POINT REYES STATION, Calif. — It seems a perfect marriage of nature and commerce. As boats ferry oysters to the shore, pelicans swoop by and seals pop their heads out of the water. But this spot on the Point Reyes National Seashore has become a flashpoint for a bitter debate over the limits of wilderness and commercial interest within America’s national parks. The National Park Service has said it cannot renew the permit to farm oysters in a tidal estuary here, which lapses in 2012, because federal law requires it to return the area to wilderness by eliminating intrusive commercial...