The season for hatchery chinook salmon on the South Fork of the Salmon River will close at 9:00 p.m. tonight, July 5. Fish and Game director Rod Sando signed the South Fork closure notice today after fisheries staff advised him that the quota for incidental catch of listed chinook salmon had been reached. Seasons on spring chinook have already closed in the Little Salmon, North Fork and mainstem Clearwater rivers. Seasons remain open on the Lochsa and South Fork of the Clearwater rivers. Seasons for salmon are based on quotas, as well as time span. As the adult fish cross dams on their upstream spawning migration, biologists count them and estimate how many are hatchery fish and how many are natural fish. The sport fishery is directed at surplus hatchery fish, however, in areas like the South Fork there are naturally-produced fish which also get caught and released by anglers. These fish are listed under the Endangered Species Act. The number of listed chinook that sport anglers may catch and release is limited by a quota to protect listed fish that are destined to spawn in streams. When the quota of listed chinook adults is reached, the sport season is closed. Although the overall run size is large, the percentage of listed fish has declined from what was expected, resulting in the closure. A similar "listed fish quota" closure occurred on the South Fork in 1997.