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PubMed2004

A model of navigation-induced currents in inland waterways and implications for juvenile fish displacement.

The likely extension of commercial inland navigation in the future could increase hazards directly impacting on the nurseries of freshwater fish, especially for smaller individuals with limited swimming abilities. One limitation of the evaluation of inland navigation on fish assemblages is the lack of suitable hydraulic models. This article presents a hydraulic model to assess the increase of navigation-induced physical forces due to higher vessel speed, length, and drought in a low-flowing waterway related to maximum swimming performance of fish to (1) foresee hazards of enhancement of inland navigation, (2) derive construction measures to minimize the hydraulic impact on small fish, and (3) improve fish recruitment in waterways. The derived model computed current velocities induced by passing commercial vessels in inland waterways experimentally verified and parameterized in a German lowland waterway. Results were linked with a model of maximum fish swimming performance to elucidate consequences for freshwater fish populations. The absolute magnitude of navigation-induced current limits the availability of littoral habitats for small fish. Typical navigation-induced current velocities of 0.7-1 m/s in the straight reaches of waterways will be maintained by fish longer than 42 mm only. Smaller juveniles unable to withstand those currents could become washed out, injured, or displaced. In contrast, in small local bays, the navigation-induced current declined significantly. According to our model, in a 20-m extended bay, the return current drops below 0.11 m/s, corresponding to the maximum swimming speed of a 9-mm-long fish. Thus, enhancing shoreline development by connecting oxbows, tributaries, and especially by purpose-built bays limits the impact on fish recruitment without restricting navigation resulting in more precautionary and sustainable inland navigation.

Animals↗
PubMed1983

Drinking induced by angiotensin II in fishes.

Among 20 species of freshwater fishes examined, Pseudorasbora parva, Rhodeus ocellatus, Cobitis anguillicaudatus, Carassius auratus, Oryzias latipes, Gambusia affinis, and Gyrinocheilus anymonieri were found to drink water like seawater fishes, while 13 remaining species did not drink. For fish species found exclusively in fresh water, angiotensin II (AII) treatment did not induce drinking. In contrast, those freshwater fishes which survive in estuarine brackish water (Leuciscus hakonensis, C. carassius, Parasilurus asotus, G. affinis, Chaenogobius annularis, Tridentiger obscurus, and G. anymonieri responded to AII by drinking. Furthermore, some freshwater fishes which survive either in hypertonic water (C. auratus) or in sea water (Anguilla japonica and O. latipes) also responded to AII by drinking. Of 17 seawater fishes examined, Eptatretus burgeri, Triakis scyllia, and Heterodontus japonicus failed to drink water, and for Trachurus japonicus, Platichthys bicoloratus, and Glossogobius giuris fasciatopunctatus, water intake was minor (similar to freshwater fishes). The 11 remaining seawater fishes drank water. AII did not induce drinking in fishes living exclusively in sea water. However, seawater fishes which survive either in tide pools (Chasmichthys dolichognathus gulosus) or in brackish water (Sillago japonica, Mugil cephalus, G. giuris fasciatopunctatus) responded to AII by drinking. P. bicoloratus, Acanthopagrus schlegeli, and Fugu niphobles were exceptional, in that they survive in brackish water, but did not respond to AII. Although some exceptions exist, it is generally concluded that a drinking response to AII is characteristic of fishes which encounter water more hypertonic than that in which they typically reside. Accordingly, a drinking mechanism induced by AII may be a compensatory emergency reaction to dehydration stress.

Angiotensin II↗
PubMed1990

Effect of fish oil on atherosclerosis and lipoprotein metabolism.

