3,367 research outputs found
fish and fishery products microbiology bacteria causing fish spoilage
No full textThis material describe bacteria which causing spoilage in fish and seafood products
Fish research project, Oregon
No full textprepared by: James R. Ruzycki, Lance R. Clarke, Michael W. Flesher, Richard W. Carmichael, Debra L. Eddy.Title from PDF title page (viewed on February 16, 2023)."Lower Snake River Compensation Plan: Oregon evaluation studies"--Cover.This archived document is maintained by the State Library of Oregon as part of the Oregon Documents Depository Program. It is for informational purposes and may not be suitable for legal purposes.Includes bibliographical references (pages 23-24).Financed by the U.S. Fish and Wildlife Service under the Lower Snake River Compensation Plan.Mode of access: Internet from the Oregon Government Publications Collection.Text in English
Diseases of Asian seabass (or barramundi), Lates calcarifer Bloch
No full textOther than the study by Griffiths (2009) on gill diseases, there has been no comprehensive study and report on the major diseases of Asian seabass (or barramundi) Lates calcarifer Bloch. It is a food fish species of growing importance in Asia and Australia. This study investigates some of the major diseases encountered in the various stages of the culture of L. calcarifer, at the histopathological, ultrastructural and molecular levels. Culture practices can have significant impacts on fish health. Disease outbreaks are influenced by factors involving the host, environment and pathogen. Current knowledge on diseases of L. calcarifer, and these factors which may influence disease outbreaks are discussed in Chapter 1.
This is the first report of an intestinal Eimeria infection in L. calcarifer. The Eimeria infection was associated with severe pathology and significant mortality in the absence of other pathogens. It was detected in diseased L. calcarifer in all five nurseries in Ca Mau, Vietnam. Although these were small scale nurseries which stocked an average of 3000 to 5000 fish at any one time, a mortality rate of up to 30% was reported and is the cause of significant economic losses for these nurseries. Moderate to heavy Eimeria infestation were observed in greater than 80% of diseased fish examined. This high rate of Eimeria infestation is suspected to be linked to the low daily water exchange rates practised in these nurseries. However, the examination of only diseased fish does not allow the determination of prevalence. A systemic iridovirus infection was concurrently observed in some of the fishes but was not consistently present when compared to the Eimeria infection. Molecular analysis showed that the Eimeria of L. calcarifer from Vietnam formed clades with the Eimeria detected in L. calcarifer cultured in Australia, but clustered separately from other known Eimeria species. Although Cryptosporidium was detected in these L. calcarifer tissues, it could not be demonstrated histologically or ultrastructurally, suggesting a low grade infestation or perhaps an environmental contaminant in fish tissues tested. In situ hybridization using labeled PCR products showed that labeled DNA probes generated from 18S PCR products could not be used to distinguish between closely related genera such as Cryptosporidium and Eimeria. Future investigation to determine the origin, transmission and risk factors associated with this Eimeria infestation in L. calcarifer are needed.
‘Scale drop syndrome’ is a novel disease first reported in L. calcarifer in Penang, Malaysia in 1992. Cases with similar gross and clinical presentations were observed in Singapore in 2002, 2006 and 2009. Affected fish have loose scales, which dropped off easily when handled. The disease was initially observed in 100-300g fish, and later in larger fish up to 5kg bodyweight. Cumulative mortalities of 40 to 50% were reported by farms, posing significant economic losses of larger more valuable fish. This investigation forms the first pathological description of ‘scale drop syndrome’ (SDS) in L. calcarifer. To aid recognition of new cases for study, a case definition was developed for ‘scale drop syndrome’ in L. calcarifer as a systemic vasculitis associated with tissue necrosis in all major organs including the skin, with apparent targeting of cells of epithelial origin. Attempts to isolate or detect the causative agent(s) by cell culture, PCR and immunohistochemistry have proven unsuccessful. Further studies to elucidate the definitive aetiology, isolate the causal agent(s) and reproduce the disease will help better understanding and control of SDS.
Although systemic iridoviral disease has been previously reported in many freshwater and marine fish species, this study forms the first report of this disease in L. calcarifer. Systemic iridoviral disease was observed in 5 to 20g L. calcarifer usually 2 to 3 weeks post-transfer into sea cages at two farms. Inclusion bodies suggestive of a systemic iridovirus infection were observed in clinically healthy L. calcarifer from the land-based nursery of one of these two farm; the presence of an iridovirus infection was supported by positive PCR results using Red Sea bream iridovirus (RSIV) primer 1. The presence of inclusions was not accompanied by any tissue necrosis in these clinically healthy fish. This finding suggested that the systemic iridovirus infection occurred before stocking at sea, and did not originate from wild fish or older fish in adjacent sea cages as initially suspected by this farm. Immunohistochemistry on tissues of clinical cases of systemic iridovirus gave positive results using the Red Sea bream iridovirus monoclonal antibody (RSIV M10), although intensity varied between tissues, possibly related to varying exposure of different tissues to fixation chemicals. Inclusion bodies in clinically healthy fish from the same farm did not show positive reaction with RSIV M10. This may be due to a lack of antigenic expression by the viral infected cells at this early stage of infection.
