water Article Conserving Mekong Megafishes: Current Status and Critical Threats in Cambodia Teresa Campbell 1,* , Kakada Pin 2,3 , Peng Bun Ngor 3,4 and Zeb Hogan 1 1 Department of Biology and Global Water Center, University of Nevada, Reno, NV 89557, USA;
[email protected] 2 Centre for Biodiversity Conservation, Royal University of Phnom Penh, Phnom Penh 12156, Cambodia;
[email protected] 3 Wonders of the Mekong Project, c/o Inland Fisheries Research and Development Institute, Phnom Penh 12300, Cambodia 4 Inland Fisheries Research and Development Institute, Fisheries Administration, Phnom Penh 12300, Cambodia;
[email protected] * Correspondence:
[email protected]; Tel.: +01-775-682-6066 Received: 2 June 2020; Accepted: 20 June 2020; Published: 25 June 2020 Abstract: Megafishes are important to people and ecosystems worldwide. These fishes attain a maximum body weight of 30 kg. Global population declines highlight the need for more information ≥ about megafishes’ conservation status to inform management and conservation. The northern Cambodian Mekong River and its major tributaries are considered one of the last refugia for Mekong megafishes. We collected data on population abundance and body size trends for eight megafishes in this region to better understand their conservation statuses. Data were collected in June 2018 using a local ecological knowledge survey of 96 fishers in 12 villages. Fishers reported that, over 20 years, most megafishes changed from common to uncommon, rare, or locally extirpated. The most common and rarest species had mean last capture dates of 4.5 and 95 months before the survey, respectively. All species had declined greatly in body size.