The fish farming activities carried out on the estate offer a series of environmental benefits for the hydrology and ecology of the marshlands of the Guadalquivir. Extensive and semi-extensive fish farming has attracted a range of nesting and migratory species of birds. The total bird population of Veta la Palma can reach a figure of 600,000 covering some 250 different species, of which more than 50 suffer some degree of threat in other areas. As such, the artificial wetland habitat created on the estate plays an essential part in the conservation of European birds by guaranteeing food both for the species which complete their development cycle from birth on the island before migrating, and those which, during the course of migration between Africa and Europe, stay in the area temporarily to find food.
The extensive farming ponds are characterised by their stability in terms of the area flooded (8000 acres), depth (40-50 cm), renovation level (1 hm3/day in summer) and salt content. This helps to reduce the impact of changes in the levels of salt content and water as well as the concentration of nutrients in the estuary, thereby contributing to a massive development of micro-algae which are capable of assimilating the excessive amounts of nitrogen and phosphorus in the water. In this way, the water from Veta la Palma which is returned to the river is of exceptional quality in terms of its physical and micro-biological properties. Furthermore, the creation of more than 100 islands in the ponds for the nesting of waterfowl together with the revegetation of 93 miles of banks, have improved the landscape of the estate considerably. The artificially flooded areas also play a vital role in the protection of the natural fish population of the estuary of the Guadalquivir itself including migratory species such as the common eel (Anguilla anguilla) or striped mullet (Mugil cephalus), and other species which complete part of their natural cycle in the estuary such as sole (Solea solea, S. senegalensis), maegre (Argyrosomus regius), or sea bass (Dicentrarchus labrax), as well as marine species such as the black sea anchovy (Engraulis encrasicholus) or wedge sole (Dicologoglossa cuneata). In a study carried out by the Doñana Biological Station, it was noted that “…to preserve the abundance and diversity of waterfowl in Doñana, it is obvious that it is necessary to manage areas such as Veta la Palma which can provide high food biomass (invertebrates and macrophytes) for birds”. Veta la Palma is part of both the Doñana Biosphere Reserve and the Natura 2000 Network, and has been designated a RAMSAR site of international importance.