FISHERIES IN CZECHOSLOVAKIA

Longtime tradition of fisheries in Czechoslovakia which dates from the 12th century has some specific characteristics. Traditional technology of carp culturing (two and four years culturing) has been kept on 52 000 ha of fish farms basing its production by using natural fish food which gives the best quality of consumption fish. The results of the culture are: After the first year of culturing the average individual weight was 30— -50 g, at the end of the second year 250-500 g, at the end of the third year 1200-1800 g and at the end of the fourth year 2200-3000 g. Due to geographic and climate conditions in Czechoslovakia the individual weight could be even after the third year of life 2000-2800 g applying some specific technology. One of the method of the intensive fish production on carp ponds is polyculture. There is a list of fish used in polyculture with carp: predatory fish: pike fish (Esox lucius), pike perch (Stizostedion lucioperca), sheat (Siluris glanis), eel (Anguilla anguilla), rainbow trout (Salmo gairdneri), (Coregonus lavaetus maraena, Coregenus peled), herbiovorous fish — grass carp, big head and silver carp (Ctenopharyngodon idella, Hypophthalmichthys molitrix and Aristichthys nobilis) and tinch fish (Tinea tinea). Besides traditional technologies new industrial methods of intensive fish culturing are introduced using channels and net cages. An intensifications of fish culturing was enabled by artificial spawing of fish in the warm waste waters of energetic and industrial objects. The basic force in the development of fisheries in Czechoslovakia is scientific and researching activity as well as education. Since 1921. has existed The Institute for Fisheries and Hydrobiology in Vodnany, then The Institute for Fisheries and Hydrobiology in Bratislava, The Agricultural University in Brno has also The Department for Fisheries and Hydrobiology and the subject fisheries exists in other high schools in Prag, Češke Budejovice and Nitra. They also have special schools, one in Trebon lasting for three years and the other one in Vodnjani lasting for four years educating fish professionals. The development of fisheries and an increase of fish production is improved by trade, packing; the quality of products and advertising

FISHERIES IN CZECHOSLOVAKIA

Longtime tradition of fisheries in Czechoslovakia which dates from the 12th century has some specific characteristics. Traditional technology of carp culturing (two and four years culturing) has been kept on 52 000 ha of fish farms basing its production by using natural fish food which gives the best quality of consumption fish. The results of the culture are: After the first year of culturing the average individual weight was 30— -50 g, at the end of the second year 250-500 g, at the end of the third year 1200-1800 g and at the end of the fourth year 2200-3000 g. Due to geographic and climate conditions in Czechoslovakia the individual weight could be even after the third year of life 2000-2800 g applying some specific technology. One of the method of the intensive fish production on carp ponds is polyculture. There is a list of fish used in polyculture with carp: predatory fish: pike fish (Esox lucius), pike perch (Stizostedion lucioperca), sheat (Siluris glanis), eel (Anguilla anguilla), rainbow trout (Salmo gairdneri), (Coregonus lavaetus maraena, Coregenus peled), herbiovorous fish — grass carp, big head and silver carp (Ctenopharyngodon idella, Hypophthalmichthys molitrix and Aristichthys nobilis) and tinch fish (Tinea tinea). Besides traditional technologies new industrial methods of intensive fish culturing are introduced using channels and net cages. An intensifications of fish culturing was enabled by artificial spawing of fish in the warm waste waters of energetic and industrial objects. The basic force in the development of fisheries in Czechoslovakia is scientific and researching activity as well as education. Since 1921. has existed The Institute for Fisheries and Hydrobiology in Vodnany, then The Institute for Fisheries and Hydrobiology in Bratislava, The Agricultural University in Brno has also The Department for Fisheries and Hydrobiology and the subject fisheries exists in other high schools in Prag, Češke Budejovice and Nitra. They also have special schools, one in Trebon lasting for three years and the other one in Vodnjani lasting for four years educating fish professionals. The development of fisheries and an increase of fish production is improved by trade, packing; the quality of products and advertising

WATER CHEMISTRY IN CARP PONDS

Istraživanja su provedena u četiri šaranska ribnjaka pojedinačne veličine 100, 173 i 202 ha. Istraženi su osnovni hidrokemijski parametri i kvalitativni sastav planktona radi uvida u ihtiohigijensko stanje ribnjaka. Od kemijskih su parametara istraženi količina O2, CO2, NO3-; NH4+, NO2-,PO43-, potrošak KMnO4 i pH, to njihov horizontalni raspored. Sve istražene ribnjake karakterizira različita bioproduktivnost (tabl. 1. i 2). Kemizam je vode u svim ribnjacima za vrijeme uzgojne sezone varirao unutar široke amplitude. Vrijednosti svih parametara bile su unutar dopuštenih razina za šaranske ribnjake, osim količine kisika otopljenog u vodi u ribnjacima veće bioproduktivnosti (tabl. 3 - 6). U svim je ribnjacima bila jasno izražena horizontalna distribucija istraženih hidrokemijskih parametara (tabl. 3 - 6) bez obzira na razinu bioproduktivnosti.A research has been done in four carp ponds measuring 100, 173 and 202 ha each. In order to understand ichthyohygienic state of the ponds, basic hydrochemical parameters and qualitative composition of plankton were investigated. The following chemical parameters were investigated: the quantity of O2, CO2, NO3-; NH4+, NO2-,PO43-, consumption of KMnO4 and pH and their horizontal distribution. All the ponds are characterized by dissimilar bioproductivity (tables 1 and 2). Water chemistry in all the ponds during the culturale season varied within large amplitude. All the parameters were within limits permissible for carp ponds, except for the quantity of dissolved oxygen in ponds of higher bioproductivity (tables 3-6). No matter what the bioproductive value was, hydrochemical parameters in each pond had distinct horizontal distribution tendency