Data: 2014-10-15 02:00 PM
Orador/Formador: Ver programa
Local: IPMA Algés Lisboa
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Contacto telefónico: 213027000
The commercial landings of the common octopus Octopus vulgaris in Portugal increased 50% in the last 20 years. Our data show that this increase has been associated with the increasing importance of the common octopus as revenue guaranty in non-octopus targeting fisheries. The species shows large fluctuations in landings that can reach up to 50 % between consecutive years in some landing ports. The common octopus is a short-living semelparous species with a recruitment to fisheries almost entirely dependent of the pre-settlement environmental conditions. Studies made in the golf of Cadiz and in leeward Algarve, in the south Atlantic Iberian coast reveal that increasing rainfall and extreme sea surface temperature values on early life stages affect landings. However, the environmental conditions in the Portuguese northwest coast are different from those of the south coast. In the northwest coast, the oceanographic conditions are highly dynamic, influenced by a strong seasonal upwelling in spring-summer and strong northwesterly winds during autumn-winter, associated to important estuarine systems that contribute largely to the freshwater input on the coastal systems. Here we investigate how the environmental parameters associated with upwelling conditions, and freshwater input affect the abundance of the common octopus on the Portuguese northwest coast. Dynamic factor analyses of a monthly abundance index are applied on a seven years time series, using sea surface temperature, rainfall, river runoff, and an upwelling index as explanatory variables.