Habitat use, migration pattern and population dynamics of chevron snakehead Channa striata in a rainfed rice farming landscape

Habitat use, migration, mortality and growth of the chevron snakehead Channa striata in a rainfed rice farming landscape of north-east Thailand were studied through a tagging experiment. A total of 751 fish were captured, tagged and released during three distinct events in the late dry season, and in the beginning and at the end of the wet season. Rice fields provided the major wet season habitat for C. striata. Small trap ponds built to provide dry season habitat on farms provided 20% of catches and, if not harvested, could increase recruitment to the spawning stock by > 30% despite accounting for < 1% of dry season habitat by area. Migrations were localized (mostly < 500 m). Up-migration from perennial to seasonal water bodies at the beginning of the wet season involved longer distances and took place over a longer time than down-migration at the end of the wet season. Natural mortality rates were extremely high, particularly during the period of down-migration. Fishing mortality rates were high in absolute terms, but contributed only 6-36% to the total mortality. Growth was seasonal with a maximum towards the end of the wet season. Snakeheads have successfully colonized the rainfed rice farming landscape, where populations can withstand intensive exploitation and respond well to aquatic habitat management on farmland. (c) 2005 The Fisheries Society of the British Isles