This review primarily covers work on the effects of dietary n-3 fatty acids on lipoprotein metabolism and atherosclerosis that has been done in a nonhuman primate model, the African green monkey, and puts it in context with work of others using humans and other experimental animals. Detection of effects of n-3 fatty acids in the monkey model was facilitated by a considerable enrichment of dietary fat with fish oil (about 20% of dietary calories came from menhaden oil in the fish oil group or about 5 g/1000 cal of n-3 fatty acids). This group was compared with a group fed lard isocalorically substituted for fish oil, such that the percentage of saturated fatty acids was essentially equivalent in the 2 dietary groups. Cholesterol concentrations in whole plasma, LDL and HDL were about 1/3 lower in the fish oil group, as was apo A-I concentration, but apo B concentration was not different. The fish oil group had plasma LDL particles that were smaller, contained fewer cholesteryl ester molecules and had lower cholesteryl ester transition temperatures due to a relative enrichment of n-3 fatty acids in the CE fraction. In addition, hepatic cholesterol and cholesteryl ester concentrations were significantly lower in the animals fed fish oil. Liver perfusion was used to show that hepatic secretion of cholesterol and triglyceride was lower in the fish oil group, although the number of cholesterol and triglyceride enriched apo B-containing particles secreted was not different. We also demonstrated a lower plasma LCAT reactivity for the plasma phospholipids of the animals fed fish oil. Taken together, these findings clearly demonstrate important effects of n-3 fatty acids on cholesterol metabolism in a primate model that have not been previously recognized. In addition, the monkeys fed fish oil had less atherosclerosis in the coronary arteries and in the aorta. Thus, these findings indicate that, in addition to the many other effects of fish oil in eicosanoid production, fish oil effects on cholesterol metabolism, per se, can have an important role in limiting atherosclerosis.

Animals↗
PubMed1984

A review of the Food and Drug Administration risk analysis for polychlorinated biphenyls in fish.

This paper reviews the Food and Drug Administration (FDA) analysis of the risk to humans from consuming fish contaminated with polychlorinated biphenyls (PCBs). In brief, the FDA methodology employed "high" dose experiments on animals and extrapolated the observed rates of certain types of cancer at these elevated doses to the low doses found in human diets. These extrapolations were then used to define a recommended tolerance level of 5 ppm, and proposed reduction to 2 ppm, for fish sold in interstate commerce. Unfortunately, as is shown here, such a procedure is extremely sensitive to the basis for extrapolation. Important elements of the FDA analysis include the following: (i) FDA assumed a particular form of the dose-response model: the one-hit model. Many other models have been proposed and, on balance, appear equally plausible. These models estimate lower risks than does the one-hit model. (ii) FDA calculated 99% upper confidence bounds on these risks and, moreover, emphasized cases of fish eaters who consume greater amounts of PCB-contaminated fish than do 98.5% of the U.S. population. (iii) FDA based PCB ingestion computations on consumption of raw fish, whereas most fish are cooked before eating, and it is known that PCB levels in cooked fish are lower than PCB levels in raw fish. (iv) FDA based estimates of cancer risk on the assumption that PCB levels in fish would be constant over the nominal 70-year human life span used in the FDA "lifetime risk" computation. Recent data suggest that PCB levels have been declining in fish (particularly in sport fish) and humans as well. Such trends imply significantly lower cumulative lifetime PCB doses than were assumed in the FDA analysis. (v) FDA assumed that humans and test animals are equally sensitive to PCB ingestion when measured on a parts per million in diet basis. Extrapolations on an equivalent consumption per unit of body weight, thought appropriate by most researchers, result in much lower health risks. In short, when confronted with methodological choices, the FDA consistently selected "worst case" or conservative assumptions over other alternatives of at least equal plausibility. This philosophy of choice was explicitly acknowledged by the FDA. What was omitted from the FDA analysis, however, was the possible degree of overstatement of these risks. The results of replicate risk computations using alternative assumptions to examine the possible magnitude of overstatement of health risk are summarized in Table 12. As can be seen, this overstatement could easily account for a discrepancy of several orders of magnitude between actual and calculated risks.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed2007

Chemical contaminants in fish feeds used in federal salmonid hatcheries in the USA.

