段每经历一次饵料转变,都会带来仔稚幼鱼的快速增长;该鱼摄食时间主要集中在白天,随着个体生长发育,饵料出现顺序依次为原生动物、轮虫、桡足类、蒙古裸腹蚤。研究表明,豹纹鳃棘鲈室外大型水泥池人工育苗模式克服了池塘育苗受自然环境影响大和室内水泥池育苗水体小、开口饵料匮乏的缺点,育苗成功率和出苗率比较稳定。     

豹纹鳃棘鲈仔、稚、幼鱼的形态观察

参照鮨科鱼类胚后发育时期划分的一般方法,结合豹纹鳃棘鲈的形态特征将其胚后发育时期划分为仔鱼期（分卵黄囊期仔鱼和后期仔鱼）、稚鱼期和幼鱼期,并对各时期的形态特征进行了描述。记录了各时期的形态特征,豹纹鳃棘鲈体型修长,幼鱼通体红色,在鱼体上有数列排列整齐的蓝色或黑色斑点;在早期发育阶段第二背鳍棘和腹鳍棘的绝对平均长度可达13．12mm和10．19mm,而臀鳍发育较慢,当腹鳍棘和第二背鳍棘开始回收时其臀鳍棘才开始长出。     

温度对豹纹鳃棘鲈幼鱼呼吸代谢的影响

研究了温度为15、20、25、30、35℃时豹纹鳃棘鲈幼鱼的代谢情况,并分析了幼鱼利用蛋白质、脂肪和糖类作为能源物质的供能情况。试验结果表明,在15~30℃范围内,各试验组耗氧率、排氨率和二氧化碳排出率均随温度的升高而升高,且差异显著(P0.05);在15~30℃范围内,各试验组呼吸熵、氨熵、代谢率和排泄率均随温度的升高而升高,35℃时均下降。根据氧氮比的分析结果可知,豹纹鳃棘鲈幼鱼主要利用脂肪和蛋白质供能,且随着温度的升高,脂肪和碳水化合物供能的比例逐渐增大。Q10的变化规律反映出豹纹鳃棘鲈幼鱼的适温范围为15~30℃,且温度显著影响豹纹鳃棘鲈幼鱼的代谢率。     

Effects of size and fragmentation of marine reserves and fisher infringement on the catch and biomass of coral trout, Plectropomus leopardus, on the Great Barrier Reef, Australia

Abstract  A spatially structured simulation model of the population dynamics and line fishing exploitation of common coral trout, Plectropomus leopardus Lacepède, was used to evaluate the effects of infringement and different amounts and arrangements of marine reserves on the Reef Line Fishery of the Great Barrier Reef, Australia. With no marine reserves and under a constant future effort level equal to that for 1996, the size of the population was reduced and the biomass stabilised at about 40% of pre-exploitation levels. Marine reserves were ineffective at conserving biomass when limited infringement was allowed throughout an entire reserve. When infringement was absent altogether or limited to the edges of reserves, larger marine reserves lead to lower total catches and higher overall biomass. When infringement was limited to reserve edges, a single large closure was more effective at conserving biomass than more fragmented arrangements. Simulations suggested that marine reserves might lead to better conservation of a fishery-targeted species if infringement is negligible or limited to reserve margins. Even where infringement occurred only at the edges of reserves, a network of small reserves may be less effective at conserving a targeted species than a smaller number of larger reserves.     

Gill pathology caused by infestations of adult and preadult Dissonus manteri Kabata (Copepoda: Dissonidae) on coral trout, Plectropomus leopardus (Lacépède), (Serranidae)

Adult and preadult Dissonus manteri attached to the gills of Plectropomus leopardus cause significant pathology in the form of large hyperplastic nodules on the afferent (leading) edges of gill filaments. Nodules result from the dual actions of parasite attachment and feeding. The host response is characterized by severe epithelial hyperplasia, supplemented by fibroplasia and inflammation. Parasites attach close to the gill arch near the base of filaments. They have little effect on gill vasculature as the maxillipeds penetrate the filament superficial to the efferent filament artery and do not interfere with the blood vessels of the secondary lamellae. Tissue proliferation is limited to the wide portion of filament 'edge' epithelium in the proximal third and also does not extend to the secondary lamellae. Nodules are most numerous towards the ends of hemibranchs and are generally absent from the central regions. Leading hemibranchs bear significantly more nodules than their trailing counterparts. Of the total number of nodules, 20.5% are located on the pseudobranchs. Distribution patterns are considered to be primarily the result of D. manteri avoiding strong water currents, although this cannot explain the difference between numbers on leading and trailing hemibranchs.     

温度、盐度和pH值对豹纹鳃棘鲈早期发育的影响

研究了不同温度、盐度和pH值对豹纹鳃棘鲈（Plectropomus leopardus LacSpSde）受精卵的培育周期、孵化周期、孵化率和畸形率的影响,并测定了各环境因子条件下仔鱼的不投饵存活系数（SAI）。结果表明：豹纹鳃棘鲈受精卵孵化适宜温度为24～30℃,最适温度为26～28℃;受精卵孵化适宜盐度为25～45,最适盐度为25～30;受精卵孵化适宜pH值为6．0～8．5,最适pH值为7．0～8．5。由仔鱼不投饵系数可知,豹纹鳃棘鲈仔鱼生存的适宜温度为20～30℃,最适生存的温度为20～26℃;仔鱼生存的适宜盐度为10～40,最适生存的盐度为20～35;仔鱼生存的适宜pH值为5．5～8．5,最适生存的pH值为7．0～8．5。豹纹鳃棘鲈受精卵和仔鱼对温度、盐度和pH值3种环境因子的耐受能力的范围基本一致。