Population growth and mass mortality of an estuarine fish,Acanthopagrus butcheri,unlawfully introduced into an inland lake

• 1. In 2006, two periods of hypoxia resulted in the death of approximately 35 tonnes of black bream (Acanthopagrus butcheri) in Lake Indoon, a small inland lake in Western Australia.
• 2. Acanthopagrus butcheri was the first fish species to be recorded in this lake, along with the mosquitofish (Gambusia holbrooki) which was also observed during sampling in 2006. Acanthopagrus butcheri appears to have been introduced to Lake Indoon between 1998 and 2003 and formed a self‐sustaining population. It is believed to have been deliberately introduced for the purpose of creating a recreational fishery, despite the existence of substantial penalties for illegal translocation of fish in Western Australia.
• 3. Recent human‐induced environmental changes, including rising groundwater and salinization, have probably aided the establishment of both species in Lake Indoon. The importance of salinity to recruitment success by A. butcheri was indicated by the presence of only two age classes in 2006, with estimated recruitment dates coinciding with the years of highest recorded salinity in the lake.
• 4. The ‘fish kills’ provided an opportunity to examine aspects of A. butcheri biology in a relatively low salinity environment which is atypical for this estuarine species. In particular, the recruitment period in Lake Indoon was delayed until autumn/winter, rather than spring/summer as seen in other populations. Biological responses in Lake Indoon have implications for natural populations living in estuaries with modified salinity regimes.
• 5. The ecological, social and economic impacts potentially arising from the introduction of fish to Lake Indoon, which is an important migratory bird habitat and a recreational amenity for local residents and tourists, illustrate the complexities of fish translocation and the need for rigorous assessment before stocking to identify potential costs and benefits.

Copyright © 2008 John Wiley & Sons, Ltd.     

Characterization of vitellogenin induced by estradiol-17β in protandrous black porgy,Acanthopagrus schlegeli

The objectives of this study were to isolate and characterize vitellogenin from plasma of estradiol-treated protandrous black porgy,Acanthopagrus schlegeli. Vitellogenin concentrations in plasma measured by a validated enzyme-linked immunosorbent assay (ELISA) were also compared. Two-year-old black porgy (n=20) were fed with estradiol-17 (4 mg kg^–1 of feed). Plasma was collected for purification of vitellogenin. Two forms of vitellogenin were found in plasma after chromatography on Sepharose CL-2B column and hydroxylapatite, and polyacrylamide gel electrophoresis. Black porgy vitellogenins are phospho-lipo-glycoproteins based on their chemical staining properties. The apparent molecular weights of the two forms of vitellogenin were 636 kDa and 321 kDa, respectively. The amino acid composition of purified vitellogenin was also analyzed after acid hydrolysis. The presence of immunoreactive vitellogenin was identified in the plasma and mucus extract from control and estradiol-induced females on the basis of Western blotting. Serial dilution of the plasma and mucus extract taken from estradiol-induced black porgy showed reactivity to an antiserum against lipovitellin in the ELISA, whereas mucus extract and plasma from male fish did not. Significantly higher concentrations of plasma vitellogenin were detected in estradiol-stimulated black porgy than in the control males.     

The effect of salinity on growth and survival of juvenile black bream (Acanthopagrus butcheri)

Growth and survival of juvenile black bream (Acanthopagrus butcheri) were determined at salinities from 0 to 60 ppt (in 12-ppt increments) and from 0 to 12 ppt (in 4-ppt increments) in two separate trials of 6 and 4 months duration, respectively. Juvenile black bream were able to survive and grow at salinities ranging from freshwater (0 ppt) to 48 ppt. Osmotic stress was evident at 60 ppt, however, survival was not significantly affected. Fish reared at 24 ppt in trial 1 had a specific growth rate of 2.34±0.03%/day, a rate significantly higher only to those fish reared at 60 ppt (2.16±0.04%/day). Growth was greater at 24 ppt in association with the highest food intake and most efficient FCR. Although both food intake and FCR were not significantly higher than those obtained with fish reared at 12, 36 and 48 ppt, the combination of the two factors being optimised at 24 ppt lead to the greatest growth. Analysis of data from the second trial found no significant difference in the growth rate of black bream reared at salinities ranging from freshwater to 12 ppt, with SGR ranging from 1.92±0.05%/day to 2.05±0.02%/day. Variable results in freshwater between the two trials suggested that total hardness of freshwater may influence survival and/or an ontogenetic change in salinity tolerance may occur.     