Viral nervous necrosis (VNN) is a serious disease of hatchery reared L. calcarifer fry in this study. Mortalities of 50 to 100% were reported in 3wo fry. VNN can be difficult to diagnose in older fry, where it can be associated with few vacuolations or an absence of viral inclusions
‘Pot belly disease’ (PBD) was previously reported in L. calcarifer fry less than 1g, in association with an intracellular coccobacillus infection and mortalities of 80 to 100%. In this study, PBD was observed in 120g L. calcarifer at two sea cage farms, in association with significant granulomatous enteritis. The extent of the granulomatous enteritis is likely to have an effect on affected fish. It was observed concurrently with systemic iridoviral disease at one farm and nocardiosis at another farm. Diagnosis by histopathology and the lack of other confirmatory tests for PBD may result in underdiagnosis of this disease. The epidemiology of PBD needs further study to establish origin and modes of transmission, to facilitate better disease control.
Diseases associated with infections by ubiquitous bacteria such as Vibrio, Tenacibaculum were commonly observed in L. calcarifer post-handling. Tenacibaculosis and vibriosis often occurred concurrently with other diseases such as streptococcosis, systemic iridviral disease or PBD. Streptococcosis can affect fish up to 3kg bodyweight, resulting in significant mortalities greater than 40 to 50%. Like SDS, because streptococcosis can affect up to market size fish, they can cause considerable economic losses. Although vaccines against Streptococcosis are available, conflicting views are held on the efficacy of Streptococcus vaccines by various research groups. Overall, the South-east Asian L. calcarifer farms which practiced vaccination against Streptococcus iniae reported a reduction of mortality, especially in fish greater than 1 to 1.5kg bodyweight.
Nocardiosis has been reported as an emerging disease in marine food fish species caused by acid fast filamentous branching bacterium. Although nocardiosis was observed histopathologically in L. calcarifer at two sea cage farms, the numbers of samples examined were small and no other tests were attempted due to lack of suitable samples. More intensive and extensive study is needed to determine the significance of nocardiosis in L. calcarifer. Chronic granulomatous enteritis was not uncommon in the cases submitted to the Fish Health Laboratory in Perth. Although the peritonitis was associated with heavy bacteria infection, it is unclear if these are secondary invaders. Schipps, Bosmans & Humphreys (2009) reported that Vibrio harveyi and Photobacterium damsela damsela vaccinations appeared to be not efficacious, suggesting that these bacteria were not the primary cause of the disease.
It is well recognized that disease outbreaks in farmed fish are influenced by the interaction between host, the environment and pathogens. While serious diseases are often reported in association with specific aquatic pathogens, not much is known about the risk factors which trigger fish disease outbreaks. Disease outbreaks often occur after stressful events such as net transfers, recent handling or poor water quality. In fact, diseases are often caused by ubiquitous pathogens that are commonly present in the culture environment. Although further research is necessary to gather more information to improve diagnosis and management of specific diseases, general health management strategies can be applied at the various stages in the culture of L. calcarifer to minimize disease outbreaks. This is discussed for L. calcarifer in Chapter 6.
Observations of types of disease agents may be influenced by site conditions or the types of tests or materials examined. For example, some parasites may be more prevalent in certain sites where intermediate hosts abound, or loosely attached ectoparasites may be lost unless wet mount microscopic examinations of fresh tissues were carried out. The study of emerging diseases such as scale drop syndrome (SDS) or pot belly disease (PBD) in L. calcarifer has been hampered by lack of confirmatory diagnostic tools and inadequate knowledge on critical epidemiological factors such as mode of transmission or potential reservoirs. While ideally identification and isolation of the causal agent will help fulfil Koch’s postulates, it may be possible to improve the understanding of disease via cohabitation or infectivity trials using tissue homogenates from diseased fish when pure isolates are not available. There is a need to conduct research to not only establish a definitive aetiology, but also to identify risk factors to facilitate successful disease control. The successful management of disease in aquaculture does not lie in any one strategy but an integrated management of all risks encountered during the culture cycle against disease occurrence or incursions
Preliminary data on the influence of rearing temperature on the growth and reproductive status of fathead minnows Pimephales promelas
No full textThis article has been made available through the Brunel Open Access Publishing Fund and is available from the specified link - Copyright @ 2011 Brian JV et al.An investigation into the influence of temperature on the growth and reproductive status of the fathead minnow Pimephales promelas revealed that, while there was no clear effect of treatment on sex differentiation, ovarian tissue from female fish reared under the highest temperature regime contained large amounts of undefined tissue containing no germ cells. Furthermore, both male and female fish exhibited differences in length mass, condition and somatic indices, and in the expression of secondary sexual characteristics. The patterns observed are discussed in the context of climate change
Fish consumption, does it beneficially affect markers of colorectal carcinogenesis?