Recent studies have demonstrated that fish feeds contain significant concentrations of contaminants, many of which can bioaccumulate and bioconcentrate in fish. Organochlorine (OC) contaminants are present in the fish oils and fish meals used in feed manufacture, and some researchers speculate that all fish feeds contain measurable levels of some contaminants. To determine the concentration of contaminants in feeds used in US Fish and Wildlife Service's National Fish Hatcheries, we systematically collected samples of feed from 11 cold-water fish hatcheries. All samples (collected from October 2001 to October 2003) contained at least one polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF), polychlorinated biphenyl (PCB) congener, or dichlorodiphenyltrichloroethane (DDT) metabolite. Of the 55 samples in which they were analyzed 39 contained PCDDs, 24 contained PCDFs and 24 contained DDT or its metabolites. There were 10- to 150-fold differences in concentrations of total PCBs, PCDDs, PCDFs and DDT. Although PCBs were the most commonly detected contaminant in our study, concentrations (range: 0.07-10.46 ng g(-1) wet weight) were low compared to those reported previously. In general, we also found lower levels of OCs than reported previously in fish feed. Perhaps most notable was the near absence of OC pesticides - except for DDT or its metabolites, and two samples containing hexachlorocyclohexane (HCH). While contaminant concentrations were generally low, the ecological impacts can not be determined without a measure of the bioaccumulation of these compounds in the fish and the fate of these compounds after the fish are released.

Animal Feed↗
PubMed2005

Analytical methodology for the identification of estrogenic contaminants in fish bile.

Effluents from wastewater treatment works (WwTWs) contain estrogenic contaminants that can cause feminised responses in fish. In order to assess the identity of estrogenic contaminants taken up by fish exposed to effluents, an analytical method was developed to detect estrogenic substances in fish bile, where many xenobiotics are excreted and concentrated. Estrogenic metabolites in bile were deconjugated using enzymatic hydrolysis and the estrogenic activity was determined using a yeast estrogen receptor transcription screen (YES). Hydrolysed samples were concentrated by solid-phase extraction (SPE) prior to fractionation by reversed-phase high-performance liquid chromatography (HPLC). Active HPLC fractions were detected by YES assay and analysed by gas chromatography-mass spectrometry (GC-MS) after trimethylsilylation. The method was validated using bile samples from immature female rainbow trout, which had been exposed to either tap water or an undiluted estrogenic effluent for 10 days. Hydrolysis of bile from effluent-exposed fish was complete within 16 h add most of the estrogenic activity in the bile was released by 3-glucuronidase rather than sulfatase or 3-glucosidase treatment. The estrogenic activity of hydrolysed bile from effluent-exposed fish ranged between 530 and 1440 ng E2eq/mL and was 17-48-fold greater than the activity of bile from reference fish exposed to tap water. The estrogenic activity of bile samples decreased with time in storage (at-70 degrees C by 7% per month). The recovery of estrogenic activity from SPE was 96 +/- 7% (mean +/- SD), from HPLC fractionation 87 +/- 7% and for the whole method 81 +/- 7% (n = 7). 17beta-Estradiol, estrone, 17alpha-ethinylestradiol, nonylphenol and short-chain nonylphenol polyethoxylates were all identified from GC-MS analysis of active HPLC fractions of bile from effluent-exposed trout, whereas only 17beta-estradiol was detected in bile from fish exposed to tap water. There were also several other minor estrogenic components, at present unidentified, in bile of effluent-exposed fish. The work shows that fractionation of fish bile is a useful approach to identifying mixtures of estrogenic contaminants taken up by fish from WwTW effluents and has the potential for application in the detection of other endocrine disrupting chemicals in fish tissues.

Animals↗
PubMed2005

Effects of industrial metals on wild fish populations along a metal contamination gradient.

