The Bay of Cádiz in South of the Iberian Peninsula is surrounded by a vast area of marshes formerly associated to the mouth of Guadalete River. Since centuries this area has been exploited for natural resources, salt and seafood. Transformation of wetlands and marshes for salt extraction was already documented several centuries ago but was intensified during 18th and 19th centuries. The result is a huge area of intricate saltponds, main and secondary sea channels and natural marshes that offers a unique landscape of great ecological and cultural value. The permanence of inundate areas during many months a year along with marshes of tidal influence created an interesting ecosystem with high diversity of macroinvertebrates as well as high biomass productivity. This biological richness explains its use as a natural nursery area for fish coastal communities as alternative to river estuaries. Besides, this area is placed in the route of migratory birds between Europe and Africa. Extensive fish polyculture is an activity that was developed in association to salt works. A typical saltpond property (salina) is formed by a first reservoir pond that takes the water directly from the sea channel throughout a pond-monk, followed by a labyrinth-shaped evaporation ponds system and finally by the crystallisation ponds. The water column in these ponds system is progressively lower from 1-1.5 m in the reservoir to just few centimetres in the crystallisation ponds. The reservoir pond, called “estero”, accounts for almost a third of the total surface and is the place traditionally used for fish farming.

This study has been carried out with the financial support from the Commission of the European Communities, specific RTD programme “Specific Support to Policies”, SP-2005-44483 “SEACASE - Sustainable extensive and semi-intensive coastal aquaculture in Southern Europe”, and does not necessarily reflect the European Commission views and in no way anticipates the Commission’s future policy in this area.

Peer reviewed