Text and photographs by Kyle Dickman.
I'm at Khone Falls on the Mekong River in Laos with filmmaker-kayaker Trip Jennings (above, center) and Zeb Hogan (below), the host of the National Geographic Channel's Monster Fish show and an expert on the region's fishes.
We're trying to figure out how a proposed dam at the falls, one of the world's most productive fisheries, will affect migratory fish that range from pinky-sized carp to 500-pound catfish–Southeast Asia's whiskered equivalent of salmon. (Follow their progress here.)
At Khone Falls, the river divides into hundreds of different channels and drops off a 60-foot cascading waterfall. Which channels fish use to migrate depends on the size of the waterfall. Basically, the bigger the vertical drop, the fewer fish use the channel to migrate.
We've outfitted Trip's kayak with a depth-finder and a GPS to map water velocity, depth, and gradient. We're hoping to figure out what the migration parameters are for different species of fish (as in, big fish migrate up this channel because the water velocity is less than 20 mph, or whatever the case may be). What we find, will tell us if other channels share the same characteristics as Don Sahong, the site of the proposed dam. Don Sahong is hypothesized to be used most by migratory fishes because of its relatively mild whitewater.
We've been at Khone Falls for four days now. The first two days we rode mopeds past water buffalo and monasteries to scout waterfalls. On Sunday, we decided to run Somphamit Falls, a difficult stair-stepping 60-foot drop with fish traps lining the banks. Trip fired it up, recorded the data, and sent it to Sea Floor Systems, the California-based company who designed the system we're using to process the data.
The fish traps suggest fish use Somphamit Falls as a migratory channel, but the data will show us whether they're making it past the waterfall in dry season or being turned back. Does this channel share some of the same characteristics as Don Sahong? I'll let you know what we find out.
This expedition was funded in part by the National Geographic Expeditions Council.