海水鱼类亲体必需脂肪酸营养的研究进展

脂肪酸营养特别是其中的必需脂肪酸在海水鱼类生殖调控方面具有重要的生理作用。饲料中二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)以及花生四烯酸(ARA)含量在调控海水鱼类性腺发育、排卵、孵化率及仔鱼质量等方面作用显著。本文主要从必需脂肪酸需求量、对繁殖性能影响、对机体脂肪酸存储影响及对内分泌调控作用4个方面归纳总结了海水鱼类亲体脂肪酸营养的研究概况,并重点分析探讨了在内分泌调控方面的研究进展,同时对后续的研究重点提出了一些建议。     

Methods of microbial control in marine fish larval rearing: clay‐based turbidity and passive larval transfer

This study focused on methods to reduce bacterial loads in the larval culture tanks of California yellowtail (Seriola lalandi). We conducted two trials to evaluate methods to minimize bacterial loads in the larval rearing water. The first trial examined the use of bentonite clay as a turbidity agent to replace algae in a green water‐type environment. This trial consisted of three treatments: (1) clay with continuous feeding (CCO), (2) clay with batch feedings (CBA) and (3) algae paste with batch feedings (ALG). The results showed that both clay treatments had significantly fewer Vibrio colonies in the water column (CBA – 180 ± 78; CCO – 377 ± 120 CFU mL^?1) than the ALG treatment (5692 ± 2396 CFU mL^?1) after 14 days of culture. Survival was significantly higher in the CCO treatment (14.1 ± 2.6%) than either the CBA (2.3 ± 0.5%) or ALG treatments (2.8 ± 1.5%). The second trial attempted to limit bacterial loading in the larval culture tank by passively transferring the larvae into an adjacent, clean tank at 1, 5 and 9 days post hatch during the first 2 weeks of culture. The results from this trial showed that after 12 days of culture, water in the transfertank had fewer Vibrio colonies (1025 ± 541 CFU mL^?1) than the water in the control tanks (1962 ± 1415 CFU mL^?1). Also, survival was significantly higher among larvae that were transferred (43.9 ± 13.5%) than in the control tanks (23.1 ± 6.3%).     

海水鱼脂类营养与饲料的研究进展

脂类在鱼类营养中起着重要的作用,能为机体提供生长所需的必需脂肪酸等营养物质,机体中的必需脂肪酸对维持细胞结构和功能的完整性至关重要。此外,脂类在能量供应方面也起着重要作用。本文主要介绍了海水鱼类必需脂肪酸、鱼油替代、脂类营养与水产品品质关系以及海水鱼饲料这四个方面的研究现状,并就未来海水鱼脂类营养与饲料的研究重点进行了展望。     

Dynamic regulation of larval fish self‐recruitment in a marine protected area

The factors that regulate the self‐recruitment of fish larvae were explored in Cabrera National Park (CNP), an insular Marine Protected Area (MPA) located off southern Mallorca (Western Mediterranean). Our study attributes the regulation of larval arrival to the MPA to a combination of retention by topographically generated circulation patterns around the island and shelf break frontal dynamics. Specifically, within the shelf, interaction of the wind‐induced oscillatory flow with the island was shown to generate ephemeral recirculation patterns that, over time, favor larval retention in the proximity of the MPA. According to our measurements, oscillatory flows produced by wind‐forced island‐trapped waves (ITWs) dominate the flow around CNP. ITW‐forced dispersion simulations were in agreement with the observed distributions of several typical fish species that breed in the CNP. A second regulator of environmental variability is the influence of boundary currents and open ocean mesoscale structures at the shelf break. These structures generate frontal zones that are comparatively more long‐lived than inner‐shelf circulation patterns, and they were shown to act as barriers to the offshore dispersion of coastal fish larval assemblages. Finally, inferences from larval size distributions around the MPA together with particle‐tracking model simulations suggested the relevance of behavioral processes for larval recruitment to the MPA. Based on these observations, the waters around the CNP can be viewed as a relatively stable system that allows breeding fish populations to rely on self‐recruitment for their long‐term persistence, independent of other source populations along the coast of Mallorca.     

