Tanzanian fishermen are using a rather aggressive approach to increase their catches – they toss a homemade bottle bombs into the sea, killing hundreds of fish at one time. This dangerous tactic, also known as blast fishing, indirectly threatens surrounding marine life.

Blast fishing first appeared in Tanzania in the 1960s and was later outlawed in 1970. However, this fishing style is on the rise again and experts believe it is in part because materials are cheap and easily accessible with local mining and construction programs underway in the area.   

"With numerous blasts occurring daily on reefs all over the country over a period of several decades, the overall impact of dynamite fishing on coral reefs in Tanzania has been devastating," Greg Wagner, of the University of Dar es Salaam in Tanzania, wrote in a 2004 study.

With a single blast up to 400 kg of fish will surface and be scooped up by fishermen, who bring in a profit of $1,800 in market sales. When these bombs are thrown overboard the underwater shock waves produced by the explosion stun the fish, rupture their swim bladders that help control their natural buoyancy, causing them to float to the surface where nets await.

According to the anti-blast fishing operation known as SmartFish, Tanzania is the only country in Africa where blast fishing still occurs on a large scale, along the country's entire coastline from Mtwara to Tanga, and off nearby islands.

"If this illegal practice is not stopped, gradually Tanzania could easily end up with a wasteland of ocean," Michael Markovina, a SmartFish officer, told BBC.

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