CAGE BREEDING OF WARM WATER FRESHWATER FISH SPECIES

Sedamdesetih godina prošlog stoljeća i Hrvatska se aktivno uključila u suvremene europske trendove uzgoja riba u plutajućim kavezima. Osim s raznim vrstama morskih riba pokušalo se i s uzgojem pastrva, šarana, soma, ozimica i lososa. Od svih navedenih slatkovodnih vrsta uspostavljeni su čvrsti standardi samo za kavezni uzgoj kalifornijske pastrve. Uzgoj ostalih slatkovodnih vrsta riba u kavezima zadržao se na razini sporadičnih pokušaja više eksperimentalnog nego profitabilno komercijalnog tipa. Uporna nastojanja da se ovlada i tehnikom uzgoja toplovodnih vrsta slatkovodnih riba u kavezima proizlaze iz zapaženih prednosti takvog uzgoja poput jednostavnosti provedbe tehnoloških mjera, lakše uspostave uzgojnog sustava, jednostavnije manipulacije, mogućnosti gušćeg nasada na jedinicu volumena uz visoku razinu proizvodnje, lakše prilagodbe zahtjevima tržišta i manje početne investicije u objekte. Unatoč brojnih prednosti kao značajniji razlozi izostanka masovnije primjene tehnologije kaveznog uzgoja toplovodnih vrsta slatkovodnih riba navode se problemi u kontinuiranom osiguranju i nabavi odgovarajućih kategorija i količina zdrave mlađi za nasad, specifičnosti i promjenjivosti fizikalno kemijskih karakteristika recipijenta te ljudske pogreške. Valorizirajući nedostatke i prednosti konačna prosudba o opravdanosti uzgoja pojedinih slatkovodnih vrsta toplovodnih riba u kavezima mora se bazirati i na biološkim i na ekonomskim čimbenicima. Temeljem dosadašnjih spoznaja za uzgoj u kavezima, a pravilo vrijedi za gotovo sve sustave intenzivnog uzgoja, povoljna je samo ona vrsta riba za kojom postoji potražnja na tržištu i koja ima visoku cijenu. Tehnologija koja zahtjeva prehranu visokokoncentriranim hranidbenim smjesama uz ostale troškove proizvodnje je skupa te je s jeftinijim vrstama riba nemoguće postići rentabilnost. Pored toga proizvodnja mora biti marketinški orijentira tj. prije početka proizvodnje neophodno je provesti odgovarajuće mjere istraživanja tržišta (mogućnost plasmana) i ekonomske ili gospodarske promidžbe.In the 1970s, Croatia became actively involved in the contemporary trend of breeding fish in floating cages. In addition to various species of marine fishes, breeding was attempted with trout, carp, catfish, cisco and salmon. Of the above freshwater fish species, specific standards were established only for the cage breeding of rainbow trout. Cage breeding of the remaining species remained at the level of occasional attempts, with more of an experimental than a commercial character. The regular attempts to master this technique for cage breeding of warm water freshwater fish species were aimed at achieving the known benefits of such breeding, such as simplicity of implementing technological measures, easier establishment of the breeding system, simpler manipulation, the possibility of denser colonies per unit volume with a high level of production, easier adaptations to market conditions and fewer initial structural investments. Despite the many advantages, the main reasons for the lack of greater implementation of the cage breeding technology for warm water species of freshwater fish include problems in obtaining the appropriate category and quantity of healthy fry, the specificity and applicability of physical and chemical properties of the recipients and human error. In evaluating the advantages and disadvantages, the final decision on the justification of cage breeding for individual warm water freshwater species must be based on both biological and economic factors. Based on the knowledge of cage breeding acquired to date, the rule for virtually all intensive breeding systems is that it is only recommended for those species with high market demand and a high market price. The technology that demands nutrition with highly concentrated feed and other production expenditures is costly, and is therefore not profitable with less expensive fish species. Furthermore, production must be market oriented, i.e. the appropriate market research measures, and economic promotion, must be implemented prior to starting production

