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Titolo: An experimental management of the octopus fishery in Sardinia
Data di pubblicazione: 2013
Abstract: In Sardinia, the largest segment (about 80%) within the fleet is represented by small-scale fisheries, whose productivity for the year 2011 was 5056 tons equal to an induced €35,290 m (Irepa , 2012). These are almost all family business small boats that operate primarily with passive gear such as nets, lines, pots and/or traps. The specificity in the use of gears is closely related to the time of year and the depth in which they operate. In particular, the fishery by traps with bait (Carchinus aestuarii) is usually carried out in spring - summer within a depth of 50 metres and brings to catch the common octopus Octopus vulgaris Cuvier , 1797 with a very low by-catch (Cuccu et al., 1999). Among the Italian regions Sardinia is the largest producer of Octopus with 1672 tonnes and € 9,3 m of profitability in 2011 (Irepa, 2012). However, FAO statistics show continuous temporal fluctuations of the octopus landed on the island, particularly in the last decade; in fact the production has gone from 3400 t in 2001 to 1586 in 2010. This negative trend reflects the more general decline that has been registered worldwide for this species ( FAO, 2006 , 2013). Despite the lack of Italian measures to regulate the fishery of O.vulgaris, the Autonomous Region of Sardinia has put in place some regulations fixing the minimum landing size (300 g) and limiting the number of traps (i.e. Decree n° 22 of 17/07/2002). Regional annual fishing bans, were decreed with differences in the timetable according to the different maritime districts to protect the recruitment (Decrees n° A/68 2067 of 29/08/2008 and n° A/87 2067 of 08/09/2009). In the absence of fishing bans, despite the regulation of the minimum size, starting at the end of the summer in conjunction with the bulk of recruitment (Cuccu et al., 1999) the capture and illegal marketing of undersized octopuses (<300 g) can represent a problem. Only a few fishermen under their own decision, stop the trap fishery and divert towards other artisanal activities. In the belief that the problem of octopus fishery should be addressed at national level taking into account the socio-economic and bio-ecological aspects, we report an experimental management that fishermen and researchers have carried out in a maritime district of central western Sardinia. This experience is based on the annual monitoring of the commercial octopus fishery by traps. Small specimens are, tagged and realised in a restricted sea area where the fishery has been temporary banned. Moreover on the ground of this area some artificial dens have been laid as shelter and for the spawning. The recapture of tagged specimens inside the area of release and near it suggest that saving the youngest octopuses from the trade could be a guarantee for the fishery in the following year, in agreement with the validity of a regulation on the minimum commercial size. At the same time the observation of spawning females inside the artificial dens confirms the effectiveness of this experiment to create spawning area. However other results like the different sizes at maturity in the two genders (Cuccu et al., 2013) and also the possible temporal skidding of the recruitment among the years, show the need of flexible regulations to be determined on the base of an annual monitoring at local level in close cooperation with the fishermen
Tipologia:4.2 Abstract in Atti di convegno

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