YUGOSLAVIA

by

N. Fijan
National Correspondent
Veterinary Faculty, University of Zagreb
Biology and Pathology of Fish and Bees
Heinzelova 55
P.O. Box 190
41001 Zagreb

I. FISHERY BIOLOGY AND MANAGEMENT

In accordance with the existing legislation, the sport fishing organizations, fishery working organizations or associacions of fishermen which were given or wish to obtain right to exploit open waters of a region or of a water body have to secure the preparation and the execution of the basis for fishery management in such waters. Plans for basis of management are being prepared and renewed when necessary by specialized fishery institutions after an analysis of physico-chemical, biological and ichthyological characteristics and of an estimation about the bioproductional capacity. They contain recommendations and norms for stocking and exploitation. This work has resulted in accumulation of data and publications on hydrological, hydrochemical and saprobiological investigations of the status and changes in various open waters.

The protection of endemic species, especially the salmonid ones is one of the proposed future priorities for regions where such species exist.

Regular stocking of lake Ohrid with eel, which became necessary after the construction of the hydroelectric dam, is giving positive reults.

Crayfish populations started to recuperate in some of the localities which were previously devastated by diseases or overfishing. In other water bodies, where ecological changes caused declines or disappearance of crayfish such recuperation has not been noted. Studies on distribution, influence of water regulation work and on some diseases are in course in SR Slovenia and SR Croatia.

II. FISH CULTURE AND DISEASES

1. Pond culture

The majority of production is now based upon controlled reproduction with artificial fertilization. The newest large hatchery successfully applies recirculation of water. Incubation of Chinese carp eggs in rectangular plastic tanks (2–4 m³) with aeration and a slow flow of water is advantageous in comparison to use of vertical incubators under conditions of one of the hatchery.

In production experiments with fry and fingerlings, high yields 3.000–4.500 kg/ha were obtained in o,5–2 ha ponds on two farms with a technology which encompasses pond preparation, manuring, feeding with formulated diet, polyculture, aeration and disease prevention. Interesting results were also obtained on another farm with organic or inorganic fertilization only: yields between 900 and 1120 kg could be economically interesting. Hovewer, the fingerling production is still not quite satisfactory due to problems associated with the predominantly large size of ponds and consequent problems with diseases and bird predation.

Analyses of two and three summer production cycles for consumption size carp indicated the tradition and the market demand for three summers old fish of over 1,3 kg to cause a significant increase in production cost.

Chinese carps are being reared in polyculture with carp in Yugoslavia for 20 years. During the past 14 years, their participation in total yield has increased in SR Croatia (and similarly in other parts of the country) from about 3 per cent to over 20 per cent. Up to 30–50 per cent of Chinese carps in a balanced polyculture with a total yield of up to 2.800 kg/ha are not impeding the growth of carp.

After the initial predominance of grass carp, the bighead has occupied the leading place because of its fast growth rate. Recently, the participation of the latter in yield is being decreased because of its competition with carp and in order to restore the drop in yield of carp. Silver carp production is beneficial to the total yield but causes difficulties due to mortalities after handling and limited acceptability on the market. Bighead silver carp hybrids are gaining the importance.

Diseases are the principal problem in the production. Difficulties in prevention, diagnosis and treatments for diseases in huge ponds are the main reason for the recent tendency to reconstruct such ponds into smaller ponds for higher yields.

New veterinary legislative regulations on diseases of animals, including fishes, are recently in the procedure of preparation and adoption.

Predatory birds, especially the growing populations of cormorants, are causing large losses on a constantly increasing number of farms. The number of new nesting areas around farms is alarming. The problem of predation by this protected species is being negotiated with corresponding agencies.

2. Culture of salmonids in flow-through systems

Yields in rainbow trout farms have slightly decreased due to difficulties with the import of food ingredients. Basic standards for broodstock selection on farms have been established in SR Slovenia.

The culture of other salmonids for stocking is gaining importance. The essential role of copepods for feeding of grayling fry and fingerlings has been established.

3. Cage culture

This type of fish culture is still in initial phases of development. Rainbow trout isbeing cultivated in brackish waters. Culture of wels is in development, on several locations. Fattening of carp in cages with high protein food gave excellent results and meat quality, but can not compete economically with pond culture.

III. FISH AND POLLUTED WATER

Enforcement of legislation is slowly reducing the incidence and severity of acute and chronic cases of water pollution. For instance, in SR Slovenia the number of such cases has decreased from 100 in 1983 to 40 in 1984 and 36 in 1985. Biotests are being introduced for monitoring of areas under threat.

Initial studies on influence of cage culture on a shallow lake have shown an increase in oxygen demand and plancton population around installations. Further work is in progress.

Carp farms are not influencing the water quality of adjacent waters.