Growth and survival of selected aquatic animals in two saline groundwater evaporation basins: an Australian case study

Evaluation trials were undertaken in two evaporation basins filled with saline groundwater to identify finfish and shellfish that have the potential to survive and grow in these conditions. Test animals were reared in replicate culture units in each of two basins filled with saline groundwater located in the Goulburn–Murray Irrigation District (GMID), south‐eastern Australia. Salinity in basin 2 (9.5–24.6 p.p.t., mean 16.8 p.p.t.) was significantly higher than in basin 1 (8.8–15.2 p.p.t., mean 11.6 p.p.t.). Some differences were observed between the ionic concentrations in the groundwater and sea water (at 10 p.p.t.) and may have affected growth and survival of some species. Survival and growth for oysters (Crassostrea gigas and Saccostrea glomerata) in the basins were low. Shrimps (Penaeus monodon and Marsupenaeus japonicus) did not survive beyond 3 weeks. Of the eight species of fish stocked into the basins, Salmo salar, Macquaria novemaculeata and Acanthopagrus butcheri survived and grew in both basins. Oncorhynchus mykiss did not survive in the low‐salinity basin, whereas Bidyanus bidyanus did not survive in the high‐salinity basin. These results indicate that some species of fish in particular can be cultured in saline groundwaters within the GMID.     

中性植酸酶替代磷酸二氢钙对黑鲷生长和磷利用的影响

以鱼粉、豆粕、菜粕等为蛋白原料设计配方, 磷酸二氢钙的添加量分别为1.5%、1.0%、0.5%和0(对应的饲料组为P1.5、PP1.0、PP0.5和PP0组), 其中PP1.0、PP0.5和PP0组中均添加200 mg/kg的中性植酸酶, 开展为期8周的黑鲷(Acanthopagrus schlegelii)养殖实验, 以探讨中性植酸酶替代磷酸二氢钙对黑鲷生长和磷利用的影响。结果显示, 黑鲷摄食实验饲料8周后, 各组间成活率无显著差异(P>0.05); 摄食饲料PP1.0、PP0.5和对照组(P1.5组)实验鱼的增重率无显著差异(P>0.05), 但均显著高于PP0处理组, 饲料系数则显著低于PP0处理组(P<0.05)。摄食不同饲料的黑鲷全鱼中蛋白质、脂肪、灰分及钙磷含量在不同组间均无显著差异(P>0.05)。添加植酸酶的各组鱼磷的表观消化率均显著高于对照组(P<0.05)。随着磷酸二氢钙添加量的降低, 黑鲷对干物质和蛋白质的表观消化率呈升高的趋势, 当饲料中磷酸二氢钙的添加量降到0时, 黑鲷对干物质和蛋白质的表观消化率显著高于对照组(P<0.05)。以上结果说明, 在本研究配方下, 黑鲷正常生长对饲料有效磷的需求量≥0.51%; 磷酸二氢钙可部分被植酸酶替代, 当黑鲷饲料中含有20%鱼粉、32%豆粕和12%菜粕, 且植酸酶添加量为200 mg/kg时, 与饲料中添加1%的磷酸二氢钙相当; 在不影响黑鲷生长的前提下, 植酸酶部分替代磷酸二氢钙不仅可降低无机磷的添加, 同时可提高饲料中磷的利用率, 降低磷排放。

     

Effect of salinity on reproductive performance of Acanthopagrus latus (Houttuyn) in spawning tanks

