First-ever stock assessments in Lake Edward System, East Africa using data-poor methods developed at GEOMAR

A new paper co-authored by Dr Rainer Froese (Senior Scientist at GEOMAR and Co-founder of FishBase), “Assessment of exploited fish species in the Lake Edward System, East Africa” applied data-poor methods developed at GEOMAR and produced several first-ever stock assessments.

Summary: The unknown status of inland fish stocks hinders their sustainable management. Therefore, increasing stock status information is important for sustainable inland fisheries. Fisheries reference points were estimated for five exploited fish species (11 stocks) in the Lake Edward system, East Africa, which is one of the most productive inland water systems. The aim was to ascertain the status of the fisheries and establish reference points for effective management. The reference points were based on four linked stock assessment approaches for data‐limited fisheries. Estimates showed poor stock status with the stocks defined as either collapsed, recruitment impaired or overfished. However, higher catches could be obtained under sustainable management. Estimates of maximum sustainable yield (MSY) and supporting biomass (Bmsy) are provided for 10 of the stocks as targets for rebuilding plans. The immediate target of management should be rebuilding biomass to Bmsy. Applicable measures include shifting length at first capture to the length that maximizes catch without endangering size structure and biomass, and livelihood diversification out of fisheries.

“This [study] goes to show that these [advanced and computer intensive stock assessment] methods are applicable in the real world and have impact for better management of scarce resources and related food security,” according to Dr Froese.  “It also shows that these ‘marine’ methods work fine in freshwater systems,” he added.

Dr Froese also pointed out its connection to the ‘MSY needs no epitaph‘ paper he recently co-authored with Dr Daniel Pauly (Principal Investigator at Sea Around Us and Co-founder of FishBase) since “the data-poor methods use the original MSY concept rather than the degraded versions that promote stock reductions to 30-40% of unfished biomass, where stocks are unable to fulfill their ecosystem roles.”

About Joann Glorioso

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