A research study conducted by a team of scientists from the University of Seville and the University of Cádiz has discovered that the Guadalquivir estuary has environmental conditions that are favorable for anchovy breeding, leading to four times more productivity compared to the Guadiana estuary. The factors contributing to this productivity include high water turbidity, organic matter in suspension, and a specific salinity gradient. The study also found that the Guadalquivir's unusual turbidity, which is higher than most European rivers due to agricultural practices, plays a crucial role in increasing food availability and enhancing breeding areas for various fish species. The research involves comprehensive analysis of environmental and biological factors in the four main estuaries of the Gulf of Cádiz over a five-year period, providing crucial insights for fishery management and adaptations to climate change.