Ceramic clay reduces the load of organic matter and bacteria in marine fish larval culture tanks

Ceramic clay has been increasingly used to improve contrast and prey detection in tanks for rearing of fish larvae. In contrast to live microalgae or algae pastes, clay increases turbidity without contributing to the organic matter load. In addition, clay may aggregate and sediment organic matter and bacteria, facilitating its removal. Marine larvae are sensitive to infections by opportunistic bacteria. Fish, algae, and live feed increase the microbial carrying capacity of the rearing water which allow exponential growth of bacteria and favor fast-growing opportunists. Reducing substrate levels by replacing microalgae with clay may reduce bacteria proliferation and benefit larvae. We compared the effects of three rearing regimes including live Isochrysis galbana, Nannochloropsis oculata paste, and ceramic clay on the bacterial community, concentration of organic matter, and growth and survival of Atlantic cod larvae (Gadus morhua L.). The application of clay resulted in reduced substrate levels for bacteria in the rearing water compared to the addition of live algae or algae paste. To some extent, clay aggregated and transported organic matter to the bottom of the larval fish tanks, where it could be effectively removed. Fish tanks receiving clay showed a lower abundance of bacteria in the water than tanks added algae paste or live algae. Fish tanks with algae paste showed a higher abundance of bacteria and a higher share of cultivable bacteria and TCBS counts than the other two treatments. Tanks with live algae showed low relative abundances of opportunistic bacteria and TCBS counts in both water and rotifers. Cod larvae in tanks with clay or live algae initiated exponential growth earlier than larvae in tanks with algae paste. Larvae in tanks receiving clay had significantly higher dry weight than larvae in tanks receiving algae paste at day 5 and 20 post hatching. The survival of larvae in the tanks added clay was variable. Two of the three tanks with clay had significantly higher larval survival than the tanks with live algae or algae paste. However, one tank with clay underwent 100% mortality. It is not possible to conclude whether this was related to the use of clay or an incidental development of a harmful microbial community in this tank. The effects of clay addition on larval performance should be studied further. Clay addition appears to be an easy way to reduce bacterial load during early first feeding of marine larvae without compromising the beneficial effects of turbidity.     

Vitamin K in fish nutrition

Vitamin K belongs to the lipid soluble vitamins, and occurs naturally as phylloquinone (vitamin K₁) and menaquinone (vitamin K₂). In addition, there is a synthetic provitamin, menadione (vitamin K₃), primarily used as a vitamin K source in animal feed. Menadione is unstable during feed processing and storage and the dietary content may reach critically low levels. Recent publications also question the availability of menadione in feed for salmonids. Vitamin K plays vital roles in blood coagulation and bone mineralization in fish, but the suggested minimum requirement varies considerably depending on the vitamin K source used. Vitamin K deficiency is characterized by mortality, anaemia, increased blood clotting time and histopathological changes in liver and gills. However, one should assess both inherent and supplemented forms of vitamin K in feeds for exact determinations, as relevant novel feed ingredients of plant origin may be sufficient to meet the requirement for vitamin K. The current review gives an overview of the biochemical role of vitamin K, and discusses vitamin K requirement in fish in light of updated literature, with special emphasis on salmonids.     

海水仔稚鱼早期阶段氨基酸的营养生理研究进展

深海海鱼鱼卵中的游离氨基酸占鱼卵总氨基酸含量的近50％（干重），游离氨基酸库中的游离氨基酸似乎是卵黄蛋白的水解产物。仔鱼吸收卵黄内源营养的过程中，游离氨基酸库中的游离氨基酸逐渐减少，到仔鱼开始摄食时，库中的游离氨基酸已近枯竭，游离氨基酸不仅是代谢能源，而且是体蛋白合成的基本原料，仔鱼开始摄食后，氨基酸作为分解代谢的重要物质，可能有高达60％的能量由氨基酸提供，由于仔稚鱼的生长主要是通过合成蛋白质增加鱼体的重量，加之仔稚鱼的生长速度很高，因此，仔稚鱼需要其饲料中有较高的氨基酸含量。仔鱼开始摄食后，其消化系统对蛋白质的水解和吸收能力较弱，海水仔稚鱼的早期阶段，仔鱼的肠道对游离氨基酸的吸收要高于对多肽和蛋白质中氨基酸的吸收，仔鱼开始摄食后，由浮游生物获得大量的游离氨基酸，用微粒饲料培育仔稚鱼，微脂粒技术可能是向饲料中添加游离氨基酸的实用技术。     

