71-74 degrees. Trolled 30 to 200 fathoms. No tuna for us and that bite was north according to radio and reports at dock. There was a real good dolphin bite for us. We picked up 13 dolphin to just over 25lbs, average size was 15 lbs. Caught a 20lb wahoo off the weather buoy in the afternoon. At two o'clock in 30 fathoms and 72 degrees the way back start screaming. Our initial thought was tuna then I see a marlin air out. We crank all the lines in and turn towards fish as almost all the line on our 50 wide is gone. Spend about 40 minutes fighting it and get the release, blue marlin, estimated 200lbs. Other boats caught some blues and whites from chatter on radio.