If you were to visit Veta La Palma in southern Spain, you might think you had strayed into a nature reserve. The 113 square kilometre estate with its network of shallow ponds and marshland hosts 250 different species of bird, including spoonbills, egrets and flamingos. But in fact, Veta La Palma is a commercial fish farm - with a difference.
As wild fish stocks decline and concerns grow about the environmental impact of intensive fish farms, there is clearly room for an alternative model of aquaculture. Veta La Palma not only avoids damaging the environment - it actually creates an ideal habitat for a whole range of species, and sees the fish as just one element of the broader ecosystem.
Land which had been drained and used to grow rice has been re-flooded, using the tides and powerful pumps to bring water in from the river and along a network of canals. The fish begin life in the on-site hatchery before being released into the 45 ponds and left to feed on naturally occurring micro-algae and shrimp, which reach the ponds from the estuary through the channel system. The shallow pools and Spanish sunshine create the perfect conditions for algae, the staple food for crustaceans - and they in turn become fish food. No dioxins or antibiotics are used, and to keep the fish healthy they are kept at a low density and are not harvested until they weigh 1kg each - unlike fish from intensive aquaculture, which are kept in crowded conditions and harvested at 250-500g.
The 1,500 tonne annual harvest includes sea bass, sea bream, sole and shrimp. With so many delicious potential meals on offer, it is no wonder Veta La Palma attracts such a vast number of birds - up to 60,000 at a time, many of them threatened species. Some come to nest, others stop off to feed whilst migrating between Africa and Europe.
Around 20 per cent of Veta La Palma's fish stocks are eaten by birds - but this is seen as a small price to pay for their contribution to the island's ecosystem. And there are also tangible benefits to having an abundant bird population - their movement oxygenates the water, and they also act as an indictor for the overall health of the system.
But ultimately this is still a business. The fish harvested here are extremely high-quality, and are sold to gourmet food shops and haute cuisine restaurants in Italy, France, Spain, Portugal, Germany and the US.
Russell Beard meets Miguel Medialdea, Veta La Palma's head biologist, for a tour of this unique aquaculture system.
earthrise airs each week at the following times GMT: Friday: 1930; Saturday: 1430; Sunday: 0430; Monday: 0830.
Click here for more on earthrise.