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Tambaqui stocks in decline

Léo Ramos Chaves / photo taken at São Paulo aquarium Tambaqui, one of the most popular dishes in ManausLéo Ramos Chaves / photo taken at São Paulo aquarium

Interviews with 392 fishermen from rural communities near the city of Manaus suggest that overfishing of tambaqui (Colossoma macropomum) is affecting stocks of the fish along a thousand kilometers of the river Purus, a tributary of the river Solimões. Tambaqui is a culinary favorite in the Amazonian capital, a metropolis immersed in the rainforest with more than 2 million inhabitants. The average size of the fish has halved and it is less frequently caught, according to a study by researchers from British and Brazilian universities (PNAS, July 24). The researchers asked fishermen about the size and number of tambaqui they had caught in the days leading up to the interview, using their responses to estimate the characteristics of tambaqui populations as they moved away from the metropolis. Tambaqui caught in the river Purus within 500 kilometers of Manaus weighed around 2.5 kilograms, on average. A thousand kilometers from the Amazonian capital, they weighed as much as 4.5 kilograms. The decreasing size of the tambaqui creates an economic problem for fishermen from communities near Manaus. With fewer large fish, which sell for higher prices, their income is reduced. Furthermore, by catching more smaller fish, which may not have reached reproductive age, stocks are less likely to be replenished, impacting long-term fishing activity. Overfishing of tambaqui can also affect its ecological role as a seed disperser, since smaller fish carry seeds smaller distances. The authors of the study attributed the declining stocks in the Manaus region to the high demand and the ease of conservation and transportation offered by large boats that supply ice to small fishermen and buy the fish from them.