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Optimizing fish structure in angling ponds focusing on white fish
33-36Views:188According to new amendments of laws, commercial fishing licenses of natural waters shall not be issued from the calendar year 2016 in Hungary. However, the most settlement of white fish to angler ponds originated from natural waters. Currently, there is no sufficient quantity of fish species belonging to this group available to fulfil the settlement commitments of fish farmers. The aim of this recent study is to develop a breeding and production technology that is suitable for settlement of large quantities of this fish species of appropriate length of (4–5 cm). The following methods are investigated: aquaculture cage system (pond-in-pond system), monoculture and mixed population with different ratio of white fish in fish structure. Due to the different environmental needs of different fish species, many parameters need to be investigated, for example: stocking density, feeding, oxygen level, monoculture or mixed populations, growth potential and mortality. A preliminary experiment was carried out following the artificial propagation of ide (Leuciscus idus) following a 21-day larval rearing experiment in which the effect of different stoking density was investigated for mortality and growth. On the basis of the expected results, the optimal conditions for the aquaculture cage system will be described, regarding to the white fish stock.
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A gombatermesztés szerepe az átalakuló magyar mezőgazdaságban
15-22Views:98The structure of Hungarian agriculture should be changed before the EU accession. The new structure should fulfill EU requirements and also produce competitive products. Unconventional products (mushroom, fish, honey etc.) have a lot of advantages: they can be produced on small farms, their trade is mainly free of regulation and their markets are almost unlimited. This paper deals with one of these alternative agricultural enterprises, namely mushroom production. Hungarian mushroom production – in spite of difficulties – has witnessed remarkable expansion: it has increased its production by fourfold and its export by fivefold in less than ten years. The low level of wages gives Hungary significant advantage over its competitors. If we could ensure the appropriate infrastructure (technical advice, bank loans, etc.) the mushroom industry would become one of the most profitable sectors of Hungarian agriculture.
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Data to the growth of yoy (0+) tenches (Tinca tinca L.) in Tisza Lake
102-105Views:132Young of the year (YOY) tenches (Tinca tinca L.) were caught in relatively great number in Tisza-Lake at the Tiszafüred section on last days of October in 2004. The standard length of these fishes varied between 20 and 46 mm. It seemed that the collected sample could provide appropriate data to examine the size-structure of YOY tenches, so we measured their standard body-lengths in mm and -weights in hundred parts of gramm unit. After the statistical analysis were found the follows:
1. The curve of length frequency corresponds with normal distribution, i.e. there was not found multimodal curve as could be expected in the case of a periodic spawning species.
2. The average standard length of the examined individuals – although the environmental conditions of the population is good – was only 31 mm. It is far below the 37 mm average of the lowest growth of tench population was found in the scientificpapers.
3. More than 20% of measured sample belonged to the range of 20-26 mm. The estimated ages of these fish specimens are about 70 days, according the scientificpapers.
By right of above mentioned can be concluded that the sample represents only one age-group from a late spawning, and not the whole range of YOY tenches, so these data can give information about the size structure only of this group. The 31 mm average standard length of individuals, origin from spawning in late July or beginning of August is accordance with age and environmental conditions as well.