The purpose of this study was to examine relationships among water, sediment, and fish tissue metal concentrations as they relate to fish diversity, tissue metal accumulation, and fish morphometric and reproductive condition. Fish were captured in 12 lakes near Sudbury, Ontario, Canada, that ranged in their degree of metal contamination. In general, metal concentrations in water and sediment decreased with increasing distance from industrial operations. However, only Cu and Ni demonstrated this trend in sediments. Although 20 fish species were identified in the 12 lakes, only one species, yellow perch (Perca flavescens), was common to all 12 lakes. Fish diversity was only associated with sediment metals, suggesting that short-term processes are much less important than long-term processes for fish community recovery in metal-contaminated lakes. Multivariate characterization of water metal concentrations resulted in three lake clusters: Group 1 consisted of reference lakes; Group 2 lakes had high alkalinity, conductivity, hardness, pH, waterborne metals (especially Se), and sediment Cu and Ni concentrations; Group 3 lakes had high pH, waterborne and sediment Cu, and sediment Ni, intermediate alkalinity, conductivity, and waterborne metals (except Al and Fe), and low hardness and waterborne Al and Fe. Liver Cd, Cu, Ni, Pb, and Zn, muscle Zn, and intestinal Cd and Zn were highest, and muscle Cu and male gonadosomatic index (GSI) were lowest, in Group 3 fish. Liver, muscle, and intestinal Se concentrations, and Fulton's condition factor (FCF), hepatosomatic index (HSI), and male GSI were highest in Group 2 fish. Group 1 fish had the highest muscle Hg concentrations and female GSI. Muscle Se appeared to have an antagonistic effect on muscle Hg accumulation as a function of distance from smelting operations. Neither Cu nor Ni, both metals of concern in the Sudbury area, was useful for predicting fish condition, probably because of homeostatic regulatory control. Liver Cd accumulation, which was negatively related to FCF (r = -0.16; P < 0.05), exhibited strong, nonlinear inhibition (r2 = 0.99; P < 0.0001) as a function of water hardness. Because Cd was not detected in water samples in this study, we suspect that branchial Ca2+ uptake may play some role in reducing dietary Cd uptake in hard water lakes. Selenium has received relatively little attention in the contaminated systems around Sudbury, yet our results demonstrated that tissue Se was related to all condition metrics studied. Moreover, evidence was provided that suggests that there is a gender-specific interaction between dietary Se and Cu uptake that may contribute to decreased female reproductive condition in wild yellow perch.

Animals↗
PubMed2004

Temporal variation of blood and hair mercury levels in pregnancy in relation to fish consumption history in a population living along the St. Lawrence River.

Fish consumption from the Great Lakes and the St. Lawrence River has been decreasing over the last years due to advisories and increased awareness of the presence of several contaminants. Methylmercury (MeHg), a well-established neurotoxicant even at low levels of exposure, bioaccumulates to differing degrees in various fish species and can have serious adverse effects on the development and functioning of the human central nervous system, especially during prenatal exposure. Most studies on MeHg exposure have focussed on high-level consumers from local fish sources, although mercury (Hg) is also present in fresh, frozen, and canned market fish. Moreover, little information exists on the temporal variation of blood and hair Hg in pregnant women, particularly in populations with low levels of Hg. The aim of the present study was to characterize the temporal variation of Hg during pregnancy and to investigate the relation between fish consumption from various sources prior to and during pregnancy and maternal cord blood and mother's hair Hg levels. We recruited 159 pregnant women from Southwest Quebec through two prenatal clinics of the Quebec Public Health System. All women completed two detailed questionnaires concerning their fish consumption (species and frequency) prior to and during pregnancy. The women also provided blood samples for all three trimesters of pregnancy and hair samples after delivery of up to 9 cm in length. Blood and hair Hg levels were analyzed by cold-vapor atomic-absorption and -fluorescence spectrometry methods, respectively. Results showed that maternal blood and hair Hg levels decreased significantly between the second and third trimesters of pregnancy. However, cord blood Hg was significantly higher than maternal blood at birth. Maternal hair was correlated with Hg blood concentration and was highly predictive of the organic fraction in cord blood. A strong dose relation was observed between the frequency of fish consumption before and during pregnancy and Hg exposure in mothers and newborns. Fish consumption prior to and during pregnancy explained 26% and 20% of cord blood Hg variance, respectively. For this population, detailed multivariate analyses showed that during pregnancy market fish (fresh, canned, and frozen) were more important sources of Hg exposure than were fish from the St. Lawrence River. These results should be taken into account for future advisories and intervention strategies, which should consider Hg levels in different species from all sources in order to maximize the nutritional input from fish and minimize the toxic risk.

Adolescent↗
PubMed2005

Hair mercury (signature of fish consumption) and cardiovascular risk in Munduruku and Kayabi Indians of Amazonia.

