Virgin Fish Research Articles

The characteristics of PUFAs-rich virgin fish oil as affected by size of tuna eye

Abstract. Trilaksani W, Riyanto B, Ramadhan W, Sinulingga F, Fauziah S. 2023. The characteristics of PUFAs-rich virgin fish oil as affected by size of tuna eye. Biodiversitas 24: 6545-6556. The food supplement market expects growth in demand for long-chain omega-3 fatty acids, particularly Eicosapentaenoic Acid (EPA) and Docosahexaenoic Acid (DHA), which play crucial for brain development and can lower the chances of health issues like depression, Myocardial Infarction (MI), thromboembolism, and cardiac arrhythmias, and have anti-viral effects, boosting the immune system during the pandemic. Therefore, to meet this demand, exploring new sources is crucial. Tuna eyes have emerged as a potential source of DHA; however, quality and standardized sizes pose a challenge as they are by-products. The purpose of this research was to determine how the eye size of tuna affected the quality and yield of fish oil, which is a novel source of omega-3 fatty acids. This study determined the virgin oil profile of tuna eyes, which met the quality standards. The investigation covered morphology, chemical composition, heavy metal content, oil yield and quality, fatty acid composition, and related health lipid indices (Atherogenicity Index (AI) and Thrombogenicity Index (TI)). For the size specifications, tuna eyes were classified into three groups based on their diameter, namely 'small' (<6 cm), 'medium' (6-9 cm), and 'large' (>9 cm). The results showed that eye size directly influenced the weight, fat content, and oil yield, with negligible disparity in chemical composition except for the fat content; the larger the eyes, the higher the oil yield. Tuna eye oil had a safe composition for consumption with low or undetected heavy metals, the oil's oxidative level met CODEX standards, and the fatty acid profile revealed DHA as the most abundant fatty acid, reaching 36.95%. The predominance of n-3 series values in the fatty acid composition of tuna's eye was 9-12 times greater than that of n-6 fatty acid values. The values of AI and TI were 0.33 and 0.12; 0.47 and 0.20; 0.55 and 0.20 for large, small, and medium eyes, respectively. The study highlights tuna eyes' unique characteristics and potential applications in the food supplement industry.

INDUCED BREEDING AND FRY NURSING OF MYSTUS VITTATUS (BLOCH 1797)

The work is related to optimization of PG dose and survivability of the spawn of Mystus vittatus in the tank nursery at Arabpur Fish Farm in Jessore, Bangladesh during 2000 to 2002. Trial doses of PG used for induced breeding of M. vittatus were 1 to 4 mg PG in the first dose and 4 to 8 mg in the second dose for female. On the other hand, the male fishes were administered only a single trial dose of 2, 3 and 4 mg PG. Induced breeding was successfully done in M. vittatus with 3 mg of PG kg-1 body weight in first dose and 6.0 mg PG in second dose for female and a single dose of 3 mg PG for male for virgin fish, F1 and F2 generation. The tank nursery performance of the fry was studied in regard to length, weight, production and survivability rate. Live animal feeds (rotifers) were used. The highest growth and survivability of the fish fry was obtained by using rotifers of 40 cumm-1 and 20 cumm-1, respectively.

The effect of pregnancy on metabolic scaling and population energy demand in the viviparous fish Gambusia affinis.

Metabolism is a fundamental attribute of all organisms that influences how species affect and are affected by their natural environment. Differences between sexes in ectothermic species may substantially alter metabolic scaling patterns, particularly in viviparous or live-bearing species where females must support their basal metabolic costs and that of their embryos. Indeed, if pregnancy is associated with marked increases in metabolic demand and alters scaling patterns between sexes, this could in turn interact with natural sex ratio variation in nature to affect population-level energy demand. Here, we aimed to understand how sex and pregnancy influence metabolic scaling and how differences between sexes affect energy demand in Gambusia affinis (Western mosquitofish). Using the same method, we measured routine metabolic rate in the field on reproductively active fish and in the laboratory on virgin fish. Our data suggest that changes in energy expenditure related to pregnancy may lead to steeper scaling coefficients in females (b=0.750) compared to males (b=0.595). In contrast, virgin females and males had similar scaling coefficients, suggesting negligible sex differences in metabolic costs in reproductively inactive fish. Further, our data suggest that incorporating sex differences in allometric scaling may alter population-level energy demand by as much as 20-28%, with the most pronounced changes apparent in male-biased populations due to the lower scaling coefficient of males. Overall, our data suggest that differences in energy investment in reproduction between sexes driven by pregnancy may alter allometric scaling and population-level energy demand.