Progress on larval and juvenile nutrition to improve the quality and health of seawater fish: a review

In seedling production of seawater fish, providing appropriate nutrition is a necessity for successful production of quality larvae and juveniles. Mass-produced live prey organisms, such as the rotifer Brachionus plicatilis species complex and brine shrimp Artemia spp., alone do not provide sufficient nutrition to the larvae and juveniles of seawater animals. This inadequacy has led to various problems related to fish quality and health, including increased incidence of morphological and behavioral abnormalities and mass mortalities. It is, therefore, important to identify the factors associated with these problems to improve seedling production techniques. This review collates the efforts made during the past two decades in larval nutrition–focusing on advances made in the use of certain nutrients, such as docosahexaenoic acid, vitamin A derivatives, and taurine that are important for the mass production of seawater fish larvae and juveniles–with an aim to improve the quality and health of fish.     

A review of existing fish assemblage indicators and methodologies

Abstract  Fish assemblage indicators developed throughout the world were reviewed and key differences in methodologies depending on ecoregions, basins and contrasting fish fauna summarised. Common elements of existing Indices of Integrity were identified to support the development of a European-wide fish index. These include, using reference condition, accounting for natural fish assemblage variability, evaluating metric precision and selecting the most sensitive and complementary metrics. For future developments, it was recommended to pay more attention to temporal variability in fish assemblages, age structure of key (sentinel) species and fish migration. Testing hypotheses at different steps of the process seems to be the appropriate way to design fish indices.     

Cryopreservation of sperm in marine fish

Since the first work of Blaxter in 1953, fish sperm cryopreservation has been attempted on about 30 marine species. The present paper reviews the techniques used and the results published in these species. Particular attention is paid to the handling procedure of sperm before freezing, the problems of semen ageing and semen contamination with urine. The quality of frozen–thawed semen was evaluated using previously standardized biotests, such as a two‐step motility activation technique adapted for the different species and fertilization assays using a discriminating insemination technique. Most extenders used in marine fish are saline or sugar solutions. From the investigated cryoprotectants, dimethyl sulphoxide (DMSO) generally leads to the best results. Cooling rates range from 8 °C to 99 °C min^?1; the thawing rate is generally high. Compared with freshwater species, a high percentage of spermatozoa survives cryopreservation. Therefore, and because of the simplicity of the techniques, the cryopreservation of marine fish sperm is suited for application in aquaculture.     

Commercial marine fish farming in Singapore

Commercial marine fish farming in Singapore is mainly the culture of economically important foodfish species in floating cage nets. There are 84 licensed fish farms occupying 46.5 hectares (ha) of coastal waters. Production from these farms accounts for the bulk of aquaculture production in Singapore, being 3554 tonnes (‘metric tons’, t) in 1995, or 98% of total production of 3625t. The commonly cultured species are the green mussels, Perna viridis L., which form the bulk of production (70.4%), finfish like the groupers, Epinephelus tauvina Forsskal and E. malabaricus Schneider, Asian sea bass, Lates cakarifer Bloch, and snappers, Lutjanus johni Bloch and L. argentimaculatus Forsskal, and crustaceans like the mangrove crab, Scylla serrata Forsskal and spiny lobster, Panilurus polyphagus Herbst. The basic farm structure for fish and mussel culture is the floating wooden raft. In finfish farming, polyethylene cage nets are attached to the raft in which popular foodfishes are cultured. The mussel raft is a structure to which polyethylene ropes are attached to collect and grow out green mussels from natural spatfall. Fish seeds for farming are mostly wild-caught. Only the Asian sea bass and the banana shrimp (Penaeus merguiensis de Mann) are produced by commercial hatcheries in Singapore and the region. The fry of pompano (Trachinotus blochii Lacepede, and T. falcatus Klausewitz & Nielsen) are imported from Taiwan. Trash fish is still the main feed used for the farming of finfish and crustaceans like the mangrove crab and lobster because it is cheap and readily available. This paper also reviews the economics of commercial finfish and mussel farming in Singapore today.     