Fish is an important natural resource in the diet of inhabitants of the Amazon rain forest and a marker of its consumption (hair Hg) was used to compare selected cardiovascular risk parameters between tribes of Eastern Amazonia. Three Munduruku (Terra Preta, Kaburua, Cururu) villages and one Kayabi village at the banks of head rivers (Tapajos, Tropas, Kabitutu, Cururu, Curuzinho, Teles Pires) of the Tapajos Basin were studied in relation to fish Hg concentrations, mercury in hair (fish consumption) and erythrocytes, body mass index (height/weight, kg/cm2), and blood pressure. The mean fish Hg concentrations were higher in predatory (578.6 ng/g) than in nonpredatory species (52.8 ng/g). Overall only 26% of fish Hg concentrations were above 500 ng/g, and only 11% were above 1000 ng/g. There was no systematic trend in fish Hg concentrations from rivers with a history of gold-mining activities. The biomarker of fish consumption (hair Hg) was significantly associated with erythrocyte-Hg (r=0.5181; P=0.0001) and was significantly higher in Kayabi (12.7 microg/g) than in the Munduruku (3.4 microg/g). Biomarker-assessed fish consumption rate was higher in the Kayabi (110 g/day) than in the Munduruku villages (30 g/day). Although no significant differences in body mass index (BMI) were observed between tribes, there was a trend of lower increase in blood pressure with age among the higher fish consumers (Kayabi). Summary clinical evaluation did not detect neurologic complaints compatible with Hg intoxication (paraparesis, numbness, tremor, balancing failure), but endemic tropical diseases such as clinical history of malaria showed a high prevalence (55.4%). Fish is an abundant natural resource, important in the Indian diet, that has been historically consumed without perceived problems and can easily be traced through hair Hg. The exposure to freshwater fish monomethyl mercury is less of an issue than endemic infectious diseases such as malaria and lack of basic medical services.

Adolescent↗
PubMed2004

New method for rapid and sensitive quantification of sulphide-producing bacteria in fish from arctic and temperate waters.

The offensive, fishy, rotten H2S-off-odours in spoiled, aerobically and cold stored fish from arctic and temperate waters are generally caused by sulphide-producing bacteria (SPB), mainly Shewanella putrefaciens. In the present work, a new, rapid, simple and accurate method for estimation of the SPB content in fish from these areas is described. The quantification is based on the formation rate of iron sulphide during growth of SPBs incubated at 30 degrees C in a liquid growth medium containing cysteine, sodium thiosulphate and iron(III)citrate as specific substrates for iron sulphide formation. The iron sulphide turns the medium grey and masks the background fluorescence in the medium when the SPB content in the assay is approximately 10(9) cfu/ml. The fluorescence change could be detected instrumentally and the colour change visually. The method was developed and evaluated in tests with S. putrefaciens CCUG 13452 DT as well as naturally occurring SPBs in cod, salmon, wolf fish and coal fish. A linear correlation between the SPB count and detection time was obtained over the entire range from 1 to 10(9) cfu SPB/g, corresponding to detection times 17 and 1 h, respectively. The correlation is described by the equation: log cfu/g fish= -0.59(+/- 0.17) x DT+ 9.65(+/- 0.09), where DT is the detection time in hours. The model was valid for all the tested fish species and all tested naturally occurring SPBs in these species. The regression coefficients (R2) for cod, coal fish, wolf fish and salmon were 0.99, 0.92, 0.97 and 0.97, respectively. The detection level of the method is 1 SPB per sample tube, corresponding to 16 cfu/g fish. The method could be used to predict the remaining shelf life of the fish for different markets, even when the time-temperature history during storage of the fish is unknown.

Animals↗
PubMed2005

Influence of intensive fishing on the partitioning of mercury and methylmercury in three lakes of Northern Québec.

