Is traditional fisheries management correctly addressing the possible causes of fish production decline? The relationship between environmental degradation and artisanal river fisheries in the Magdalena River basin, Colombia

Abstract

Context Overfishing has been historically considered as the main cause of fish stock depletion in the Magdalena River basin, Colombia, whereas the environmental context in which fisheries take place has not been considered. Aims The purpose of this research was to answer the following question: have anthropic activities, other than fishing, influenced the decrease in fishery production in the Magdalena River basin between 1980 and 2015? Methods We analysed diverse variables that were used as proxies for different environmental degradation processes, including sediment load, forest cover, flow rates, reservoir volume <1200 m above sea level, gold production and human population growth. We compared these variables with fishery production between 1980 and 2015 by using cluster analysis, principal-component analysis (PCA) and principal-component regression (PCR). Key results Our findings confirmed that environmental degradation accounts for 61% of the reduction of fishery production. Conclusions The traditional approach of holding fishers accountable for the decline of fishery production is misleading, and, therefore, a better understanding of the overall system is necessary before implementing restrictions on fishing activities. Implications Hence, fishery management should also integrate economic and social variables that affect ecosystem services within the basin into the analysis and decision processes.