46 JUNE 2019 • WORLD AQUACULTURE • WWW.WAS.ORG by LSU, the University of Lund or the Tetrapack laboratory. Signal crayfish are the inhabitants of waters of the river basins of Europe. The remarkable decrease of endemic crayfish in Spain was due to the change of agricultural implements, specifically the use of machinery in the fields, and from imports of the noble crayfish made from 1960 to 1965 from Germany. The crayfish from Louisiana was introduced to end the rice monoculture and make better use of pumped water, amortize the construction of paddy fields and take advantage of the energy cost realized and paid by the landlords. Around 1975, fishermen of Isla Mayor activated their eel nets without any bait as in the country of their origin and placed them with the openings against the current. With their bicycles they crossed the long stretches of canals and captured crayfish. They delivered their live capture to the few processing centers, transforming the product into merchandise. As yields of harvested crayfish increased from the rice-growing region of Andalucía, these animals were shipped to consuming markets within Spain. With remarkable speed, this new Spanish crayfish source effectively changed the trade deficit to one of Spain becoming a new exporter to France. By 1982, Spain was not only self-sufficient as an internal crayfish producer but began a profitable business of shipping surplus crayfish to French markets. This kept Spanish money at home and brought foreign capital into the economy. The situation in the country had changed; it was no longer the good of the country but the interests of politicians. A discussion had arisen between the rice farmers and the fishermen. Rice farmers paid the energy costs and the fishermen made a profit with their effort. There was no judicial or political decision on the difference in the criteria. There was a legal vacuum and animals were not considered patentable. The Supreme Court decided that it was “public water in private channels” and the animals that live in the water have no owner. It is interesting how such a small individual animal would arouse so much interest in written publications. There are about 7,500 works and articles in the press and on the Internet branded with the management of the crayfish from the Marismas and the Californian or signal crayfish Pacifastacus leniusculus as the culprit of decimation of the European species. When syphilis arrived in Europe, it was always referred to with reference to the enemy country: in Spain it was the French disease, in Germany the Italian disease, in Italy the Spanish disease. We call the fungi “crayfish plague” as though the animal is guilty of the zoospore brought from America into Europe in 1850. Among the many published studies there are three that express some hope of a resistance of some individuals of European species, or, the fungus itself has permuted. Now we speak of an As strain and a PsI strain of the genotype of the fungus, the PsI variety being more deadly than the As variety. But all the studies confirm until now the non-coexistence of fungus with the European species of crayfish. But more surprising are the studies carried out by the University of Geneva that ask: are non-native species also an enrichment of biodiversity such as peanuts, corn, potatoes, sunflower, and cacao? A non-native species can provide a valuable food source for other organisms. Non-native species can fill a role in areas where it reaches a point of no return of a native species susceptible to an epidemic invader. Non-native species like the American species of crayfish can be a catalyst for restoration of Astacus astacus and other European species. Non-native species can reestablish a native species or substitute an existing ecosystem engineer like the bottom cleaner crayfish. Procambarus clarkii has the approval of the directors of the wildlife reserve of Doñana because the crustacean supports 89 percent of the fauna that lives there thanks to the presence of the crayfish de la Marismas. But here we do not talk about species, we talk about people: 70 percent of the population, some 6,000 people, make a living in some form from the crayfish of the Marismas. In addition, the species was introduced in the 1970s by the Central Administration as a measure to support employment in rural areas. I finish with a quote from a book about crayfish in Spain from 78 years ago: We think it is idle to state that Spain has not yet achieved a position in the Yearbook; but we estimate that if it develops with the enthusiasm that seems to be starting, it is not risky to predict that in the not too distant future it will conquer the position it must occupy, with the consequent benefit for the country’s wealth. We have achieved this effort with our ingenuity, work, production, transformation and sale of the crayfishes de las Marismas. LEFT: Procambarus populations were captured with hoop nets in rice irrigation canals, rice fields and flooded areas of Coto Doñana National Park, adjacent to the famous pilgrimage village of El Rocio (pictured). Impacts from fishing activities within park lands were closely monitored by government agencies. RIGHT: Because much of the well-drained private rice-growing region remained unirrigated during the winter, Procambarus fishermen focused on other areas that were undrained and flooded by winter rains adjacent to and in national parkland.
RkJQdWJsaXNoZXIy MjExNDY=