52 June 2012 Economic fishery from Procambarus introductions into Spain Albert P. Gaudé1 Crayfish consumption by eastern Europeans dates back to antiquity and has an illustrious role in many cultural festivities. Historically, the supply of crayfish into those markets was harvested from local streams, ponds and lakes. With the increased demand for crayfish in modern times, these supplies were increasingly harvested beyond sustainable limits. Surface waters were also impacted by anthropogenic pollution, further reducing the reproductive capacity of crayfish brood stocks. In an effort to satisfy the increased culinary demand and reduced supply, authorized and clandestine introductions of crayfish from various regions of Europe and abroad began to occur. Along with some of these crayfish introductions came the fungal ‘crayfish plague’ Aphanomyces astaci. Believed to have entered during the late 1800s on the northern Mediterranean coast with introductions of the North American species Orconectes, this disease spread throughout north-central Europe and eventually into the eastern Mediterranean crayfish populations of commercially harvested Astacus in the 1980s. With the sequential collapse of traditional European crayfish sources, international trade of crayfish was dynamic. Spain’s 1979 import trade of crayfish from France of 42 t and resultant monetary deficit drew the attention of fishery economists of the post-Franco Spanish government. Between 1965 and 1972, Spanish discussions continued on possible solutions to this crayfish trade deficit. After lengthy evaluations of similar situations, a decision was made in 1972 to introduce the North American crayfish, Procambarus clarkii, into Andalucía, southern Spain (Habsburgo-Lorena 1978). Fishery Development After an initial quarantine period of P. clarkii shipments in Spanish government ponds near Badajoz, actual commercial introductions were made in 1974 into the 30,000 ha rice-field area known as Las Marismas, immediately southwest of urban Seville. As expected, the similarity of the reclaimed tidal area of Las Marismas to the native habitat of P. clarkii allowed for favorable conditions and rapid population growth in rice fields, irrigation canals and streams (Gaudé 1984). The mechanism of P. clarkii range expansion was a combination of natural migration in regional waterways and aggressive stock enhancement at the hands of crayfish harvesting fishermen, who were eager to stock additional water Early Procambarus harvest in Spain was done by simple unbaited eel traps in shallow-water habitats. bodies that could be exploited later for profit. At the onset of the population expansion, additional and unauthorized P. clarkii introductions were made to accelerate this potential fishery. Aside from commercial fishermen, numerous recreational harvesters likewise sought to seed various favorite fishing sites with readily available P. clarkii, either as mature, captured animals, or as juveniles culled from grading at crayfish processing sites. The rapid expansion and explosive population growth of P. clarkii, created by a combination of these factors, developed a harvestable range that spread to areas well outside of the initial stocking site. Populations developed throughout south-central Spain and Portugal within ten years of the Las Marismas stocking event (Gutiérrez et al. 1999). As harvestable stocks increased, so to did the acceptance of Procambarus as a European culinary crayfish. Initially, Procambarus was accepted as a substitute for traditional crayfish, but eventually it dominated consumption as a permanent replacement. By 1981, availability of Spanish Procambarus effectively reversed the crayfish trade deficit between Spain and France, thus fulfilling the government’s stated mission of the crayfish introduction project (Figure 1). Controversy The development of an Iberian Procambarus sector has been embroiled in a deep and often fierce controversy con-
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