It has been demonstrated that intensive fishing, i.e., removing more than 25% of the fish biomass, can reduce mercury levels in predator fish in a lake. We test here the hypothesis that, by removing an important part of the fish biomass from a lake, a significant amount of methylmercury can be eliminated, therefore reducing the mercury available to the remaining biota, at least in the short term. A mass burden approach is used to evaluate the partitioning of total mercury and methylmercury in natural lake ecosystems. Three small natural lakes from the James Bay territory, in northern Québec, Canada, were selected for intensive fishing. Mercury (Hg) and methylmercury (MeHg) concentrations were evaluated for sediments, water column (dissolved fraction and suspended particulate matter), plankton, aquatic invertebrates, and fish. Biomasses were determined for fish, plankton, and aquatic invertebrates. Two case scenarios are presented using different mercury contributions from the sediment component (1 cm depth, and no sediment). Our results for the scenario including the sediment contribution show that lake sediments represent over 98% of the total mercury while the biotic components represent less than 0.1% of the same burden. For methylmercury, fish account for up to 5% of the burden, while sediments make up 84.6% to 93.1%. If we put aside the sediment contribution, the methylmercury in fish partitioning can represent up to 48%. As for invertebrates, they can account for up to 48% of the total MeHg burden. We do not observe any change in the partitionings or the quantities of Hg and MeHg before and after fishing in either of the two case scenarios even when we do not take into account dynamics of the ecosystems. This will be all the more the case when the dynamics of the system are included in the analyses. Therefore, biological parameters such as growth rates or fish diet must be considered.

Animals↗
PubMed1998

Assemblages of ectoparasites of a pelagic fish, slimy mackerel (Scomber australasicus), from south-eastern Australia.

Four-hundred and fifty-three Scomber australasicus, ranging in length from 14.1 to 46.5 cm and taken in 12 samples over 5 years from a single locality in south-eastern Australia, were examined. Ten species of ectoparasites were recorded: six monogeneans, three copepods and one isopod. The maximum number of parasite species in any one fish reached five, and the maximum total parasite intensity reached 39. Host size is an important determinant of the structure of ectoparasite assemblages of slimy mackerel: the average number of species per host peaked at 2.2 in fishes between 20 and 25 cm in length, then declined in larger fish; the abundance of all parasites on each fish similarly peaked in fishes 20-25 cm (mean of 9.9). The monogenean Pseudokuhnia minor had the highest prevalence and abundance of all parasites, infecting almost 80% of fish < 25 cm long. Over half of the total number of parasites belonged to this species, and it was dominant in intensity in just over half of the fish in which it occurred. When approximate volume was considered, assemblages were dominated by Kuhnia scombercolias in fish < 20 cm, by Kuhnia scombri in fish 20-34.9 cm, and by P. minor in fish larger than 35 cm long. The intensities of these three monogeneans were very strongly and positively correlated with each other, as were the intensities of P. minor and Grubea australis; the intensities of only one pair of species were associated negatively (K. scombercolias and the isopod Ceratothoa imbricata). A nested subset analysis indicates that the ectoparasite assemblages are random. This and the low prevalences and abundances of infection, as well as low species richness per fish, indicate that infra-assemblages are isolationist.

Animals↗
PubMed2003

Total mercury and methylmercury levels in fish from hydroelectric reservoirs in Tanzania.

Total mercury (THg) and methylmercury (MeHg) levels have been determined in fish species representing various tropic levels in four major hydroelectric reservoirs (Mtera, Kidatu, Hale-Pangani, Nyumba ya Mungu) located in two distinct geographical areas in Tanzania. The Mtera and Kidatu reservoirs are located along the Great Ruaha River drainage basin in the southern central part of the country while the other reservoirs are located within the Pangani River basin in the north eastern part of Tanzania. Fish mercury levels ranged from 5 to 143 microg/kg (mean 40 microg/kg wet weight) in the Mtera Reservoir, and from 7 to 119 microg/kg (mean 21 microg/kg) in the Kidatu Reservoir downstream of the Great Ruaha River. The lowest THg levels, in the range 1-10 microg/kg (mean 5 microg/kg), were found in fish from the Nyumba ya Mungu (NyM) Reservoir, which is one of the oldest reservoirs in the country. Fish mercury levels in the Pangani and Hale mini-reservoirs, downstream of the NyM Reservoir, were in the order of 3-263 microg/kg, with an average level of 21 microg/kg. These THg levels are among the lowest to be reported in freshwater fish from hydroelectric reservoirs. Approximately 56-100% of the total mercury in the fish was methylmercury. Herbivorous fish species contained lower THg levels than the piscivorous species; this was consistent with similar findings in other fish studies. In general the fish from the Tanzanian reservoirs contained very low mercury concentrations, and differed markedly from fish in hydroelectric reservoirs of similar age in temperate and other regions, which are reported to contain elevated mercury concentrations. The low levels of mercury in the fish correlated with low background concentrations of THg in sediment and flooded soil (mean 2-8 microg/kg dry weight) in the reservoir surroundings. This suggested a relatively clean reservoir environment that has not been significantly impacted by mercury contamination from natural or anthropogenic sources.

