SHANGHAI, Apr 20 (SMM) - Rio Tinto's iron ore production and sales fell in the first quarter when compared to the previous quarter, but the company said production will increase in the second half of the year, and has kept its full-year shipment target unchanged. In the three months to March 31, total production from its iron ore operations in the Pilbara region of Western Australia was 71.7 million mt, down 6% year-on-year, the company said in a statement on Wednesday; total shipments were 71.5 million mt, down 15% from the previous quarter and down 8% from the same period last year.