Mwanza

Mwanza's economy rests on an invasive species. When British colonial officials introduced Nile perch to Lake Victoria in 1954, they triggered an ecological transformation that created Tanzania's second-largest city. This port of 1.1 million—called 'Rock City' for its distinctive boulder-strewn landscape—now processes fish from a lake that produces 500,000 tons annually, with Tanzania taking 40% of the catch. But the factory floors are emptying. Nile perch stocks have fallen 33% since 2014, and the city's six processing plants operate at less than 30% capacity. Yet Tanzania's fish exports somehow surged 41% in 2024 to $289 million, on track for $300 million in 2025. The contradiction reveals how Mwanza is adapting: better processing, new facilities compliant with EU standards, and diversification into dried fish maws for Chinese markets. Wikipedia describes Mwanza as a commercial hub; what it undersells is that the city exists because of a single ecological gamble that is now unwinding. Nile perch—an apex predator that exterminated 200+ native fish species—was supposed to create a sustainable export industry. Instead, it created a 70-year boom now showing signs of bust. The biological parallel is invasive species dynamics: spectacular initial success as the new organism outcompetes natives, followed by population collapse when the prey base is exhausted. Mwanza's future depends on whether fisheries management can stabilize stocks before the processing industry relocates. The city employs 1.2 million people across the Lake Zone in fishing and related work—livelihoods built on a mid-century experiment that may have run its course.