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The bathymetric distribution and relative abundance of cephalopods from the northern Tyrrhenian Sea have been investigated. The specimens were collected during six trawl surveys carried out from 1985 to 1987, between the isles of Elba and... more
The bathymetric distribution and relative abundance of cephalopods from the northern Tyrrhenian Sea have been investigated. The specimens were collected during six trawl surveys carried out from 1985 to 1987, between the isles of Elba and Giannutri. Cephalopods represented 9-17% of the total commercial catches. The depth of the catches ranged from 4 m to 635 m. The average catch per hour of the commercial species has been analysed. Eledone cirrhosa represents the most abundant species. Some observations on the biology of the most frequent species are given
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The presence of the deep-sea cirrate octopod Opisthoteuthis calypso Villanueva, Collins, Sanchez & Voss, 2002, a recently described species, is reported for the northern Tyrrhenian Sea (western Mediterranean). The catch was obtained... more
The presence of the deep-sea cirrate octopod Opisthoteuthis calypso Villanueva, Collins, Sanchez & Voss, 2002, a recently described species, is reported for the northern Tyrrhenian Sea (western Mediterranean). The catch was obtained during an experimental haul, on a muddy bottom at 710 m of depth. Morphometric and meristic parameters of the four specimens caught, two males and two females, fully agree with the diag- nostic characters of the species. The two males (DML 33 and 54 mm respectively) were sexually mature, with several spermatophores in the seminal vesicle; the two females (DML 29 and 30 mm respectively) were in maturation, without any oocytes in the distal oviduct and in the oviducal gland. The ovarian oocyte size distributions confirm for this species a continuous-spawning reproductive pattern, in contrast to the semel- parity shown by the majority of incirrate octopods; the stomach contents analysis highlights that predation, based on hyperbenthic crustacean prey, mainl...
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Risso's dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this study was to gain further insight... more
Risso's dolphins, pilot whales and sperm whales rarely strand in the northwestern Mediterranean. Thus, their feeding ecology, through the analysis of stomach contents, is poorly known. The aim of this study was to gain further insight into the segregation/superposition of the diet and habitat of Risso's dolphins, pilot whales and sperm whales using chemical tracers, namely, stable isotopes (δ(13)C, δ(15)N) and organochlorines. Significantly different δ(15)N values were obtained in Risso's dolphins (11.7±0.7‰), sperm whales (10.8±0.3‰) and pilot whales (9.8±0.3‰), revealing different trophic levels. These differences are presumably due to various proportions of Histioteuthidae cephalopods in each toothed whale's diet. Similar δ(13)C contents between species indicated long-term habitat superposition or corroborated important seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 μg.g(-1) lw) and higher tDDT/tPCB ratios (0.93 vs. 0.42) were observed in s...
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... alcuni parametri strutturali della comunità: numero di specie (S), indice di ricchezza specifica (d) di Margalef, indice di equitabilità (J') di Pielou e indi-ce di diversità specifica (H') diShannon-Wiener. ... [9]... more
... alcuni parametri strutturali della comunità: numero di specie (S), indice di ricchezza specifica (d) di Margalef, indice di equitabilità (J') di Pielou e indi-ce di diversità specifica (H') diShannon-Wiener. ... [9] B. Reale, P. Sartor, A. Ligas, C. Viva, D. Ber-tolini, S. De Ranieri, P. Belcari ...
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SUMMARY: A four-year time series (1994-1997) of groundfish trawl surveys performed within the European Union Project “MEDITS ” (Mediterranean International Trawl Surveys), was analysed to identify and describe the fish assemblages along... more
SUMMARY: A four-year time series (1994-1997) of groundfish trawl surveys performed within the European Union Project “MEDITS ” (Mediterranean International Trawl Surveys), was analysed to identify and describe the fish assemblages along the continental shelf and slope of Tuscany and Latium (Italy), in the north-western Mediterranean. Cluster analysis was used to group samples with similar species composition in terms of abundance, biomass and frequency of occurrence. Results allowed the identification of four to five broad assemblages along the depth gradient: a strictly coastal group (< 50 m depth), two groups in the upper and lower part of the continental shelf (essentially 50-200 m), an epibathyal group (200-450 m) and a group derived from hauls made at depths greater than 450 m. Each assemblage corresponded to a faunistic association with relatively homogeneous and persistent species composition, biomass and density indices. Key words: assemblages, cluster analysis, demersal ...
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... Graham J. Pierce 1 , Paola Belcari, Paco Bustamante, Laurence Challier, Yves Cherel 2 , Angel Gonzales, Angel Guerra, Patrizia Jereb ... M. Begoña Santos, Marina Santurtun, Sonia Seixas, Paul Shaw, Jennifer Smith, Gabrielle Stowasser,... more
... Graham J. Pierce 1 , Paola Belcari, Paco Bustamante, Laurence Challier, Yves Cherel 2 , Angel Gonzales, Angel Guerra, Patrizia Jereb ... M. Begoña Santos, Marina Santurtun, Sonia Seixas, Paul Shaw, Jennifer Smith, Gabrielle Stowasser, Vasilis Valavanis, Roger Villanueva 4 ...
The fauna of the Mediterranean basin is characterised by a high biodiversity, i.e. by a high number of species, some endemic to the area, some with a wider geographical distribution and others recently immigrating into the Mediterranean... more
The fauna of the Mediterranean basin is characterised by a high biodiversity, i.e. by a high number of species, some endemic to the area, some with a wider geographical distribution and others recently immigrating into the Mediterranean waters (Maurin, 1962; Tortonese, 1987; Fredj et al., 1992). This aspect is mainly due to the geological evolution of the basin and to its ecological and climatic features. The existence of such biological diversity certainly contributes to the health of the Mediterranean fisheries. Classical stock assessment tools indicate in most cases a general state of overexploitation and overcapacity of the fishing fleets (Caddy and Sharp, 1986). However, monospecific approaches are usually the rule. In the last 15 years there has been a growing perception that it is often ineffective to base fisheries management policies exclusively on single species approaches. High levels of variability in productivity, in abundance, in size and species composition, are not p...
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Exploitation patterns of the cuttlefish Sepia officinalis in the Mediterranean Sea were studied by investigating the fishing activity in three ports located in the Catalan (Spain), Ligurian (Italy) and Thracian (Greece) Seas. Monthly... more
Exploitation patterns of the cuttlefish Sepia officinalis in the Mediterranean Sea were studied by investigating the fishing activity in three ports located in the Catalan (Spain), Ligurian (Italy) and Thracian (Greece) Seas. Monthly collection of data on commercial landings, fishing effort and demographic structure of the catches of S. officinalis was undertaken between July 1998 and June 1999. S. officinalis was exploited simultaneously or sequentially by different gears, whose importance changed in each port. Bottom trawling accounted for the majority of the landings at all ports, followed by the medium size trammel nets. Traps played an important role in the cuttlefish landings in the Catalan Sea, while beach seines and small size trammel nets contributed to a minor part of the landings of Kavala and Livorno, respectively. A marked seasonality in the landings of different gears was observed. Trammel net and trap landings comprised mostly adult specimens of large size, while traw...