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Complex assessment of inland water fish stocks
74-80Views:69In the domestic fish production, natural waters have yielded for several years about 7-8 thousand tons. This, from the point of view of outputs, considering the almost 130 thousand hectares of natural water, is rather low, it means approximately 55-60 kg/ha mixed fish.Although the various natural waters can differ significantly on the basis of yields, yet on the majority of the territories, the results were low. In the case of our extensive still waters and rivers, the reason can undoubtedly be found in the combined effect of the lack of the possibility of reproduction of the fish stock and the over-fishing. Fishery built on planning supposes the best possible knowledge in the given circum stances of the parameters of the water area and its fishstock. Lacking this knowledge, it is not possible to establish the optimal use fulness of the resources, what is more, the management can make faulty decisions – as a result of a lack of information -, which can risk the success of later activities.
It is known that many factors have an impact on the success of the fishery, as well as some information in connection with the water area and the fish stock are necessary, the knowledge of which make it possible to manage the fishery in a planned way. One part of the information is available, while the other part is incomplete or not deep enough. The necessary data are dissimilar depending on their nature, can be obtained from different places, by different methods.
As the first step for executing the field surveys and processing data, I developed a complex model, which contains in a unified system the steps of estimating the fishstock. I made the sampling on the basis of this. Part of the model is a fish faunistic survey, as well as a morphological survey of the water area. The information gained from these are important for making more accurate the system of devices of the samplings for stock estimation (duration, number of net-rows) and for assigning its place (places representing the best way the physical characteristics of the given water area). The major stages of stock-survey: A) faunistic survey, B) physical survey of the bed, and C) sampling with the help of gill-nets. This is followed by the evaluation by the computer module.
The results of the research create a methodological and technical background for the fish faunistic and population biologic surveys still performed in different ways in our country, and by applying these methods together, all basic information about natural waters which help decision-making concerning fisheries can be obtaine deffectively. -
Effect of fish feed containing two Chinese herbal extracts (Ganodema Iucidum and Lonicera japonica) on the non-specific immune system of Nile tilapia, Oreochromis niloticus (preliminary results)
9-14Views:116The effect of two Chinese herbs (Ganoderma lucidum and Lonicera japonica) on non-specific immune response of tilapia was examined. In addition to the control (no herbs), three diet variations were used. These contained 1.0% of Lonicera, 1.0% of Ganoderma and a mixture of Ganoderma (0.5%) and Lonicera (0.5%). The respiratory burst and phagocytic activity of blood leukocytes were monitored. Three weeks after feeding, the fish were infected with Aeromonas hydrophila. The results of this study showed that feeding tilapia with Ganoderma and Lonicera alone or in combination enhanced the phagocytosis of blood leukocytes, but not the respiratory burst activity. Both herbs, when used alone or in combination, reduced mortality after challenge with A. hydrophila. The highest mortality was observed in the control fish – 56.66%, and fish fed with Lonicera extract – 43.33% while 30% of fish died in the group fed with Ganoderma and the lowest mortality (20%) was observed when the fish were fed with a combination of the two herbs. It can be concluded that the herb extracts added to this diet act as immuno-stimulants and appear to improve the immune response and disease resistance of tilapia.
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Managing the relationship between natural spawning areas on unprotected floodplains and on protected man-made fishponds
25-31Views:59The economic land management of unprotected floodplain areas is possible only if considered jointly with protected floodplain areas, for which facility fisheries provide a solution. One solution could be that a part of the natural fish increment of the spawning-grounds on unprotected floodplains be raised in protected side fishponds and then later sold. This kind of fishery utilization is also favourable from economic, conservationist and flood protection aspects.
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The impact of employment and income circumstances on the development of regions
15-19Views:161The economic condition of an area is fundamentally determined by the extent of employement, as well as the size and composition of its active population. No sustainable economic growth is possible without the necessary amount of employees with the proper skills.
As regards the proportion of employees, i.e. economically active people is significanlty lower in Hungary than not only in Western Europe, but also countries which joined the EU recently. One of the reasons for this fact is the low amount of part-time employment and the other is the phenomenon that the number of agricultural employees – who had a significant role – greatly decreased in the county.
The employment level of the population in the county is nearly identical as that of the North Great Plain region and it is lower than the country average. The activity proportion, i.e. the joint proportion of employees and unemployed people in the population between 15–74 years of age is 3 percentages lower than the country average. The proportion of unemployed people greatly varies depending on the small regions of the county. The proportion of registered unemployed people in the population of active age is the lowest in Debrecen and the highest in the Hajdúhadház small region. The unemployment of career-starters is a further problem to deal with.
The composition of employees in the county is different than the country average. When compared in terms of different economic sectors, it can be observed that agriculture, game management, forestry and fishery are more significant than the country average. Of the provider sectors, the proportion of financial activity, real estate matters and economic services is lower, while that of accommodation services and hospitality is higher than the country average.
There are regional differences similar to unemployment in terms of the income size which is the basis of personal income tax per taxpayer.
The income level in the North Great Plain region is lower than the country average mainly in terms of income paid for work, where this difference is 23%, while it is only 5% in the case of social income. Altogether, the income and expenditure data of the North Great Plain region are not favourable. -
The effect of different fat content fish feed on the production parameters and meat quality of the hybrid striped bass
33-37Views:159The interspecific ’hybrid striped bass’ is the result of cross breeding. Their offspring have got good chances of growth and tolerate extreme water temperatures and the content of dissolute oxygen more than their parents. Furthermore, they are more resistant to diseases. Therefore, the hybrid is perfectly suitable for intensive fishery production.
Our experiment lasted for seven weeks. We analysed the indices of growth and production of the hybrid as the consequence of nurturing them with two feeds of high nutritive value during this period. We examined the content of fat and of fatty acids in the flesh of these fish. There were no considerable differences in terms of weight gain, feed conversion ratio and uneven growth between the two groups, while survival was less likely among the the fish which had consumed more fat. We demonstrated, examining the flesh of the individuals which had consumed feed containing lower fat content, that it was fattier and contained more dry matter than those that had been fed of higher fat content. Besides, the content of omega-3 and omega-6 fatty acids was higher in the fish that had consumed less lipids.