Diet of demersal fish species in relation to aquaculture development in Scottish sea lochs

The diets of demersal fish, principally haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus) and several flatfish species, sampled from four Scottish sea lochs (Hourn, Kishorn, Duich and Nevis) which support aquaculture sites, were examined in order to determine whether the impact of aquaculture on benthic biodiversity would affect the diets of demersal fish. Loch Kishorn had the highest maximum planned aquaculture production, loch Nevis follows and lochs Hourn and Duich have the lowest planned production. Samples were collected from locations less than and more than 2000 m from fish farm cages. Fish close to the fish farm cages were on average of greater individual weight than those further away from fish farms. Haddock ate predominantly Malacostracan crustacea, Ophiurid echinoderms and Polychaete annelids; whiting ate predominantly Malacostracan crustacea and teleost fish and flatfish ate Malacostracan crustacea, Polychaete annelids and Ophiurid echinoderms. A small number of saithe sampled had eaten mainly fish farm pellets. Dietary variation in each species was analysed in relation to loch, proximity to aquaculture facilities and fish size. Diet of whiting varied with body size. Dietary differences were observed between the lochs and between sites close to and far from farms in two lochs although these differences cannot be specifically attributed to aquaculture development. Controlling for differences between individual lochs, proximity to aquaculture facilities did not consistently affect diet composition.     

Modelling annual cycles of primary production in different regions of the Bohai Sea

The Bohai Sea is a typical shallow sea in which the average depth of water is about 18 m, and which has a rich biodiversity and abundance of marine life. The values of primary production differ among the four different regions of the Bohai Sea. A biological model consisting of nutrients, phytoplankton, zooplankton and detritus is used to simulate the annual cycles of plankton and primary production in these four regions. The simulation is forced by monthly observational data. Water transparency, nutrient concentrations, temperature and incident irradiance influence the amount and variation of plankton and primary production. The model simulations indicate that transparency and nutrient concentration are the principal causes of the differences in primary production among the four regions of the Bohai Sea.     

基于渔盐一体化养殖的中国明对虾营养成分分析

为系统了解渔盐一体化生态养殖模式下中国明对虾(Fenneropenaeus chinensis)的营养价值,通过测定其肌肉基本营养成分(水分、粗蛋白、粗脂肪、灰分、总糖),蛋白质的氨基酸组成、脂肪酸组成、维生素和无机元素等,对其营养价值进行评价。结果显示:该养殖模式下,中国明对虾蛋白质含量较高,氨基酸种类齐全,必需氨基酸占氨基酸总量的39.03%,符合FAO/WHO的理想模式;呈味氨基酸含量高达43.73%;脂肪含量低;维生素B3和维生素E含量丰富;富含人体必需的钙、铁、锌、镁、硒等矿质元素,无重金属污染。研究表明:渔盐一体化生态养殖的中国明对虾是一种高蛋白、低脂肪、高矿物质、营养价值较高的优质海产虾类。     

Predicting the growth of gilthead sea bream (Sparus aurata L.) farmed in marine cages under real production conditions using temperature- and time-dependent models

The growth of gilthead sea bream ( Sparus aurata ) has been studied considering five multiple exponential regression models using data from 20 lots of gilthead sea bream growing in 20 marine cages from a Mediterranean commercial fish farm. The final weight ( W _f) of fish was predicted in relation to the initial weight ( W _i), time ( n ) and temperature ( T ), or the sum of effective temperatures (∑ T _ef). The estimated weight results from the simulation using the five models have been compared with the real final weight values using the mean of the absolute values of the prediction errors in short and long term (the precision value). All models presented a high determination coefficient, above 96%, and good prediction values in the short term. Regression models were tested using data from six new cages. The best models for predicting the growth of sea bream long term were the ones where final weight is expressed in relation to the initial weight and the sum of effective temperature,     and     obtaining long-term prediction errors 12.9% and 10.7% respectively.     