Animals↗
PubMed2000

A comparison of plasma vitamin C and E levels in two Antarctic and two temperate water fish species.

Antarctic fish have a high polyunsaturated lipid content and their muscle cells have a high mitochondria density suggesting that Antarctic fish are under greater oxidative stress than temperate water fish. To test this hypothesis, the plasma concentrations of the antioxidant vitamins E and C were measured in two Antarctic fish species, Pagothenia borchgrevinki and Trematomus bernacchii, and compared with the plasma concentrations of these vitamins in two New Zealand temperate water fish species, blue cod (Parapercis colias) and banded wrasse (Notolabrus fucicola). Neither vitamin is known to be synthesised in fish and so must be obtained from the diet. The plasma from both Antarctic fish species had vitamin E concentrations five to six times higher than those found in the two temperate water fish species. However, significantly higher levels of vitamin C were only found in the plasma of T. bernacchii, a benthic Antarctic fish. The average level of vitamin C in the plasma of the cryopelagic P. borchgrevinki was approximately one-third that of T. bernacchii. The T. bernacchii plasma yielded a high range of vitamin C values, possibly reflecting differences in nutritional status among the animals captured. No beta-carotene was found in any of the fish plasma samples studied. The data suggest that even though Antarctic fish live at -1.5 degrees C they may be exposed to greater metabolic stress from free radical mediated oxidation than temperate water species.

Analysis of Variance↗
PubMed2000

Comparative effects of perilla and fish oils on the activity and gene expression of fatty acid oxidation enzymes in rat liver.

The activity and mRNA level of hepatic enzymes in fatty acid oxidation and synthesis were compared in rats fed diets containing either 15% saturated fat (palm oil), safflower oil rich in linoleic acid, perilla oil rich in alpha-linolenic acid or fish oil rich in eicosapentaenoic (EPA) and docosahexaenoic acids (DHA) for 15 days. The mitochondrial fatty acid oxidation rate was 50% higher in rats fed perilla and fish oils than in the other groups. Perilla and fish oils compared to palm and safflower oils approximately doubled and more than tripled, respectively, peroxisomal fatty acid oxidation rate. Compared to palm and safflower oil, both perilla and fish oils caused a 50% increase in carnitine palmitoyltransferase I activity. Dietary fats rich in n-3 fatty acids also increased the activity of other fatty acid oxidation enzymes except for 3-hydroxyacyl-CoA dehydrogenase. The extent of the increase was greater with fish oil than with perilla oil. Interestingly, both perilla and fish oils decreased the activity of 3-hydroxyacyl-CoA dehydrogenase measured using short- and medium-chain substrates. Compared to palm and safflower oils, perilla and fish oils increased the mRNA level of many mitochondrial and peroxisomal enzymes. Increases were generally greater with fish oil than with perilla oil. Fatty acid synthase, glucose-6-phosphate dehydrogenase, and pyruvate kinase activity and mRNA level were higher in rats fed palm oil than in the other groups. Among rats fed polyunsaturated fats, activities and mRNA levels of these enzymes were lower in rats fed fish oil than in the animals fed perilla and safflower oils. The values were comparable between the latter two groups. Safflower and fish oils but not perilla oil, compared to palm oil, also decreased malic enzyme activity and mRNA level. Examination of the fatty acid composition of hepatic phospholipid indicated that dietary alpha-linolenic acid is effectively desaturated and elongated to form EPA and DHA. Dietary perilla oil and fish oil therefore exert similar physiological activity in modulating hepatic fatty acid oxidation, but these dietary fats considerably differ in affecting fatty acid synthesis.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2002

Addition of fish oil to diets for dairy cows. II. Effects on milk fat and gene expression of mammary lipogenic enzymes.

