Lipid distribution patterns of nine commercial fish in Thailand

Lipid distribution pattern is an important trait, which is related to flesh quality and the yield rate of aquaculture products. Here we investigated lipid distribution patterns by oil red O staining for nine economically important fish in Thailand. The most remarkable feature was that Siluriformes species had a thick layer of subcutaneous lipids, possibly to compensate the evolutionary loss of scales. In addition, we found several other characteristic staining patterns: (1) dotted stains at the boundary of red and white muscles and along the subcutaneous tissue in crystal‐eyed catfish, (2) double lines of staining along the subcutaneous layer in crystal‐eyed catfish, (3) dotted stains along the horizontal septum lines in hybrid catfish, (4) pronounced retroperitoneal fat accumulation in Nile tilapia and red tilapia, (5) pronounced fat accumulation in the inclinator muscle of the fins in Indian spiny turbot, (6) intense staining under the scales of common carp and (7) three dotted stains in soft finrays in clown knifefish. Although lipid distribution patterns are known to be affected by environmental conditions, the observed species differences suggest the strong genetic control of lipid distribution. This trait should be considered as a target of selective breeding especially for Siluriformes, in addition to commonly used parameters such as growth rate and disease resistance.     

Spermatozoon ultrastructure and sperm cryopreservation of the Brazilian dry season spawner fish pirapitinga,Brycon nattereri

The aims of this study were to describe the fresh spermatozoon ultrastructure using scanning and transmission electron microscopy and to improve the sperm cryopreservation methodology for the freshwater fish pirapitinga Brycon nattereri. Extenders (BTS^? and NaCl), straw volumes (0.5 and 4.0 mL), thawing temperatures (30 and 60 °C) and activating agents (0.29% NaCl and 1% NaHCO₃) were tested. Methylglycol was used as a cryoprotectant agent and sperm was frozen in nitrogen vapour (dry‐shipper). Post‐thawed sperm motility rate, motility quality (score 0=no movement; 5=rapidly swimming spermatozoa), duration of motility and spermatozoon morphology were evaluated. Fresh spermatozoon was 35.06 μm long, the head was ovoid (2.00 × 1.22 μm) with no acrosome, the midpiece was 2.15 μm long and the flagellum was 30.90 μm long with the typical 9+2 axoneme arrangement. Post‐thawed sperm motility rate (70–79% motile sperm), motility quality (score 3.1–3.7) and morphology (9.3–11.6% abnormal spermatozoa) were not affected by any of the parameters tested. The duration of sperm motility was longer when triggered in 1% NaHCO₃ (392–1031 s) compared with 0.29% NaCl (144–338 s). Brycon nattereri sperm cryopreserved under the conditions described above yields over 70% motility and should last long enough to fertilize oocytes, even after 2 years of freezing.     

Effects of natural rapids and waterfalls on fish assemblage structure in the Madeira River (Amazon Basin)

Abstract – Habitat connectivity is considered a central factor shaping ecological communities, and the effects of waterway barriers such as natural waterfalls on fish movements are expected to produce differing assemblage structures in riverine ecosystems. Here, we evaluate the influence of a sequence of waterfalls on the compositional dissimilarity of fish assemblages along the Madeira River, the largest tributary of the Amazon River. We found significant differences in species composition between rivers stretches located upstream and downstream of Teotônio waterfall and, to a less extent, Jirau waterfall, independently of the hydrological period. After accounting for the relative roles of local and regional factors in explaining fish compositional dissimilarity, we still observe a significant effect of the waterfalls. We conclude that these waterfalls act as natural ecological barriers limiting fish dispersal processes and discuss aspects of these ecological filters and the potential effects of two dams currently under construction in the Madeira River.     