黄海南部近岸海域鱼类群落结构与区系划分

黄海南部海域具有复杂的水团结构和海流环境,使该海域鱼类群落产生较为复杂的空间结构。为研究黄海南部近岸海域鱼类群落结构特征,实验根据2014—2015年对该海域进行4个季度的底拖网调查数据,利用多元统计方法分析了该海域鱼类群落的分布格局并比较了各群落的相对生物量、生物多样性、优势种等结构特征。应用聚类分析(cluster)和多维标度排序(MDS)分析将黄海南部近岸海域划分为海州湾群落与江苏近岸群落;海州湾群落的平均相对资源量和生物多样性均高于江苏近岸群落,而暖温性与暖水性鱼类所占比重相对较低;海州湾群落的优势种主要为方氏云鳚、大泷六线鱼和日本鳀等,季节变化显著;江苏近岸群落的优势种为短吻红舌鳎、途、棘头梅童鱼和黑鳃梅童鱼等,季节变化不明显。研究表明,黄海南部近岸海域可划分为海州湾区系与江苏近岸区系,其鱼类群落结构特征具有显著差异。海流、水团、底质类型及水深等环境因子是形成鱼类群落结构差异的主要因素。     

Comanagement for aquaculture: Suggestions from a comparative study between two major production areas of milkfish in the Philippines

ABSTRACT

This study examined if, and how, comanagement is effective in controlling aquaculture industry in the municipalities of Anda and Bolinao in the province of Pangasinan, in the Philippines, the locations of two major production areas of milkfish (Chanos chanos) in the country. Institutional and community analyses conducted in these study sites revealed a unique hierarchy of resource users, as well as unique social and economic problems in aquaculture, distinct from those of capture fishery. It was also indicated that comanagement is seen as a solution for essential practices to be enforced practically and sustainably for the management of this industry. To improve aquaculture governance, it is desired that the comanagement scheme shall include not only the governments and fishers but also business operators who often have large capital and a high degree of power.     

Interaction between monk seals Monachus monachus (Hermann, 1779) and marine fish farms in the Turkish Aegean and management of the problem

Mediterranean monk seals Monachus monachus attacked fish on 11 marine fish farms in the Turkish Aegean between 1992 and 2000. There were 40 attacks on fish farms where gilthead sea bream Sparus auratus and European sea bass Dicentrarchus labrax were raised in holding cages. Single seals usually attacked cages at night, regardless of the size of fish in the cages. The seals damaged both holding nets of the cages and fish and, on most occasions, fish escaped as a result of the attacks. With the exception of only one facility, all fish farms attacked by monk seals were concentrated on the large peninsulas including Karaburun and Bodrum Peninsulas, and the number of seal attacks was higher during the winter months. A direct intervention to deter seals such as the use of lights, feeding with pesticide‐injected fish, noise generation, warning and direct shots with rifles and physical exclusion of seals from holding cages by installing antipredator nets were applied to prevent or reduce seal attacks. Our study shows that deterrents such as lights and warning shots were not effective in preventing monk seal attacks. However, both curtain‐ and bag‐type antipredator nets were found to be effective.     

Space–time patterns of co‐variation of biodiversity and primary production in phytoplankton guilds of coastal marine environments

• 1. The relevance of biodiversity to ecosystem processes is a major topic in ecology. Here, we analyse the relationship between biodiversity and productivity of the nano‐ and micro‐phytoplankton guilds in coastal marine ecosystems.
• 2. The patterns of variation of species richness, diversity and primary productivity (as ¹⁴C assimilation) were studied in two marine areas: a eutrophic–mesotrophic area beside the River Po delta (northern Adriatic) and an oligotrophic area around the Salento peninsula (southern Adriatic–Ionian). The study was carried out at 23 sites in the northern area and at 45 sites in the southern area. Sites were arranged on expected spatial and temporal gradients of primary productivity variation, according to distance from the coast, optical depths and seasonal period.
• 3. 167 taxa were identified in the northern area and 153 taxa in the southern area. In both areas, the taxonomic composition of the nano‐ and micro‐phytoplankton guilds exhibited greater temporal than spatial variation. The latter was much higher in the southern area than in the northern area (average dissimilarity between stations being 70.7±0.8% and 44.7±4.2% respectively).
• 4. Primary productivity varied in space and time on the gradients considered. Phytoplankton species richness and diversity exhibited significant patterns of variation in space and time; overall, these were inversely related to the primary productivity patterns in the northern area, whereas they were directly related in the southern area.
• 5. The small individual size and the high turnover rate of phytoplankton are likely to underlie the observed relationships, which emphasized a threshold response to nutrient enrichment in agreement with the ‘paradox of enrichment’. Under resource enrichment conditions, the high turnover of producers leads to hierarchical partitioning of the available resources with an increasing dominance of a few species. Therefore, the relationship observed here seems likely to be explained by the complementarity hypothesis.

Copyright © 2003 John Wiley & Sons, Ltd.     

