Alaska Sen. Ted Stevens (R) is stirring up trouble again with a rider attached to an appropriations bill that would exempt Alaska salmon fishing from the Endangered Species Act. The Clinton administration has threatened to veto the bill over the rider, a move that could jeopardize not only the Columbia River chinook stocks that migrate off the Alaska coast, but also a recent, hard-won U.S.-Canada salmon treaty that limits Alaska’s catch. Alaska Gov. Tony Knowles (D) stopped short of endorsing Stevens’s rider, but insisted that the government should deal with hydroelectric dams and other causes of declining salmon runs before picking on fishers.