ARTIFICIAL SPAWNING OF EUROPEAN CATFISH (Silurus glanis L.) USING SMALL DOSES OF CARP PITUITARY GLANDS

Istraživanja umjetnog mriješćenja europskog soma (Silurus glanis L.) primjenom malih doza saranske hipofize (CP) provedena su godine 1997. i 1995. u proizvodnim uvjetima na mrjestilištu "Ribnjak 1905" d.d. Našice. Prije hipofiziranja somovskih ženki obavljeno je obilježavanje, odvaga, procjena stupnja zrelosti i razvrstavanje u pet stupnjeva zrelosti (SZ) prema našim vlastitim kriterijima. U kontrolnoj skupini (n=21) ženke su dobile jednokratnu injekciju CP-a u dozi 4,5 mg.kg-1 tjelesne mase (t.m.), dok su u pokusnim skupinama (n=62) matice obrađene jednokratnim niskim dozama CP-a u tri razine. Ustanovljeno je da je minimalna doza CP-a za umjetno mriješćenje soma na III. SZ 2,040,15, na IV. SZ 1,590,16 i na V. SZ 1,250,10 mg.kg-1 t.m. Istodobno efikasnost mrijesta matica u odnosu na kontrolnu skupinu nije umanjena jer se kretala od 92 do 100% (p0,05), dok je relativna plodnost na III., IV. i V. stupnju zrelosti iznosila 9,92,1, 10,41,6 i 11,51,3 %, adekvatno (p0,05). Utvrđene minimalne doze CP za mriješćenje europskoga soma 2 do 3 puta niže su od relevantnih podataka iz literature. Pretpostavlja se da će one pozitivno utjecati na ostvarenje harmonične završne zriobe oocita, a time i na bolju kakvoću ovulirane ikre.In 1997 and 1998 in the “Ribnjak 1905”•d. d. Našice hatchery artificial spawing of European catfish (Silurus glanis L.) was researched under productive conditions using small doses of carp pituitary (CP). Befiwe dosing the carp pituitary glands female catfish were marked, weighed out, grouped according-to their maturity and devided in 5 categories based on grade of their maturity (MC). We used our own criteria. In the controlled group (n=21) female catfish received a single CP shot dosed at 4.5 mg. kg -1 of the body weight (b. w.), while in the experimental group (n=62) female fish were treated with single low dosed CP on three levels. It was found out that the minimal CP dosage for the artificial spawning on the 3rd MG is 2.04+-0.15, on the 4th MG 1.59+-0.16 and on the 5th MG 1.25+-0.10 mg. kg-1 of the b. m. Simultaneously, the efficiency of spawning compared to the controlled group was not reduced because it ranged between 92-100% (p<0.0.5), while relative fertility on the 3rd, 4th and 5th maturity grade totalled 9.9+-2.1, 10.4+-1.6 and 11.5+-1.3%, (p<0.05) adequately. The established minimal CP dosages for spawning of European catfish are two to three times lower than relevant data from the reference literature. It is assumed that they will have positive influence on final harmonic maturing process of the oocytes oocita, and by that on better quality of ovulated eggs