Extraction and microencapsulation of tuna virgin fish oil with mangrove fruit extract fortified into extrusion cereals

Long-chain omega-3 fatty acids (LCn-3FA) originally from fish have been recognized plays an important role in improving health status. Fortification these LCn-3FAs into foodstuffs will enhance their nutritional and functional value, however, their vulnerability, particularly to oxidation, requires extra protection. The goals of the research were to produce tuna eyes extra virgin fish oil (EVFO) microcapsules rich in DHA protected by mangrove fruit extract as a natural antioxidant and to obtain an extruded cereal with EVFO microcapsules. EVFO was extracted using cool centrifugation, microencapsulated by maltodextrin and arabic gum, and the cereal was formulated as extrusion flake products. The proportion of EVFO extracted from tuna eyes was 10.3596±0.73%. Mangrove fruit extract had a strong antioxidant activity with IC50 of 53.28 ppm. The best microcapsules were gained from arabic gum-maltodextrin coating material and the addition of 4000 ppm of mangrove fruit extract, which had an efficiency value of 93.71%, and round shape with size 6.26 μAm. Cereal with 35 g serving sizes and the addition of 3.6% EVFO microcapsules contributed approximately 134 kcal, 100 mg DHA, and 125 mg omega-3 increasing the great nutritional value.

Recovery of tuna virgin fish oil and formulation as a product model of emulsion food supplement

The aims of this study were to recover and characterize extra virgin fish oil (EVFO) from tuna eyes, and avoid deterioration and loss of EVFO functionality during extraction, formulation and storage of EVFO emulsion supplement. Research comprised extraction, characterization, and formulation of emulsions with addition of mangrove (Rhizophora mucronata) natural antioxidant extracts (0%, 2%, 4% and 8%), ascorbic acid (0.2%) and combination of mangrove extract and ascorbic acid (0.2%:0.2%). The extraction of EVFO used cool centrifugation technology and antioxidant activity of mangroves was measured by the ABTS method. Emulsion stability was verified for 2 weeks (25°C). The best formula was determined by using Bayes method. About 10% EVFO was isolated from tuna eye but its peroxide value was still high. The EVFO had a proportion of DHA up to 34.96%. Mangrove extract had an antioxidant activity of 52.96±0.42 ppm. The best preferred emulsion formula closest to the standard of stability was the formula added with mangrove fruit extract 0.8%. This EVFO emulsions supplement formula with serving sizes of 2 tea spoon (10 mL) donated 0.38 g of DHA which was approximately 32% of the average omega-3 requirement for the first trimester period of pregnancy.

Identification of unresolved complex mixtures (UCMs) of hydrocarbons in commercial fish oil supplements

Heightened awareness of the health benefits of fish oil consumption has led to a great increase in the number of fish oil supplements available to the consumer. Therefore manufacturers are continually looking for ways to distinguish their products from those of competitors. Minimally refined or virgin fish oils provide a unique feature; however, petroleum hydrocarbon contamination from oil spills is a reality in the world's oceans. The question arises whether oil produced from fish species caught in these polluted areas is free of petroleum hydrocarbons, with particular interest in unresolved complex mixtures (UCMs). This study investigates the presence of UCMs in commercially available fish oil supplements advertised as being virgin, as well as refined. Weathered petroleum hydrocarbons in the form of a UCM were found at 523 µg g(-1) in a virgin Alaskan salmon oil supplement. Supplements that were refined were free of this contamination. Fish used in the production of fish oil supplements appear to have accumulated petrogenic hydrocarbons in their tissues which were not removed by minimal oil refining. Further study is required to determine if there are any health implications associated with long-term consumption of these contaminated supplements.

Reproductive isolating barriers between colour-differentiated populations of an African annual killifish, Nothobranchius korthausae (Cyprinodontiformes)

Allopatric populations separated by vicariance events are expected to evolve reproductive isolating mechanisms as a result of disparate selection pressures and genetic drift. The appearance of reproductive isolating mechanisms may vary across taxa with differences in the opportunity for mate choice, and may be asymmetrical. In addition, premating barriers may be affected by individual mating experience. We used choice and no-choice experiments to investigate reproductive isolation between two allopatric (island and mainland) and colour-differentiated populations of an African annual fish, Nothobranchius korthausae. Assortative mating under experimental conditions was limited and asymmetrical. Preference for sympatric males was only expressed in nonvirgin females from one population. Virgin fish from both populations mated indiscriminately. No difference in the number of eggs laid, fertilization rate and hatching success was detected in no-choice experiments. All mating combinations produced viable offspring and no postmating barriers were detected in terms of the performance and fertility of F1 hybrids. Overall, we found little evidence for significant reproductive isolation, which is in contrast with the related killifish taxa in which assortative mating can be strong, even among allopatric populations with no colour differentiation. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 62–72.

