KETE KRACHI, Ghana — Just before 5 a.m., with the sky still dark over Lake Volta, Mark Kwadwo was rousted from his spot on the damp dirt floor. It was time for work.

Shivering in the predawn chill, he helped paddle a canoe a mile out from shore. For five more hours, as his coworkers yanked up a fishing net, inch by inch, Mark bailed water to keep the canoe from swamping.

He last ate the day before. His broken wooden paddle was so heavy he could barely lift it. But he raptly followed each command from Kwadwo Takyi, the powerfully built 31-year-old in the back of the canoe who freely deals out beatings.

“I don’t like it here,” he whispered, out of Mr. Takyi’s earshot.

Mark Kwadwo is 6 years old. About 30 pounds, dressed in a pair of blue and red underpants and a Little Mermaid T-shirt, he looks more like an oversized toddler than a boat hand. He is too little to understand why he has wound up in this fishing village, a two-day trek from his home.