The national marine committee accepted a proposal to add the endangered river dolphins to the reserve list, according to fisheries professor Thon Thamrongnawasawat, who led the survey.
The move comes after Natural Resources and Environment minister Varawut Silpa-Archa said Irrawaddy dolphins needed urgent protection to prevent their extinction in Thailand.
Prof Thon said reserved-species status for the dolphins would spark increased conservation efforts, led by the Department of Marine and Coastal Resources.
Short-term conservation measures will include boat patrols and building public awareness of the threats to Irrawaddy dolphins. In the long term, scientists will study their reproduction as well as ways to restore their habitat in Songkhla Lake. They will also increase their food stocks and create a centre to treat them.
Thon reported in April that only 14 Irrawaddy dolphins remained in Songkhla.
Irrawaddy dolphins are listed as critically endangered throughout Asia by the International Union for Conservation of Nature (IUCN), with 140 found in India, 90 in Indonesia, 90 in Cambodia, and 80 in Myanmar. Laos reported the death of its last Irrawaddy dolphin in April.
The main threats to the species are net-fishing and degradation of their habitat through human activities such as dam-building on the Mekong.