Bacteriocins and their applications for the treatment of bacterial diseases in aquaculture: a review

Aquaculture is one of the fastest growing food producing sectors in the world. The increase in the world population requires faster growth in aquaculture for better food availability and to overcome malnutrition. But this worldwide growth of aquaculture is overwhelmed by catastrophic fish diseases and spoilage during cultivation and preservation problems caused by pathogenic bacteria. Various remedies are available for food preservation and also from the bacterial diseases in the fish production. Due to the emergence of antibiotic resistance and adverse effects, an alternative to antibiotic is the need of the hour. The proteins such as bacteriocins, i.e. ribosomally synthesized antimicrobial peptides (AMPs) and possess antagonistic against closely related and other bacteria. These proteins are produced by most lineages of bacteria which are playing key roles in recognition and possess a cognate immunity system for self‐protection as well as host protection from infections. These proteins are potent immunomodulators with broad spectrum inhibition properties which are further used as novel therapeutic agents. In this review, we have tried to summarize the bacteriocins on the basis of their classifications, structural and functional attributes, mode of actions, bacteriocins isolated from fish and gut microbiota and presence of beneficiary bacteria in the fish gut. Further, this study highlighted where further research is a prerequisite to increase our basic understanding and search for novel bacteriocins to elucidate the proteins/peptides having antimicrobial properties for disease control in aquaculture as an alternative to antibiotics.     

Applications of fish nutrition research in aquaculture: the Taiwan experience

Fish is an important dietary animal protein in Taiwan. Fish production has increased from 20 000 tonnes (t) in 1938 to over 300 000 t today. The change in feed inputs from trash fish to formulated feeds enabled industrial production of fish food. Nutrition studies for shrimp began in the 1970s and continue today. Stable ascorbic acid derivatives have allowed industrial production of shrimp feeds and the development of the extensive production systems in Taiwan and elsewhere in Asia.     

The potential of aquaculture sole production in Europe: Production costs and markets

Sole is a high-value flatfish species that is highly favored in many European markets. Nowadays most sole comes from capture fisheries; however, wild supply has been decreasing because of decreasing catches due to stocks overexploitation. Due to its high price and declining landings, as well as a desire by farmers to diversify their operations, there has been an expansion in sole aquaculture production in recent years and there are ambitious plans for further growth. In this paper we assess the potential for sole aquaculture in Europe using raceways. This is done by analyzing the production costs of sole farms and the price evolution in European sole markets.     

黄海鱼类感染寄生线虫成虫的初步调查

2005年5月至2006年10月对黄海鱼类寄生线虫感染情况进行了调查,共解剖鱼类93种941尾,采集线虫24 968条,其中成虫923条,隶属于5科5属12种,占所采线虫总数的3.7%。宫脂属线虫为黄海鱼类寄生线虫成虫的优势类群,占所采线虫成虫总数的98.5%。内弯宫脂线虫为黄海鱼类寄生线虫成虫的优势种和广布种。狮子鱼宫脂线虫可能为特有种。     

东海近岸海域浮游动物群落时空分布

为探讨东海近岸海域浮游动物时空分布特征,根据2013年5月(春季)、8月(夏季)和12月(冬季)东海近岸海域3个航次的浮游动物调查资料,分析了该海域春季、夏季和冬季浮游动物的种类组成、丰度与生物量、优势种季节变化及生态类群。结果显示,3个航次共鉴定浮游动物108种(含未定种),浮游幼体14类,隶属于7门15大类,其中桡足类和水母类的种类和数量占绝对优势,桡足类为最优势类群,共47种,占总种数的43.52%,水母类共19种,占总种数的17.59%。浮游动物种类季节变化较为明显,夏季种类显著高于春季和冬季。各季节浮游动物种类数目与纬度呈负相关。浮游动物平均丰度与平均生物量随季节变化较为明显,其中平均丰度与平均生物量冬季最低,平均生物量夏季最高,平均丰度春季最高。根据浮游动物对水文环境条件耐受性和生活海区的差异性将浮游动物群落分为6个生态类群:近岸低盐种、广温广盐种、高温高盐种、近岸暖温种、暖水种和大洋广布种。其中东海北部近岸海域春、冬季近岸低盐种和广温广盐种占绝对优势,夏季暖水性种群所占比例高;长江口及邻近水域暖水性种群在春、夏、冬三季中均占主导地位;东海中南部近岸海域春、冬季暖水性种群占绝对优势,但夏季高温高盐种、大洋广布种优势明显。各季节中华哲水蚤均为优势种,但其他优势种季节更替较明显,其中春、夏两季优势种更替率为90.9%,夏、秋两季为50%。     

