Preprint volume - SIBM

Pre-print Volume - Posters
BENTHOS COMMITEE
M. MEREU, P. MASALA, A. MACCIONI, D. STACCA, AL. CAU, D. CUCCU
Department of Animal Biology and Ecology, University of Cagliari, Via T. Fiorelli, 1 – 09126 Cagliari, Italia.
cuccu@unica.it
TAGGING OCTOPUS VULGARIS (OCTOPODA: OCTOPODIDAE)
IN AN AREA OF CENTRAL WESTERN SARDINIAN WATERS
MARCATURA DI OCTOPUS VULGARIS (OCTOPODA: OCTOPODIDAE)
IN UN’AREA DELLA SARDEGNA CENTRO OCCIDENTALE
Abstract – Preliminary data on growth and movements of Octopus vulgaris wild populations of the
Mediterranean Sea recorded during a tagging program in the central western Sardinian waters were
reported and compared with literature.
Key-words: Octopus vulgaris, tagging, growth, movements, Mediterranean Sea.
Introduction - Octopus vulgaris Cuvier, 1797 has a world-wide distribution in
tropical, subtropical and temperate waters of the Atlantic, Indian, Pacific oceans and
Mediterranean Sea (Guerra, 1992). It inhabits continental shelf and slope waters,
occupying diverse habitats (Guerra, 1992). Age and growth of O. vulgaris were studied
using indirect or direct methods (Semmens et al., 2004). In particular, within direct
methods, mark-recapture experiments in wild represented useful tools to estimate age,
growth, and lifespan and also to obtain information on the movements of the species
(e.g. Domain et al., 2000; Nagasawa et al., 1993). Taking into account this, for the first
time in Mediterranean an experimental tagging program for O. vulgaris was performed
in the central western Sardinian waters. In this note, preliminary results on growth and
movements of O. vulgaris were reported.
Materials and methods - Octopus vulgaris specimens caught from May to October
2009 by crab-traps off the central western Sardinia coast at depth of 20 to 40 m were
tagged with Petersen discs on 3 rd left arm and release into the same fishing areas. For
each specimen dorsal mantle length (ML, to the nearest mm), total weight (TW, to the
nearest g) and sex were recorded before release and after recapture. Maturity stage was
determined in the recaptures, using for both sexes, the scale of Silva et al. (2002)
modified (1, immature; 2, maturing; 3, mature; 4, spawning; 5, post-spawning).
Geographical positions of release and recapture were recorded and the straight distance
between release and recapture was calculated. Interval of freedom (DF, in days) and
specific growth rates (SGR) according to Domain et al. (2000) were also determined.
Results - On the whole 132 males (ML: 32.0-130.0 mm; TW: 30-1400 g), 137 females
(ML: 32.0-145.0 mm; TW: 30-1230g) and 16 undetermined (ML: 18.0-64.0 mm; TW:
20-350 g) of Octopus vulgaris were tagged. Overall, 9 octopuses tagged were
recaptured by traps and 2 tags were found attached in a trammel net for lobster fishing,
both during the commercial fishery (Tab. 1). Four SGR positive values were recorded
for octopuses recaptured after 8-25 days. As shown in Table 1 the remaining 5
recaptures (DF: 18-30) had null or negative SGR-values. The straight distance between
release to recapture ranged from 411 to 1200 meters for males and was 20 meters for
the only female recovered.
41 st S.I.B.M. CONGRESS Rapallo (GE), 7-11 June 2010
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