No full textBackground: Fish consumption is possibly associated with a decreased risk of colorectal cancer, as has been shown in several observational studies. However, most of these studies did not discriminate between the effects of oil-rich and lean fish. To date, no randomized controlled trials (RCTs) have examined the possible beneficial effects of fish intake on colorectal cancer risk. Aim: The aim of this thesis was to investigate whether fish consumption beneficially affects markers of colorectal carcinogenesis. Methods and Results: In a case control study (363 cases, 498 controls), we studied the association of serum n 3 polyunsaturated fatty acid (PUFA) levels as a marker of oil rich fish intake with colorectal adenomas, a precursor lesion of colorectal cancer. We found that individuals with high serum long chain n 3 PUFA levels had a decreased risk of colorectal adenomas (odds ratio (OR) 0.67, 95% confidence interval (CI) 0.46; 0.96), whereas individuals with high serum n 6 PUFA levels had an increased risk of colorectal adenomas (OR 1.68, 95% CI 1.17; 2.42). In an RCT, we studied the effects of 3.5g/d fish oil (~1.5g/d n 3 PUFA) for 12 weeks on 19 serum inflammation markers in 77 healthy subjects and found that serum levels of these cytokines and chemokines were not changed. Finally, we studied the effects of increasing fish consumption compared with no additional fish, on markers of colorectal carcinogenesis in an RCT. Subjects (n=242), at an increased risk of colorectal cancer and those with no macroscopic signs of disease, were randomly allocated to receive dietary advice (DA) plus either two additional weekly portions of oil rich fish (salmon, ~1.4g/d n 3 PUFA) or lean fish (cod, ~0.09 g/d n 3 PUFA), or only DA for six months. We observed no change in apoptotic and mitotic cell numbers after the 6 months intervention with either salmon or cod compared with DA. Furthermore, colorectal genotoxicity, levels of cytokines and chemokines in colonic biopsies and feces, and fecal calprotectin were also not markedly changed after fish consumption. Only serum C reactive protein (CRP) levels were statistically significantly decreased after consumption of salmon ( 0.5 mg/l, 95% CI 0.9; 0.2) and cod ( 0.4 mg/l, 95% CI 0.7; 0.0) compared with DA. Conclusion: The results of this thesis do not provide strong evidence for beneficial effects of fish consumption on markers of colorectal carcinogenesis. <br/
Comparison of ovarian cycles of Hungarian riverine fish species representing different spawning strategies
No full textInvestigations on the ovarian cycle of fish species that inhabit Hungarian rivers are necessitated by both environmental and economic reasons. The objective of our research was to explore new fundamental knowledge concerning the ovarian cycle of the white bream (Blicca bjoerkna, Linnaeus, 1758), barbel (Barbus barbus, Linnaeus, 1758), orfe (Leuciscus idus, Linnaeus, 1758) and nase (Chondrostoma nasus, Linnaeus, 1758). Histological investigation of ovaries and determination of proportions of oocytes in different stages of development is an appropriate method for the description of spawning characteristics of these species. Our results show that the GSI value for all four investigated species starts to increase at the end of summer and reaches its maximum before spawning. In the barbel and white bream, the presence of oocytes in the stage of cortical alveoli and the heterogeneous size of oocytes in the stage of vitellogenesis in the pre-spawning period indicate that barbel and white bream are multiple spawners. In contrast, in the orfe and nase, the absence of oocytes in the stage of cortical alveoli and the homogeneous size of cells in the stage of vitellogenesis indicate that orfe and nase are single spawners
The influence of a surfactant, linear alkylbenzene sulfonate, on the estrogenic response to a mixture of (xeno)estrogens in vitro and in vivo
No full textThis is the post-print version of the final paper published in Aquatic Toxicology. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright © 2008 Elsevier B.V. All rights reserved.The effect of the presence of a surfactant on the activity of a mixture of environmental estrogens was assessed. In their natural habitat, fish are subject not only to exposure to mixtures of estrogenic compounds, as has been addressed in previous publications, but also to other confounding factors (chemical, physical and biological), which may, in theory, affect their responses to such compounds. To assess the potential for such interference, the commonly occurring surfactant, linear alkylbenzene sulfonate (LAS), was applied to the yeast estrogen screen at various concentrations, independently and together with a mixture of estrogens at constant concentrations. LAS enhanced the estrogenic activity of the mixture, an effect which became less pronounced over the course of time. This information was used to design an in vivo study to assess induction of vitellogenin in fathead minnows exposed to the same mixture of estrogens plus LAS. A similar trend was observed, that is, the response was enhanced, but the effect became less pronounced as the study progressed. However, the enhanced response in vivo occurred only at the highest concentration of LAS tested (362 μg/L), and was transient because it was no longer apparent by the end of the study. Although LAS is a significant contaminant in terms of both concentration and frequency of detection in the aquatic environment, these data do not suggest that it will have a significant impact on the response of fish to environmental estrogens
Can fish really feel pain?
