This study’s objective was to explore some of the annual Prussian carp’s (Carassius gibelio) biological characteristics (sex ratio, length–weight ratio, and gonado somatic index - GSI) in the Kopački ...Rit Nature Park in Croatia. The Prussian carp is an invasive fish species originated from Asia, which became widely distributed throughout Europe and is believed to be responsible for a decline in the number of indigenous fish, invertebrate, and macrophyte populations in different areas. The fish sampling was conducted from September to November 2017 and from February to July 2018, respectively, using electrofishing. A total of 475 fish individuals were caught and measured for the total length, standard length, body height, and body weight. Males made up 34.31% of the population of Prussian carp. The mean value of Fulton condition factor (FC) of Prussian carp in Kopački Rit was 1.77 ± 0.28. Overall, the FC value had a relatively small amplitude, but it exhibited a clear seasonal vari ability. The average GSI values of females (9.91 ± 5.34) were higher than those of males (3.58 ± 1.37) during the observed period. The average GSI values indicate that the majority of females are spawning in the late April and May, which are also the same periods when other cyprinid species are spawning, allowing the Prussian carp to exploit its gynogenesis strategy.
Cilj ovoga istraživanja bila je istražiti neke od bioloških karakteristika (omjer spolova, dužinsko-maseni odnos i gonadosomatski indeks) babuške (Carassius gibelio) tijekom jedne godine u Parku prirode „Kopački rit“ u Hrvatskoj. Babuška je alohtona vrsta ribe uvezena iz Azije koja se od tada proširila diljem Europe te se vjeruje kako je odgovorna za opadanje autohtone populacije riba, beskralježnjaka i makrofita u pojedinim područjima. Ihtiološko uzorkovanje obavljeno je od rujna do studenoga 2017. te od veljače do srpnja 2018. s pomoću elektroribolova. Ukupno je ulovljeno 475 jedinaka, na kojima je izmjerena ukupna dužina, standardna dužina, visina tijela i masa. Mužjaci su činili 34,31 % populacije babuške. Prosječna vrijednost Fultonova kondicijskog faktora (FC) za babušku u Kopačkome ritu bila je 1,77 ± 0,28. Sveukupno, vrijednosti FC-a su imale relativno malo varijacija, ali ukazuju na jasnu sezonsku varijabilnost. Prosječne vrijednosti gonado-somatskoga indeksa (GSI) za ženke (9,91 ± 5,34) bile su veće negoli za mužjake (3,58 ± 1,37) tijekom promatranoga razdoblja. Prosječne vrijednosti GSI-ja ukazuju kako se većina ženka mrijesti krajem travnja i tijekom svibnja, što je isti period kada se mrijeste i ostale ciprinidne vrste, a to babuški omogućuje da se koristi svojom strategijom ginogeneze.
Distribution of the European mudminnow, Umbra krameri, Walbaum 1792, in Croatia is scarce with only few confirmed localities. In order to confirm presence of the European mudminnow in amelioration ...canal network along the Drava River an electrofishing was conducted in the small Mlinski canal. Ten specimen of European mudminnow were caught During sampling. Using ImageJ software a truss network was constructed between landmark points on photographs of caught specimens. Total body lengths of caught European mudminnow ranged from 61 to 100 mm (72.00±11.52 mm) whereas standard one ranged from 52 to 85 mm (60.30±10.08 mm). Body weight were relatively small ranging from 1.81 to 7.59 g (3.80±1.89 g), while the Fulton condition factor ranged from 0.76 to 1.23 (0.96±0.15). This new locality of the European mudminnow is situated about 50 km downstream from the last confirmed site in Croatia.
Informacije o distribuciji crnke, Umbra krameri Walbaum 1792, u Hrvatskoj su oskudne, uključujući svega nekoliko potvrđenih lokaliteta. U svrhu potvrđivanja prisutnosti crnke u mreži melioracijskih kanala u blizini rijeke Drave, obavljeno je uzorkovanje ribe elektroagregatom na Mlinskome kanalu. Tijekom uzorkovanja ulovljeno je 10 primjeraka crnke. Korištenjem računalnoga programa ImageJ razvijena je metoda razgranate mreže na fotografijama ulovljenih crnki. Ukupna dužina ulovljenih crnki bila je od 61,00 do 100,00 mm (72,00±11,52 mm), a standardna dužina iznosila je od 52,00 do 85,00 mm (60,30±10,08 mm). Ukupna tjelesna masa bila je relativno mala, u rasponu od 1,81 do 7,59 g (3,80±1,89 g), dok je Fultonov kondicijski indeks iznosio od 0,76 do 1,23 (0,96±0,15). Ova nalazište crnke u Hrvatskoj smješteno je oko 50 km nizvodno od zadnjega potvrđenog lokaliteta uz tok rijeke Drave.