UZGOJ SLATKOVODNE RIBE, STANJE I PERSPEKTIVE

U Vukovaru, gradu heroju, u kongresnoj dvorani Rodne kuće nobelovca Lavoslava Ružičke 17. i 18. travnja 2008. održano je 2. savjetovanje o slatkovodnom ribarstvu Republike Hrvatske s međunarodnim sudjelovanjem pod naslovom »Uzgoj slatkovodne ribe, stanje i perspektive«. Savjetovanje su organizirali Hrvatska gospodarska komora — Sektor za poljoprivredu, prehrambenu industriju i šumarstvo, Hrvatska gospodarska komora — Županijska komora Vukovar i ribnjak »Grabovo« d. o. o. Vukovar, a pokrovitelji su bili Ministarstvo poljoprivrede, ribarstva i ruralnog razvoja i Ministarstvo regionalnog razvoja, šumarstva i vodnog gospodarstva

ANALIZA MALIH OBITELJSKIH KOMERCIJALNIH RIBNJAKA U HRVATSKOJ

The significant economical and political changes that affected Croatia in last decade influenced the approach of small family farmers to fisheries as well. Most of them started that job without any knowledge and experience. That is why 13 farmers were interviewed in order to get the data about their farms, families and problems they face. The average farm has about 1 ha pond area, 4 family members and income connected with fisheries about 70% of total income. The owner is an artisan in his forties who sells about three tons of fish per year primarily through restaurant and sport fishing, as in present situation on the fish market it became obvious that persisting only on fish culture is the most difficult way to earn money. In building the ponds the rules of landscape architecture should be respected together with those of fishery science. It would be necessary to offer the farmers better conditions in bank loans to start their business as well as to reduce many taxes, which they have to pay. The Croatian Agricultural Extension Service should be organized better to serve those farmers.Značajne ekonomske i političke promjene koje su se u proteklom desetljeću dogodile u Hrvatskoj utjecale su i na male obiteljske farme da se mnoge među njima priklone i ribarstvu. Većina ih je započela ovaj posao bez ikakvog znanja i iskustva. Zbog toga smo intervjuirali 13 farmera s ciljem da prikupimo podatke o njihovim farmama, obiteljima i problemima s kojima se suočavaju. Prosječna farma posjeduje oko 1 ha vodene površine, ima 4 člana obitelji, a prihod povezan s ribarstvom sudjeluje s oko 70% u ukupnom prihodu. Vlasnik je obrtnik četrdesetih godina, koji prodaje oko 3 tone ribe godišnje prvenstveno kroz restoran i sportski ribolov, obzirom da se u današnjoj situaciji najteže zarađuje samo uzgojem riba. Pri izgradnji ribnjaka, pored pravila ribarske znanosti treba poštivati i ona uređenja krajobraza. Također je farmerima potrebno ponuditi bolje kreditne uvjete kako bi lakše započeli svojim poslom, kao i reducirati mnogobrojne naknade koje prate izgradnju ribnjaka i proizvodnju. Hrvatska poljoprivredna savjetodavna služba trebala bi se organizirati i u kvalitetnom praćenju ovakvih farmi

Rast pet populacija dvoprugaste uklije (Alburnoides bipunctatus) iz hrvatskih rijeka

Age, growth and mortality were analysed for spirlin (riffle minnow), Alburnoides bipunctatus that was collected from the five rivers in Croatia. Growth in length was very similar at all locations, so the average growth curve for this species in Croatia can be expressed as: Lt=15.2 (1-e-0,28(t+0,93)) A comparative growth index for the first five years of spirlin life was the lowest in the middle Korana river (98.0%) and the best in the middle part of the Dobra river (103.1%). All these indices are very close. The phi-primes also varied a little, resulting in the following average: ft= 4.24±0,11. Weight expressed positive allometric growth at four locations (b-value ranging from 3.10 to 3.56) and negative at only one (b=2,80). At the same location the total instantaneous mortality rate was the highest (z=1.14), while at other locations it ranged from 0.77 to 0.93. Spirlin is evidently subjected to great predation. Consequently, these results can help in comparing different water habitats.Starost, rast i mortaliteti analizirani su kod riblje vrste dvoprugaste uklije, Alburnoides bipunctatus, iz pet hrvatskih rijeka. Dužinski tempo rasta je vrlo sličan na svim lokacijama, tako da se prosječna krivulja rasta ove vrste u Hrvatskoj može izraziti sljedećom formulom: Lt=15,2 (1-e-0,28(t+0,93)) Usporedni indeks rasta u prvih pet godina života dvoprugastih uklija bio je najmanji u središnjem toku Korane (98,0%), a najbolji u središnjem toku Dobre (103,1%). Svi ovi indeksi su vrlo bliski. Performanca rasta također malo varira, dajući prosječenu vrijednost od = 4,24±0,11. Masa pokazuje pozitivan alometrijski rast na četiri lokacije (vrijednost b varira između 3,10 i 3,56), a negativan na jednoj (b=2,80). U istoj rijeci je i smrtnost najveća (z=1,14), dok se na drugim lokacijama nalazi u rasponu između 0,77 i 0,93. Dvoprugaste uklije su očito podložne velikoj predaciji. Posljedično, ovi rezultati mogu pomoći u uspoređivanju različitih vodenih biotopa

