Study on the Spread of Procambarus clarkii at Gharb (Morocco) and Its Impact on Rice Growing

The red swamp crayfish (Procambarus clarkii) is a species from the northeast of Mexico and the central south of the United States (Louisiana), actually is the dominant macroinvertebrate in several countries. It was introduced to several countries, generally for gastronomic reasons or to repopulate destroyed areas by a disease. While the first introduction of this species into the world is well-documented, little is known about its pathways of invasion and the reason for its rapid spread in several countries. P. clarkii is an aggressive crustacean that multiplies very fast and adapts to features of the invaded location. Adults of the species can disperse up to 1.6 km on land. Also, they dig deep holes which allows them to establish easily in wetlands and adjacent waterbodies that are hydrologically disconnected. This study takes place in the Gharb area (northwestern of Morocco) where several carcasses of P. clarkii have been found in different places. In the present study, it is a question of understanding how this species was introduced in this area, to establish a map of propagation of the species, and to evaluate the damage that it would have caused in the rice growing of Gharb. In Morocco, it was first sighted in the Gharb area in 2008 in the commune of Sidi Allal Tazi. Following this discovery, possible ways of the species introduction and the dispersal modes were explored that P. clarkii could use to invade the Gharb area. The results of this study can be used by natural resource managers, rice farmers, fishermen and the local population, to help them to locate the spread of P. clarkii, to identify vectors that move P. clarkii across political boundaries and illustrate the importance of limiting and prohibiting the movement of this invasive species across boundaries or into new ecosystems.