This paper reports the results of a diet analysis from the digestive tracts of 203 great cormorants shot at the Donji Miholjac fishponds in eastern Croatia, in the period 2000-2002. Eight fish ...species were determined. The dominant species was common carp (Cyprinus carpio) with a relative frequency of 73.4%, followed by grass carp (Ctenopharingodon idella) (11.6%), bighead carp (Aristichthys nobilis) (7.2%), pikeperch (Sander lucioperca) (2.0%), wels catfish (Silurus glanis) (1.7%), pike (Esox lucius) (1.5%), topmouth gudgeon (Pseudorasbora parva) (1.5%) and Prussian carp (Carassius auratus gibelio) (1.1%). The diet spectrum of the great cormorants from the Donji Miholjac fishponds was in accordance with the structure of the fish population in the fishponds. The average stomach weight per bird was 244 g. When birds shot with an empty stomach were excluded, the average stomach weight increased to 286 g. The length of consumed fish ranged from 40-335 mm, with 47% of the fish belonging to the length category 100-149 mm. The study revealed no significant relationship between the weight of the consumed fish and the body weight of male and female cormorants.PUBLICATION ABSTRACT
The record is confirmed of a “Clariobranchus” hybrid Clarias gariepinus × Heterobranchus sp. specimen in the River Danube in Croatia. Clarias gariepinus was introduced to Europe for farming and ...research purposes. Because of their faster growth and short time to achieve market size, “Clariobranchus” hybrids have gained attention in European aquaculture. To date, no record has been found in the literature of “Clariobranchus” hybrid escapees in inland waters of Europe. The present finding suggests that the “Clariobranchus” hybrid escaped from an unprotected aquaculture system or open pond farm. The threat of establishment of a population of this hybrid in suitable environments, such as thermal ponds, cannot be ruled out.
Official data of the Ministry of Agriculture, Directorate of Fisheries was used in order to analyze commercial fishing on the Danube in the Republic of Croatia between 2004 to 2009 (average annual ...catch was 39,088.05 kg ± 7,450.06 kg. The number of approved and used licenses varied between 19 and 25, out of a possible 30. A high percentage of fishermen (32.28 % ± 7.55 %) who ignored the legal obligation to deliver full data on the catch and tools used was determined. Catch per unit effort (CPUE) varied greatly with an average of 0.985 ± 0.29 kg • tool hour-1. The Fox and Schaefer models of maximum sustainable yield in the Danube indicate relatively low fishing quota (42.0 – 44.0 t) in comparison to the anticipated (101.9 – 130.5 t). In order to improve fishery management, it is necessary to enhance the education and control of recreational and commercial fishermen, as well as to form a joint administrative body with the Republic of Serbia.
U 2014. godini, u izdavaštvu Veterinarskog fakulteta u Zagrebu, tiskan je jedinstven i specijaliziran „Višejezični rječnik za ribarsku struku“ na hrvatskom, latinskom, engleskom i češkom jeziku; prvi ...takve vrste u Republici Hrvatskoj. Autori na vrlo jasan i koncepcijski pregledan i lako prihvatljiv način, na 732 stranice, abecednim redom, sintetiziraju i objašnjavaju preko 7000 jezičnih jedinica, gramatičkih, normativnih, terminoloških i leksikoloških podataka iz ribarstva; od ihtiologije, sistematike, akvakulture, fiziologije, anatomije, patologije do ribolova, prerade i ekologije, omogućavajući tako čitatelju brzo snalaženje i jednostavno pronalaženje rješenja za prijevod pojedinih riječi i pojmova. Ovaj rječnik uvelike će doprinijeti edukaciji i razvoju samosvijesti korisnika.
Various cormorant diet assessment methods are used to assess their daily meal in order to evaluate, using these and other data, the damage to commercial fish farms as well as the damage on open ...waters caused by cormorants. All of the parameters used for evaluating the damage to fish stock (number of birds, density and fish structure, daily meal, fish price, degree of protection and preservation etc.) are specific for an individual fishpond or other body of water and can only be used for that locality and not elsewhere. The results on the lowest and highest values of fish mass that cormorants eat daily vary extensively. By examining the available literature, the following values for individual adults have been determined: pellets — 347 g, pellets of captive cormorants — 371 g, stomach content — 359.5 g, regurgitations — 260 to 539 g, energy requirements — 751 g, stomach temperature — 336±98 g.
Postembryonic rearing of carp larvae (Cyprinus carpio) in closed recirculatory system was conducted in 2009 at the fish farm Ribnjak LLC, Donji Miholjac, Croatia. The research was conducted in two ...test groups (A and B with three iterations in each) with a control group (C). Test group A (3 tanks x 250 l) consisted of 150 000 larvae (density of 200 larvae*l-1), test group B (3 tanks x 500 l) consisted of 600 000 larvae (density of 400 larvae*l-1), and the control group (C) was a mud fish pond T-6 which was stocked by 800 000 larvae*ha-1 under standard production conditions. In this research, basic physical and chemical water parameters were controlled (temperature, oxygen, pH, total ammonia and nitrites). Initial measuring of carp larvae total length (TL) was conducted prior to their placement into tanks (N=120). On the fourth, sixth, eighth and tenth day of research 20 larvae (N=140) were taken out of every tank as well as out of control group and measured. Feeding with live feed began on the third day after hatching (larval TL 6.00 plus or minus 0.36 mm). Ten minutes after feeding live feed to larvae for the first time, 20 larvae (N=120) were taken out of every tank and a high portion of larvae that accepted live feed (89.17 plus or minus 3.76%) was determined by a magnifying glass. Feeding artificial feed began on the seventh day after the hatching. After ten minutes, a high portion of larvae who accepted artificial feed (96.67 plus or minus 2.58%) was determined. Since the end of the research, the determined length increment (ITL) per day was 0.41 plus or minus 0.04 mm, a very high survival rate was established (group A: 96%, group B: 93%). Feeding frequency was four times a day in five-hour intervals (at 06:00, 11:00,16:00 and 21:00 hours). The research was terminated after ten feeding days due to deteriorating condition of zoohygienic filter. The total of 3807 g of live feed and 1080 g of artificial feed was used.
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