基于线粒体COI基因的部分鲇形目鱼类系统发育研究

本文选择COI基因片段作为分子标记,对部分鲇形目鱼类(Siluriformes)进行系统发育研究。应用通用引物PCR扩增得到13种鲇形目鱼类的134条COI基因,并与Gen Bank中获得15种鲇形目鱼类的51条COI基因进行比对分析。结果显示:鲇形目鱼类COΙ基因存在碱基插入缺失现象较少,为越南隐鳍鲇(Pterocryptis cochinchinensis)、丝尾鳠(Hemibagrus wyckioides)和黄颡鱼(Pelteobagrus fulvidraco)3种共计5个位点;平均碱基含量A+T(55.5%)显著高于G+C(44.5%)。利用Kimura’s 2-parameter计算28个物种的种间平均遗传距离为0.195,23个物种的种内平均遗传距离为0.006。系统发育树的分析结果表明,Neighbour-Joining(NJ)树较Maximum Likelihood(ML)树更为适合鲇形目鱼类的遗传发育分析;COI基因在科及其以下水平的系统进化关系与传统分类方法所认同的结果一致性较高,达到82.9%以上;在目水平的一致性的可信度较低,仅为71%;半鲿属聚为单系类群,黄颡鱼属、属和拟鲿属三者聚为一支,黄颡鱼属与拟鲿属的亲缘关系较近。     

Relationships between Octopus vulgaris landings and environmental factors in the northern Alboran Sea (Southwestern Mediterranean)

The relationships between environmental factors and fluctuations in Octopus vulgaris landings in the northern Alboran Sea are studied from 1987 to 2007. Landings during this period show both a long term decrease and a strong inter-annual variability. An exploratory phase revealed that local coastal temperatures and those averaged for the whole Alboran Sea during the previous year were the main factors controlling such variability. Warm anomalies have a detrimental effect on the octopus landings on the following year and this suggests that the decreasing trend in octopus landings could be partially linked to the long term warming observed in the Western Mediterranean. It is not yet clear which are the specific mechanisms linking warm anomalies to landing decrease. Nevertheless some hypotheses are proposed and a statistical model is developed for attempting to predict octopus landings one year ahead.     

Winter distribution and movements of northern Atlantic cod (Gadus morhua) along the Newfoundland—Labrador continental shelf edge derived from observations on commercial trawlers

Catch-effort data recorded by observers aboard commercial trawlers fishing the Newfoundland-Labrador continental shelf during the winters of 1980–1991 were used to define the distribution and movements of pre-spawning and spanning Atlantic cod, Gadus morhua. Although cod were widely distributed over the outer continental shelf in the months of January to April, commercial concentrations were consistently located in three areas along the shelf edge. These three areas, constituting only 16% of the 190000 km² fishing ground for northern cod, were centred north-east of Belle Isle Bank, north-east of Funk Island Bank, and between Funk Island Bank and the northern Grand Bank Tow positions with catch rates 5000 kg h^-1 were plotted on a weekly basis to define movements of cod schools during the winters of 1986–1988. It was assumed that change in the collective position of trawlers taking large quantities of cod reflected shoal movements. Analyses indicate that cod moved southeast along the shelf edge in January and February of each year, crossing from NAFO Division 2J into 3K Each March, cod in Division 3K apparently moved northwest against prevailing ocean currents into the Hamilton Bank region of 2J. These movements do not appear to be a direct response to ocean temperature or pack ice conditions, although cod moving along the shelf break were generally in bottom waters of 24°C. We suggest these patterns reflect the migratory behaviour of pre-spawning and spawning cod.     

Relationship between freshwater input to the coastal zone and the historical landings of the benthic/demersal fish Eleginops maclovinus in central-south Chile

The ecosystem off central-south Chile is one of the most productive marine systems in the world, providing approximately 4% of worldwide fish captures. We analysed the effect of freshwater input (river runoff and rainfall) to the coastal zone in central-south Chile (36°00'–37°30' lat. S) on the landings of the Róbalo ( Eleginops maclovinus ) using the following data: Róbalo annual landing statistics, monthly mean and annual mean runoff of Itata (1975–91) and Bio-Bio rivers (1975–94), and cumulative monthly rainfall and annual mean rainfall (1975–94). Time series were smoothed using three-point equally weighted running means. To analyse the relationship between Róbalo's landing and river runoff, as well as rainfall, Pearson's product-moment correlation analyses were conducted at relevant lag times. The statistical significance of correlation coefficients was calculated taking into account intraseries autocorrelation. Our results showed that Róbalo's landings were significantly correlated to freshwater input to the coastal zone in central-south Chile. Thus, significant correlation coefficients were found between annual Róbalo's landings and: (i) annual mean runoff of the Itata ( r =−0.94) and Bio-Bio ( r =−0.80) rivers lagged 3 and 4 years, respectively, and (ii) annual mean rainfall lagged 4 years ( r =−0.75). The lag time at which highest correlation coefficients between annual mean environmental and annual landing time series took place (i.e. 3–4 years) corresponded to the age at which Róbalo reaches the minimum exploitation size. Accordingly, we hypothesize that river runoff and rainfall strongly influence the survival rate of Róbalo's early stages during the first year of life.     

