Small changes, big impacts: Geographic expansion in small-scale fisheries

Abstract

Small-scale fisheries are an important, yet neglected, millenarian activity that has been undergoing significant changes that threaten its future. Understanding how this activity is spatially distributed and the factors that drive its use of the marine space over time can shed some light on how fishing efforts and their impacts have moved over different parts of coastal marine ecosystems. This study investigated changes to the spatial distribution of small-scale fisheries along the Brazilian equatorial region between 1994 and 2014 and the factors, from ecological to socioeconomic, that influenced this shift. Bayesian hierarchical spatial models were used together with environmental variables, and species and fisheries data to identify fisheries spatial variations. Fisheries spatial transitions were also assessed to determine whether they occurred as a result of significant changes to target species and their abundance, fisheries technology and efforts, and/or economic revenues. A relevant shift in the fisheries spatial distribution was detected and demonstrated that fishing has been mostly moving from shallow to deeper waters. Although the target species remained the same in 1994 and 2014, abundance of these species decreased significantly over time, which has consequently affected fisher revenues. It is possible that, when new and further areas were exploited, initial catches were either better or similar to previous catch levels in older and closer grounds, which may have masked earlier signs of overfishing. Even small changes, such as shifting fishing grounds to a few kilometers offshore, could be a proxy for negative socioeconomic and ecological changes in fishing communities that is brought about by resource decline in areas closer to the coast. An important step toward detecting signs of ecological collapse with social consequences is to identify additional fisheries changes not commonly reported in landing data, such as ground shifts.