Head on down the path from the entrance of the Wildlife Exploitation Preserve. This will lead you into the preserve itself. You have a number of stalkers to deal with right at the start. Find the river in the Stalker area and cross the first stone bridge over it.
After the stone bridge, turn to the right. Start on up the slope and deal with the Rakks that attack you. There are a few more Stalkers in the area for you to deal with as well. Just keep follow the slope up and to the right. Before long you will find Mordecai. Talk with him to finish this objective.