No full textWe review studies claiming that fish feel pain and find deficiencies in the methods used for pain identification, particularly for distinguishing unconscious detection of injurious stimuli (nociception) from conscious pain. Results were also frequently misinterpreted and not replicable, so claims that fish feel pain remain unsubstantiated. Comparable problems exist in studies of invertebrates. In contrast, an extensive literature involving surgeries with fishes shows normal feeding and activity immediately or soon after surgery. C fiber nociceptors, the most prevalent type in mammals and responsible for excruciating pain in humans, are rare in teleosts and absent in elasmobranchs studied to date. A-delta nociceptors, not yet found in elasmobranchs, but relatively common in teleosts, likely serve rapid, less noxious injury signaling, triggering escape and avoidance responses. Clearly, fishes have survived well without the full range of nociception typical of humans or other mammals, a circumstance according well with the absence of the specialized cortical regions necessary for pain in humans. We evaluate recent claims for consciousness in fishes, but find these claims lack adequate supporting evidence, neurological feasibility, or the likelihood that consciousness would be adaptive. Even if fishes were conscious, it is unwarranted to assume that they possess a human-like capacity for pain. Overall, the behavioral and neurobiological evidence reviewed shows fish responses to nociceptive stimuli are limited and fishes are unlikely to experience pain
CpG inclusion in feed reduces sea lice, Lepeophtheirus salmonis, numbers following re-infection
No full textLepeophtheirus salmonis infections in Atlantic salmon, Salmo salar, have been characterized by little to no hyperplastic response and a biphasic immune response that results in chronic inflammation with tissue repair as the infection progresses. We hypothesized that CpG administration with prior lice exposure would enhance epithelial inflammatory mechanisms and boost the Atlantic salmon immune response to L. salmonis, leading to greater protection against infection. We administered multiple exposures of L. salmonis to two groups of Atlantic salmon and compared responses against first-time exposed Atlantic salmon. Following re-exposure, CpG fed fish exhibited increased skin expression of interleukin (IL)-1β and IL-12 β compared to control previously exposed (CPE) and control first-time exposed (CFE) animals, respectively. This inflammatory enhancement occurred with significantly lower expression of matrix metalloproteinase-9 (MMP 9), both systemically (spleen) and locally (skin). Reduced MMP 9 expression was a hallmark of the re-infected fish (occurred in both tissues at both times). When significant differences were present in the skin or spleen, the two re-exposed groups showed greater similarity than with the first exposure group. Lice numbers on CpG fed fish were significantly lower than CFE fish at 7 days post-re-infection (dpri), and although they were not significantly different at 17 dpri, the trend of lower lice levels remained. CpG fed fish also showed nearly twofold greater protection than CPE when compared to the CFE group (48.5% vs. 27.0% reductions at 7 dpri and 27.2% vs. 13.1% reductions at 17 dpri, respectively). The enhanced protection of CpG oligodeoxynucleotide administration to previous exposure was consistent across all body surfaces and suggests that CpG can not only enhance innate responses to L. salmonis in Atlantic salmon, but also further stimulate adaptive responses
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Analysis of Ichthyomechanical Data for Fish Passage or Exclusion System Design
No full textFish speed and stamina, locomotion, and the mechanics of fish swimming, are key to the development and design of passage, exclusion, and guidance systems such as fishways (including culverts), fish screens, fish barriers (including sea lamprey velocity barriers), and fish louvers. The large amount of data available, although primarily from laboratory respirometer studies and unevenly distributed between species, offered an opportunity to consider its systematic application to the development, design, and testing of such devices. With this motive, comprehensive searches were made and literature on fish swimming performance tests was compiled, and published data were entered on spreadsheets. This data base includes the following information: scientific and common fish species name, swimming mode, fish length (l in m), swimming speed (U in m/s), endurance or time to fatigue (t in s), water temperature during testing, life stage (e.g. juvenile or adult), test method (e.g. constant or increasing velocity), number of fish tested, regressions of swimming speed versus fish length for specific endurance times as reported in the literature, publication reference (author and date), and relevant comments (Katopodis and Gervais 1991). The data base may be consulted for information on specific species, although many species either have very limited data or are not represented at all. The data base, which is available on request, is presently been revised and updated. Investigators with additional data which do not appear in primary publications, are encouraged to provide it for inclusion
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