Model‐based assessment of local‐scale fish larval connectivity in a network of marine protected areas

We assessed by numerical modeling the coastal fish larval dispersion along the southern coast of Mallorca (Balearic Islands, NW Mediterranean) with the objective of determining the factors that contribute to successful recruitment. We assumed that fish larvae dispersal is mainly regulated by physical transport. Currents are mainly wind driven in this area; therefore, changes in wind forcing have a first‐order impact on larval transport. The synoptic wind patterns were systematically analyzed based on self‐organizing map analysis. The wind fields were clustered using a neural network pattern recognition approach into two modes, producing opposite along‐shelf flow. The seasonal changes between spring and summer in the dominance of either mode modulate the along‐shelf circulation, producing flow shifts under some circumstances. This variability in the wind regime was consistent throughout the 10 years analyzed (2000–2009). Using the Princeton Ocean Model (POM) and a particle‐tracking algorithm, we analyzed the effect of wind‐forced currents in the connectivity among near‐shore habitats. We show that, at the spatial scale considered, the coastal morphology and stochastic wind forcing favor local recruitment (mean of 30% self‐recruitment). Maximum transport distances of 20–30 km were typically associated with particles left to drift for 21 days. The implications for the performance of the four marine protected areas near SW Mallorca Island are discussed. Our results suggest that, although wind episodes determine the fate of short‐time spawning events, on a seasonal basis, regular larval supply to coastal zones is ensured by wind stochasticity.     

Recent advances in lipid nutrition in fish larvae

Due to the importance of dietary lipid utilization for larval rearing success, increasing attention has been paid during the last years to different aspects of larval lipid nutrition such as digestion, absorption, transport and metabolism, which are frequently studied by different research groups. The present study reviews the published information on these aspects, including some recent results obtained in our laboratory, that contribute to a better understanding of larval lipid nutrition.Neutral lipase activity was found in the digesta of larval gilthead seabream as early as first feeding, followed by a significant increase which reached up 8 times the initial levels at day 15 and was clearly influenced by the fatty acid composition of dietary lipids. Accordingly, the capacity for lipid absorption by the intestinal epithelium has been also observed at the onset of exogenous feeding, although the specific location in the different digestive tract segments differ with species. Whereas the capacity to absorb lipid increases with development in live prey-fed larvae, this improvemment is delayed in larvae fed formulated diet. Increasing dietary phosphatidyl cholines levels enhanced lipid absorption regardless of whether it is of soybean or marine origin, but the latter improved hepatic lipid utilization. Enzymatic, histological and biochemical evidences suggest that marine fish larvae are able to effectively digest and absorb n-3 HUFA-rich triacylglycerols, but feeding with phosphoacylglycerols, particularly if they are rich in n-3 HUFA, would enhance phosphoacylglycerols digestion and specially lipid transport alowing a better n-3 HUFA incorporation into larval membrane lipids and promoting fish growth. Although the essentiality of n-3 HUFA for larval marine fish has been studied extensively, only recently has the importance of dietary arachidonic acid in the larvae of few species been recognised. Evidences for competitive interactions among these essential fatty acids suggest that besides a minimum dietary requirement for each essential fatty acid, their relative ratios must also be considered.     