Evaluation of nutritional values of selected commercial fish meal sources in turbot (Psetta maxima) diets

This study was conducted to evaluate nutritional values of selected commercial fish meals (FM) with two experiments in diets of turbot. In experiment I, five diets based on two Peruvian anchovy meals (one is a flame‐dried FM: Peru‐1 and the other steam‐dried FM: Peru‐2), a Danish FM (Danish LT), a domestic anchovy LT meal (Domestic LT) and an Alaskan white FM (WFM) as major protein source were formulated to contain 56% protein. The diets were fed to fish with an initial average weight of 119.4 ± 0.1 g for 9 weeks. Growth rate, feed utilization, whole body and visceral compositions, nitrogen, lipid and energy balances did not significantly change in Experiment 1 among the treatments. In Experiment 2, four diets based on three FMs (Domestic LT, Danish LT and Peru‐1) and their mixture (Mix FM) were formulated to contain 50% protein and fed to triplicated groups of fish with an average initial weight of 51.4 ± 0.1 g for 6 weeks. Once again, there were no significant differences in growth rate and feed consumption among the treatments. However, fish on Mix FM diet had significantly better FCR and PER than the others. The results of two experiment indicated that Danish LT and Domestic LT were better in terms of phosphorus (P) retention and losses than two Peruvian FMs and WFM, suggesting that although different sources of FMs were comparable in terms of growth and feed utilization, they could lead to substantial differences in environmental impacts.     

渤海渔业生物重金属污染及风险评价

重金属污染是渤海长期面临的环境问题之一,同时对渤海海产品安全和人体健康构成潜在风险。为了解渤海海域鱼类重金属污染状况,在该海域采集的渔业生物中随机选取了10种144条鱼类样本,运用电感耦合等离子体质谱法测定了鱼类肌肉组织中重金属Cu、Zn、Pb、Cd、Cr和As的含量;采用单因子污染指数法、内梅罗综合污染指数法和金属污染指数法评价了单一重金属和综合重金属污染情况;采用每日摄入量和目标危害系数评估了渤海鱼类重金属污染对人体的食用安全风险。研究结果显示,渤海鱼类肌肉中重金属Cu、Zn、Pb、Cd、Cr和As的平均含量分别为(0.702±0.680)、(9.697±5.279)、(0.035±0.059)、(0.029±0.035)、(0.093±0.091)和(0.959±0.813) mg/kg。与我国其他海域相比,渤海鱼类重金属含量处于较高水平。鱼类重金属污染评价结果显示,Cd和无机As (iAs)为渤海鱼类重金属污染的主要元素,细纹狮子鱼(Liparistanakae)受到重金属综合污染的程度最大。食用风险评估结果表明,摄食渤海鱼类带来的重金属每日摄入量处于较低水平,所有鱼类样本单一...     

Rates of fish waste production and effluent discharge from a recirculating system (biofish) under commercial conditions

Application of the regulatory principle of ‘best available technology’ (BAT) to fish farm effluent control has, to some extent, been a driving force for the development of new culture and treatment technology. In Norway today, there are a number of farms for the production of Atlantic salmon, Salmo salar L., smolts and brown trout, Salmo trutta L., fingerlings that utilize microstrainers for the removal of particles from the effluent water. At least one commercial farm also utilizes a simplified recirculation system called BIOFISH as a demonstration of new and alternative technology for the production of brown trout restocking fish. In this paper, calculated effluent discharge and rates of waste production from the biofish demostration trials are compared to literature data and to measurements on un-treated as well as microstrained effluents from the production of Atlantic salmon smolts in a traditional flow-through tank system. Rates of fish waste production in the biofish trials were obtained from mass-balance calculations based on measured concentrations of water quality parameters at several points in the system. The results of these calculations show fish waste production rates that are low, but comparable to data found in the literature. Given the level of waste treatment that takes place in the biofish tanks, the specific effluent discharge levels from those tanks, in terms of grams per kilogram biomass and grams per kilogram feed, are considerably lower than those found for salmon smolt production in traditional flow-through tanks. There are also substantial differences in hydraulic self-cleaning properties of the two systems and a corresponding difference in the distribution of effluent discharge during normal tank operation and during tank/effluent pipeline flushing. The results presented here give valuable information related to: (1) waste output characterization; (2) the long-term efficiency of commercially available particle separation systems; and (3) the capabilities of the simplified biofish recirculation technology under field conditions.     

