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Design, sampling and data interpretation constitute an important challenge for wildlife surveillance of avian influenza viruses (AIV). The aim of this study was to construct a model to improve and enhance identification in both different periods and locations of avian species likely at high risk of contact with AIV in a specific wetland. This study presents an individualbased stochastic model for the Ebre Delta as an example of this appliance. Based on the Monte-Carlo method, the model simulates the dynamics of the spread of AIV among wild birds in a natural park following introduction of an infected bird. Data on wild bird species population, apparent AIV prevalence recorded in wild birds during the period of study, and ecological information on factors such as behaviour, contact rates or patterns of movements of waterfowl were incorporated as inputs of the model. From these inputs, the model predicted those species that would introduce most of AIV in different periods and those species and areas that would be at high risk as a consequence of the spread of these AIV incursions. This method can serve as a complementary tool to previous studies to optimize the allocation of the limited AI surveillance resources in a local complex ecosystem. However, this study indicates that in order to predict the evolution of the spread of AIV at the local scale, there is a need for further research on the identification of host factors involved in the interspecies transmission of AIV

Fa poc, desembre del 2018, es van trobar a la platja del Serradal de Castelló de la Plana restes de cranc blau, Callinectes sapidus Rathbun, 1896. És un primer registre municipal més dels què, en els últims anys, s’han indicat per a diverses poblacions del litoral castellonenc. Aquesta notícia va ser l’espurna que va engegar aquest treball. El cranc blau és un decàpode al·lòcton, originari de la costa occidental de l’Atlàntic, que està en expansió a diverses parts del món i també, en temps recents, a la Mediterrània occidental. Se’l considera una de les 100 espècies amb més potencial invasor a la mar Mediterrània. Els restaurants especialitzats en menjars mariners sovintegen vora mar. I a vora mar els cerquen els comensals quan volen fer un àpat de marisc o peix fresc. Són un bon exemple de cuina de proximitat. Es pot assumir que, quan un restaurador inclou un producte principal en la seua carta, s’acompleixen aquestes dues condicions: que disposa de la matèria prima a prop de casa i que té assegurat el subministrament. A partit d’aquestes premisses, s’ha dissenyat un treball per contrastar, per aquest mètode indirecte, l’expansió del cranc blau, nord enllà i sud ençà, del delta de l’Ebre, on va aparèixer el 2012. S’ha fet una enquesta a 127 restaurants del litoral, de 19 municipis des de Salou fins a Borriana. S’ha preguntant si es té el cranc blau a la carta i, en el seu cas, quin any es va introduir. Les dades obtingudes, tant per any d’introducció com per percentatge de restaurants del municipi que l’han incorporat, mostren com, a partir del focus inicial del delta de l’Ebre, s’ha produït una expansió a tramuntana i a migjorn. Aquesta expansió ha estat molt ràpida i continua creixent. Cada any es van incorporant nous restaurants que ofereixen cranc blau en les seues cartes. L’ús principal que se’n fa és en arrossos (com ara l’arròs melós de cranc blau) o per a l’obtenció de brou que s’incorpora després a altres plats. Les poblacions de cranc blau han de ser molt grans i encara creixents perquè cada any se’n pesca més i a més llocs que l’anterior i, tot i això, no minva la seua expansió. El procés de ràpida introducció en les cartes dels restaurants n’és una mostra evident. Les abundants captures mantenen un preu baix que el fa molt competitiu respecte a d’altres alternatives com ara el llamàntol. Els resultats confirmen que, en aquest moment, l’espècie humana és el principal depredador sobre el cranc blau, a la zona d’influència del delta de l’Ebre. Recently, in December 2018 to be exact, the remains of a blue crab, Callinectes sapidus Rathbun, 1896 were found on the Serradal beach in Castelló de la Plana. It was the first recorded finding in this town but just one of many reported over the last few years from other towns on the coast of Castelló province. This news was the spark that set this work in motion. The blue crab is an oceanic decapod, originating on the western coast of the Atlantic, which is expanding in several parts of the world including, in recent times, the western Mediterranean. It is considered one of the 100 species with the most invasive potential in the Mediterranean Sea. Restaurants specialising in seafood can often be found by the sea and diners looking for fresh seafood or fish seek them out. They are a good example of proximity cuisine. It can be assumed that when a restaurateur lists a principal product on their menu two conditions are met: he has the raw material near hand and that the supply is guaranteed. Based on these assumptions, this research has been designed to indirectly contrast the expansion of the blue crab to the north and south of the Ebre Delta, where it first appeared in 2012. A survey of 127 coastal restaurants in 19 municipalities from Salou to Borriana was carried out. The owners were asked if they had blue crab on their menus and, if so, what year it was introduced. The data obtained, both by year of introduction and by percentage of restaurants in the municipality that have added it to their menus, shows how from the initial focus of the Ebre Delta there has been an expansion both north and south. This expansion has been very rapid and continues to grow. New restaurants are adding blue crab to their menus every year. The primary dishes combine blue crab with rice (such as Honeyed Rice with Blue Crab) or for making broth, which is then added to other dishes. The blue crab population must be very large and, despite record levels of catches by local fisherman, it continues to grow and expand. Their speedy inclusion onto restaurant menus is clear evidence. Such abundant catches keeps the price low and makes it very competitive with respect to alternatives such as the pricier lobster. The results confirm that, at this time, humans are the main predator of the blue crab in and around the Ebre Delta.