More than 250 male and female yellowfin seabream (Acanthopagrus latus) were caught in the creeks near the Mahshar area in the north‐west of Persian Gulf using fishhooks to study the effects of salinity on reproductive indices. The experiments were carried out using three salinity treatments (30 ± 1 g L^?1, 35 ± 1 g L^?1 and 40 ± 1 g L^?1) with three replications. A total of six males and three females were randomly introduced to each tank. The survival rate of the broodstock was estimated at more than 90% at different salinity levels and the maximum rate was observed at 30 g L^?1 of the experiment rate. The percentage of buoyant eggs was more than 90% at 40 g L^?1 and it was significantly different from other treatments. The average number of eggs per female (312 914 ± 65 085), and the average number of eggs per kilogram of female (649 460 ± 173 574) at 40 g L^?1 were more than those in the other treatments but no significant differences were observed (P ≤ 0.05). The average percentage of fertilized eggs (86.7%) and the average percentage of hatched larvae (67%) at 40 g L^?1 treatment was more than those at 30 g L^?1 and 35 g L^?1 treatments but no significant differences were observed (P ≤ 0.05). At 40 g L^?1 salinity, in all spawning cases, the released eggs were hatched. Overall, the present study has shown that better buoyant eggs of A. latus can be obtained at salinity 40 g L^?1. On the other hand, the percentage of fertilized eggs and hatched larvae were not affected by salinity.     

Fresh-Keeping Effects of Melanin-Free Extract From Squid Ink on Yellowfin Sea Bream (Sparus latus) During Cold Storage

Squid ink, a by-product from the squid production process, has been demonstrated to be a multifunctional marine bioactive material that can promote freshness of shiokara and peeled shrimp. However, the preservative effect it has on marine fish as well as its preservative mechanisms are still unknown. In this article, Sparus latus was used as a model to assess the preservative effects and the possible mechanism of the ink through chemical parameters, antibacterial effect, and sensory analysis. Melanin-free extract from squid ink at a concentration of 45 mg/mL and pH 8.5 was revealed to be effective in prolonging cold storage shelf life of Sparus latus, which was confirmed through comprehensive sensory analysis evaluation and measurement of chemical changes including pH, microbial count, total volatile basic nitrogen (TVB-N) value, and nucleotide analysis. It was also discovered that the extract mainly suppressed putrefying bacteria separated from Sparus latus, and the bacteriostatic range was confirmed to be wide. Squid ink significantly prolonged the cold storage period of Sparus latus, indicating that it may be developed to be a natural preservative for marine products.     

鱼类标志放流步骤的优选及其在黄鳍棘鲷中的应用

鱼类标志放流过程中,关键细节缺失参考依据易导致标志鱼因标志操作不规范而死亡(或导致标志脱落),从而影响基于标志群体抽样的增殖效果评估、放流群体时空格局等后续研究的准确性。本研究以南海重要增殖放流鱼类黄鳍棘鲷为对象,采用多因素方差分析对比了标志过程中关键操作(标志前麻醉与否、标志部位、植入角度)的生长率、存活率、标志保留率的差异。40 d的实验结果显示,不同标志操作对鱼的生长无显著影响。麻醉与否对实验鱼的存活率影响极显著。标志部位、植入角度对标志保留率影响显著。优选出的最佳标志操作组合为麻醉,将T型标志以45°植入背鳍基前部肌肉(存活率95.56%、标志保留率98.89%)。综合以往资料,本研究提出了黄鳍棘鲷[体长(10.05±0.39)cm]T型标志操作规范建议,为今后科学开展标志放流提供参考依据:①标志前暂养,将待标志鱼放入培育池内暂养3 d或以上,标志前24 h停食;②材料消毒,将T型标志和标志枪针头用75%酒精浸泡消毒5 min;③麻醉,用30 mg/L丁香酚溶液(或MS-222麻醉剂)麻醉至鱼体腹部向上翻转时,迅速进行标志;④标志,用标志枪针头拨去标志部位的1个鳞片,然后针头与鱼体呈45°将T型标志植入背鳍基前部肌肉;⑤鱼体消毒,将标志鱼放入含有5%聚维酮碘(或高锰酸钾)的海水溶液中药浴消毒30 min;⑥标志后暂养,消毒后的标志鱼人工暂养7 d后可放流。     