Utjecaj hranidbenog režima na preživljavanje šaranskih mladunaca tijekom testa na salinitetni stres - kratko priopćenje.

Experiments were carried out on common carp (Cyprinus carpio L.) larvae in a recalculating aquatic system for a period of 21 days. Four feeding variants with different transition times from live (nauplii of Artemia salina) to artificial feed (Biomar larviva) were examined. The greatest average total length (25.72 ± 3.37 mm) and weight (213.81 ± 105.52 mg) was achieved by common carp larvae fed over the whole period with nauplii of the brine shrimp (group D). A significantly higher (P<0.05) final bodyweight was reported in group D in comparison with groups A and B. Survival in groups B, C and D was high (81.53, 84.14, 80.66% respectively) but not in group A (32.44 - 43.36%) with the earliest transition to artificial feed. A salinity stress test was carried out on the final day of rearing. Common carp fry survival in the salinity stress test was analyzed using the Kaplan - Meier test. High significant differences (P<0.001) have only been reported between feeding treatments at 14‰ salinity level.Istraživanja su provedena na ličinkama šarana (Cyprinus carpio L.) u uzgojnim uvjetima recirkulacijskog sustava u trajanju 21 dan. Promatrana su četiri hranidbena režima s različitim prijelazima sa žive hrane (naupliji artemije, Artemia salina) na umjetnu hranu (Biomar larviva). Najveću prosječnu dužinu tijela (25,72 ± 3,37 mm) i masu tijela (213,81 ± 105,52 mg) ostvarile su ličinke šarana hranjene čitavo vrijeme nauplijima artemije (A. salina) u skupini D. Značajno signifikantna (P<0,05) završna tjelesna masa utvrđena je u skupini D u odnosu na skupine A i B. Najveći postotak preživljavanja utvrđen je u skupinama B, C i D (81,53; 84,14; 80,66 %), dok je u skupini A s najranijim prijelazom na umjetnu hranu postotak preživljavanja znatno manji (32,44 - 43,36 %). Test na salinitetni stres proveden je zadnjeg dana uzgoja. Preživljavanje mladunaca šarana tijekom salinitetnog stresa analizirano je Kaplan-Meierovim testom. Statistički značajna razlika (P<0,001) utvrđena je između hranidbenih režima samo pri salinitetu od 14‰

The Natural Diet of Five Cyprinid Fish Species

The investigation of the ichthyofauna in the upper part of the Croatian section of the Sava river, the so called barbel zone, showed that very frequent and quite numerous fish species were chub (Leuciscus cephalus (L., 1758)), bleak (Alburnus alburnus (L., 1758)), spirlin (Alburnoides bipunctatus (Bloch, 1782)), barbel (Barbus barbus (L., 1758)) and stream barbel (Barbus meridionalis petenyi Heckel, 1847). There are very few published papers on the biology of these fish species, and even less on their natural feeding in the open waters. Although these fish species economically less important, is play an important role in the open waters ecological niche. One of the most important factors for the ecological niche is food web. Therefore, the purpose of this paper was to revise the research and written documentation collected on the feeding of chub, bleak, spirlin, barbel and stream barbel in Croatia and in Europe. More important results on recent research done for each fish species in various waters in Europe are also presented in this paper