Sixteen Holstein cows in mid-lactation were used to determine whether alterations of mammary fatty acid metabolism are responsible for the milk fat depression associated with consumption of fish oil. Cows were given a total mixed ration with no added fish oil (control), unprotected fish oil (3.7 % of dry matter), or glutaraldehyde-protected microcapsules of fish oil (1.5% or 3.0% of dry matter) for 4 weeks. Milk samples were taken once a week and a mammary biopsy was taken from a rear quarter at the end of the treatment period. Milk fat content was lower in cows given unprotected fish oil (26.0 g/kg), 1.5% protected fish oil (24.6 g/kg) and 3% protected fish oil (20.4 g/kg) than in cows fed the control diet (36.0 g/kg). This was mainly due to a decrease in the synthesis of short-chain fatty acids. Consumption of protected fish oil decreased the abundance of lipogenic enzymes mRNA in the mammary gland. Acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase mRNAs for cows given 3% protected fish oil averaged only 30%, 25% and 25% of control values, respectively. Dietary addition of unprotected fish oil slightly decreased mRNA abundance of these enzymes but markedly reduced the amount of lipoprotein lipase mRNA. Milk fat content was significantly correlated with gene expression of acetyl-CoA carboxylase, fatty acid synthase, and stearoyl-CoA desaturase but not lipoprotein lipase. These results suggest that fish oil reduces milk fat percentage by inhibiting gene expression of mammary lipogenic enzymes.

Acetyl-CoA Carboxylase↗
PubMed1999

Fishing in urban New Jersey: ethnicity affects information sources, perception, and compliance.

Recreational and subsistence angling are important aspects of urban culture for much of North America where people are concentrated near the coasts or major rivers. Yet there are fish and shellfish advisories for many estuaries, rivers, and lakes, and these are not always heeded. This paper examines fishing behavior, sources of information, perceptions, and compliance with fishing advisories as a function of ethnicity for people fishing in the Newark Bay Complex of the New York-New Jersey Harbor. We test the null hypothesis that there were no ethnic differences in sources of information, perceptions of the safety of fish consumption, and compliance with advisories. There were ethnic differences in consumption rates, sources of information about fishing, knowledge about the safety of the fish, awareness of fishing advisories or of the correct advisories, and knowledge about risks for increased cancer and to unborn and young children. In general, the knowledge base was much lower for Hispanics, was intermediate for blacks, and was greatest for whites. When presented with a statement about the potential risks from eating fish, there were no differences in their willingness to stop eating fish or to encourage pregnant women to stop. These results indicate a willingness to comply with advisories regardless of ethnicity, but a vast difference in the base knowledge necessary to make informed risk decisions about the safety of fish and shellfish. Although the overall median income level of the population was in the $25,000-34,999 income category, for Hispanics it was on the border between $15,000-24,999 and $25,000-34,999.

Black or African American↗
PubMed1999

The long-term effect of advice to eat more fish on blood pressure in men with coronary disease: results from the diet and reinfarction trial.

BACKGROUND: Systematic reviews of fish and fish oil supplements have reported modest reductions in blood pressure (BP). Many of the trials included in these reviews used high doses of fish oil and most were of short duration. METHOD: Between 1983 and 1987 2033 men under the age of 70, who had recently suffered a myocardial infarction, were enrolled in a 2-year trial of dietary advice-the Diet and Reinfarction Trial (DART). Participants were randomised in a factorial design to receive intensive advice to eat more fish, less fat or more fibre. Those men randomised to receive fish advice were encouraged to eat two portions of fatty fish each week. Intake of eicosapentaenoic acid was 0.33 g per day in the fish advice arm and 0.10 g per day in men not given fish advice. RESULTS: The difference in systolic BP in the fish advice arm, adjusted for age and BP at baseline, was -0.61 mm Hg (95% CI -2.15, 0.92) at 6 months and 0.40 mm Hg (95% CI -1.33, 2.13) at 2 years. The difference in diastolic BP in the fish advice arm, adjusted for age and BP at baseline, was -0.50 mm Hg (95% CI -1.47, 0.46) at 6 months and 0.19 mm Hg (95% CI -0.88, 1.26) at 2 years. CONCLUSIONS: Advice to eat modest amounts of fish has little effect on BP in men with coronary disease.

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