黑鲷♀×真鲷♂反交子代与黑鲷的CaM基因克隆与mRNA表达分析

为分析黑鲷♀×真鲷♂(Acanthopagrus schlegelii♀×Pagrosomus major♂)反交子代在生长、发育等经济性状优于黑鲷亲本(A.schlegelii)的分子遗传差异,本研究克隆了反交子代(PA)与黑鲷(As)的Ca M基因,运用生物信息学方法对基因PACa M与As Ca M的序列进行了详细分析;同时通过荧光定量分析了PACa M与As Ca M在仔鱼及2龄成鱼不同组织的表达特征。研究结果表明,PACa M基因c DNA全长1180 bp,As Ca M基因c DNA全长1241 bp,均具有一个450 bp的开放阅读框,编码149个氨基酸,分子量约16.84 k D,等电点为4.09;序列比对、结构比较等分析表明,PACa M和As Ca M属Ca M基因家族,具有4个EF-hand钙结合功能域。定量分析表明Ca M在两种鱼的仔鱼及成鱼的脑与性腺中有较高表达;PACa M和As Ca M在仔鱼及成鱼的鳃、肌肉及性腺中的表达存在显著差异(P0.05),在脑、肝及肾中的表达没有明显差异(P0.05);PACa M在仔鱼中表达量最高,As Ca M在成鱼性腺中表达最高,均显示了Ca M基因在生长与繁殖中的重要作用。研究结果为鲷科属间杂交获得的子代与亲本性状差异的功能基因表达提供一些基础资料。     

黑棘鲷内脏结节病病原的分离、鉴定及致病性研究

2017年4月,浙江台州某海水养殖公司跑道式养殖池黑棘鲷大量发病,病鱼活力下降、食欲减退、体表溃疡,剖检可见肝脏、脾脏、肾脏肿大且有不同程度的白色结节,同时伴随大量腹水。用胰蛋白胨大豆琼脂(TSA)从典型结节病濒死黑棘鲷器官分离到革兰阴性短杆菌。分离病原菌AS15对健康黑棘鲷的致病力结果显示,AS15腹腔注射可使健康黑棘鲷发病死亡,死亡黑棘鲷可出现自然发病症状,在(24±1)°C的条件下,(25±2) g黑棘鲷的半数致死浓度(LD_(50))为6.5×10~4 CFU/尾。经API 20E鉴定,分离菌株AS15生理生化特性与类杀鱼爱德华氏菌LADL05-105和迟缓爱德华氏菌典型菌ATCC15947相似度为86.2%,与杀鱼爱德华氏菌ET~T883的相似度为82.8%;AS15的16S rDNA与杀鱼爱德华氏菌ET~T883同源性达99%,gyrB与类杀鱼爱德华氏菌LADL05-105和杀鱼爱德华氏菌ETT883同源性分别为100%和98%;16S rDNA进化树显示,AS15与ETT883、LADL05-105聚为一簇,gyrB进化树与LADL05-105、NCIM2056聚为一簇;采用4种爱德华氏菌属种特异性引物对AS15进行PCR分析,结果显示,AS15可扩增出类杀鱼爱德华氏菌的种特异性片段,不能扩增出迟缓爱德华氏菌、鲇鱼爱德华氏菌、杀鱼爱德华氏菌的种特异性片段,表明AS15属类杀鱼爱德华氏菌成员。分析了AS15的菌毛基因、sodB等毒力基因,发现AS15具有fimA、fimB、fimC、fimD等4种菌毛基因和sodB、citC、esrB、mukF、katB等毒力基因。本实验首次从黑棘鲷上检出致病性类杀鱼爱德华氏菌,该菌对黑棘鲷的发病机制和毒力机理还需进一步研究。