CORMORANT – A PROBLEM AND A POSSIBLE SOLUTION

Veliki vranac, kormoran (Phalacrocorax carbo) ihtiofagna je ptica koja se nakon stavljanja pod totalnu zabranu lova godine 1979. razmnožila u enormnim količinama uzrokujući goleme štete na ribnjacima i otvorenim vodama. Ribnjaci su dovedeni na prag rentabilnosti, a otvorene vode opustjele - negdje je riblji fond smanjen i do 90 %. Do sada je već bilo mnogo sastanaka na raznim, pa i državnim razinama, o tome kako smanjiti štete od kormorana, no bez rezultata. U radu se predlaže radikalna i ekonomski prihvatljiva mjera kojom će se broj kormorana u nekoliko godina smanjiti na onaj broj pri kojemu će on obavljati zadaću koju mu je namijenila priroda: čišćenje voda od bolesnih riba, gdje neće biti više tolikih šteta, a broj kormorana bit će ekološki prihvatljiv. Mjera se sastoji u tome da se u nekoliko godina sruši sve drveće na kojem se gnijezde kormorani, nakon što snesu jaja. Pa eventualno i drugi put tijekom godine, ako ih ponovno snesu. Tako će iz populacije ispasti cijela jedna generacija. Na drveću nema posebne štete, jer ono u najviše 2 godine i onako ugiba zbog jakoga herbicidnog djelovanja kormoranova izmeta. Na razini pojedinih država, kao i na europskoj razini treba hitno formirati komisije od kvalificiranih stručnjaka (ornitolog, agronom - ribarski stručnjak, veterinar - specijalist za bolesti riba, šumar, ekolog i eventualno drugi) koja će odrediti duljinu trajanja ove mjere, vodeći računa o tome da se u današnjim uvjetima totalne zaštite populacije kormorana podvostručuje svake 3 i pol godine, a ujedno poslije i kontrolirati populaciju.Cormorant (Phalacrocorax carbo) is ichthyophagous bird which has bred in great numbers causing great damages in ponds and open waters after its hunt was fully banned in 1979. Ponds have been led to the treshold of profitabi]ity and open waters have been deserted - fish stock has decreased even for 90% at particular locations. There have been held numerous meetings on decreasing the damages caused by cormorants, some of them even on the state level but they gave no results. This work suggests a radical and economically acceptable measure by which the number of cormorants shall in a few years be decreased to the number which permits them to exercise its natural function: clearance of water from diseased fish. Damages will not be so great as they are now and the number of cormorants will be ecologically acceptable. The essence of the measure is following: after cormorants lay their eggs, all trees on which they build their nests should be cut down in few years period. Trees should be cut down perhaps two times in the same year if cormorants lay their eggs again. Thus, a whole generation shall be eliminated from the population. There shall be no damage on trees because they would normally be ruined in two year period because of herbicide effect of cormorants\u27 droppings. Commissions consisting of qualified experts Cornithologist, agronomist - fish expert, veterinarian - expert for fish blights, forester, environmentalist and perhaps other experts) should be established on the level of individual states as well on the Europian level. The commission should determine the duration of the measure taking into account that the cormorant population doubles every three and half year in existing conditions of total protection. The commission should exercise the control of the population after measure has been carried out