中华绒螯蟹对赖氨酸、蛋氨酸和精氨酸的需要量

为探究饲料中辅酶渣替代鱼粉对中华绒螯蟹生长性能、健康情况和肠道菌群的影响,以中华绒螯蟹幼蟹 (0.70±0.01g)为研究对象,分别以等蛋白的辅酶渣替代基础饲料中鱼粉的0% (对照组,含20%鱼粉)、20%、40%、60%、80%、100% (记为C、T20、T40、T60、T80、T100)的饲料投喂8周。结果显示,与C组相比,T40组生长性能无显著改变,T60组肌肉粗蛋白含量显著降低。T80组、T100组生长性能、体粗蛋白和粗脂肪含量显著降低;与C组相比,替代组血清谷丙转氨酶 (ALT)、谷草转氨酶 (AST)、碱性磷酸酶 (AKP)、甘油三酯 (TG)水平未见显著差异,总蛋白水平 (TP)在T100组显著降低。血清葡萄糖 (Glu)在替代组中显著降低。T60、T80、T100组的血清总胆固醇 (T-CHO)、高密度脂蛋白胆固醇 (HDL-C)含量显著降低,T80、T100组的血清低密度脂蛋白胆固醇 (LDL-C)含量显著降低;与C组相比,各替代组肝胰腺超氧化物歧化酶 (SOD)活性无显著差异,谷胱甘肽过氧化物酶 (GSH-Px)活性显著上升,T100组丙二醛 (MDA)含量显著降低;C、T40、T80组肠道菌群α多样性指数无显著差异,主坐标分析显示T80组蟹肠道菌群组成较C组发生改变。研究表明,辅酶渣替代饲料中40%的鱼粉对幼蟹的生长、抗氧化能力、肠道菌群无负面影响,但当替代比例超过80%时将导致幼蟹的生长性能下降、营养物质积累减少和肠道菌群稳态发生改变。

     

基于水声技术的黄海近海鱼类活动定点监测研究

为了研究黄海近海鱼类活动规律,采用自主研制的科研型鱼探仪于2015年11月22日至12月5日对调查海域的鱼类活动进行了首次声学调查,统计分析鱼类活动规律。在调查海域布放4套鱼探仪设备对鱼类进行定点长时间监测,并将采集到的鱼类回波数据利用水声技术进行分析和处理,得到调查海域单体鱼类目标强度在垂直方向上的分布、鱼类目标强度大小的分布以及鱼类在不同水层和不同时间段的活动情况。结果显示,调查海域冬季鱼类主要活动在4~10 m的中上水层,鱼类分布随着水层深度的逐步增加而急剧减少;从9∶00至13∶00鱼类活动频度呈增大趋势,并在13∶00至14∶00频度达到顶峰(约为38%),随后频度减弱;统计得到该海域鱼类目标强度主要以-49~-40 d B占比最高,目标强度大于-40 d B的鱼类均匀分布在整个水层,目标强度小于-40 d B的鱼类主要分布在4~10 m浅水层。研究表明,采用水声技术能够实现对鱼类活动的监测;调查海域的鱼类目标强度分布比较集中,鱼类在深度上的分布主要集中于中上水层,鱼类在不同时间段的活动情况随水温变化而变化,温度升高鱼类活动频度增加,反之则降低。由此可知,该海域鱼类的种类以暖水物种为主。     

Population ecology and prey consumption by fathead minnows in prairie wetlands: importance of detritus and larval fish

Abstract –  The fathead minnow Pimephales promelas occurs in high densities in wetlands of the prairie pothole region (PPR) of North America, but food resources sustaining these populations are poorly known. We assessed population dynamics and prey consumption of fathead minnow populations in three PPR wetlands for 2 years. Fish density peaked at 107 fish per m² for all age classes combined. Larval and juvenile fish dominated these populations in terms of abundance and accounted for 83% of total prey consumption. Detritus dominated fish diets, representing 53%, 40% and 79% of diet mass for larval, juvenile and adult fish respectively. Detritus consumption was positively related to minnow density and negatively related to invertebrate abundance, but only for adult fish. Seasonal production:biomass ratios were unrelated to proportions of detritus in the diet for all ages of fish, indicating that detritus is an important food resource capable of meeting metabolic demands and sustaining fish growth in high-density populations. Detritus consumption may also weaken links between abundance of invertebrate prey and minnows, promoting dense fish populations with strong, consistent influences on wetland ecosystems.     

