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

Growth and Gonad Changes in Stony Sea Urchin, Paracentrotus Lividus (Lamark, 1816) Fed Artificially Formulated Feed and Benthic Macrophyte Diet

This study reported the efficiency of artificially formulated feed and benthic macrophyte diet on growth and gonad development of cultured stony sea urchin, Paracentrotus lividus (Lamark, 1816). An initial sample of 720 individual urchins was gathered in coastal area of SE Adriatic, near Dubrovnik, Croatia and for the purposes of the experiment, was held in a flow-through system. Sea urchin were fed four test diets A, B, C and D. Diet A consisted of seaweeds collected in the natural habitat of sampled sea urchin, artificial diets B, C, and D contained a different ratio of ingredients. The feed mixtures differed in respect to corn meal content; B (22%), C (30%) and D (35%) as well as the distribution of fish meal content; B (15%), C (5%) and D (0%). Prior to the commencement of feeding, sea urchins in all groups were starved for 15 days. During the period of starvation, recorded total urchin weight, gonadosomatic index (GSI) and gonad weight values for all experimental groups, showed a declining trend except in the control group, where they stayed the same. After 30 days, the declining trend of morphometric values was recorded for treatment A and the control group. During the two months of the intensive feeding conditions in the regimes with artificially prepared feed, B, C and D a growing trend was recorded for all morphometric values, and it was particularly evident in the treatment C. In the last month of the experiment, a significant decline in the GSI and gonad weight values were observed for the groups, A and the control. The differences among the artificially formulated feeds expressed through increase of GSI and gonad mass values revealed that the best among them was artificial feed C whose variance in consistence of essential nutritional components fits between prepared feeds B and D. Based on the results of our study we conclude that the artificially formulated feed is adequate food for sea urchins in a controlled environment, especially when it contains a smaller animal protein component (5- 10%) and a larger share of plant components (over 90%)

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

THE INFLUENCE OF NUTRITIVE ANTIBIOTIC ON THE PRODUCTION RESULTS OF ONE-YEAR OLD CARP (CYPRINUS CARPIO)

U koncentriranu kompleksnu hranu za jednogodišnji šaranski mlad uključen je virginiamycin, antibiotik grupe "in feed". U ribnjačarskim uvjetima praćeno je njegovo djelovanje na prirast mase, konverziju hrane, te postotak preživljavanja. Pokus je postavljen u četiri objekta pojedinačne površine od 2 200 m², vodenog stupca 180 cm. Svaki od ribnjaka nasađen je sa 10 000 komada šaranskog mlada, prosječne individualne mase 8,7 kg. Hranidba se osnivala isključivo na peletiranoj kompleksnoj hrani sa 32% bjelančevina u razdoblju od 20. kolovoza do 02. listipada 1991. godine. Razlika između dvije hranidbene smjese sastojala se u zastupljenosti virginiamycina. U dva ribnjaka za hranidbu upotrijebljena je kontrolna hrana bez promotora rasta, dok se u preostala dva objekta upotrebljavala hrana s koncentracijom virginiamycina od 40 ppm. Kako se radi o uzgoju s intenzivnom hranidbom bez aeracije i protoka vode, redovito su praćeni fizikalno- kemijski parametri uzgojne sredine. Pokazatelji kvalitete vode mjereni su istovremeno u svakom od četiri pokusna ribnjaka. Na osnovi rezultata o kakvoći vode i njihovoj statističkoj obradi, može se ustvrditi da se radi o vrlo dobroj kakvoći vode pokusnih objekata, te da nije bilo negativnog djelovanja na proizvodne rezultate riba. Utiecaj virginiamycina na prirast mase šaranskog mlada nije dao očekivane rezultate, odnosno nije ustanovljena značajna razlika individualnog prirasta mase riba između ispitivanih grupa na 5%-tnoj razini (P>0.05). Ukupni prirast mase riba kod grupa hranjenih smjesom u kojoj je zastupljen virginiamycin, za 8% je veći u odnosu na kontrolnu grupu. Navedena razlika prirasta ukupne mase riba posljedica je povoljnijeg preživljavanja u postotku od 7% u odnosu na kontrolu. Najizraženije djelovanje virginiamycina odrazilo se na indeksu konverzije hrane. Pri hranidbi riba ad libitum u ribnjacima gdje je upotrijebljena krmna smjesa s virginiamycinom pokazao se hranidbeni koeficijent povoljniji za 16,7% i 8,9%, te 14,8% i 7,2% u odnosu na hranidbeni koeficijent u kontrolnim objektima. Razlozi ovako malom djelovanju promotora rasta na prateće parametre mogu biti višestruki. Općenito poznati različiti učinci u pojedinih ribnjaka mogli su se ispoljiti tijekom pokusnog razdoblja. Relativno mala gustoća nasada od 4-5 riba po m² omogućava prisutnost prirodne hrane, a time i njenu veću zastupljenost u obrocima riba. Visoke hranidbene vrijednosti žive prirodne hrane u stanju su znatno umanjiti nutritivnu aktivnost virginiamycina.The experiment was performed in four 2200 m² ponds, each of which was stocked with 10 000 one-year old carp fingerlings of the mean mass of 8,7 g. The fish in two of the ponds which served as the control ones, were fed on 32% protein pellets, while in the other two ponds they were getting same pellets with nutritive antibiotic "Virginiamycin" in concentration of 40 ppm. The water level was 180 cm, and statistical analysis proved good water quality. The experiment ran from August 20ᵗʰ to October 2ᶯᵈ 1991. At harvest, there was no significant difference (P>0,05) among the individual mass of carp from the four ponds. On the other hand, feed conversion rate was better in the ponds where the nutritive antibiotic was applied (7,2% - 16,7%). Although the percentage of survival was also 8% better, that was not statistically significant (P>0,05). Relatively low effects of the growth promoters could be due to small stocking density (4-5 fish m⁻²) that allowed natural food to predominate. This fact backs up the results of other researches, who believe that high nutritive value of natural food diminishes the nutritive activity of ,,Virginiamycin"