Trends in NE Atlantic landings (southern Portugal): identifying the relative importance of fisheries and environmental variables

Time series of commercial landings from the Algarve (southern Portugal) from 1982 to 1999 were analyzed using min/max autocorrelation factor analysis (MAFA) and dynamic factor analysis (DFA). These techniques were used to identify trends and explore the relationships between the response variables (annual landings of 12 species) and explanatory variables [sea surface temperature, rainfall, an upwelling index, Guadiana river (south‐east Portugal) flow, the North Atlantic oscillation, the number of licensed fishing vessels and the number of commercial fishermen]. Landings were more highly correlated with non‐lagged environmental variables and in particular with Guadiana river flow. Both techniques gave coherent results, with the most important trend being a steady decline over time. A DFA model with two explanatory variables (Guadiana river flow and number of fishermen) and three common trends (smoothing functions over time) gave good fits to 10 of the 12 species. Results of other models indicated that river flow is the more important explanatory variable in this model. Changes in the mean flow and discharge regime of the Guadiana river resulting from the construction of the Alqueva dam, completed in 2002, are therefore likely to have a significant and deleterious impact on Algarve fisheries landings.     

Gastric coccidiosis in Thoracocharax stellatus caused by Goussia guamaensis n. sp. (Apicomplexa: Eimeriidae) from the Amazon region

Ninety‐seven specimens of spotfin hatchetfish, Thoracocharax stellatus, an ornamental freshwater species from the Amazon basin, were captured in the basin of the Guamá River in the municipality of Belém, in northern Brazil, and analysed for coccidiosis infection. Overall, 26 of the specimens were infected by apicomplexan parasites of the genus Goussia, with unsporulated forms being found in the gastric epithelium and sporulated forms in the intestinal lumen. The spheroid oocysts (mean diameter: 13.2 ± 1.7 μm) have four elliptical sporocysts. A partial sequence of the SSU rDNA of the new species was obtained, which contained 1,121 base pairs, with 43.8% guanine + cytosine (G + C), and the bases distributed as follows: A = 28.1%, C = 18.3%, G = 25.5% and T = 28.1%. The combined analysis of the morphometric and phylogenetic evidence confirmed that the specimens represented the genus Goussia and were allocated to a new species, Goussia guamaensis n. sp., which is described here.     

北方地区鲤鱼复养技术

鲤鱼是北方地区主要的养殖鱼类品种.传统的鲤鱼商品鱼养殖方式普遍采取春放秋捕,由于秋季商品鱼集中上市,导致了卖鱼难、鱼价低,效益不高.     

Growth of Amazon ornamental fish Nannostomus beckfordi larvae (Steindachner, 1876) submitted to different stocking densities and feeding management in captivity conditions

The study evaluated productive performance of larvae Nannostomus beckfordi submitted to feeding management (Experiment one) and different stock density (Experiment two) in captivity conditions. The first experiment evaluated feeding rate (100 and 200 nauplii of artemia larvae^?1 day^?1) and feeding frequency (2 and 4× per day). Second experiment evaluated different stock density (1, 5, 10, 20, 40 larvae per litre). At the end of 15 days, for both experiment, the survival and productive performance such as total length (TL), final weight (FW), specific development rate (SDR), specific growth rate (SGR), uniformity for weight (UW) uniformity for length (UL) and relative condition factor (Kr) was determined. For the main results, there is no significant difference to the rate and feeding frequency. The stock density has no significant difference for UW, Kr and survival. Nonetheless, a reduction in the TL, FW, SDR, SGR and FW with the increase in density (20 for 40 larvae per litre) was observed. Thus, for this species Nannostomus beckfordi during to initial stage using exogenous feeding, it is recommended 20 larvae per litre fed with 100 nauplii per larvae having two meals per day.     