Perch production in forest lakes: the contribution of abiotic and biotic factors

Horppila J, Olin M, Vinni M, Estlander S, Nurminen L, Rask M, Ruuhijärvi J, Lehtonen H. Perch production in forest lakes: the contribution of abiotic and biotic factors.
Ecology of Freshwater Fish 2010: 19: 257–266. © 2010 John Wiley & Sons A/S Abstract – The biomass, growth and production of perch (Perca fluviatilis (L.)) in five humic forest lakes in southern Finland were estimated and the abiotic and biotic factors contributing to the between‐lake differences were explored. The average perch biomass in the study lakes varied from 13.1 to 45.6 kg·ha^?1 and annual production from 6.0 to 16.5 kg·ha^?1. The highest biomass and production were found in Lake Majajärvi with highest water colour and nutrient concentration. Variability in fish density rather than in individual growth rate seemed to be the main factor behind the between‐lake differences in perch production. No dependence of perch production on water transparency was found, because transparency had a stronger effect on individual growth than on fish density. The length increment of perch in their second year increased significantly with water transparency but at older ages no such dependence was found. At age of 4 years, the growth rate of perch decreased with perch density, indicating intraspecific competition for benthic food resources. At age of 7 years, the growth rate increased with increasing roach (Rutilus rutilus (L.)) abundance, suggesting that roach served as a resource for piscivorous perch. The effects of predatory top‐down control on perch populations were probably obscured due to the variable size and water quality of the study lakes.     

Fish assemblages of the northern Argentine coastal system: spatial patterns and their temporal variations

The springtime spatial pattern of demersal fish assemblages in the northern Argentine coastal ecosystem (34°–41°S) and their relationships with environmental variables were investigated over 6 years (1981, 1983, 1994, 1995, 1998 and 1999). For each fish assemblage area for each year, we identified the most common species and those species that had the highest ability to discriminate it from adjacent assemblage areas. Within each area, species were considered as resident (common in all years) or facultative (contributing to less than 90% of similarity within any year). The analysis (detrended canonical correspondence analysis), conducted using species abundances (t nm^?2) and environmental data, indicated that six fish assemblage areas are consistently distinguishable. The fish assemblage areas correspond to inner, central and middle regions of the Río de la Plata estuary, and inner, central and middle regions of the coastal shelf. Spatial differences in the composition among areas were primarily due to changes in species composition rather than changes in relative abundance, and were primarily related to water mass characteristics. Salinity in the estuary and temperature on the shelf were more relevant to the spatial structuring of the fish community in each environment. The assemblage areas showed a remarkable degree of temporal persistence in species composition and geographical location. The facultative species contributed more to the species composition temporal dynamics than resident species. El Niño (La Niña) condition, associated with increase (decrease) of the Río de la Plata freshwater discharge, produced a movement of the estuarine assemblage areas to the coastal shelf (upriver). Under normal freshwater discharge conditions, the boundaries of the fish assemblages were relatively more stable.     

Phaeobacter grown in biofilters: a new strategy for the control of Vibrionaceae in aquaculture

Growth, biofilm formation, antagonism and residence time in green seawater tanks maintained under fish rearing conditions of Phaeobacter 27‐4 were studied in commercial biofilters made from plastic, sintered glass and ceramic. Phaeobacter reached 10⁸–10⁹ CFU cm^?3 and formed rosettes in all materials, but a multilayer biofilm was only observed in the ceramic biofilters. In sterile seawater, plastic and ceramic biofilters reduced Vibrio anguillarum and V. splendidus concentration in one‐two Log after 24–48 h, showing 10²–10³ CFU mL^?1. Sintered glass biofilters only inactivated V. anguillarum. In Marine Broth, sintered glass and ceramic biofilters inhibited V. anguillarum growth in two‐three Log, showing 10⁴–10⁵ CFU mL^?1 after 24 h. Plastic biofilters reduced V. anguillarum concentration in one Log after 48 h. V. splendidus growth was only inhibited by sintered glass and ceramic biofilters in one‐two Log, showing 10⁷ CFU mL^?1 after 24 h. Phaeobacter also diminished biofilters colonization by the pathogens, both in seawater and in MB. Phaeobacter residence time in green seawater tanks maintained under fish rearing conditions was longer with sintered glass and ceramic biofilters. The latest showed the lowest detachment and, after 11 days, Phaeobacter (10⁶ bacteria·cm^?3) covered more than 80% of biofilters total culturable bacteria. DGGE profiles showed that Phaeobacter biofilters stabilizes the green seawater bacterial microbiota.