T-bar anchor tags and Petersen discs were used during a preliminary
mark–recapture experiment in the wild on 268 Octopus vulgaris.
Discs, despite causing some injuries, were characterized by a
quicker healing (within 5 days) and a higher retention rate than T-bar
tags (about 97% versus 22%, respectively), therefore they were considered
the best technique for tagging the animals in the subsequent growth
studies. From 2010 to 2013, a total of 1604 O. vulgaris
(74.4% with a total weight <300 g) were tagged with discs and
released in an area of the central western Sardinian Sea (western
Mediterranean Sea). Ninety-one specimens were recaptured after 4–63 days
of freedom, 59 of which (31 males and 28 females) showed positive growth
increments after a minimum time of 8 days at liberty. In general, a high
individual variability (0.96–9.09 g day−1) and higher mean
daily growth rates in females (3.07–3.65 g day−1) than in
males (2.08–2.98 g day−1) were recorded, but this difference
was not statistically significant. Using tag–recapture data, the first
exponential growth curves for both sexes of Octopus vulgaris
of small–medium size from the Mediterranean Sea were obtained,
and compared with those available in the literature for the
species.