温台渔场3种经济鱼类体长频次分布与采样量间关系的比较

为了量化和比较温台渔场3种经济鱼类体长频次分布与实际收集的观测样本之间的关系,本研究基于收集的样本体长信息能够反映研究区域鱼种真实的体长组成信息这一假设,根据春、夏两季在温台渔场采集的3种经济鱼类(小黄鱼、银姑鱼和龙头鱼)的体长数据,利用计算机模拟方法设计了不同的样本量方案.利用均方差异值(mean square di...     

Comparative efficacy of trash fish versus compounded commercial feeds in cage aquaculture of Asian seabass (Lates calcarifer) (Bloch) and tiger grouper (Epinephelus fuscoguttatus) (Forsskål)

Trash fish/low valued fish is still the most commonly used feed in marine cage culture in Asia. Use of trash fish is controversial with regard to the sustainability of the farming practices, and related issues on environmental degradation. In this study, the results of farm based trials on Asian seabass (Lates calcarifer) and tiger grouper (Epinephelus fuscoguttatus) to evaluate the efficacies of the use of commercial pellet feed in comparison to trash fish/low valued fish in marine cages in Thailand are presented. In spite of the variations observed in each of the farm sites, the results indicate that the overall growth performances and fish survival rates between the two feed types were similar, for both species. However, better cost‐benefit and resource use were recorded for fish reared on trash fish/low valued fish. No significant differences were observed in water quality parameters, dissolved oxygen, transparency and ammonia, between sites where pellet or trash fish were used, inside and outside the cages and for both species. The results of the present study are discussed in the light of the current controversies on the use of trash fish/low valued fish in marine cage culture.     

胶州湾外南沙水域渔业资源与文昌鱼数量调查评估及其栖息环境保护

应用扫海面积法，并根据鱼类和文昌鱼栖息特点，采用了不同拖网取样方式，对胶州湾外南沙周围24km^2水域5、6月渔业资源数量与文昌鱼(Branchiostoma belcheri Gary)数量进行了调查评估。5月捕获的鱼类共28种，总资源量275479kg，其中玉筋鱼居第1位，资源量265200kg。捕获的无脊椎动物共13种，总资源量3489kg。6月文昌鱼数量约为18720000尾。同时，还指出了栖息环境面临的问题以及保护栖息环境的重要性和必要性。     

Behavioral interactions between coho (Oncorhynchus kisutch) and chinook salmon (Oncorhynchus shawytscha) and prey fish species

Abstract— The predator-prey behavioral interactions between two salmon species, coho salmon ( Oncorhynchus kisutch ) and chinook salmon ( Oncorhynchus tshawytscha ), and their prey species were examined under laboratory conditions. These behaviors were studied to determine the bases for prey selection by salmon in Lake Michigan and ultimately facilitate predictions on shifts or changes in salmon diets. Chinook and coho salmon captured all prey items in the open water portion of the aquarium, and they had similar attack behaviors. Average attack swimming speeds varied from 2.6 to 3.6 m/s, and average escape swimming speeds varied from 2.6 to 2.9 m/s. There were no significant differences in attack swimming speeds and escape swimming speeds. There was a significant difference in median reactive distances between the prey captured and those that escaped. There was no reactive distance (0.00 m) for 96% and 98% of the successfully captured prey by chinook and coho salmon, respectively. Only 4% and 10% of the unsuccessful attacks by chinook and coho salmon, respectively, had no reactive distance (0.00 m). Salmon would repeatedly attack a school and capture individuals separated from the school. Alewives, bloaters and fathead minnows were easy prey because they remained in the open water portion of the aquarium and stayed in schools until only a few individuals remained. The schooling behavior of spottail shiners and emerald shiners was an effective anti-predation tactic against salmon attacks. After some experience with yellow perch, salmon were reluctant to attack them and would often break off attacks on them. When coho salmon were presented with different proportions of bloaters and yellow perch, they significantly attacked and captured bloaters in preference to yellow perch.