The composition of the catch of the deep sea trawl fleet of Porto Santo Stefano (northern Tyrrhenian Sea, western Mediterranean) was analysed. In the period 199599 observations were carried out on board commercial vessels, collecting data for about 500 trawling hours. Nephrops norvegicus, Parapenaeus longirostris and large specimens of Merluccius merluccius were the targets on the fishing grounds from 300 to 450 m, while Aristaemorpha foliacea, Aristeus antennatus and N. norvegicus were targeted from 450 to 650 m depth.By-catch dominated the biomass caught and it was characterized by a high degree of species richness, as a consequence of the reduced selectivity of the bottom trawl gear. An important fraction of the by-catch was made up of non-target commercial species, these providing an important added value to the landings. There was almost no discarding of target species. Annual average discards were about 20% of the total catch. Discarding of commercial species was mostly due to specimens under commercial size, while discarded non-commercial species included large numbers of small sized species of fishes and crustaceans. The results seem to indicate that this kind of fishery achieves a reasonable compromise between efficiency of resource utilisation and impact on the demersal communities.

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.

Several internal structures have been used to estimate age in the cephalopod Octopus vulgaris, but with limited accuracy. We estimated age by investigating growth increments (rings) in the upper beaks of octopus collected between 2003 and 2010 in the Bay of Naples, Italy (Mediterranean Sea). To validate the daily periodicity of ring deposition, 'thermal shock marking' was for the first time applied to live octopuses fished between 2009 and 2010; this method produced a mark on the beak corresponding to the day of thermal shock, enabling us to elucidate the relationship between ring number and time elapsed (i.e. ~30 d). In addition, rings were counted in > 700 preserved specimens of O. vulgaris collected between 2003 and 2009, also in the Bay of Naples. The estimated age of of these octopuses ranged from about 70 to 370 d. Specimens with similar body weights had different numbers of rings, confirming the view that body size is a not a good index of age. Additionally, the relationship between body weight and number of rings was affected by sex and season, with the distance between rings clearly correlated to seasonal temperature oscillations. Our data suggest that different cohorts of octopus exist in the Bay of Naples and that temperature has a strong influence on growth. Overall the results demonstrate that growth increments in the upper beak of O. vulgaris provide a reliable method of aging that can be applied to assessing differences in the growth patterns in wild populations, and one that provides a record of environmental influences upon an individual. KEY WORDS: Octopus · Age · Thermal marking · Upper beak · Seasonal variability Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 441: 141-149, 2011 142 Age determination in cephalopods has been based on both indirect and direct methods. Indirect methods are not reliable with cephalopods (e.g. Semmens et al. 2004), mainly because growth in any cephalopod species appears to be affected by a series of both biotic and abiotic factors, leading to large individual variability (Mangold 1983, Forsythe & Van Heukelem 1987, Domain et al. 2000, Belcari et al. 2002. As a consequence, body size (weight and dorsal mantle length) is not a reliable indicator of age. For this reason indirect methods require validation by at least one direct method (Krstuloviç Šifner 2008).Among direct methods, one of the most useful means of age estimation in cephalopods is statolith increment analysis. This method has been systematically applied to squids (Arkhipkin & Laptikhovsky 1994, Jackson 1994, Rocha & Guerra 1999, Arkhipkin 2005, Ikeda & Kobayashi 2010 and to cuttlefish (Raya et al. 1994, Bettencourt & Guerra 2001, Challier et al. 2002. Unfortunately, statolith analysis is not useful here as octopus species, including Octopus vulgaris, lack growth rings in this structure (Young 1960, Lombarte et al. 2006). In the case of O. vulgaris, other internal structures have been analysed over the past 20 yr for direct age determination. ...

Information on distribution, abundance and size composition of the common octopus Octopus vulgaris was obtained from the MEDITS trawl surveys, carried out in a wide area of the Mediterranean basin from 1994 to 1999. The species showed a wide geographic distribution, since it was collected in all the major areas investigated, but differences were highlighted among the 40 geographic sectors sampled. O. vulgaris showed a narrow depth distribution, mostly restricted to within 100 m. Catches below 200 m were scarce and occasional at deeper sea bottoms. Further analysis between major areas in the depth strata 10-50 m and 50-100 m showed the Alborán Sea and Sardinian waters as the areas where the abundance of the species was the greatest. Size frequency distributions showed a wide size range, even if large individuals were represented in a very low proportion. The surveys highlighted the relevant presence of small individuals in almost all the analysed areas. Recruits with a modal length of 5-6 cm mantle length constituted the dominant mode in the histograms of a great extent of the Italian coasts and in Morocco and Corsica waters.

a b s t r a c tRisso'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 (d 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 d 13 C contents between species indicated long-term habitat superposition or corroborated important seasonal migrations. Lower congener 180 concentrations (8.20 vs. 21.73 lg.g À1 lw) and higher tDDT/ tPCB ratios (0.93 vs. 0.42) were observed in sperm whales compared with Risso's dolphins and may indicate wider migrations for the former. Therefore, competition between these species seems to depend on different trophic levels and migration patterns.