IV. STATISTICS

1. General

The official Federal statistical data are presenting the fisheries in a global form - they are not separating the catches from the aquacultural production. Definite data were published for 1983 and estimates given for 1984+.

In 1983, the total catch of freshwater fishes was 26.527 tons. The common carp participated in this total with 14.405 tons. For 1984, the total catch was estimated to be 25.098 tons and 13.568 tons there of was the catch of the carp.

The total fish consumption per capita was on a constant increase from 1960 (1,5 kg/person/year) untill 1981 (4,3 kg/person/year), but has decreased in 1983 to 3,4 kg/person/year.

⁺ Anon: Statistički godišnjak. Vol. 32.Beograd, 790 pp. 1985

2. Open waters

The Fragmentary published data and informations indicat diverging trends in different Republics and water bodies.

In SR Slovenia with sport fishery as the principal user of these (mostly oligotrophic) waters, the production is on a slight increase. Annual catches of salmonids amount about 51 tons (rainbow trout 42 per cent, bronon trout about 35 per cent, grayling about 16 per cent, while Hucho hucho and other species comprise the rept). Catch of cyprinids totals about 213 tons.

Waters of this republic are being stocked with seven salmonid species.

In SR Croatia, sport and commercial catches are slightly increasing, the 988 tons being highest in the decade.

Catches in large lakes in SR Macedonia during the period 1973–1982 have decreased when compared with the period 1945–1955, with a tendency of worsening in the structure of species.

3. Fish culture

Data on fish culture are regularly presented for SR Croatia+. These data reflect well the general situation in carp farming in the whole country.

In 1984, the average yield in 12.559 ha of carp ponds was 1.204 kg/ha, 9,8 per cent less than in 1983. The food conversion rate was 2,7. The corn was the predominant additional food, followed by wheat, barley and formulated feeds.

The structure of market - size fish consisted of 73,3 per cent of common carp and 20,37 per cent of chinese carps, while predators (wels, pikeperch), tench and trashfish, comprised the rest.

The production of rainbow trout in SR Croatia in 1984 was 586 tons, 12 per cent less than in 1983. Being one of smallest producers, of trout in the country, the tendencies in this Republic are not as typical for the whole country as in the case of pond farming.

⁺ Turk, M.: 1985 Freshwater fisheries of SR Croatia for the year 1984. Ribarstvo Jugoslavije 40(3--6), 97–102

V. BIBLIOGRAPHIC REFERENCES

AL-SABTI K., FIJAN N.,KURELEC B.: 1984. Frequency of caromosomal aberrations in the rainbow trout (Salmo gairdneri, Rich.) exposed to detergent and benzene. Veterinarski arhiv, 54(2):83–89.

APOSTOLSKI K.: 1985. Lake fisheries in Macedonia. Ribarstvo Jugoslavije,40(1): 10–15.

APOSTOLSKI K.,RŽANIčANIN B.: 1984. Basic elements for programming cage fish culture. Ribarstvo Jugoslavije, 39(5–6):90–94.

BUDIHNA N.: 1985. Geographical distribution of crayfish Astacus astacus L. 1758 in the river Mura basin (Slovenia, Yugoslavia). Ichthyos 2:18–22.

CAKIĆ P.: 1984. Supplement to distribution of Pseudorasbora parva (Schlegel 1842) in Yugoslavia. Ribarstvo Jugoslavije, 39(5–6): 87–89.

DEBELJAK LJ.,FAŠAIĆ K.: 1985. Daily changes of some hydrochemical parameters in a carp fish-pond. Veterinarski arhiv, 55(1): 23–30.

DELIĆ A.: 1985. The lenght and weight growth rate of open water fish of the community of NovaGradiška. Ribarstvo Jugoslavije, 40 (4–5–6): 80–85.

FAŠAIĆ K.,DEBELJAK LJ.,POPOVIĆ; J.,GABRIĆ Z.,KRNJAKOVIĆ S.: 1984. Carp fingerlings culture under the conditions of intensive fertilization. Ichthyologia, 16(1):85–100.

GREGURIĆ J.,MUIĆ V.: 1985. Salmonelosis in fish. Ribarstvo Jugoslavije,40(4–5–6): 90–92.

GROZA T.: 1984. Influence of food on the development of the common carp (Cyprinus carpio L.) intestine in conditions of fish ponds and open waters. Ribarstvo Jugoslavije, 39(5–6):95–97.

HABEKOVIĆ D.: 1984. Recent news on herbivorous fish. Ribarstvo Jugoslavije, 39 (5–6):72–74.

HACMANJEK M.: 1985. Telohanelosis - a more and more frequent disease on Yugoslav fish farms. Ribarstvo Jugoslavije, 40(4–5–6):94–96.

