big river fishing help??

hi :
in the last days i were fishing in ephurates for carp we got nothing for three days

but as soon as the dark fall all fish lift the place , at first we didnot knew why , but after a short time my rod stert to act strongley , i pull it and tried to land the fish , but it was too big to land with smalle gear , the line broke and the fish gone , it hapend three times >
at end we give up coz we couldnot land the fish and went home
when we ask about thies big fish the locals tald use its sturgeon . big sturgeons .

any one can give me help about how to fish them and land them ?

Will this help any? http://www.flyanglersonline.com/cst/cst83198.php