Not Only the Tragedy of the Commons: Misperceptions of Bioeconomics

An exploratory search for explanations of mismanagement of renewable resources, other than the theory of the commons, was performed by an experiment. Eighty three subjects, mostly recruited from the fisheries sector in Norway, were asked to manage the same simulated virgin fish stock, one subject at a time. Exclusive property rights were granted to rule out the commons problem. Despite perfect property rights, subjects consistently overinvested, leading to an average overcapacity of 60%. The resource was reduced by an average of 15% below its optimal level. Overcapacity and tough “quotas” resemble the situation in Norwegian and other fisheries during the past few decades. The likely explanation of the observed behaviour is misperception of feedback, a phenomenon that occurs in many experimental studies of dynamically complex systems. Such misperceptions add a new and important dimension to the problem of renewable resource management, beyond the commons problem.

The entrainment and gating of the endogenous circannual rhythm of reproduction in the female rainbow trout (Salmo gairdneri)

The endogenous circannual rhythm of maturation in the female rainbow trout and associated changes in serum oestradiol-17β and vitellogenin (as calcium) can be entrained by abrupt changes in the photoperiod. Groups of virgin fish (which naturally spawn in December) maintained under LD 18∶6 from mid-January (Year 1), and then subjected to a reduction to LD 6∶18 either on 1st March (Group A), 1st April (Group B), 1st May (Group C) or 1st June (Group D), commenced spawning on 31st July, 13th and 30th August, and the 16th September, respectively. Fish maintained on LD 18∶6 throughout the experiment (Group E) commenced spawning on 10th October. These advances in the timing of spawning can be described in the form of a phase-response curve analogous to the entrainment behaviour of circadian oscillators. It is concluded that under natural conditions the annual change in photoperiod serves to continuously entrain the circannual clock thus ensuring that maturation and spawning occur at the optimal season for the survival of the species.

A Spurious Correlation in an Interpopulation Comparison of Atlantic Salmon Life Histories.

We tested two hypotheses concerning geographical variation in Atlantic salmon (Salmo salar) life histories: (1) mean age at first reproduction is positively correlated with growth rate at sea and (2) within-population variation in age at first reproduction first increases and then decreases with latitude. Data on growth and age at first reproduction were compiled from 41 populations in eastern North America. Data reliability was checked by a redetermination of ages based on scale examination. The proportion of fish that were incorrectly aged was small (°0.7%); however, aging errors were primarily of one kind; salmon that had previously spawned were misclassified as virgin fish of an older age class. Growth rate at sea was found not to be positively correlated with age at maturation. Schaffer and Elson's (1975) positive correlation between growth and age at first reproduction can be attributed to a subtle statistical artifact caused by aging errors. We also found that within-population variation of age at maturation was not related to latitude. We conclude that tests of life history theories should not assume constancy in life history traits, such as mortality, among populations.

Seasonal and sex-bound variation in the carbohydrate metabolism of the liver of the whitefish

Seasonal variations in the weight of the liver, its glycogen content and two carbohydrate enzyme activity values were studied in specimens of Coregonus nasus (Pallas), sensu Svärdson. 1. 1. The results obtained for virgin fish and for maturing or spent males revealed similar patterns of variation, though the figures for the virgin fish were generally somewhat higher. 2. 2. The group of males in spawn, measured in October, stood out by virtue of the high liver glycogen content recorded. 3. 3. Compared with the other groups, the mature or spent females had larger livers from July (the onset of rapid gonadal development) to January, lower liver glycogen content during the winter, lower G6Pase activity during September-November and lower glycogen phosphorylase activity from August until the spring. 4. 4. The main reasons for these sexual differences are thought to be the vitellogenetic role of the liver and an estrogen-induced inhibition in the carbohydrate metabolism. 5. 5. The high glycogen content observed in November and the winter months, the increased liver size found in virgin fish and the increase in G6Pase activity in midwinter are all associated with seasonal acclimatization. The increase in glycogen phosphorylase activity in virgin fish and in males took place during the autumn. 6. 6. On one occasion very low G6Pase activities were found, together with rapidly increasing glycogen content in the liver. 7. 7. In general, the liver glycogen content decreased considerably in the spring while the sea was still frozen over, though this decrease was completed between taking the May and June samples. The phenomenon was accompanied by high glycogen phosphorylase activity, especially in the virgin fish.

The interaction of endocrine and experiential factors in the regulation of sexual behaviour in the female guppy Poecilia reticulata.

