Impacts of global environmental change and aquaculture expansion on marine ecosystems

Abstract

The stability of world's reduction fisheries and the global fishmeal market they support is explored through a geographically-specific, global bio-economic model, driven by three interactive forcing factors: climate-driven changes in the biological production of regional fish stocks, the potential global expansion of aquaculture demand for fishmeal and differential management schemes. The model captures approximately 85% of the world's fishmeal and fish oil data and is driven by trade data from the period 1997–2004. Twenty-year model simulations are conducted considering, on the production side, a random recruitment variability of the fish stocks supporting all regional production systems, plus an El Niño-type perturbation altering the productivity of Peruvian and Chilean stocks. The production systems are confronted with two alternative aquaculture expansion scenarios, allowing for the quantification of the synergism between regional climate-driven fluctuations and economic globalization of marine commodities in determining sustainable and unsustainable pathways for the world's reduction fisheries. The simulation results are compared to trends in regional climate indices, trade information from international markets and aquaculture and small pelagic fisheries data. The work pioneers the quantification of the double exposure created by climate variability and change and economic globalization on particular natural resources and explains the stakes involved in the development of fishmeal trade for global aquaculture expansion for marine fish populations. The results demonstrate that regional stocks can recover from climate-driven fluctuations unless these act simultaneously to an expansion in international market demand, and are subject to sub-optimal management schemes. It is argued that the dynamics of the fishmeal price since the early 1990 already responds to the balance between climatic variability in production and market developments, as mimicked by the model. Furthermore, under sub-optimal management scenarios, a sequential pattern of overexploitation emerges as an endogenous property of the interaction between regional climatic disturbances and a globalized trade system. It is concluded that the way we manage climate impacts, both at regional and global level, will determine the sustainability of the world's reduction fisheries, a conclusion that could be extended to other, similarly affected, natural resources.