Historical depletion and future drought-driven risks to Gulf of Mexico fisheries production

A major depletion of ~42% in total fisheries production occurred in the Gulf of Mexico in the early 1990’s but received limited scientific attention. Here, we show that terrestrial drought in the US during the late 1980s, combined with high Gulf menhaden (Brevoortia patronus) fishing pressure, led to a depleted forage base, with cascading effects on other species and fisheries in the Gulf, acting primarily via a reduction in Mississippi River flow. Ecosystem model simulations support these findings, and more importantly, indicate that anticipated frequent and intense drought conditions under the RCP 8.5 scenario in the US are projected to cause periodic depletions of biomass and catches of ~61% by 2050, and ~72% by 2100, substantially more acute than previous estimates for the Gulf. There is an urgent need to explore possible mitigation strategies and the mechanisms by which drought conditions affect the Gulf and other marine ecosystems. Extreme and prolonged drought on land can strongly affect downstream marine ecosystems and their fisheries. This study shows that historical drought drove major Gulf of Mexico fishery declines, and models predict even greater future losses under projected drought.