Abstract1. A large proportion of virgin female guppies, Poecilia reticulata, are highly responsive when first placed with actively courting males. This responsiveness wanes over several days if a female is repeatedly exposed to male courtship in a standard test situation (15 mins./day on alternate days). The decline in response occurs even though copulation is prevented by presenting males which have been gonopodectomized (gonopodium removed). Many females become responsive again for a short period(s) some time after the initial period of receptivity at the start of testing. Examination of individual records of females tested for up to 6 weeks suggests that there are cycles in responsiveness which correspond closely to the 20-21 day cycle in receptivity demonstrated in nonvirgin fish (Liley, 1966). The data indicate that a virgin female is likely to be initially highly responsive whatever the stage of her endogenous cycle, hut after involvement in courtship a cycle in responsiveness becomes apparent. 2. Naive virgin females were highly responsive when first tested 2, 10 or 24 days after ovariectomy (Experiment 2). However in contrast to intact fish there was no reappearance of receptive behaviour after sexual activity observed at the start of testing had waned. 3. The rate of decline in responsiveness of naive virgin females is to some extent dependent upon the courtship testing regime (Experiment 3). Most females tested with gonopodectomized males for 20 minutes per day had become unresponsive by the 6th or 7th day; receptivity of females tested at 3 and 6 day intervals declined more slowly but eventually reached the same level as fish tested every day. Testing females with intact males on the first three days resulted in a more rapid drop in female responsiveness. Ovariectomized females were less responsive and their receptively waned more rapidly than intact females. 4. In experiment 4, an attempt was made to determine whether the high initial responsiveness of virgin females was due to the fact that they had been deprived of social stimulation provided by males. Virgin females were tested with gonopodectomized males on 8 consecutive days during which their receptivity declined to a low level. Females were then isolated from males individually or in groups for 1, 2, 3, 4 or 6 weeks before being retested with gonopodectomized males. There was no recovery of responsiveness to a level typical of naive virgin fish in the previously isolated females. Any recovery of responsiveness which did occur was that which might be expected on the basis of each female having the potential to undergo a cycle in receptivity related to an endogenous cycle of approximately 20 days. 5. It is concluded that there is a cycle in receptivity in virgin females which reflects an endocrine cycle in ovarian activity. In addition naive fish show an initially high level of response which is not dependent on the immediate ovarian hormone state and masks the cycle regulated by the ovary. The responsiveness of naive fish habituates as a result of exposure to male courtship. It is suggested that the interaction between the decremental effects (habituation) induced by courtship and the incremental effects of ovarian hormone and short-term incremental effects of courtship may interact in a manner which adjust female receptivity to the social environment, terminating sexual responsiveness once insemination has occurred a number of times.

Variable Seaward Migration of Salmon

Salmon (Salmo salar) kelts from hatchery operations, when liberated in rivers and in or near river estuaries, show by the distribution of the recaptured fish an extent of seaward migration that varies from river to river, apparently in relation to the character of the estuary and river influence in the sea. For the very large St. John river (N.B.) they are mainly in the long, deepish estuary and rarely leave the zone of river influence, while for the smallish Margaree river (N.S.), with a short, shallow estuary well emptied by the tide, they are mainly near the coast outside the estuary and commonly wander to distant places in various directions. This distribution may (Margaree) or may not (St. John) correspond with that of virgin fish. The Miramichi (N.B.) with strong river influence and long estuary resembles the St. John, while the Annapolis and Philip rivers (N.S.) with slight river influence are more like the Margaree.For each river and location of liberation, the extent of seaward distribution is found to vary with differences in river discharge during a presumed settling-down period after liberation. Sharp freshets are correlated with more riverward distribution at least for a time. Heavy floods are correlated with a more seaward distribution. Continued low water is correlated with a wide distribution.

Sea Movements of Canadian Atlantic Salmon Kelts

Salmon related to various rivers of eastern Canada were tagged and liberated after spawning, by the Department of Fisheries in various years from 1913 to 1936. Analysis of the recaptures shows varied movements, the differences from river to river and for the one river from year to year being seen as due to differences in the environment. When liberated in or even outside the estuary, they may enter and ascend the river while still in the kelt condition, if suitable freshets occur.As kelts and as clean fish in both first and second years after liberation, they are principally found in the estuary, distinctly more riverward than the virgin fish. However, when swept out of the estuary, as occurs in a river like the Margaree and, if return is difficult, their distribution will differ but little from that of the virgin fish.A pronounced zone of river influence in the sea is seen as holding the salmon to the locality near the river mouth, as for the Saint John river of New Brunswick. With an indistinct zone, more or less of the salmon wander to other regions, largely in correspondence with water movements.The length of time between successive spawnings is found to correspond with the time between the smolt stage and first spawning and to be related to sea temperature during the spring and summer.