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

GENETIC MARKERS ASSISTED SELECTION IN AQUACULTURE

Akvakultura je industrija u razvoju s ukupnom globalnom vrijednošću od 56 milijardi dolara. Proizvodnja se temelji na oko 210 vrsta, od kojih šarani i kamenice imaju najveću proizvodnju. Neke od vrsta u akvakulturi nastoje se proizvodno unaprijediti ciljanim selekcijskim radom, koji se primarno temelji na metodama populacijske genetike. Glavni cilj uzgojnih programa u akvakulturi jest povećanje profitabilnosti i održivosti, uz očuvanje genetske varijabilnosti uzgajanih vrsta. Aktualnim uzgojno–selekcijskim programima nastoje se unaprijediti salmonidi, škampi i tilapije, uz napomenu da su pozitivni učinci kod salmonida najizraženiji. Tijekom zadnjih desetljeća razvoj molekularne genetike omogućio je pojačavanje selekcijskoga pritiska putem uporabe genetskih markera koji imaju izravne ili posredne učinke na proizvodne odlike. Cilj je ovog rada prikazati nova dostignuća, mogućnosti, ali i probleme pri integraciji markerima potpomognute selekcije u akvakulturi.Aquaculture is an increasing industry, with a total value of 56 billion US$. Production is based on about 210 species of which the carps and oysters have the largest world–wide production. Aquaculture industry strives to improve production of some species with selection targeted work, which is primarily based on methods of population genetics. The main goal of breeding programs in aquaculture is to increase the profitability and sustainability, while maintaining genetic variability in the cultured stock. Current breeding selection programs strive to improve salmonids, shrimps and tilapia with the proviso that the positive effects at salmonids are most stated. During the last decade development of molecular genetics provides the ability of increasing selection pressure through the use of genetic markers that have direct or indirect effects on the production value. The aim of this work is giving the display of new achievements, capabilities, but also having problems in the integration of marker assisted selection in aquaculture

Growth dynamics of the chub fish in the river Sava

Istraživanja klena (Leuciscus c. cephalus L. 1578) i dinamike njegova rasta provedena su ljeti godine 1991., te u tijeku proljeća, ljeta i jeseni godine 1992. u rijeci Savi uzvodno od Podsuseda (kod Zagreba) na dvije postaje (područje Medsave). Utvrđeno je da klen stalno naseljava ovo područje u količinama koje su unutar vrijednosti utvrđenih prethodnim istraživanjima (brojnost 22,30%, ihtiomasa 45-51%). Rezultate istraživanja prikazuju tabl. 1-3. i sl. 1-7. Dobna je struktura klenova unutar dobi od 0 do 4+, pri čemu prevladavaju mlade dobne skupine. Dužinsko-visinski odnosi i koeficijenti uhranjenosti klena postupno se povećavaju s dobi, dok su sezonske razlike minimalne. Utvrđen je znatno sporiji dužinski rast 3+ i 4+ klenova, dok je maseni rast klena sporiji već od dobi 1+, te osobito usporen u dobi 2+, 3+ i 4+ u usporedbi s rezultatima nekadašnjih istraživanja. Pogoršani uvjeti obitavanja posljednjih godina u rijeci Savi uzrok su usporena rasta klena, što je osobito izraženo u dinamici masenog rasta.Investigations on the chub fish (Leuciscus c. cephalus L. 1578) and its growth dynamics were carried out in the summer of 1991, and during the spring, summer and autumn of 1992 in the river Sava downstream from Podsused (near Zagreb) on 2 locations (area of Medsava). It was determined that the chub is constantly inhabiting this area in numbers which are within the values determined in previous investigations (numerousness 22-30%, ichtyomass 45-51%). The results of investigations are presented in Tables 1-3 and in Figures 1-7. The age structure of the chub is between 0 to 4+, with a dominance of younger age groups. Length and height relations and feeding coefficients of the chub gradually increase with age, while the seasonal differences are minimal. A significantly slower growth rate in length was determined for the chub 3+ and 4+, while the weight growth has an already slower rate from age 1+, then particularly slow at age 2+, 3+ and 4+ in relation to the results of previous investigations. Deteriorating living conditions over the past few years in the river Sava is the cause of the slower growth rate of the chub, which is especially emphasized in the dynamics of weight growth

THE USE OF MOLECULAR METHODS ON WILD BOARS (Sus scrofa L.)

The existence of high diversity between animal populations and species, negative human infl uence through overexploitation, as well as changes of natural habitats, both ensured the fact that animal entered into the focus of many molecular biological investigations. The goal of this paper has been directed on the review of the most used techniques in the differentiation of animal populations, including their advantages and weaknesses