Nile perch (Lates niloticus) are being illegally fished in Lake Victoria, Africa’s biggest lake, driven by demand for their swim bladders from traditional Chinese medicine (see also Nature 551, 541; 2017).
Fishers can be paid ten times more for the bladder than the price they can achieve for fish flesh, so the flesh has become a by-catch of the bladder harvest. Large fish have large bladders, and so poachers target fish that are bigger than the 85-centimetre upper legal length limit; these are not accepted by regulated processing factories. Large fish are protected because they are substantial spawners, and removing them could affect stock recruitment.
Furthermore, fish-processing factories will not accept legally sized Nile perch carcasses that have already been opened to remove the swim bladder, so several factories have closed because the bladder trade has cut the supply of fish. This has reduced local employment and the volume of fish sold to export, affecting earnings from abroad.
Fishery resources from Lake Victoria underpin the livelihoods of more than 35 million people, and fish products contribute about 2% to the combined gross domestic product of Tanzania, Kenya and Uganda (see go.nature.com/2bmpevq).
Although the Nile perch is an introduced species in Lake Victoria and has severely affected natural fish abundance and biodiversity, it has brought some food security and economic prosperity to the region. Traditional medicine threatens both.
Nature 553, 27 (2018)