Researchers at the Technion-Israel Institute of Technology have found that, contrary to the common notion that fish have three-second memories, they can in fact remember things for four or five months. The team - Boaz Zion, Ilan Karplus and Assaf Baraki of the Agricultural Engineering Institute - have even managed to train fish to swim to the source of an audible signal, expecting to find dinner. Thus while their memories may be good, they still aren't very brainy - a combination that could be a boon to fishermen. Fish are commonly raised in cages near protected coasts. This technique is widely used around the world and requires investment in cages, rafts and manpower for supervision, feeding and catching. But it's also controversial, as their excrement pollutes the coastal waters and environment. The Technion researchers tried to find a new application of technology for cultivating fish in the open sea that didn't harm the environment but was still profitable. As Russian Nobel Prize-winning physiologist Ivan Pavlov conditioned dogs to salivate when they heard the ringing of a bell, the Technion trio taught young fish to associate an underwater signal with food. After a month of such conditioning, the fish were then released into the sea. When they were big enough to be marketed, they were called back using the signal, and were then netted. The researchers said the technique offered many advantages, such as reduced environmental impact due to the fish being grown in their natural environment rather than a crammed cage. Feeding would also be much cheaper, as the fish would mostly feed themselves. The work was presented at a recent conference on Land, Environment and Agriculture organized by the Israel Land Science Association and the Israel Association for Agricultural Engineering. Prof. Avi Shaviv, head of the Technion's Environment, Water and Agriculture Unit, said that there had been a revival of interest among young students in the fields of agriculture and water. "This has almost doubled the number of students registering for these fields in the Technion and other universities," he said.