ILIĆ V.: 1984. Pike, pikeperch and carp fish spawnings in closed backwaters connected to the main river by a sluice. Ribarstvo Jugoslavije,39(2):42–44.

JEROMEL T.,AVŠIĆ F.: 1985. Fish culture and hydroaccumulation. Veterinarstvo Jugoslavije, 40(2–3):60–62.

KARAMATIĆ V.: 1984. Duck breeding on fish ponds. Veterinarstvo Jugoslavije, 39 (5–6): 109–111.

MILINKOVIĆ R.: 1985. Influence of different diets on the quality and production of fish eggs and rainbow trout fry (Parasalmo gairdneri Rich.). Veterinarstvo Jugoslavije, 40(1): 2–9.

MIŠETIĆ S., NOVAčIĆ D.: 1984. Influence of big head (Aristichtys nobilis Rich.) on zooplankton dynamics and the growth rate on common carp. Veterinarstvo Jugoslavije, 39(3–4): 65–71.

MUNJKO I., HEGEDIĆ D.: 1985. Aliphatic and aromatic hydrocarbons in industrial wastewaters. Ribarstvo Jugoslavije, 40(2–3): 37–40.

OCVIRK J.: 1984. Health problems inbrook trout (Salvelinus fontinalis M.) production in Slovenia, Yugoslavia. Ichthyos, 1:14–17.

OCVIRK J.: 1985. Growth dinamics of pike (Esox lucius Linnaeus 1758) in lake Vrana, island Cres, Croatia. Ichthyos, 2:11–17.

PETRINEC Z., DORDEVIĆ V.: 1985. Artificial spawning of the silver carp (Ctenopharyngodon idella Val.). Ribarstvo Jugoslavije, 40(2–3): 40–42.

POPOVIĆ J., FAŠAIĆ K., HOMEN Z.: 1984. Eel (Anguilla anguilla L. 1758) comparative research of lenght-mass relation from two different ecosystems. Ichthyologia, 16(1–2): 29–41.

RŽANIčANIN B., SAFNER R., TREER T.: 1985. Influence of external factors on the growth of common carp (Cyprinus carpio) in cage culture. Ribarstvo Jugoslavije, 40(2–3): 49–51.

RŽANIčANIN B., SAFNER R., TREER T.: 1984. Results of the first cage culture of carp (Cyprinus carpio) on lake Vrana near Biograd n/m. Ribarstvo Jugoslavije, 39(2): 29–31.

RŽANIčANIN B., TREER T., SAFNER R.: 1984. Results of the first cage culture of sheat fish (Silurus glanis L.) on lake Vrana near Biograd n/m. Ribarstvo Jugoslavije, 39(2): 32–35.

SOFRADŽIJA A., VUKOVIĆ T., HADŽISELIMOVIĆ R.: 1984. Ihtiofauna of river Mlječanica on a wide area of the future thermal touristic centar of Meduvode (Bos. Dubica). Ribarstvo Jugoslavije, 39(2): 25–29.

STANKOVIĆ L., PETROVSKI N., KAPAC E., NAUMOVSKI M.: 1984. Saprobiological conditions of the varoar river and its fish populations. Ribarstvo Jugoslavije, 39(1): 1–4.

SVIRčEVIĆ V.: 1985. Endoparasitic helmints of freshwater fish intae river Tisa. Ribarstvo Jugoslavije, 40(2–3): 27–37.

TESKEREDŽIĆ E.: 1985. Fish cage culture. Ribarstvo Jugoslavije, 40(2–3): 42–48.

TOMEC M.: 1984. Estimation of Saprobiological water quality in carp ponds of SR Croatia. Ribarstvo Jugoslavije, 39(2): 36–42.

TURK M.: 1985. Culture of two and three year old fish (carp) for consumer use (consumption). Ribarstvo Jugoslavije, 40(4–5–6): 68–73.

TURK M.: 1985. Freshwater fisheries of the SR of Croatia for the year 1984. Ribarstvo Jugoslavije, 40(4–5–6): 97–102.

TURK M.: 1984. A twenty year culture of herbivorous fish in the fish ponds of Yugoslavia. Ribarstvo Jugoslavije, 39(3–4):59–64.

VELJOVIĆ P.: 1985. Food spectar of Esox luciusL., Stizostadion lucioperca L., in the middle of the river Sava. Ribarstvo Jugoslavije, 40(2–3): 51–55.

VOVK J.: 1984. Dietary problems with zooplankton in fry breeding of grayling (Thymallus thymallus L.). Ichthyos, 1:2–6.

VRHOVŠEK D., KOSI G., KRALJ M., BRICELJ M.: 1985. Biological evaluation of water quality of river Sava from Zidani Most to Croatian border. Ichthyos 2:1–10.

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