鱼类磷脂营养生理研究进展

磷脂作为类脂的一种,对鱼类(尤其是仔、稚鱼)的生长、存活、发育及抗应激能力等具有重要作用。作者综述了磷脂的生物学特征、在鱼体内的消化、吸收及转运过程、磷脂的合成途径及其与胆固醇的交互作用等,在此基础上比较了鱼类和甲壳类对磷脂需要量的差异,为鱼类养殖过程中磷脂的应用提供了理论指导。     

A review of mycobacteriosis in marine fish

Mycobacteriosis is a serious and often lethal disease of fish, affecting a wide range of species globally both in culture and wild settings. Caused by several species of the genus Mycobacterium , the disease has received considerable attention in recent years because of the discovery of new species in piscine hosts, epizootics in wild fisheries, and the ability of a few species to infect humans. The impact of this disease in aquaculture and the aquaria trade has been well reported and there is currently no widely accepted cure other than depopulation and facility disinfection. However, the impact on wild fisheries is poorly understood and may relate to species-specific interactions (host–pathogen) and possibly environmental stressors. In this review, much of what is known about mycobacteriosis in marine fish is summarized with particular attention to an epizootic in striped bass, Morone saxatilis , (Walbaum), in Chesapeake Bay, USA.     

小肽及其在鱼类营养中的应用

小肽作为蛋白质的主要消化产物,在氨基酸消化、吸收和代谢中起着重要作用。主要对小肽的概念、分类、小肽理论的提出与发展、小肽的吸收机制和特点、小肽在水产养殖中的应用及影响鱼类利用小肽的因素等方面的内容作一概述,并提出一些存在的问题。     

Microbial communities in various waters used for fish larval rearing

A major concern in larvae production is a mass mortality caused by fish diseases. In larvae production, pumped‐up natural seawater filtered through a sand filter system is used for fish rearing, and microalgae and rotifer cultures. Here, we investigated the community structures of eukaryotic microbes, as well as total bacteria and vibrios, in various processed ‘waters’ used in a larvae production site. We observed that ultraviolet irradiation of seawater was effective to reduce not only total bacteria and vibrios but also eukaryotic microbes. Moreover, the community structures of total bacteria and vibrios in rearing waters for fish larvae were different from those in rotifer cultures fed with Chlorella, but rather similar to those in natural seawater and microalgae cultures. These results suggest that the bacterial community in rearing waters may originate mainly from natural seawater and then be selected by microalgae in rearing water. Overall, this study provides useful information for avoiding the risk of fish disease outbreaks in a larvae production site.     

海水养殖鱼类消化酶研究进展

综述了海水养殖鱼类消化酶活性研究的以下三方面：（1）消化酶活性的研究,内容包括消化酶的活性分布,温度、pH、外界环境及季节变化对消化酶活性的影响;（2）不同生长阶段消化酶活性的变化,内容包括与仔鱼生长发育相对应的消化酶形成的时间,稚鱼、幼鱼在生长进程中,消化酶的变化规律;（3）鱼类的食物组成对消化酶活性的影响,内容包括饲料的种类和性质,以及饲料不同成分对鱼类消化酶的分泌、活性的影响,进而对饲料利用率的影响。本本对海水养殖鱼类消化酶的活性进行了较为系统的综述,为海水养殖鱼类饲料的开发提供参考数据。     

Patterns of population variability in marine fish stocks

Exploited marine fish and invertebrate stocks fluctuate in a myriad of complex patterns, exhibiting variability on interannual, decadal, and longer time scales. To characterize various patterns of variation, time series of catch, catch per unit effort, or biomass from 30 stocks were examined with a variety of statistical methods including autocorrelation analysis and Lowess smoothing. A hierarchical cluster analysis classified the stocks into six identifiable groups: steady-state; low-variation, low-frequency; cyclic; irregular; high-variation, high-frequency; and spasmodic. The observed patterns are consistent with life history traits; for example, stocks with high variability are generally small, pelagic species whereas low-variability stocks are generally slow-growing, demersal fish. Each of the six general patterns of variability can be produced from a simple multiple-equilibrium population model by varying the intrinsic rate of population growth, and the time scale and amplitude of environmental variability. Suitable management policies depend on the type of variation observed, and the vast majority of stocks examined do not correspond to the steady-state assumptions of classical fisheries models. For example, management of spasmodic stocks may alternate between periods of active exploitation and periods of rebuilding, a process enhanced by the existence of alternative fisheries.